Issued at 3:58 PM CDT, Friday, July 31st, 2009
On this date in 2006… A record high temperature of 95 degrees occurred at Duluth, MN.
Forecast Discussion for Northeast Minnesota and Northwest Wisconsin
Partly sunny to mostly cloudy skies were common across our area Today with an area of scattered showers and isolated thunderstorms affecting parts of Northeast Minnesota and Northwest Wisconsin This Afternoon thanks in part to some lingering cold air aloft with -14 degree C 500 mb temperatures. Brief heavy downpours have been the biggest threat from this activity Today. High temperatures were generally in the upper 60s and 70s Today with 300 PM 850 mb temperatures of +11 to +13 degrees C. Afternoon dewpoints were running in the 50s with PWS of 0.80″-1.00″. Weather map This Afternoon featured an area of low pressure of 1006 mb centered over Southern Manitoba Province with a secondary low of 1006 mb centered over the Northeast South Dakota-Southeast North Dakota area. A strong cold front was connected to both lows and extended from far Northwest Minnesota to Southeast North Dakota to Eastcentral South Dakota as of 3 PM CDT.
(Today’s Upper Level Analysis)
A powerful shortwave and upper level trough with 60 meter 12 hour 500 mb height falls was shifting south-east into North Dakota This Afternoon with unseasonably cold H5 temperatures of -18 to -22 degrees C found over Manitoba and Saskatchewan Provinces. A strengthening H3 jet streak of 80 knots was located on the backside of this system over Eastern Saskatchewan Province This Afternoon per RUC model analysis with a 70 knot H3 jet streak found on the south-southeast side of this system from Southeastern Montana through Southern North Dakota and Northern South Dakota.
A strong cold front will push east through our area during the night. Warm air advection and some moist advection will commence This Evening ahead of this potent weather system. A 30-45 knot southwesterly H85 jet is forecast to develop ahead of the cold front by mid-Evening and this combined with strong forcing and convergence near the frontal boundary will lead to a fairly widespread area of rain with scattered thunderstorms across all of our area Tonight. The precipitation will spread west to east through the night…reaching areas from International Falls toward Grand Rapids…Brainerd…and Aitkin between 600 PM-800 PM…then spreading east toward Ely…Duluth…Hinckley…and Pine City between 900 PM-1100 PM…The rain area will then reach far Northeast Minnesota and Northwestern Wisconsin toward Midnight or a little after the Midnight hour. Instability looks fairly weak with CAPES generally under 500 j/kg with Lifted Indices of zero to around -2 degrees C…as a result the potential for severe weather is quite low. However this system is very dynamic and will have lots of upper level support working for it with a 60-80 knot H3 jet stream which is forecast to extend from the Dakotas toward Northcentral Minnesota Tonight. With all this upper air support and the strong lift associated with the cold front we should see at least some thunderstorm activity occur with a threat for locally heavy rainfall. Lows Tonight will be in the 40s and 50s with some 60s possible toward Hayward and Park Falls. Winds will be out of the south, southwest, or southeast at 10-20 mph with winds shifting to the northwest at 10-25 mph during the night as the cold front moves through.
(Saturday and Saturday Night)
Strong cold air advection will be in full force on Saturday as H85 temperatures drop to +4 to +8 degrees C across our area. The strong cold front will exit to our east early Saturday with a powerful H5 low centered to our north-northeast while unusually cold air in the upper levels spreads south into our area on Saturday. Look for partly-mostly cloudy skies Tomorrow with a risk for a few showers or possibly a thunderstorm or two mainly across Northern areas of Minnesota. Highs Tomorrow will be in the 60s and lower 70s but some areas north of the Iron Range could hold in the 50s if clouds remain persistent. Lows Tomorrow Night will be in the 40s and 50s with partly-mostly cloudy skies expected. Look for gusty northwest winds at 15-30 mph Tomorrow with winds under 15 mph from the northwest Tomorrow Night.
Plenty of model uncertainty continues Today from late this weekend into early next week. Models are struggling with the timing of disturbances/low pressure systems as well as the track of such features and with how far north-east to push the warmer air. The GFS continues to be the warmest model with +12 to +20 degree C H85 temperatures surging north-northeast into most of our area later this weekend…The NAM on the other hand is much cooler with H85 temps of just +4 to +8 degrees C with all the warm air remaining south of our area…but it could clip the Brainerd area on Sunday. The GEM-GLOBAL and UK models push warmer air into our local area but they hold it off until early next week…
With chilly air remaining to our north and the warmer air trying to push in from the Northern Plains…a fairly strong baroclinic zone will become established which is fairly rare for early August. This baroclinic zone combined with a fast northwest flow aloft will result in a couple of low pressure systems traversing the Northern Plains/Upper Midwest from Sunday into early next week. Again timing of all this is subject to change.
Any one of those disturbances could trigger some shower or thunderstorm activity over portions of our area from later this weekend into early next week. This setup actually is favorable for severe weather to develop…but questions remain on if enough moisture and instability can build north out ahead of these systems.
High temperatures Sunday and Monday will be in the 60s and 70s…these temperatures may end up cooler or warmer though depending on how everything sets up. Low temperatures Sunday Night and Monday Night will be in the 40s and 50s.
5 Day Forecast for Duluth/Superior
.Tonight… Rain and a few thunderstorms developing after 9 PM. Mostly cloudy. Low 50 to 55. Wind south at 10 to 20 mph becoming northwest at 15 to 25 mph after Midnight.
.Saturday… Windy. Variable cloudiness. An Afternoon shower or thunderstorm possible. High 67 to 72. Wind northwest at 15 to 30 mph. Chance of rain 20%.
.Saturday Night… Becoming partly cloudy. Low 47 to 52. Wind northwest at 10 to 15 mph.
.Sunday… Partly sunny. High 68 to 73.
.Sunday Night… Partly to mostly cloudy. Showers possible. Low 50 to 55. Chance of rain 20%.
.Monday… Showers possible. Partly sunny. High 70 to 75. Chance of rain 20%.
.Monday Night… Partly cloudy. Low 48 to 53.
.Tuesday… Partly cloudy. High 65 to 70.
Normal High Temperature Today 77 degrees
Normal Low Temperature Today 56 degrees