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Noon - Mesoscale update
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The National Weather Service has issued a wind advisory is in effect for the region - boaters use caution. Winds will gust from 30-40 mph (even higher) through the afternoon and evening hours.
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Right from the start let's take a look at the update for the tornado, damaging wind, and hail risk. .
First graphic will be the tornado risk zone for today (see scale at the top) - then the damaging wind graphic is second and finally hail is the third graphic. You get the general idea from these graphics as to where the greatest risk for severe weather will be today (the further west/north you go - the better chance for severe thunderstorms).
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Note that our risk won't arrive until late tonight and early on Monday morning - see discussion below the graphics. .
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The line of thunderstorms will then become a squall line after 11 pm tonight. This line of thunderstorms will then push into southeast Missouri and the northwest part of southern Illinois late tonight and early Monday morning. Then for far southern IL and western KY it should arrive after 3 am tomorrow morning.
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CAPE values at this hour are over 1000-2000 in most of our counties. CAPE is basically energy - energy for thunderstorms. CAPE into the thousands means that there is a lot of energy. However, there is also warm air aloft - this warm air keeps thunderstorms from forming. Think about a parcel of air - in order for it to rise it must be warmer than the surrounding air. Air is lifted up in order to form storms. If the the air reaches a level where the surrounding air is warmer - then the air sinks back down to the surface. This is a CAP. We will be under this CAP most of the afternoon and evening.
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12 PM - mesoscale update for southern IL, southeast MO, western KY, northeast AR, western TN. .
Temps are warming into the 80s at this hour. Strong southerly winds are gusting over 30 mph in many of our counties. A strong CAP will keep us dry this afternoon. By 6-10 pm tonight supercells will form and stretch from near or west of St Louis to Springfield, MO. These storms will move east/northeast through the night and early AM hours..
The line of thunderstorms will then become a squall line after 11 pm tonight. This line of thunderstorms will then push into southeast Missouri and the northwest part of southern Illinois late tonight and early Monday morning. Then for far southern IL and western KY it should arrive after 3 am tomorrow morning.
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Some of these storms may produce hail and high winds (greater than 50 mph). An isolated tornado can't be ruled out - especially over the northern half of southern IL and eastern Missouri. The line of storms will linger over our region into the late morning hours on Monday. Showers and storms should move out of the area by 3 PM.C.
CAPE values at this hour are over 1000-2000 in most of our counties. CAPE is basically energy - energy for thunderstorms. CAPE into the thousands means that there is a lot of energy. However, there is also warm air aloft - this warm air keeps thunderstorms from forming. Think about a parcel of air - in order for it to rise it must be warmer than the surrounding air. Air is lifted up in order to form storms. If the the air reaches a level where the surrounding air is warmer - then the air sinks back down to the surface. This is a CAP. We will be under this CAP most of the afternoon and evening.
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In order to overcome the CAP one or two things must happen - something must lift the air in such a manner that it is forced to break the CAP (such as a cold front) or the air above must cool (allowing the parcels of air to continue to rise instead of sink back down). Those two items will happen tonight. A cold front will arrive and help lift the air and temperatures above us (higher levels of the atmosphere) will cool. This will allow air to rise and form thunderstorms.
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We have been placed under a slight risk for severe thunderstorms for tonight and Monday morning. A slight risk (from the Storm Prediction Center - the agency that forecasts severe weather) means that scattered severe storms are likely to occur. I know - I know - slight to most people means something totally different. But that is their wording - I wish they would change the terminology. I would rather say that scattered reports of severe weather are likely tonight and tomorrow morning in our region.
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Again, the main concern tonight and tomorrow morning will be damaging winds and hail up to the size of quarters (possibly a little larger). Thankfully the line of storms won't arrive until late late tonight - instability (CAPE) won't be as high - this should at least help weaken the line of storms (somewhat). Areas to our west may see more significant severe weather this afternoon - from St Louis down to Springfield, MO. Always northern Illinois into Wisconsin may have significant severe weather later today.
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REMEMBER - it only takes one bad storm to cause problems. A good example was the Ballard County cell last week that produced tornadoes. So - even though the risk for severe weather isn't great - it also isn't zero.
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REMEMBER - it only takes one bad storm to cause problems. A good example was the Ballard County cell last week that produced tornadoes. So - even though the risk for severe weather isn't great - it also isn't zero.
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Severe thunderstorm and tornado watches may be issued later today and tonight for portions of our region. Stay tuned to NOAA Weather Radio or your local media for updates.A few maps from a high resolution model (models forecast weather) - this is showing the evolution of the line of showers and thunderstorms. I believe this particular model has a grasp of the way this line of storms should develop later tonight. So - for today at least - I will use it for guidance. This is basically a future-cast radar.
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The first image would be around 10 PM tonight
The second image would be around 3 AM Monday morning
The third image would be around 8 AM Monday morning
The fourth image would be around 2 PM on Monday
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CLICK IMAGE TO VIEW THE REAL SIZE.
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Latest watches and warnings - click your state and zoom down
http://weather.weatherobservatory.com/maps/severe/warnings/all/us.html
Previous discussion
Sunday, April 10, 2011
I will update the blog a few times today. If there are any changes in the Storm Prediction Center's severe weather outlook - or other forecast changes then I will update accordingly.
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Windy today. Wind gusts over 30-40 mph possible. Storms arrive late tonight into Monday morning. Isolated severe storms possible - main concern would be high winds. Will monitor and update as needed.
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Hope everyone enjoyed the warm temperatures on Saturday? We were well into the 80s across most of the region. ---
Thunderstorms developed on Saturday morning. I recorded dime size hail at my place in Massac County - others reported hail the size of quarters. A few severe thunderstorm warnings were issued.
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Temperatures today will once again rise into the 80s. Along with the warm temperatures will come strong southerly winds - winds will gust out of the south at speeds of 30+ mph. Boaters should use caution on area lakes.
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A cold front will arrive in the region late tonight and early on Monday morning. This front will bring a chance for showers and thunderstorms.
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Right now I am thinking the showers and storms won't arrive until after midnight in western Kentucky and most of southern Illinois. A few of the storms could produce high winds and small hail. Rainfall totals of 1/2" or so will be possible in the heavier cells.
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This forecast covers far southern Illinois, southeast Missouri, and western Kentucky---
Highs: around 85 degrees | Wind: South/southwest winds at 15-20 mph with gusts to 30-40 mph.
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Sunday night: Showers and thunderstorms late. Some storms may be severe. Mild.
Lows: around 65 degrees | Wind: South winds at 10-15 mph with gusts over 20 mph. ---
Monday: A chance for showers and thunderstorms. Rain ending during the afternoon. Turning cooler. Windy.
Highs: early in the day - in the 70s then falling in the afternoon | Wind: South/southwest winds at 10-20 mph - gusting to 30 mph becoming west at 15-25 mph with gusts over 35 mph. ---
Monday night: Partly cloudy. Cooler..
Lows: around 45 degrees | Wind: West at 10-15 mph. ---
Tuesday: Sunny and cooler.
Highs: around 70-73 degrees | Wind: North wind at 10 mph.---
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Video has been posted and updated on the Weather Observatory web-site (simply click on the day of the week for the latest video).
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The forecast for severe or extreme weather risk for today, tonight, and tomorrow: A chance for a few severe thunderstorms late tonight and into Monday morning. Gusty winds and small hail being the primary concern. Will monitor and update later today.
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We have a number of new radars available on our Weather Observatory web-site!---
We now offer St Louis, Mt Vernon, Evansville, Poplar Bluff, Cape Girardeau, Marion, Paducah, Hopkinsville, and Dyersburg Interactive City Radars. We also have the two regional radars and now offer you three GR Earth radars.
http://www.weatherobservatory.com/weather-radar.htm---
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1. Another chance for showers and storms will arrive on Thursday/Friday.
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Meteorologist Beau Dodson---
McCracken County Office of Emergency Management
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