Issued at 3:34 PM CDT, Friday, September 9th, 2010
Forecast Discussion for Northeast Minnesota and Northwest Wisconsin
Low pressure averaging 996 mb was centered over Eastern Saskatchewan Province as of 3 PM with a cold front attached to this low extending southeast into the Eastern Dakotas. Showers and isolated thunderstorms have been occurring Today out ahead of this front across the Western half of Minnesota with some of that rain affecting northwest parts of our area, generally west of a line from International Falls to Backus. Partly cloudy-mostly sunny skies occurred in the Arrowhead of Minnesota as well as portions of Northwest Wisconsin Today while clouds were on the increase from southwest to northeast over the remainder of our area. Highs Today ranged from 55 to 65 degrees with a few locations reaching 70 degrees from Hinckley, east through Hayward, Ashland and Park Falls. Winds Today were out of the south or east at 5-15 mph with higher gusts, especially near Lake Superior.
Today's Upper Level Analysis:
Southwest flow aloft covered the Upper Midwest Today with an upper level trough progressing east through the Rockies and Northern Plains with another upper level trough covering Eastern Canada and the Northeast U.S. per RUC model analysis and water vapor satellite imagery. An upper level ridge was in the process of shifting south/east out of the Upper Midwest and Western Great Lakes Today in response to the approaching cold front from the Dakotas.
Low pressure of around 995 mb will move east into Central Manitoba Province with high pressure averaging 1020 mb remaining over Eastern Ontario Province. A cold front attached to the Manitoba low will move across Northern Minnesota and Northwest Wisconsin from west to east Tonight. Dewpoints in the 47-57 degree range, PWS increasing to between 1.00-1.50" and 850 mb td's rising to between +8/+12 degrees C will combine forces with the lift provided by the approaching cold front as well as a rather vigorous disturbance heading E/NE out of the Northern Plains will lead to another rain event in our local area Tonight. Rain will generally move in a east/northeasterly direction, meaning that most of Northwest Wisconsin and the Arrowhead of Minnesota will be dry through around 9-10 PM with rain chances reaching those areas between 10 PM-Midnight. The remainder of our area will see the rain startup before 10 PM. There will be some weak instability moving in Tonight with CAPES generally <200 j/kg this combined with a southerly low level jet of 30-40 knots ahead of the cold front will lead to isolated thunderstorm activity which will be embedded within the area/s of rain Tonight.
The rain will diminish Overnight especially west of a line from International Falls to Aitkin with areas of rain continuing Overnight for Northwest Wisconsin, Eastern-Northeast Minnesota.
Rainfall totals for Tonight should average between one quarter to one half inch, with locally higher amounts possible.
Mostly cloudy skies with lows in the 40s and 50s are forecast Tonight with the potential for some patchy fog. Winds will be out of the south, east or west at 5-15 mph with higher gusts.
Saturday and Saturday Night:
Deep low pressure of 990-992 mb will be centered well to our northwest during this period with a cold front exiting to our east by Saturday Morning, an area of high pressure building in behind this front will be centered well to our southwest. Showers along with patchy fog may persist through Tomorrow Morning in Northwest Wisconsin and in far Northeast Minnesota, otherwise partly-mostly cloudy skies are forecast on Saturday with maybe a spotty Afternoon shower thanks to colder temperatures aloft (H5 readings around -15 degrees C) Highs Tomorrow will be in the 60s with maybe an isolated 70 degree temperature. Lows Tomorrow Night will be mainly in the 40s with partly cloudy skies. Winds will be out of the west during this period at 10-20 mph.
Strong low pressure of 987-990 mb will reach Hudson Bay Canada from Sunday into Monday. A new cold front will develop and push southeast through Northern Minnesota and Northwest Wisconsin on Sunday. Moisture will be limited with this next boundary, but there will be some instability with CAPES <500 j/kg along with Lifted Indices of +2/-2 degrees C. This could be enough when combined with the marginal moisture in place to pop a few showers or thunderstorms Sunday Afternoon/Evening, especially in Eastern Minnesota and Northwest Wisconsin. Highs on Sunday will be in the 60s and 70s with lows Sunday Night in the 40s. Dry weather is expected Monday and Monday Night with highs in the 50s to lower 60s with lows in the 30s and 40s.
5 Day Forecast for Duluth/Superior
.Tonight... Breezy with occasional rain developing between 7-9 PM. Rain continuing at times Overnight. Isolated thunderstorms also possible along with patchy fog. Mostly cloudy. Low 47 to 52. Wind east to southeast at 10 to 20 mph with gusts of 20 to 30 mph especially This Evening.
.Saturday... Considerable cloudiness. Showers possible. High 60 to 65. Wind west at 10 to 20 mph. Chance of rain 20%.
.Saturday Night... Partly cloudy. Low 45 to 50. Wind west at 5 to 15 mph.
.Sunday... Partly sunny. High 68 to 73.
.Sunday Night... Variable cloudiness. Showers possible early. Low 43 to 48. Chance of rain 20%.
.Monday... Partly cloudy. High 57 to 62.
.Monday Night... Partly cloudy. Low 38 to 43.
.Tuesday... Partly cloudy. High 55 to 60.
Normal High Temperature Today 66 degrees
Normal Low Temperarture Today 47 degrees