/Issued 4:03 PM CDT, Monday, July 8, 2013/
-“U shape” dip, see it over Washington state? Well, that’s the disturbance which will track east during the next 24 hours. As that energy comes this way it may help to spawn some strong-severe thunderstorm activity in NE MN and NW WI on Tuesday. (Source, 12z RAP model 500mb)
-Here’s a water vapor satellite loop from Today. Note the swirl/twisting motion over the Northwestern U.S., quite a potent system for early July.
Weather tidbits for Duluth, Minnesota (Airport location)
*The high temperature on Sunday (July 7) failed to reach 70 degrees for the 1st time since June 22. 69 F on 7/7 and 64 F on 6/22.
*July is off to a warmer than normal start. The average monthly temperature (thru the 7th) 67.6 degrees which is 2.9 degrees above average.
*0.34″ of rain has fallen so far this month which is 0.69″ below average.
*As a whole, the summer has been slightly drier than normal with 4.88″ of rain since June 1, this is 0.38″ below average.
*Yearly precipitation total remains well above normal though. 18.22″ of precipitation since January 1 which is 4.04″ above average.
Today’s Weather Summary for Northeast Minnesota and Northwest Wisconsin
Another nice summer day away from Lake Superior Today with partly to mostly sunny skies with highs in the mid 70s to mid 80s. Dense fog and drizzle near Lake Superior slowly eroded through the day with at least partial sunshine developing This Afternoon but temperatures remained cool with 50s and 60s common near the big lake. Winds Today were light and variable in direction at 5 to 15 mph.
Forecast Discussion for Northeast Minnesota and Northwest Wisconsin
Short Term Forecast – Confidence: High.
Tonight (July 8th)
A weak area of high pressure will remain over Lake Superior Tonight while a cold front drops slowly SE reaching a line from Southern North Dakota to Northwest Minnesota by dawn. Another boundary over Central Iowa might lift a bit to the north during the night, but for the most part it should remain south of Minnesota. Partly to mostly cloudy skies are expected in our area Tonight with areas of dense fog and drizzle redeveloping once again near Lake Superior. The best chance for any showers and thunderstorms looks like it’ll remain west/south of the Northland Tonight, but certainly can’t rule out a few showers or thunderstorms in Western parts of the area. Lows will be in the 50s and 60s with winds out of the south or east at 5 to 15 mph.
-Areas in gray are under a dense fog advisory once again. Starts at 11 PM Tonight and goes until 12 PM CDT Tuesday. The entire North Shore and South Shore of Lake Superior and the Twin Ports of Duluth and Superior are included in this advisory. (Source, NWS Duluth hazards map)
Tuesday and Tuesday Night (July 9th)
A potent disturbance across the Northwest U.S. Today will head east into the Northern Plains, Upper Midwest, and Western Great Lakes during this period. A cold front which is forecast to be over NW Minnesota Tomorrow Morning will drop south/east into Tuesday Evening while an area of low pressure passes south of the Northland.
A very moist and unstable airmass will be found out ahead of the disturbance and various boundaries on Tuesday with dew points away from Lake Superior reaching the 60s and 70s with CAPE of 1000-2500 j/kg and Lifted Indices of -3 to -8C. So no doubt there’s going to be plenty of fuel/juice in the air for thunderstorm development. Will also have sufficient lift thanks to the cold front and vigorous disturbance.
One problem could be cloud-cover and if this is extensive and lingers much of the day, this would limit the amount of heating and would also keep the instability down. Another potential problem could be subsidence that may occur behind any sort of Morning thunderstorm complex.
If we do get enough clearing/heating to take place on Tuesday, then there could be some severe thunderstorms in the Northland with the main threats being from large hail and damaging winds. The 0-6 KM Bulk Shear and Effective Bulk Shear is forecast to be in the 30-40 knot range with strong upper level winds of 70-90 knots to our northwest and mid level winds of 40-55 knots streaking east out of the Dakotas. So there is quite a bit of support in terms of the amount of winds aloft and with the amount of shear.
High temperatures on Tuesday will be in the 70s and 80s with cooler temperatures near Lake Superior. Lows Tuesday Night will be in the 40s and 50s. South, west or east winds Tomorrow at 5 to 15 mph will become west Tomorrow Night at 10 to 20 mph.
-Here’s the surface map for Tuesday PM per NCEP/WPC. Cold front heads into the Northland along with an area of low pressure, often times this would lead to some active weather anytime you see this sort of setup during the summer months. Will see what happens Tomorrow.
Extended Forecast – Confidence: High.
Wednesday through Friday (July 10th-12th)
Wednesday and Thursday are shaping up to be classic summer days as high pressure builds over the Upper Midwest. Highs are forecast to be in the 70s to lower 80s with lows in the 40s and 50s. Southerly flow returns on Friday with increasing amounts of moisture, but right now it doesn’t look like will have any showers or thunderstorms to deal with at least on Friday. Highs will be in the 70s and 80s on Friday with cooler temperatures along the North Shore of Lake Superior.
Long Range Forecast – Confidence: High.
Showers or thunderstorms are possible at times from the 13th-15th. Near to above average temperatures are forecast through this period.
5 DAY FORECAST FOR DULUTH/SUPERIOR
*Dense Fog Advisory 11 PM Tonight until Noon CDT Tuesday*
.Tonight… Partly cloudy with areas of dense fog and drizzle developing. Low 53 to 58. Wind east at 5 to 15 mph.
.Tuesday… Areas of dense fog and drizzle. Considerable cloudiness with showers or thunderstorms. High 70 to 75 but cooler near Lake Superior. Wind east to southeast at 10 to 15 mph.
.Tuesday Night… Showers or thunderstorms possible during the Evening. Partly to mostly cloudy. Low 50 to 55. Wind becoming west at 10 to 20 mph.
.Wednesday… Partly cloudy. High 73 to 78.
.Wednesday Night… Mostly clear. Low 50 to 55.
.Thursday… Partly cloudy. High 78 to 83.
.Thursday Night… Partly cloudy. Low 55 to 60.
.Friday… Partly sunny. High 75 to 80.
Normal temperatures for Today
Sunrise Tuesday: 5:24 AM CDT
Sunset Tuesday: 9:03 PM CDT