Issued at 2:00 PM CDT, Thursday, July 8th, 2010
Forecast Discussion for Northeast Minnesota and Northwest Wisconsin
Mild temperatures continued Today with middle 70s to lower 80s common over all but extreme Northern Minnesota with lower 70s up at International Falls (2 PM) Partly-mostly sunny skies were found across our area Today with a comfortable day in terms of humidity as dewpoints were generally in the 50s with PWS around 0.80". A cold front was moving southeast out of Northwestern Minnesota early This Afternoon and the airmass along and ahead of this front in Northcentral Minnesota was becoming a bit unstable per latest meso-analysis, a few light rain showers have developed This Afternoon over portions of Northern Minnesota, generally north and northwest of a line from Walker to Ely Minnesota. None of the showers have been heavy thus far with most locations only receiving trace amounts of rain.
Today's Upper Level Analysis:
The flow aloft has turned more westerly over the Upper Midwest Today compared to recent days. An upper level low (564 meters) was heading east through Western-Northern Ontario Province This Afternoon per water vapor satellite imagery with a northwest flow aloft spreading southeast out of Westcentral Canada into the Northern Plains behind that upper low. 850 mb temperatures across Northern Minnesota and Northwest Wisconsin ranged from +11/+13 degrees C This Afternoon.
Spotty showers and isolated thunderstorms will occur mainly over Northcentral Minnesota This Evening as some cold air aloft (H5 temperatures around -14 degrees C) combines with some instability with CAPES around 500 j/kg and Lifted Indices around -2 degrees C with Lapse Rates from 6.0-8.0 c/km to help generate some spotty convection This Evening. The best chance for seeing this activity should remain north of a line from Hackensack in Cass County Minnesota toward Floodwood in Southwest St. Louis County, then through the Arrowhead of Minnesota. Partly cloudy skies will be found across our area Tonight with patchy late night fog possible, especially in locations that do see some showers late This Afternoon-Evening. Lows Tonight will be in the 50s, but some 40s could occur in the typical chilly spots. Winds Tonight will be out of the west, southwest, or northwest under 20 mph.
Friday and Friday Night:
The cold front which will pass through our area the rest of Today and Tonight will settle south and out of our area Tomorrow and Tomorrow Night, but some lingering cold air aloft will remain over Northern Minnesota and this combined with daytime heating could help develop a few spotty showers Friday Afternoon and Friday Evening north of a line from Grand Rapids to Silver Bay Minnesota. Partly cloudy skies will be found across our area Friday and Friday Night with highs in the 70s to lower 80s with lows Friday Night in the 50s to lower 60s. Winds during this period will be out of the west at 10-20 mph.
An area of high pressure will build into the Upper Midwest by way of the Northern Plains through Friday Night, this high will shift off to our east by Saturday which will cause southerly winds to develop across our local area. Dewpoints will increase to the 60s for Saturday and possibly into Sunday as well. A cold front will be dropping southeast through Northern Minnesota and Northwest Wisconsin Saturday Night into Sunday and this front combined with the increasing moisture and instability along and ahead of this boundary should result in the development of scattered showers and thunderstorms in our area from Saturday Afternoon through Sunday. There continues to be timing issues between the forecast models Today in regards to the cold front this weekend, so changes to the forecast could occur.
Right now it doesn't look like there will be much of a widespread severe risk with this system due to weak shear and generally weak winds aloft, but the low level jet looks decent (25-35 knots) and winds will also be changing directions with height (SW at 850 mb) versus (W-NW at 500 mb), so we do have some positives to support severe thunderstorms. If the winds aloft and speed shear can increase, then the prospects for a more organized severe weather threat could occur in portions of our area.
High temperatures on Saturday will be in the 70s and 80s with lows Saturday Night mainly in the 60s. Highs on Sunday will be mainly in the 70s with lows Sunday Night in the 40s and 50s.
5 Day Forecast for Duluth/Superior
.Tonight... A few showers possible between 5 PM-8 PM, otherwise partly cloudy. Low 53 to 58. Wind west at 5 to 15 mph.
.Friday... Mostly sunny. High 78 to 83. Wind west at 10 to 20 mph.
.Friday Night... Partly cloudy. Low 57 to 62. Wind southwest at 5 to 15 mph.
.Saturday... Partly sunny. High 80 to 85.
.Saturday Night... Showers or thunderstorms possible. Mostly cloudy. Low 60 to 65. Chance of rain 30%.
.Sunday... Showers or thunderstorms possible. Mostly cloudy. High 73 to 78. Chance of rain 30%.
.Sunday Night... Partly to mostly cloudy. Low 51 to 56.
.Monday... Partly sunny. High 70 to 75.
Normal High Temperature Today 76 degrees
Normal Low Temperature Today 54 degrees