Thursday, June 18, 2009
Severe Thunderstorm Watch includes Stearns until 9 PM
The Storm Prediction Center has issued Severe Thunderstorm Watch 465 until 9 PM. The watch does include Stearns County, but Stearns is on the far-most eastern side of the watch, and it is entirely possible portions of the watch could be replaced by another one later today. We will look in this watch box for large hail up to 2.5" in diameter and damaging winds to 70 mph, though remember that severe storms do have the capability of producing tornadoes. Stay tuned for more updates throughout the afternoon and evening. It is still very likely that it's going to be a very severe weather day statewide. Already a couple storms in the Alexandria area as I type this are severe, and the storm forming west of St Cloud could turn severe soon.
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 465
NWS STORM PREDICTION CENTER NORMAN OK
150 PM CDT THU JUN 18 2009
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
PARTS OF CENTRAL AND WESTERN MINNESOTA
PARTS OF SOUTHERN NORTH DAKOTA
PARTS OF NORTHERN AND EASTERN SOUTH DAKOTA
EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 150 PM UNTIL
900 PM CDT.
HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 10 MILES EAST OF
BRAINERD MINNESOTA TO 45 MILES WEST SOUTHWEST OF MOBRIDGE SOUTH
DAKOTA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED
WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 461...WW 462...WW
463...WW 464...
DISCUSSION...AS AIR MASS CONTINUES TO DESTABILIZE THUNDERSTORMS WILL
INCREASE IN NUMBER AND INTENSITY ACROSS THE WATCH AREA THRU THE
AFTERNOON. WITH MLCAPES AOA 2500...STEEP LAPSE RATES AND FAVORABLE
SHEAR ENVIRONMENT...SUPERCELLS ARE LIKELY. LARGE HAIL AND DAMAGING
WINDS WILL BE ASSOCIATED WITH ANY SUPERCELL ALONG WITH POSSIBLE
BRIEF TORNADOES.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 23025.
...HALES
Current Warnings
Moderate Severe Weather Risk: Tornado Threat
The Set-Up
The STC area is under a slight risk of severe weather today, but just miles south of the St. Cloud area and stretching far into Iowa is under a moderate risk of severe weather – the moderate risk is as close as the Annandale area.
Right now we have a cap on the atmosphere due to storms that moved through earlier today. It's already hot and muggy out and we are starting to see the one thing we didn't need to see – the sun. It's only going to make things worse. We also have high dew points, an unstable atmosphere, strong "wind shear" aloft (we have winds from the south at the surface and winds from the west in the upper atmosphere, giving enhanced shear and a spin to the atmosphere for later) and we also still have some boundaries left over from last night's storms. All of these criteria make conditions ripe for more potentially violent, dangerous weather later today and tonight.
Storms could start sparking at any time, especially once we get to the 3 PM hour, and last through most of the evening and long into the overnight. Statistically, there is a 5-10% probability of a tornado within 25 miles of any town as you go from St. Cloud southward through the late evening hours, and even as you get into southern MN there is a 15% probability of it. Tornado touchdowns are probable, especially in the dinner and rush hour timeframe, but it is yet unclear the extent of the best touchdown area at this time. Outside activities will likely be cancelled at some point once these storms start.
The Risks
This is the tornado outlook from 1130 this morning from the Storm Prediction Center. The circles entail the probability of a tornado touchdown within 25 miles of any point. As stated earlier, there is a 5-10% risk for much of southern and central Minnesota, even a 15% risk in far southern MN into IA. Many ingredients for isolated tornado-producing supercell thunderstorms are present. Watches and warnings, especially tornadic ones, across parts of central and southern Minnesota are likely. The blue lined "hatched" area indicated a 10% or greater probability of an EF-2 to EF-5 tornado within 25 miles of a point.
This is today's hail outlook as of 1130. It shows the probability of 3/4" of larger hail within 25 miles of a point, while the blue lined "hatched" area is a 10% or greater probability of hail 2" or larger within 25 miles of a point. The area is under a 30% risk of large hail, but the hatched area and the 45% risk area is both less than 60 miles south of the area. Remember, the hail criterion is now up to 1" for severe hail in the Midwest, including Minnesota.
Here is the damaging wind threat. It showers the probability of damaging winds of 50 knots or higher with 25 miles, and the blue lined "hatched" area of 65 knots or greater. We are also under a 30% risk of these damaging winds, but the main risk will be south into Illinois later tonight as the storms form into a line and bow out, creating even stronger winds.
Tornado Protection
This is taken directly from Paul Douglas's blog, which you can find a link to below
"In a tornado the safest place to ride out the storm:
* Basement, under the stairs. Statistically this is the safest place to be, under a desk or heavy piece of furniture if possible.
* Small, windowless room on the ground floor, like a closet or bathroom. People have survived F-5 tornadoes by hiding in their bathtubs, a mattress or blanket (or pillows) on top of them.
* Avoid outer walls/windows. Most tornado injuries are the result of flying debris and head trauma. That's why it's preferable to get below grade, underground if at all possible.
* In a school or office seek shelter near the interior of the floor, a concrete-reinforced stairwell or bathroom usually provides the best protection.
* Avoid mobile homes (which can become airborne at wind speeds as low as 80 mph). Avoid large rooms, gymnasiums, auditoriums - these are the first to collapse when a tornado hits.
* In a vehicle you can usually drive away from the storm. If that's impossible get out of your vehicle and seek shelter in a nearby building - OR - a ditch. Do NOT ride out the storm inside a car or truck or underneath a vehicle. Do NOT seek shelter under a bridge overpass (a wind-tunnel effect can increase the threat of flying debris hitting you there)."
Today, especially from 3 PM to midnight, looks like it could be very dangerous weatherwise. Keep ahead of the weather especially if you have any outdoor events. Stay with local media sources, NOAA weather radio, and these websites for the very latest:
My blog at http://kidweather.blogspot.com/
My Facebook page
My twitter at http://www.twitter.com/weathrlver
And a few other places—
Paul Douglas St. Cloud Weather Blog at http://pauldouglassaintcloud.blogspot.com/
Fox 9 Weather Chat at http://www.myfoxtwincities.com/generic/weather/Weather_Chat
National Weather Service Chanhassen at http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=mpx&storyid=28783&source=0
Storm Prediction Center http://www.spc.noaa.gov/
Wednesday, June 17, 2009
June 17 Severe Weather Blog
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 449
NWS STORM PREDICTION CENTER NORMAN OK
700 PM CDT WED JUN 17 2009
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTH CENTRAL AND NORTHEAST IOWA
SOUTH CENTRAL AND SOUTHEAST MINNESOTA
EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 700 PM
UNTIL 100 AM CDT.
TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 15 MILES WEST SOUTHWEST OF
FAIRMONT MINNESOTA TO 25 MILES SOUTH OF LA CROSSE WISCONSIN. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU9).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 439...WW 440...WW
441...WW 442...WW 443...WW 445...WW 444...WW 446...WW 447...WW
448...
DISCUSSION...A VERY UNSTABLE ENVIRONMENT IS PRESENT ACROSS S/SE MN
INTO NRN IA...ALONG AND S OF A SURFACE WARM FRONT AND WEAK SURFACE
WAVE IN SRN MN. BOUNDARY LAYER DEWPOINTS IN THE 70S AND
TEMPERATURES IN THE 80S ARE CONTRIBUTING TO MLCAPE VALUES OF
3000-4000 J/KG...AND EFFECTIVE BULK SHEAR OVER THIS AREA IS AOA 50
KTS. THE ENVIRONMENT STRONGLY FAVORS DISCRETE SUPERCELL
DEVELOPMENT...WHILE THE RICH LOW-LEVEL MOISTURE AND 0-1 KM SRH AOA
200 M2/S2 WILL FAVOR TORNADIC SUPERCELLS. GIVEN THESE ENVIRONMENTAL
CONDITIONS...AN ISOLATED STRONG TORNADO MAY OCCUR. OTHERWISE...VERY
LARGE HAIL AND ISOLATED DAMAGING WINDS WILL BE POSSIBLE.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 29025.
...THOMPSON
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