yes…but we got fully dry in Nov month & less in Dec month…last year…
I too wish cyclones to form..let it form in Nov end or Dec…
yes thats great rajkmr in nov or dec we get our share
infact Nov/dec cyclones will be strong enough to produce more rain..& the very very imp one…it won’t move away frm us..it will cross either TN or S.AP..
The low pressure area over northwest Bay of Bengal and
neighbourhood persists with associated upper
air cyclonic circulation extending upto midtropospheric levels.
Melting Arctic Permafrost Looms as Major Factor in Warming, Climate Change
Permafrost, which is frozen ground that doesn’t melt during the summer, covers 24 percent of the land in the northern hemisphere. It also stores approximately 1.5 trillion tons of carbon – twice the amount of carbon currently in the atmosphere.
Description: As the anniversary of the September 11, 2001 terrorist attack approaches, a test of the Tribute in Light Memorial illuminates a passing cloud above lower Manhattan. The twin towers of light, made-up of 44 searchlights near Ground Zero, are meant to represent the fallen twin towers of the World Trade Center. Depending on weather conditions, the columns of light can be seen for at least 20 miles around the trade center complex. U.S. Coast Guard
Anticyclone
An anticyclone is a region of high atmospheric pressure relative to the surrounding air, generally thousands of kilometres in diameter and also known as a high or high-pressure system. Anticyclones appear on weather charts as a series of concentric, widely spaced isobars of 1000 mbs and above. The roughly circular closed isobar at its central region indicates the area of highest pressure.
Bubble High Thunderstorms develop as warm, moist air rises turning into rain or hail. As the thunderstorm reaches its mature stage, violent updrafts are noted and precipitation begins. At the onset of precipitation, strong downdrafts develop. Falling precipitation reverses rising air columns by frictional drag and cooling, and the storm eventually begins to dissipate or collapse.
Cloud seeding Cloudseeding is the technique of inducing rain from a cloud, usually by dropping suitable particles into clouds containing supercooled water in an attempt to cause them to dissipate, modify their structure, or alter the intensity of associated phenomena, such as wind speed or hail.
Natural rainfall occurs when supercooled cold water contacts particles of dust, salt or sand forming ice crystals. The ice crystals provide a nucleus (tiny solid or liquid particles, suspended in the atmosphere) around which more water droplets can attach, increasing the size of the droplet, or in colder air snow flakes. When the droplet or snow flake, becomes large enough, it falls as snow or rain.
Dew point (ger: Taupunkt; fr:point de rosée)
or condensation point is the temperature at which a parcel of air must be cooled at constant pressure and humidity mixing ratio until it reaches saturation, and at which condensation of water vapor forms either as dew, cloud droplets, ice crystals, mist or fog.
Nondimensional “unit” of radar reflectivity which represents a logarithmic power ratio (in decibels, or dB) with respect to radar reflectivity factor, Z.
Divergence
The expansion or spreading out of a vector field; usually said of horizontal winds. It is the opposite of convergence. Divergence at upper levels of the atmosphere enhances upward motion, and hence the potential for thunderstorm development (if other factors also are favorable).
Convergence
A contraction of a vector field; the opposite of divergence. Convergence in a horizontal wind field indicates that more air is entering a given area than is leaving at that level. To compensate for the resulting “excess,” vertical motion may result: upward forcing if convergence is at low levels, or downward forcing (subsidence) if convergence is at high levels. Upward forcing from low-level convergence increases the potential for thunderstorm development (when other factors, such as instability, are favorable). Compare with confluence.
Dew Point Depression
The difference in degrees between the air temperature and the dew point.
Dew Point Front
A narrow zone (mesoscale feature) of extremely sharp moisture gradient and little temperature gradient. It separates moist air from dry air. Severe weather can be associated with this front. It is also known as a “dryline” or “dry front”.
DEWP
On a buoy report, the dewpoint temperature taken at the same height as the air temperature measurement.
Convection
Generally, transport of heat and moisture by the movement of a fluid.
In meteorology, the term is used specifically to describe vertical transport of heat and moisture in the atmosphere, especially by updrafts and downdrafts in an unstable atmosphere. The terms “convection” and “thunderstorms” often are used interchangeably, although thunderstorms are only one form of convection. Cbs, towering cumulus clouds, and ACCAS clouds all are visible forms of convection. However, convection is not always made visible by clouds. Convection which occurs without cloud formation is called dry convection, while the visible convection processes referred to above are forms of moist convection.
Convective Clouds
The vertically developed family of clouds are cumulus and cumulonimbus. The height of their bases range from as low as 1,000 feet to a bit more than 10,000 feet. Clouds with extensive vertical development are positive indications of unstable air. Strong upward currents in vertically developed clouds can carry high concentrations of supercooled water to high levels where temperatures are quite cold. Upper portions of these clouds may be composed of water and ice.
Shear
Variation in wind speed (speed shear) and/or direction (directional shear) over a short distance within the atmosphere. Shear usually refers to vertical wind shear, i.e., the change in wind with height, but the term also is used in Doppler radar to describe changes in radial velocity over short horizontal distances.
Shelf Cloud
A low, horizontal wedge-shaped arcus cloud, associated with a thunderstorm gust front (or occasionally with a cold front, even in the absence of thunderstorms). Unlike the roll cloud, the shelf cloud is attached to the base of the parent cloud above it (usually a thunderstorm). Rising cloud motion often can be seen in the leading (outer) part of the shelf cloud, while the underside often appears turbulent, boiling, and wind-torn.
Rame… info like this is actually a sight for sore eyes in the blog… Pretty much all your posts today has actually been informative and interesting compared to the bulletins and imd info which gets copy pasted here! Good Job Rame!
Sky Condition
Used in a forecast to describes the predominant/average sky condition based upon octants (eighths) of the sky covered by opaque (not transparent) clouds.
Sky Condition Cloud Coverage
Clear / Sunny 0/8
Mostly Clear / Mostly Sunny 1/8 to 2/8
Partly Cloudy / Partly Sunny 3/8 to 4/8
Mostly Cloudy / Considerable Cloudiness 5/8 to 7/8
Cloudy 8/8
Fair (mainly for night) Less than 4/10 opaque clouds, no precipitation, no extremes of
visibility/temperature/wind
Squall
A strong wind characterized by a sudden onset in which the wind speed increases at least 16 knots and is sustained at 22 knots or more for at least one minute. 2. In nautical use, a severe local storm considered as a whole, that is, winds and cloud mass and (if any) precipitation, thunder and lightning.
Squall Line
A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorms.
Supercell
Short reference to Supercell Thunderstorm; potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours.
Supercell Thunderstorm
Potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours. Supercells usually move to the right of the mean wind. These are called “Right Movers” and they are favored with veering winds. Occasionally, these thunderstorms will move to the left of the mean wind. These thunderstorms are called “Left Movers”. These supercells typically don’t last as long as their “Right Mover” cousins and they usually only produce large hail (greater than 3/4 inch in diameter) and severe wind gusts in the excess of 58 miles an hour. Left Movers are favored when you have backing winds.
Radar will observe essentially one long-lived cell, but small perturbations to the cell structure may be evident. The stronger the updraft, the better the chance that the supercell will produce severe (hail greater than 3/4 inch in diameter, wind gusts greater than 58 miles an hour, and possibly a tornado) weather.
Severe supercell development is most likely in an environment possessing great buoyancy (CAPE) and large vertical wind shear. A Bulk Richardson Number of between 15 and 35 favor supercell development. Typically, the hodograph will look like a horse shoe. This is due to the wind speed increasing rapidly with height and the wind direction either veering or backing rapidly with height.
KT
(Knot)- Unit of speed used in navigation, equal to 1 nautical mile (the length of 1 minute latitude) per hour or about 1.15 statue miles per hour, or 0.5 meters/sec).
Let’s hope that whatever is gonna strike WB/Orissa should not go past tropical storm intensity. Tropical storms are fine, but if it becomes severe, chances of a good NEM will end even before the NEM starts 😐
it is assumed prediction, and if there is a system and if it moves towards north, it is going to be an NEM failure in 2013.
Sea Breeze Front
The leading edge of a sea breeze, whose passage is often accompanied by showers, a wind shift, or a sudden drop in temperature.
Sea Level Pressure
The sea level pressure is the atmospheric pressure at sea level at a given location. When observed at a reporting station that is not at sea level (nearly all stations), it is a correction of the station pressure to sea level. This correction takes into account the standard variation of pressure with height and the influence of temperature variations with height on the pressure. The temperature used in the sea level correction is a twelve hour mean, eliminating diurnal effects. Once calculated, horizontal variations of sea level pressure may be compared for location of high and low pressure areas and fronts.
Sea Surface Temperatures
The term refers to the mean temperature of the ocean in the upper few meters.
Barogram
An analog record of pressure produced by a barograph
Barograph
A barometer that records its observations continuously.
Barometer
An instrument that measures atmospheric pressure.
Barometric Pressure
The pressure of the atmosphere as indicated by a barometer.
Base Reflectivity
One of the three fundamental quantities (along with base [radial] velocity and spectrum width) that a Doppler radar measures. Reflectivity is related to the power, or intensity, of the reflected radiation that is sensed by the radar antenna. Base reflectivity is expressed on a logarithmic scale in units called dBZ. The term “base” refers to the product being “basic”, with little advanced processing performed on the data. Base reflectivity is related to rainfall intensity (e.g., drop size and rainfall rate) and hail size (for large values of reflectivity).
Beaufort Scale
The Beaufort wind scale is a system used to estimate and report wind speeds when no measuring apparatus is available. It was invented in the early 19th Century by Admiral Sir Francis Beaufort of the British Navy as a way to interpret winds from conditions at sea. Since that time, the scale has been modernized for effects on land.
Beaufort Force 0 – Wind less than 1 kt, Calm, Sea surface smooth and mirror-like. Smoke rises vertically.
Beaufort Force 1 – Wind 1-3 kt, Light Air, Scaly ripples, no foam crests. Smoke drift indicates wind direction, still wind vanes.
Beaufort Force 2 – Wind 4-6 kt, Light Breeze, Small wavelets, crests glassy, no breaking waves. Wind felt on face, leaves rustle, vanes begin to move.
Beaufort Force 3 – Wind 7-10 kt, Gentle Breeze, Large wavelets, crests begin to break, scattered whitecaps. Leaves and small twigs constantly moving, light flags extended.
Beaufort Force 4 – Winds 11-16 kt, Moderate Breeze, Small waves 1 -4 ft. becoming longer, numerous whitecaps. Dust, leaves, and loose paper lifted, small tree branches move.
Beaufort Force 5 – Winds 17-21 kt, Fresh Breeze, Moderate waves 4 -8 ft taking longer form, many whitecaps, some spray. Small trees in leaf begin to sway.
Beaufort Force 6 – Winds 22-27 kt, Strong Breeze, Larger waves 8 -13 ft, whitecaps common, more spray. Larger tree branches moving, whistling in wires.
Beaufort Force 7 – Winds 28-33 kt, Near Gale, Sea heaps up, waves 13 -20 ft, white foam streaks off breakers. Whole trees moving, resistance felt walking against wind.
Beaufort Force 8 – Winds 34-40 kt Gale, Moderately high (13 -20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks. Whole trees in motion, resistance felt walking against wind.
Beaufort Force 9 – Winds 41-47 kt, Strong Gale, High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility. Slight structural damage occurs, slate blows off roofs.
Beaufort Force 10 – Winds 48-55 kt, Storm, Very high waves (20 -30 ft) with overhanging crests, sea white densely blown foam, heavy rolling, lowered visibility. Seldom experienced on land, trees broken or uprooted, “considerable structural damage”.
Beaufort Force 11 – Winds 56-63 kt, Violent Storm, Exceptionally high (30 -45 ft) waves, foam patches cover sea, visibility more reduced.
Beaufort Force 12 -Winds 64+ kt, Hurricane, Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced.
Blizzard
(abbrev. BLZD)- A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer:
Sustained wind or frequent gusts to 35 miles an hour or greater; and
Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than ¼ mile)
Hail Size
Typically refers to the diameter of the hailstones. Warnings and reports may report hail size through comparisons with real-world objects that correspond to certain diameters:
Description | Diameter (inches)
Pea | 0.25
Marble or Mothball | 0.50
Penny or Dime | 0.75
Nickel | 0.88
Quarter | 1.00
Half Dollar | 1.25
Walnut or Ping Pong Ball | 1.50
Golfball | 1.75
Hen’s Egg | 2.00
Tennis Ball | 2.50
Baseball | 2.75
Tea Cup | 3.00
Grapefruit | 4.00
Softball | 4.50
RADAR
Acronym for RAdio Detection And Ranging; a radio device or system for locating an object by means of ultrahigh-frequency radio waves reflected from the object and received, observed, and analyzed by the receiving part of the device in such a way that characteristics (as distance and direction) of the object may be determined.
Radar Range
Distance from the radar antenna. The WSR-88D radar has a range for velocity products out to 124 nautical miles and reflectivity products out to 248 nautical miles.
Radar Reflectivity
The sum of all backscattering cross-sections (e.g., precipitation particles) in a pulse resolution volume divided by that volume. The radar reflectivity can be related to the radar reflectivity factor through the dielectric constant term |K|^2, and the radar wavelength.
Radar Reflectivity Factor (z)
z = the sum (over i) of (N_i * D_i^6), where N_i is the number of drops of diameter D_i in a pulse resolution volume. Note that z may be expressed in linear or logarithmic units. The radar reflectivity factor is simply a more meteorologically meaningful way of expressing the radar reflectivity.
Those logging in today are virtually assured of understanding the various complex weather terminologies commonly discussed by weather experts..Though these terms and terminologies are readily available in various weather related web pages,it becomes imperative for us to go through and refresh ourselves time and again..Keeping this in mind,RameshSquall has been posting some important notes on the terminologies used..Informative to all and sundry,,Kea can have a separate page on weather terminologies commonly used for easy reference..Bloggers would benefit a lot..This could be added to Data pages of Pradeep, Kar etc.. Good job Rame…Ensure the posts are not lengthy ones..That’s it..
I will once again not miss the opportunity to suggest. . Separate page for bulletins, nowcast, farmer’s bulletin etc..
People coming to blog should see originality. .especially new folks will run away if they keep seeing imd updates here which is easily accessible anyway and is child’s play
Relative Humidity
A dimensionless ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature. As such, relative humidity by itself does not directly indicate the actual amount of atmospheric moisture present. See dew point.
Relative Vorticity
The sum of the rotation of an air parcel about the axis of the pressure system and the rotation of the parcel about its own axis.
KeaWeather Archives 
Hi frnds…
Good Morning…Let us welcome the NEM 2013…NEM Month begins…
we should have a special NEM
i too hope…we need only LPA’s in Oct/Nov….we will get our share…
cyclones will spoil our play…like last year NILAM..
y cyclone gave heavy rain
yes…but we got fully dry in Nov month & less in Dec month…last year…
I too wish cyclones to form..let it form in Nov end or Dec…
yes thats great rajkmr in nov or dec we get our share
infact Nov/dec cyclones will be strong enough to produce more rain..& the very very imp one…it won’t move away frm us..it will cross either TN or S.AP..
we should hope this year strong cyclone possible
Accu predicts NE winds from Oct 14th..
http://www.accuweather.com/en/in/chennai/206671/daily-weather-forecast/206671?day=14
But widespread rain from Oct 26th only…
rajkmr who is the winner month contest
i don’t know correctly for all places…admin has to finalize the report…
but for Nunga…it may be Pj or Raijin…
Paul… Nov/Dec cyclones are powerful…
Memories of Thane…that was an powerful storm…just uploading the images…
Nisha..
ya very powerful cyclone hope this year to happen
Thane has brought me to this blog
yes, we are nearing that season
More rain predicted for Chennai this week-In Tamil Nadu, the monsoon activity is expected to revive next week before the end of the season. This week, the State is expected to get rainfall of 1 mm daily as against its daily quota of 4-5 mm, he said.
http://www.thehindu.com/todays-paper/tp-national/tp-tamilnadu/more-rain-predicted-for-chennai-this-week/article5188153.ece
Great news,
but more rains expected during weekend.
Good Morning bloggers
Good morning folks
NEM season has begun 🙂
welcome nem
Climatalogically ,nem hasn’t begun… Ha ha
why?
Good Morning All,
NEM season has begun
Good morning
partha sir most model says heavy rain on 9th and 10th
That’s too long Paul
http://chennaibulletin.com/live-weather/doppler-radar-products/
reason for pasting this link here? imd homepage itself is down since yesterday..where is this chennaibulletin page gonna work?
yes, but i did not see this. i thought it will work.
Top 10 rainfall statistics from 01st June to 30th September
http://tamilnaduweatherman.blogspot.in/2013/07/tamil-nadu-top-10-rainfall-in-this-swm_31.html
partha sir cyclone possible i think so most model says heavy rain on 9th and 10th
Preliminary Rainfall in and around Chennai Region
in mm ending 8.30 am on 01.10.2013
Korattur Anicut – 15
Meenambakkam – 12
Chembarabakkam Lake – 10
Katupakkam – 9
Poonamalle – 7
Poondi Lake – 6
Avadi – 5
Tiruvallur – 5
Taramani – 5
Vellore – 5
Redhills – 3
Guindy – 3
Puzhal – 3
Katpadi – 3
Madhavaram – 3
Nungambakkam – 2
this is calculate to NEM account
Latest SST
Tropical storm crossing thailand
http://www.tmd.go.th/en/storm_tracking.php?id=125
the system is going to cross Orissa / WB and our NEM is going to be delayed to this month end
Current position of LPA
upper wind at 850HPA
Wind direction starting to change in south chine sea on 08th October.
IMD totally down.
Yes indeed 😆
System developing in bay on 11th, moving north towards WB on 14th.
The chief amounts of rainfall (2
cm or more) recorded at 1730 hours IST of yesterday were:
Dharamshala6; Barmer5; Bhira and Jagdalpur4
each; Cannur and Agumbe3 each and Meerut,
Baharampur, Cherrapunji, Bhubaneshwar and
Chandbali2 each.
31.9 high till now in nunga as recorded at 9.30am in imd
The upper air cyclonic circulation over southeast Rajasthan &
neighbourhood extending upto 3.6 Km
above mean sea level persists
The low pressure area over northwest Bay of Bengal and
neighbourhood persists with associated upper
air cyclonic circulation extending upto midtropospheric levels.
As i said earlier after 05th or 06th October, SWM will withdraw from north india and some parts of central india.
RADAR working now
http://chennaibulletin.com/live-weather/doppler-radar-products/
Once again NW india becoming dry.
ramanan says nem starts next week. is it true
where he said?
http://www.maalaimalar.com/2013/10/01100342/next-week-north-east-monsoon-s.html
Odisha Rains
Stations MM
NAWARANGAPUR 65
G.UDAYAGIRI-AGRO 62
JHARSUGUDA 60
RANITAL-AGRO 55
KORAPUT 49
MAHISAPAT 43
KHURDAH 38
PURI 33
NAYAGARH 29
BHUBANESWAR_AGRO 29
NAWAPARA 19
KENDRAPARA 6
PARALAKHEMUNDI 3
JAGATSINGHPUR 2
CUTTACK 2
Next 5 days forecast for Chennai city – 14MM possible?
http://202.54.31.51/gfs_city_fc/
only 14mm.oh oh
This link is as good as the farmer’s bulletin
Chattisgarh Rains in MM
KORBA 48
MAHASAMUND 24
RAIPUR_AGRO 7
DANTEWARA 2
AMBIKAPUR 1
KAWARDHA 1
sunny at the moment
The GFS is showing the weak system close to Orissa / West Bengal on 17th
Will NEM be affected ??
Surely NEM onset would be affected, the moisture creation would go for a toss
oh no nem onset delay
Rain in West Bengal in MM
SAGAR_ISLAND 124
KOLKATA 59
KHARAGPUR_AGRO 43
CANNING 40
TAMLUK 35
BARUIPUR_AGRO 23
BASIRHAT 18
SURI 16
KALYANI_AGRO 12
BURDWAN 10
KRISHNAGAR 8
RAIGANJ 6
ULUBERIA 1
Hiiii Partha sir is the cyclone is confirmed
No, lets wait, but if cyclone forms, it is not good for NEM.
Why it will nt good for nem
which cyclone ?
Cyclone over bay in second week of october
Good afternoon to all bloggers
IMD site is working now
it is working
hi rame1975
Tropical Depression Sepat
Last Updated: 10/1/2013, 5:30:00 AM (India Standard Time)
Wind: 55 KPH
Location: 29.0N 218.3E
Movement: NW
track forecast
Read more at http://www.wunderground.com/hurricane/western-pacific/2013/Tropical-Depression-Sepat#z1ddwHLTw60JZY1s.99
Tropical Storm Fitow
Last Updated: 10/1/2013, 11:30:00 PM (India Standard Time)
Wind: 75 KPH
Location: 14.1N 227.9E
Movement: NW
track forecast
Japan will get smashing rains.
What Is a Haboob?
Haboobs are dust storms caused by strong winds flowing downward and outward from thunderstorms.
Read more at http://www.wunderground.com/news/what-haboob-20130927#85T7y0e5V960FL38.99
Nice picture to explain a layman.
THANKS PARTHA
Melting Arctic Permafrost Looms as Major Factor in Warming, Climate Change
Permafrost, which is frozen ground that doesn’t melt during the summer, covers 24 percent of the land in the northern hemisphere. It also stores approximately 1.5 trillion tons of carbon – twice the amount of carbon currently in the atmosphere.
Read more at http://www.wunderground.com/news/melting-arctic-permafrost-looms-major-factor-warming-climate-change-20130927#lEXD3UZ2QXRpa9Su.99
Supercell over Florida Bay
Sometimes You Get Lucky
♦ The feeble offshore trough from Karnataka coast to Kerala coast persists.
Any idea about temp of NUnga and Meena now ?
around 33C i think
The clouds seem to speak
Description: As the anniversary of the September 11, 2001 terrorist attack approaches, a test of the Tribute in Light Memorial illuminates a passing cloud above lower Manhattan. The twin towers of light, made-up of 44 searchlights near Ground Zero, are meant to represent the fallen twin towers of the World Trade Center. Depending on weather conditions, the columns of light can be seen for at least 20 miles around the trade center complex. U.S. Coast Guard
Some scattered clouds seen
Today rain chances are bleak … I think so
not a drop of cloud over TN
@ VELA , @ NOVAK
Any idea about temp of NUnga and Meena now ?
current wind directions in India as per Weather online
http://www.weatheronline.in/main/includes/operational/graphics/wind_anim_in.gif?1380610840
WEATHER ONLINE FORECAST FOR CHENNAI 4 day
http://www.weatheronline.in/India/Chennai.htm
WEATHER ONLINE FORECAST FOR CHENNAI 05 oct to 08 oct
http://www.weatheronline.in/India/Chennai/Day5to8.htm
Anticyclone
An anticyclone is a region of high atmospheric pressure relative to the surrounding air, generally thousands of kilometres in diameter and also known as a high or high-pressure system. Anticyclones appear on weather charts as a series of concentric, widely spaced isobars of 1000 mbs and above. The roughly circular closed isobar at its central region indicates the area of highest pressure.
More on this :http://www.weatheronline.in/reports/wxfacts/Anticyclone.htm
Bubble High
Bubble High Thunderstorms develop as warm, moist air rises turning into rain or hail. As the thunderstorm reaches its mature stage, violent updrafts are noted and precipitation begins. At the onset of precipitation, strong downdrafts develop. Falling precipitation reverses rising air columns by frictional drag and cooling, and the storm eventually begins to dissipate or collapse.
For More info :http://www.weatheronline.in/reports/wxfacts/Bubble-High.htm
Cloud seeding
Cloud seeding Cloudseeding is the technique of inducing rain from a cloud, usually by dropping suitable particles into clouds containing supercooled water in an attempt to cause them to dissipate, modify their structure, or alter the intensity of associated phenomena, such as wind speed or hail.
Natural rainfall occurs when supercooled cold water contacts particles of dust, salt or sand forming ice crystals. The ice crystals provide a nucleus (tiny solid or liquid particles, suspended in the atmosphere) around which more water droplets can attach, increasing the size of the droplet, or in colder air snow flakes. When the droplet or snow flake, becomes large enough, it falls as snow or rain.
More info at http://www.weatheronline.in/reports/wxfacts/Cloud-seeding.htm
Dew Point
Dew point (ger: Taupunkt; fr:point de rosée)
or condensation point is the temperature at which a parcel of air must be cooled at constant pressure and humidity mixing ratio until it reaches saturation, and at which condensation of water vapor forms either as dew, cloud droplets, ice crystals, mist or fog.
More on Dew point at http://www.weatheronline.in/reports/wxfacts/Dew-Point.htm
NEM onset is 10th October.
http://www.accuweather.com/en/in/chennai/206671/daily-weather-forecast/206671?day=10
Today’s ECMWF will confirm the onset of NEM
Temp will completely change from 09th or 10th onwards, bye bye hot days
NICE TO HEAR
FLASH NEWS, FLASH NEWS
NEM Onset by 09th pr 10th. LPA forming over south bay on 09th.
PARTHA . Pls check link. It says page not found
i have posted revised link.
woww nice
Dear All,
NEM Onset Link
http://www.ecmwf.int/products/forecasts/d/charts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!192!Asia!pop!od!oper!public_plots!2013100100!!/
http://www.ecmwf.int/products/forecasts/d/charts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!216!Asia!pop!od!oper!public_plots!2013100100!!/
More easterly waves expected from 11th.
Forecast till 07th October
http://www.ncmrwf.gov.in/t574-model/t574-meteo-agro/wche1.htm
What is dBZ used in RADAR ?
Nondimensional “unit” of radar reflectivity which represents a logarithmic power ratio (in decibels, or dB) with respect to radar reflectivity factor, Z.
Divergence
The expansion or spreading out of a vector field; usually said of horizontal winds. It is the opposite of convergence. Divergence at upper levels of the atmosphere enhances upward motion, and hence the potential for thunderstorm development (if other factors also are favorable).
Convergence
A contraction of a vector field; the opposite of divergence. Convergence in a horizontal wind field indicates that more air is entering a given area than is leaving at that level. To compensate for the resulting “excess,” vertical motion may result: upward forcing if convergence is at low levels, or downward forcing (subsidence) if convergence is at high levels. Upward forcing from low-level convergence increases the potential for thunderstorm development (when other factors, such as instability, are favorable). Compare with confluence.
Dew Point Depression
The difference in degrees between the air temperature and the dew point.
Dew Point Front
A narrow zone (mesoscale feature) of extremely sharp moisture gradient and little temperature gradient. It separates moist air from dry air. Severe weather can be associated with this front. It is also known as a “dryline” or “dry front”.
DEWP
On a buoy report, the dewpoint temperature taken at the same height as the air temperature measurement.
The temp between the dry air and moist is taken as dew point temp.
Waiting for IMD to update its NWP and MID DAY Bulletin
Thanks partha for the new link
What about Weatheronline forecast ?
Climatology
The science that deals with the phenomena of climates or climatic conditions.
Climometer
An instrument that measures angles of inclination; used to measure cloud ceiling heights.
Convection
Generally, transport of heat and moisture by the movement of a fluid.
In meteorology, the term is used specifically to describe vertical transport of heat and moisture in the atmosphere, especially by updrafts and downdrafts in an unstable atmosphere. The terms “convection” and “thunderstorms” often are used interchangeably, although thunderstorms are only one form of convection. Cbs, towering cumulus clouds, and ACCAS clouds all are visible forms of convection. However, convection is not always made visible by clouds. Convection which occurs without cloud formation is called dry convection, while the visible convection processes referred to above are forms of moist convection.
TEMP AS PER IMD UPDATE 11.30am IS 33 WITH STRONG WNW WINDS
Hope it does no cross 35 deg celsius
Convective Clouds
The vertically developed family of clouds are cumulus and cumulonimbus. The height of their bases range from as low as 1,000 feet to a bit more than 10,000 feet. Clouds with extensive vertical development are positive indications of unstable air. Strong upward currents in vertically developed clouds can carry high concentrations of supercooled water to high levels where temperatures are quite cold. Upper portions of these clouds may be composed of water and ice.
you are providing nice info, great job
Thanks Partha
Shear
Variation in wind speed (speed shear) and/or direction (directional shear) over a short distance within the atmosphere. Shear usually refers to vertical wind shear, i.e., the change in wind with height, but the term also is used in Doppler radar to describe changes in radial velocity over short horizontal distances.
Shelf Cloud
A low, horizontal wedge-shaped arcus cloud, associated with a thunderstorm gust front (or occasionally with a cold front, even in the absence of thunderstorms). Unlike the roll cloud, the shelf cloud is attached to the base of the parent cloud above it (usually a thunderstorm). Rising cloud motion often can be seen in the leading (outer) part of the shelf cloud, while the underside often appears turbulent, boiling, and wind-torn.
Rame… info like this is actually a sight for sore eyes in the blog… Pretty much all your posts today has actually been informative and interesting compared to the bulletins and imd info which gets copy pasted here! Good Job Rame!
Thanks Sailu for your compliments.
Latest MJO position
Latest vorticity over west pacific, storm approaching Japan.
sorry north america
in atlantic
Sky Condition
Used in a forecast to describes the predominant/average sky condition based upon octants (eighths) of the sky covered by opaque (not transparent) clouds.
Sky Condition Cloud Coverage
Clear / Sunny 0/8
Mostly Clear / Mostly Sunny 1/8 to 2/8
Partly Cloudy / Partly Sunny 3/8 to 4/8
Mostly Cloudy / Considerable Cloudiness 5/8 to 7/8
Cloudy 8/8
Fair (mainly for night) Less than 4/10 opaque clouds, no precipitation, no extremes of
visibility/temperature/wind
Global SST Anomalies
Last 30 days rainfall anomalies
Squall
A strong wind characterized by a sudden onset in which the wind speed increases at least 16 knots and is sustained at 22 knots or more for at least one minute. 2. In nautical use, a severe local storm considered as a whole, that is, winds and cloud mass and (if any) precipitation, thunder and lightning.
Squall Line
A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorms.
Supercell
Short reference to Supercell Thunderstorm; potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours.
Supercell Thunderstorm
Potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours. Supercells usually move to the right of the mean wind. These are called “Right Movers” and they are favored with veering winds. Occasionally, these thunderstorms will move to the left of the mean wind. These thunderstorms are called “Left Movers”. These supercells typically don’t last as long as their “Right Mover” cousins and they usually only produce large hail (greater than 3/4 inch in diameter) and severe wind gusts in the excess of 58 miles an hour. Left Movers are favored when you have backing winds.
Radar will observe essentially one long-lived cell, but small perturbations to the cell structure may be evident. The stronger the updraft, the better the chance that the supercell will produce severe (hail greater than 3/4 inch in diameter, wind gusts greater than 58 miles an hour, and possibly a tornado) weather.
Severe supercell development is most likely in an environment possessing great buoyancy (CAPE) and large vertical wind shear. A Bulk Richardson Number of between 15 and 35 favor supercell development. Typically, the hodograph will look like a horse shoe. This is due to the wind speed increasing rapidly with height and the wind direction either veering or backing rapidly with height.
KT
(Knot)- Unit of speed used in navigation, equal to 1 nautical mile (the length of 1 minute latitude) per hour or about 1.15 statue miles per hour, or 0.5 meters/sec).
KTS
Knots
Let’s hope that whatever is gonna strike WB/Orissa should not go past tropical storm intensity. Tropical storms are fine, but if it becomes severe, chances of a good NEM will end even before the NEM starts 😐
Storm forming over bay and moving towards north bay on 17th
no signs of NEM – on 8th Oct
First SWM needs to start withdrawing from Maharashtra. Then we can hope for NEM onset
Well said SUSA.
SWM is hesitant to withdraw completely before 10th
in the beginning 09th, 10th and 11th we should get some TS, but after 11th we should be prepared for long dry spell of atleast 15 days.
Confirmed or assumed prediction ?
it is assumed prediction, and if there is a system and if it moves towards north, it is going to be an NEM failure in 2013.
Sea Breeze Front
The leading edge of a sea breeze, whose passage is often accompanied by showers, a wind shift, or a sudden drop in temperature.
Sea Level Pressure
The sea level pressure is the atmospheric pressure at sea level at a given location. When observed at a reporting station that is not at sea level (nearly all stations), it is a correction of the station pressure to sea level. This correction takes into account the standard variation of pressure with height and the influence of temperature variations with height on the pressure. The temperature used in the sea level correction is a twelve hour mean, eliminating diurnal effects. Once calculated, horizontal variations of sea level pressure may be compared for location of high and low pressure areas and fronts.
Sea Surface Temperatures
The term refers to the mean temperature of the ocean in the upper few meters.
When ENSO is neutral anything can happen, let hope for the best
Looks like another SWM style LPA on 10th 😡 This is terrible for NEM, might only set in by November!
this time LPA form over south bay.
Current lower level winds
http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=indian&sat=wm5&prod=ir&zoom=&time=
ACC moving along the LPA over Odisha, shear is at 50 knots
Shear Tendency is increasing
Barogram
An analog record of pressure produced by a barograph
Barograph
A barometer that records its observations continuously.
Barometer
An instrument that measures atmospheric pressure.
Barometric Pressure
The pressure of the atmosphere as indicated by a barometer.
Vorticity increasing over Chattisgarh
http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=indian&sat=wm5&prod=vor&zoom=&time=
Another 2009 like year ??
Mid level shear
http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=indian&sat=wm5&prod=midshr&zoom=&time=
Important term used in Doppler Radar
Base Reflectivity
One of the three fundamental quantities (along with base [radial] velocity and spectrum width) that a Doppler radar measures. Reflectivity is related to the power, or intensity, of the reflected radiation that is sensed by the radar antenna. Base reflectivity is expressed on a logarithmic scale in units called dBZ. The term “base” refers to the product being “basic”, with little advanced processing performed on the data. Base reflectivity is related to rainfall intensity (e.g., drop size and rainfall rate) and hail size (for large values of reflectivity).
Current divergence
http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=indian&sat=wm5&prod=dvg&zoom=&time=
Beaufort Scale
The Beaufort wind scale is a system used to estimate and report wind speeds when no measuring apparatus is available. It was invented in the early 19th Century by Admiral Sir Francis Beaufort of the British Navy as a way to interpret winds from conditions at sea. Since that time, the scale has been modernized for effects on land.
Beaufort Force 0 – Wind less than 1 kt, Calm, Sea surface smooth and mirror-like. Smoke rises vertically.
Beaufort Force 1 – Wind 1-3 kt, Light Air, Scaly ripples, no foam crests. Smoke drift indicates wind direction, still wind vanes.
Beaufort Force 2 – Wind 4-6 kt, Light Breeze, Small wavelets, crests glassy, no breaking waves. Wind felt on face, leaves rustle, vanes begin to move.
Beaufort Force 3 – Wind 7-10 kt, Gentle Breeze, Large wavelets, crests begin to break, scattered whitecaps. Leaves and small twigs constantly moving, light flags extended.
Beaufort Force 4 – Winds 11-16 kt, Moderate Breeze, Small waves 1 -4 ft. becoming longer, numerous whitecaps. Dust, leaves, and loose paper lifted, small tree branches move.
Beaufort Force 5 – Winds 17-21 kt, Fresh Breeze, Moderate waves 4 -8 ft taking longer form, many whitecaps, some spray. Small trees in leaf begin to sway.
Beaufort Force 6 – Winds 22-27 kt, Strong Breeze, Larger waves 8 -13 ft, whitecaps common, more spray. Larger tree branches moving, whistling in wires.
Beaufort Force 7 – Winds 28-33 kt, Near Gale, Sea heaps up, waves 13 -20 ft, white foam streaks off breakers. Whole trees moving, resistance felt walking against wind.
Beaufort Force 8 – Winds 34-40 kt Gale, Moderately high (13 -20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks. Whole trees in motion, resistance felt walking against wind.
Beaufort Force 9 – Winds 41-47 kt, Strong Gale, High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility. Slight structural damage occurs, slate blows off roofs.
Beaufort Force 10 – Winds 48-55 kt, Storm, Very high waves (20 -30 ft) with overhanging crests, sea white densely blown foam, heavy rolling, lowered visibility. Seldom experienced on land, trees broken or uprooted, “considerable structural damage”.
Beaufort Force 11 – Winds 56-63 kt, Violent Storm, Exceptionally high (30 -45 ft) waves, foam patches cover sea, visibility more reduced.
Beaufort Force 12 -Winds 64+ kt, Hurricane, Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced.
@Partha
You sure about south bay ?? Then we’ll have a spell similar to what we got this August. btw, i got to go out now.
yes, as of now that is the status from ECMWF.
IMD has come down a lot, so far no mid day update.
What do you mean by that ?
there is an update given in the afternoon, that is delayed
Rather than a cyclone, if it is an LPA forming in 10 days, then it would be vital NEM.
Absolutely.
Rain in MM in odisha
BALASORE 194.7
SONEPUR 89
CHANDBALI 82.1
BARIPADA 54.2
BHAWANIPATNA 51
KORAPUT 50.8
PHULABANI 50
BHUBANESWAR 38.8
BOLANGIR 30.6
JHARSUGUDA 26.6
TITILAGARH 17.2
PURI 16.2
GOPALPUR 13.8
SAMBALPUR 12.4
KEONJHARGARH 11.1
TALCHER 10
PARADIP 8.4
ANGUL 7.6
MALKANGIRI 4
SUNDARGARH 3.2
CUTTACK 2.4
HIRAKUD 0.4
some clouds on west
Rain at 08.30 in TN in CM
Poonamallee (Tiruvallur Dist), Chennai AP (Kancheepuram Dist), Chembarabakkam (Tiruvallur Dist), Tiruvallur (Tiruvallur Dist) 1 each.
Nowcast
http://www.imdchennai.gov.in/nowcast.htm
Blizzard
(abbrev. BLZD)- A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer:
Sustained wind or frequent gusts to 35 miles an hour or greater; and
Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than ¼ mile)
Hail
Showery precipitation in the form of irregular pellets or balls of ice more than 5 mm in diameter, falling from a cumulonimbus cloud.
wind direction from S from 8th. 1st real indication of SWM withdrawl
http://foreca.com/India/State_of_Tamil_Nadu/Chennai?tenday
HAIL SIZES
Hail Size
Typically refers to the diameter of the hailstones. Warnings and reports may report hail size through comparisons with real-world objects that correspond to certain diameters:
Description | Diameter (inches)
Pea | 0.25
Marble or Mothball | 0.50
Penny or Dime | 0.75
Nickel | 0.88
Quarter | 1.00
Half Dollar | 1.25
Walnut or Ping Pong Ball | 1.50
Golfball | 1.75
Hen’s Egg | 2.00
Tennis Ball | 2.50
Baseball | 2.75
Tea Cup | 3.00
Grapefruit | 4.00
Softball | 4.50
RADAR
Acronym for RAdio Detection And Ranging; a radio device or system for locating an object by means of ultrahigh-frequency radio waves reflected from the object and received, observed, and analyzed by the receiving part of the device in such a way that characteristics (as distance and direction) of the object may be determined.
Radar Range
Distance from the radar antenna. The WSR-88D radar has a range for velocity products out to 124 nautical miles and reflectivity products out to 248 nautical miles.
Radar Reflectivity
The sum of all backscattering cross-sections (e.g., precipitation particles) in a pulse resolution volume divided by that volume. The radar reflectivity can be related to the radar reflectivity factor through the dielectric constant term |K|^2, and the radar wavelength.
Radar Reflectivity Factor (z)
z = the sum (over i) of (N_i * D_i^6), where N_i is the number of drops of diameter D_i in a pulse resolution volume. Note that z may be expressed in linear or logarithmic units. The radar reflectivity factor is simply a more meteorologically meaningful way of expressing the radar reflectivity.
Those logging in today are virtually assured of understanding the various complex weather terminologies commonly discussed by weather experts..Though these terms and terminologies are readily available in various weather related web pages,it becomes imperative for us to go through and refresh ourselves time and again..Keeping this in mind,RameshSquall has been posting some important notes on the terminologies used..Informative to all and sundry,,Kea can have a separate page on weather terminologies commonly used for easy reference..Bloggers would benefit a lot..This could be added to Data pages of Pradeep, Kar etc.. Good job Rame…Ensure the posts are not lengthy ones..That’s it..
Thanks NOVAK
Good point Novak to create a separate page for posting detail info on weather topics, pics, videos.
Inform Kea
Thanks
I will once again not miss the opportunity to suggest. . Separate page for bulletins, nowcast, farmer’s bulletin etc..
People coming to blog should see originality. .especially new folks will run away if they keep seeing imd updates here which is easily accessible anyway and is child’s play
Relative Humidity
A dimensionless ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature. As such, relative humidity by itself does not directly indicate the actual amount of atmospheric moisture present. See dew point.
Relative Vorticity
The sum of the rotation of an air parcel about the axis of the pressure system and the rotation of the parcel about its own axis.