Saturday, May 22, 2010

5/22/10: Saturday's Weather Report

Issued at 3:34 PM CDT, Saturday, May 22nd, 2010

A cluster of showers and embedded thunderstorms tracked east out of Western Minnesota and through portions of Northcentral and Eastcentral Minnesota This Morning into the early Afternoon hours Today. This area of precipitation was accompanied by some strong winds which caused some damage around parts of our area. Here are some storm reports from Today per NWS Duluth, MN.

11:45 AM CDT 5/22/10: Non Thunderstorm Wind Damage at Cohasset MN (Itasca County) 45 mph wind gusts with many 4" diameter branches down, some trees and power lines down as well.

12:20 PM CDT 5/22/10: Non Thunderstorm Wind Damage at Keewatin MN (Itasca County) 45 mph wind gusts with small limbs blown down, small objects blowing around.

12:00 PM CDT 5/22/10: Non Thunderstorm Wind Damage at Hill City MN (Aitkin County) Power lines and trees down.

11:30 AM CDT 5/22/10: 60 mph non thunderstorm wind gust 1 mile South of Brainerd MN (Crow Wing County)

11:45 AM CDT 5/22/10: 6 miles West of Grand Rapids MN (Itasca County) 40 mph non thunderstorm wind gusts.

11:20 AM CDT 5/22/10: Brainerd MN (Crow Wing County) Local Law Enforcement reported several trees down, power lines down. Tree on car at Brainerd International Raceway.

10:40 AM CDT 5/22/10: Walker MN (Cass County) Large Pine Tree fell over power line, power outage reported.

10:42 AM CDT 5/22/10: Hackensack MN (Cass County) 40 mph non thunderstorm wind gusts, small limbs down. MN DOT Chamberlain MN-64 Mile Post 42 measured a wind gust to 56 mph.

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Low pressure of 992 mb was centered in Southern South Dakota late Today with a 994 mb low centered in Southern Saskatchewan Province Canada, another area of low pressure 988 mb was centered in Northern Colorado. A warm front extended from Southern South Dakota to Southwest Minnesota with a cold front heading east into the Western Dakotas. An initial burst of moist advection helped to generate an area of mainly light rain showers and gusty winds This Morning and early Afternoon in Western-Southern parts of our local area, most of the measurable rain with amounts under one quarter inch affected the Southern 1/2 of Cass County, Crow Wing County, far Southern Pine Counties in Minnesota along with far Southern parts of Washburn County in Northwest Wisconsin. Mostly cloudy skies through early This Afternoon has given way to some partial sunshine during the mid Afternoon hours. High temperatures Today were in the middle 60s to lower 70s with cooler 50s near Lake Superior. 850 mb temperatures as of 3 PM ranged from +11/+18 degrees C across Northern Minnesota and Northwest Wisconsin. Dewpoints Today were in the 40s and 50s, with 60+ degree dewpoints surging north out of Southern Minnesota late Today. 850 mb td's as of mid-Afternoon were in the +6/+9 degree C range across our local area with PWS ranging from 0.80"-1.20". Winds Today were out of the south or east at 5-15 mph with higher gusts.

Today's 500 mb analysis:

Southwest flow aloft covered the Upper Midwest Today with an upper level trough in place across the Northern Rockies/Pacific Northwest per RUC model analysis and water vapor satellite imagery. Strong upper level jet (100-130 knots) extended from Southcentral California through Central Wyoming into the Western High Plains per RUC model analysis.

Tonight:

A southerly low level jet will increase to 40-55 knots Tonight across the Upper Midwest which will continue to pump warm and moist air north into our area. A warm front will head north-northeast out of Southwest Minnesota during the night, and this front combined with an increase in instability with CAPES building to between 1000-2500 j/kg Overnight, along with Lifted Indices of zero/-6 degrees C may help to pop a few showers and thunderstorms, especially in Western-Northern areas Tonight.

There is at least a limited threat for isolated severe thunderstorms Overnight, mainly along and west of a line from International Falls to Leader Minnesota with hail up to 1" in diameter and damaging wind gusts approaching 60 mph being the main threats. Locally heavy downpours and dangerous lightning strikes will also occur in any thunderstorm Tonight.

One limiting factor that may prevent thunderstorms from developing Tonight will be the presence of warm mid level temperatures as 700 mb temps continue to rise to around +10 degrees C later in the night. Low temperatures Tonight will be in the 50s and 60s across Northern Minnesota and Northwest Wisconsin with cooler temperatures near Lake Superior. Winds will be out of the south or east at 10-20 mph with some higher gusts.

Sunday and Sunday Night:

Low pressure will pass off to our west/northwest during this period. A cold front currently in the Western Dakotas will move east and will reach Central Minnesota Sunday Afternoon before stalling out in that general area Sunday Night.

A very moist and unstable airmass will be found over most of our area Sunday and Sunday Night with CAPES ranging from 1500-3500 j/kg with Lifted Indices of -2/-6 degrees C. Dewpoints are forecast to be in the 60s, possibly near 70 degrees...especially away from Lake Superior, 850 mb td's will range from +10/+18 degrees C while PWS range from 1.00"-1.50"!

Plenty of fuel and moisture will be in place for thunderstorms, but warm mid level temps with +10/+12 degree C H7 temperatures and +12/+18 degree C H85 temperatures will also cover most of our area Sunday Afternoon-Evening which may prevent thunderstorms from developing.

If this cap can erode, then scattered showers and thunderstorms would develop during the late Afternoon and Evening hours across Northcentral-Eastcentral-Northeast Minnesota and Northwest Wisconsin.

The threat for widespread severe weather seems low at this time due to winds aloft generally around 30-40 knots while the low level jet decreases to 20-30 knots, the 0-6 km BULK SHEAR and EFFECTIVE BULK SHEAR also isn't the best, with speeds generally around 30 knots in our area per 09z SREF model.

With that said, the combination of high instability and moisture combined with marginal shear along with some convergence near the boundary should cause at least an isolated severe thunderstorm risk Sunday Afternoon and Evening...Mainly over portions of Eastcentral Minnesota and far Northwest Wisconsin.

This would include an area south of a line from Walker to Grand Rapids to Two Harbors Minnesota and west of a line from around Bayfield to Shell Lake in Northwest Wisconsin.

Southern half of Cass, Crow Wing, Aitkin, Southern Itasca, Pine, Carlton, Southern half of St. Louis, Southern Lake Counties In Minnesota and Douglas, Bayfield, Burnett, and Washburn Counties in Northwest Wisconsin would be included in this risk for isolated severe thunderstorms Sunday Afternoon and Sunday Evening.

The main threats would be from large hail up to 1" in diameter and damaging wind gusts to 60 mph. Dangerous lightning strikes and heavy downpours would also occur should a thunderstorm affect your area.

High temperatures on Sunday will be in the 70s and 80s but it could be cooler at times closer to Lake Superior. Lows Sunday Night will be in the 50s and 60s. Partly-mostly cloudy skies are forecast during this period with winds out of the south, east, or west at 10-20 mph.

Extended Forecast:

A warm, moist, and unstable airmass will continue to be in place across the Upper Midwest early next week as strong low pressure passes by well to our west/northwest from Monday into Tuesday. The cold front which will stall out in Central Minnesota on Sunday will retreat back north as a warm front on Monday, then will watch a new cold front settle south/east into Minnesota from Monday Night through Wednesday. There will be a threat for a few showers and thunderstorms across our local area for Monday and Tuesday with an isolated risk for severe storms due to the high amounts of instability and moisture in place. High temperatures for Monday and Tuesday will be in the 70s and 80s in Northern Minnesota and Northwest Wisconsin with cooler temperatures at times closer to Lake Superior. Low temperatures Monday Night and Tuesday Night will be in the 50s and 60s.

5 Day Forecast for Duluth/Superior

.Tonight... Partly to mostly cloudy. Breezy at times. Low 50 to 55 but cooler near Lake Superior. Wind east to southeast at 10 to 20 mph with gusts to 25 mph.

.Sunday... Humid. Variable cloudiness. Showers and thunderstorms possible early and again by late Afternoon. High 72 to 77 but cooler closer to Lake Superior. Wind south to southeast at 10 to 20 mph. Chance of rain 30%.

.Sunday Night... Humid. Variable cloudiness. A few showers and thunderstorms possible. Low 53 to 58. Wind variable at 5 to 15 mph. Chance of rain 30%.

.Monday... Humid. Variable cloudiness. Showers or thunderstorms possible. High 73 to 78 but cooler near Lake Superior. Chance of rain 20%.

.Monday Night... Humid. Partly cloudy. Showers or thunderstorms possible. Low 55 to 60. Chance of rain 20%.

.Tuesday... Humid. Variable cloudiness. Showers or thunderstorms possible. High 73 to 78. Chance of rain 20%.

.Tuesday Night... Showers or thunderstorms possible. Variable cloudiness. Low 53 to 58. Chance of rain 20%.

.Wednesday... Partly sunny. High 75 to 80.

Normal High Temperature Today 66 degrees

Normal Low Temperature Today 42 degrees

Tim