Issued at 4:58 PM CDT, Saturday, April 2nd, 2011
-Clouds increase This Evening
-Storm arrives late Tonight with lingering effects into Monday
-Greatest snow accumulation expected to be north of the Twin Ports
-Thunder could accompany some of the precipitation early Sunday Morning
-Next system arrives around mid-week
Forecast Discussion for Northeast Minnesota and Northwest Wisconsin
A very pleasant early spring day as high pressure slides east through the Upper Midwest. Partly to mostly sunny skies were found in our area Today with high temperatures mainly in the 40s, but a few locales have reached the 50 degree mark This Afternoon. Winds Today were out of the west, north, or south under 15 mph.
Today's Upper Level Analysis:
A potent 500mb trough was digging south/east through the Pacific Northwest per water vapor satellite imagery. A west-northwest flow was occurring in the Upper Midwest Today out ahead of that H5 trough with an upper level ridge in place across the Central Plains and Southwest U.S. Note: Temperatures have warmed into the 70s as far north as Southern South Dakota Today with 80 degree temps into Southern Nebraska.
Strong area of low pressure averaging 990mb will move from Southern Montana late This Afternoon to Southern South Dakota-Northern Nebraska by 7 AM Sunday. Low level jet from the S-SE will increase to 40-55 knots to the N/NE of the surface low Tonight and this will result in a warm and moist advection pattern setting up across the Upper Midwest. Precipitation is forecast to break out by mid to late Evening west-southwest of our area, then this precip will overspread Northern Minnesota and Northwest Wisconsin late Tonight. Lows Tonight will be in the 20s and 30s and that combined with 850mb temperatures of zero to -4 degrees C should result in mostly snow in our area as the precipitation develops late Tonight. Winds will become east to southeast at 10-20 mph with higher gusts near Lake Superior.
Note: Steep mid level lapse rates pushing in from the southwest combined with the strengthening low level jet could be enough to set off isolated thunderstorms late Tonight and Sunday Morning from Northcentral to Eastern Minnesota and for parts of Northwest Wisconsin.
Sunday and Sunday Night:
Strong low pressure of 987-990mb will move across Northcentral Iowa on Sunday, before moving into Southern Lake Michigan by late Sunday Night. A warm/moist advection pattern will continue north of that low on Sunday so expect additional bands of precipitation to affect the area. At this time it appears that locations north of a Bemidji to Two Harbors, Minnesota line stand the best chance at keeping snow as the dominant precipitation type on Sunday as 850mb temperatures remain around -2/-4 degrees C which should help in preventing any rain or mixed precipitation for that area. South of that line the snow will likely mix with rain, drizzle, and sleet with a complete change-over to liquid precipitation expected along and south of a Pine River to Moose Lake to Butternut line. Areas of fog are also expected to develop on Sunday with some thick fog possible around the head of Lake Superior.
By Sunday Night, expect lingering areas of snow and flurries as moisture wraps around the low to our southeast. Any rain or drizzle should be confined to Sunday Evening and mainly for Northwest Wisconsin and Eastcentral Minnesota. Fog that does develop on Sunday should burn off Sunday Evening as winds shift directions.
Highs Tomorrow will be in the 30s with some 40s in Northwest Wisconsin. Lows Tomorrow Night will be in the 20s and 30s. Winds will be out of the east on Sunday at 10-20 mph with higher gusts. Winds Tomorrow Night will shift to the north or west at 10-25 mph.
Note: Total snowfall accumulations of 4-8" are expected by Monday for Northern Minnesota with locally greater amounts possible in the higher terrain along the North Shore of Lake Superior. 1-4" of snow is expected for the Twin Ports and for areas west and east of Duluth.
Deep low pressure of around 986mb will move into the Eastern Great Lakes/Eastern Canada on Monday while an upper level trough pushes through the Upper Midwest. Snow showers and flurries will linger in our area on Monday with up to another inch of accumulation possible mainly in Northern Minnesota and along the South Shore of Lake Superior where some lake enhanced snow could develop on Monday thanks to colder temperatures and N/NW winds on the back side of the low. Highs on Monday will mainly be in the 30s. Dry weather should return Monday Night and Tuesday with lows in the 20s and highs Tuesday in the 30s and 40s.
The next low pressure system to affect the area will be during the Tuesday Night-Wednesday time frame. This looks to be a Northern Rockies/Clipper type system and it looks to bring some rain or wet snow to Northern Minnesota and Northwest Wisconsin.
5 Day Forecast for Duluth/Superior
*WINTER WEATHER ADVISORY*
Timing: 7 AM CDT Sunday until 1 PM CDT Monday.
.Tonight... Increasing cloudiness This Evening. Snow developing between 2-5 AM. Low 29 to 33. Wind becoming east at 10 to 20 mph.
.Sunday... Snow during the Morning. Occasional snow mixed with rain, sleet, and drizzle during the Afternoon. Areas of dense fog. Total snowfall accumulations of 1-4". Breezy. High 34 to 37. Wind east at 15 to 25 mph with a few higher gusts.
.Sunday Night... Occasional light snow and flurries. Some drizzle and fog mainly early. Low 30 to 33. Wind east, becoming north to northwest at 10 to 20 mph.
.Monday... Snow showers or flurries. Mostly cloudy. High 35 to 40.
.Monday Night... Decreasing cloudiness. Low 20 to 25.
.Tuesday... Partly cloudy. High 38 to 43.
.Tuesday Night... Partly to mostly cloudy. Low 25 to 30.
.Wednesday... Rain or snow possible. Mostly cloudy. High 37 to 42.
Normal temperatures for Tomorrow
Sunrise Tomorrow: 6:45 AM CDT
Sunset Tomorrow: 7:40 PM CDT