Saturday, April 24, 2010

24 April, 2010

Today's Top Weather Stories
On Weather & Climate Through the Eyes of Mark Vogan

Breaking News USA:
MAJOR SEVERE THUNDERSTORM & TORNADO THREAT TODAY

New ACCUWEATHER: Long-Track, Destructive Tornado Crosses Mississippi Here

New THE WEATHER CHANNEL: Particularly Dangerous Situation: Tornado Outbreak Here

"OVER 40 TORNADOES TODAY ACROSS THE SOUTH. SOME WILL BE BIG WEDGES THAT LAST A LONG TIME"... Henry Margusity, AccuWeather

SPECIAL STORY BY MARK VOGAN
After a very slow start to the severe weather season, things are finally beginning to ramp up in a big way after major tornadoes struck Texas, Kansas and other adjacent states over the past 48 hours as a major storm system barrels it's way across the heartland of America... south and east of the vigorous low pressure center, Warm, Gulf air seeps northward drawing warmth and moisture put of the warm Gulf into the spinning energy cauldron centered across the central Plains and with a vibrant cold front progressing in harmony wih the low to it's southeast into this soupy, ever more summer-like air, thunderstorms are blowing up and with that spin occuring where the heat and moisture flowing out of the Gulf collides with the energy of the front and the cooler, drier air sweeping in from the northwest on the backside of the system , spin is going to create tornadoes to form with embedded supercells within the main complex lines of storm as being reported across central Arkansas and down into northern and central Louisiana this morning. The Storm Prediction Center has issued a HIGH risk for a region from south Arkansas, into central and northern Mississippi and into much of central and northern Alabama.

Whilst the morning to lunchtime threat is for particularly heavy, flooding rains, frequent cloud-to-ground lightening and possible damaging winds for Arkansas and Louisiana with reports of squall lines from AccuWeather and visible on radar, as the cold front slides east and by the time it reaches Mississippi it will be around lunchtime and early afternoon, late afternoon for Alabama, what's critical about the noon to afternoon period is that warmer, more humidity air will be in place and therefore enhancing the instability of the air and thus increasing the tornadic threat this afternoon and air temperatures rise towards 80 and coupled with dew points in the 70s, this will be plenty of fuel for a very stormy and dangerous afternoon as those skies darken on your western horizon as the noon hour approaches for those of you in Mississippi and Alabama.

A warm front to the north of the storm will and has sparked a large canopy of rains, some heavy as well as a rather mild afternoon temperaturewise.





Graphic courtesy of the Storm Prediction Center





























Graphics courtesy of The Weather Channel

Today's Weather across America
From AccuWeather














The Big Day for Tornadoes Across the South
Henry Margusity, AccuWeather Here

Tornadoes to Threaten Talladega Today
AccuWeather Here

Important Tornado Safety Tips to Follow
AccuWeather Here

Rough Seas, Thunderstorms Threaten Oil Spill Area
AccuWeather Here


Weather Talk
By Mark Vogan

Slowly but surely we're warming... Today should be the warmest day of year so far, it can only get better!

After 60s (15 to 18C) earlier in the month, then a return to 40s and 50s (5-10C) with hill snow and even sleet mixed with rain at low levels just days ago, chill verses warmer air trying to work it's way up means trees are ever so slowly showing their green leaves again but it feels like a slow process this year doesn't it. This indeed is that time (mid to late April) when things return to life with lawns needing cut and trees and shrubs blossom again with vibrant green.

The wounds of winter have been slower to heal this year and I personally am one that wants those trees to produce their flurishing green once again and the air to hit that temperature barrier into summertime (70 degrees).. The 51-degree high of yesterday and actually mid-40s for much of the day with on and off rains will be seem like winter compared to today with mid and high level patchy cloud and a hazy, filtered sun which should bring readings towards the mid-60s for many areas and likely parts of south-central England and even inland points further north under enough clear skies for the sun to beat down should see 70s for their first appearance of 2010. In between showers and perhaps a stubborn periodic return to cooler air, we are now seeing 60s regularly when the sun is out, only perhaps dropping into the mid-50s when the sun isn't around but you'll find soon enough that with rain, it stays fairly mild rather than chilly as we approach May... Soon it will be the difference between near 60 or 70 to low 70s....

More UK summer thoughts

If we get into a dominant high pressure pattern once into May this should bring mid to upper 70s to southern and central parts of England and Wales and highs in and around 70 for much of interior Scotland. There should be more sun than cloud in May and this will be crucial as to how warm June and July become... More sun, less rain means drying out of those soils. From May onwards the rate of soil moisture evaporation increases as the sun solar rays become stronger. This would mean possible "brown gassy areas" in June and July but regular sunny days and mid-80s to near 90 for the south (away from the coast which will see strong sea breezes and 10 degrees cooler) and upper 70s to around 80 for the north.

My prediction is that the warmest places in Britain should be anywhere from central London to central Manchester which could see a few days top 90 degrees (32C) with a maximum at some point in late June, July or early August of 95 degrees, some areas may find the persistent sunshine produces very dry ground. Further north Scotland, Northern Ireland should see a series of days into the mid-80s (27-30C) with the very warmest being near 88-90C in town or city centers... Official readings may see an 88 or 89 degree high. All this expected heat should tigger some fiery thunderstorms now and again which will likely threaten the south most as they should see the most intense warmth but anywhere in Britain I believe will have an increased risk of some strong thunderstorms this summer.

What's Reaching Today's Blogs?   

The Big Day for Tornadoes Across the South
Henry Margusity Blog, AccuWeather Here

Monsoon Watch - 3
Vagaries of the Weather Blog (Bombay, India) Here

Todays US Extremes
Courtesy of AccuWeather

High: 96 degrees at Death Valley, CA
Low: 18 degrees at Lake Yellowstone, WY

Todays UK Extremes
Courtesy of the Met Office

Warmest High: 70 degrees at St James Park (London)
Coolest High: 43 degrees at Lerwick (Shetland)
Coolest Low: 26 degrees at Beltasound

Todays Extremes at my house

High: 64.9 degrees (Warmest of 2010, beats 64.7)
Low 44 degrees



Thanks for reading.
-Mark

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