>23 April, 2010

Written by on April 23, 2010 in Rest of Europe with 0 Comments

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

Graphic courtesy of AccuWeather.com
Plains to Mississippi Valley Severe Storm, Tornado Threat Today
AccuWeather Here

Life-Threatening Thunderstorms Friday Evening
AccuWeather Here


other news headlines

india, asia
India Monsoon to Feature Near-Normal Rainfall
AccuWeather Here

iran, asia
Dust Storm Continues throughout Iran
AccuWeather Here

Oil rig sinks as 11 workers missing
USA Today Here

chile, south america
Magnitude 6.1 quake hits Chile, no damage reported
Los Angeles Times Here

iceland, europe
‘Explosive’ Katla Could Affect Global Temperature, Devastate Iceland
AccuWeather Here

Today’s Weather across America
from AccuWeather.com


BREAKING: Plains to Mississippi Valley Severe Storm, Tornado Threat Today Here

VIDEO:       Severe Weather Outbreak Underway! Here

Severe Weather Threatens Oil Spill Area
AccuWeather Here

Weather Talk
By Mark Vogan

My Reasons for why Temperatures now aren’t as warm and they could be and why Brits should perhaps be glad it’s not warmer now as this may signify change from above, for the better!

Whilst the rains fall here amid cool temperatures, across the Atlantic the big focus is on the severe weather and tornado threat for the southern plains, into the deep south states that will likely fire up as temperatures warm by noon and through the afternoon hours today and a surge of moister Gulf air with upper 60 to lower 70-degree dew points push into the ever increasingly unstable atmosphere across the South (Check out Todays Top Stories & Todays Weather across America for more).

It’s now April 23 and still no 100s?

We still haven’t seen any 100s across the US, the closest being 99 degrees at Death Valley, CA and I remember a 98 degrees at Laredo, TX. Usuaully we’ve seen at least a few days that have topped the century mark but so far, not this year. We’re currently on track to see no 100s until May and the only time since 2000 where America didn’t see 100 until May was in 2003 where it took up until May 3rd. Does this portray a cooler US summer, simply because we haven’t seen any real heat yet from Texas to California? No, it’s because a dominant trough has parked itself for the most part over the West and thus we’ve seen a 10-20 above normal departure over the East where high pressure has been the focus, however though we saw that early April heatwave, temps calmed down after that and remained well above normal but not outrageously, perhaps the large spread of warmth over east of Rockies has meant less intense heat because it’s hit early and when the high’s themselves have still to intensify since usually it’s not until late May and June before the sun is strong enough to pump high pressure cells which can deliver hotter surface temperatures. I believe that when you have a blowtorch of say days where highs are topping 100-105 degrees over West Texas where a strong ridge is in control, usually a lot of cold air will cover the majority of the rest of the surrounding atmosphere, this pressure from the surrounding trough may help pump the ridge and therefore bring 100s to typical early season locales such as the corridor from Texas westward to California.

Shrink and squeeze high pressure and you get strong pressure heights and warmer temperatures at the surface, but allow the high to spread from say eastern Colorado all the way up to Maine and you have too much of an area and therefore restricted “thickness values” which mean temperatures can’t achieve levels greater than a certain thereshold as the compensation of too much atmosphere to cover, limits the heat in a certain area. To experience super heat across a large area like we saw in 2006, that was in the height of summer when you get massive ridges and therefore major heat across a large area, this time of year, it’s too early and high’s are not able to become that strong for at least another 2 months…

Even we we see major heat in May or even early June, you still see other areas that are cold, even snowy. That is the exact reason why you see major heat. It’s that very surrounding weather that’s forcing warmer temperatures in that area where high pressure is dominant. Only in July or August when the sun is strongest and so too are high pressure cells where they reach there most northerly position do we see major heat waves blast large regions… Even for that to happen other factors must play out including warmer SST’s near the region of strong high pressure, as well as dry soils or simply drought conditions within a large area.

Last summer we saw the warmest ever reading in Seattle and 90s go all the way to the Arctic, this I believe was achieved because of just how cold the air was, east of the Rockies. This massive area of cool air and Canadian High pressure squeezed a vast region that would normally have this “squeezed” high covering, therefore the ridge itself was squeezed and pumped upwards into higher than normal altitudes within the atmosphere, therefore creating a much deeper column for the air to sink and heat the surface below….

.. In fact I believe a much warmer summer is in store for the US as well as here in the British Isles… This cool, unsettled pattern by the way we’re in on this side of the pond, is not a precursor of what lies ahead.

Those wanting to know what the weather will be like over the next 10 days?

I strongly believe this pattern will continue till May with days where we see a good deal of sunshine and temps warm beneath that strong sun, however though I don’t believe we will have washout days, we may see showery weather, some heavy and perhaps thundry but temps are slowly going to climb as the upper atmosphere is often sluggish in changing at the mid and upper levels of the atmosphere after a cold winter. Right now, we’re struggling to see a national maximum above 60 degrees which is pretty amazing for this late in April, however this slow warm-up despite a general high pressure dominance, is quite possibly the precursor to warmer, much warmer, sunnier times ahead as the seasonal adjustments are underway as the sun grows stronger and high pressure cells to our south grow stronger, larger and push ever closer to us.. We may find that what becomes a tropical Atlantic problem (more hurricane activity) is our gain up here as pressures lower further south and rise further north. Opposite to the past few summers where lower pressures and therefore rainy weather persisted here between 2007-2009. A 2005-2006 summer where warmer, high pressure dominated summers will return, worst case we see 2002!

What’s Reaching Today’s Blogs?

Earth’s Water Cycle has Accelerated
Climate Change, AccuWeather Here

A Swarm of Tornadoes Today and Saturday
Henry Margusity, AccuWeather Here

Heat Wave Abates Partially
Vagaries of the Weather Blog Here

Todays US Extremes
Courtesy of AccuWeather

High: 97 degrees at Laredo, TX
Low: 11 degrees at Sunset Crater, AZ

UK Extremes
Courtesy of the Met Office

Warmest High: 65 degrees at Northolt
Coolest High: 37 degrees at Loch Glascarnoch
Coolest Low: 23 degrees at Kinbrace

Todays Extremes at my house

High: 51 degrees
Low: 44 degrees

Thanks for reading.

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