Sunday, September 19, 2010

9/19/10: Sunday's Weather Report

Issued at 4:45 PM CDT, Sunday, September 19th, 2010


*The average temperature through the first 18 days of September, 2010 was 52.9 degrees at Duluth, Minnesota making it the 8th coldest start to a September on record. The coldest September ever recorded in Duluth, Minnesota occurred in 1974 with an average temperature of 50.5 degrees. Source: NWS Duluth, Minnesota.

Note: Meteorological summer (June-August) was the 8th warmest on record at Duluth, Minnesota.

Low temperature report for Sunday, September 19th, 2010. Source: NWS Duluth, Minnesota.

Duluth MN: 36 degrees

International Falls MN: 33 degrees

Hibbing MN: 30 degrees

Ashland WI: 35 degrees

Hayward WI: 31 degrees

Ely MN: 32 degrees

Bigfork MN: 34 degrees

Pine River MN: 34 degrees

Moose Lake MN: 32 degrees

McGregor MN: 34 degrees

Superior WI: 36 degrees

Siren WI: 34 degrees

Phillips WI: 36 degrees

Bruno MN: 32 degrees

Cook MN: 32 degrees

Embarrass MN: 27 degrees

Floodwood MN: 31 degrees

Kabetogama MN: 33 degrees

2 miles south of Tower MN: 31 degrees

Upson WI: 31 degrees

4 miles west of Clam Lake WI: 34 degrees

Weather History:

On this date in 1984... A record high temperature of 90 degrees occurred at Duluth, Minnesota.

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Mid and high level clouds which were rather extensive over our area This Morning and early This Afternoon gave way to increasing amounts of sunshine late Today. High temperatures were the middle 50s to lower 60s Today with a dry airmass still in place with PWS of 0.40-0.70" with dewpoints only in the 30s. Winds Today were variable under 15 mph as high pressure of 1024 mb centers itself over Northern Minnesota.

Today's Upper Level Analysis:

Westerly flow at 500 mb continued Today over the Upper Midwest with a large low pressure system covering Hudson Bay/Northeast Canada while an upper level trough heads east out of the Pacific Northwest while a broad 500 mb high pressure ridge covers the Central-Southern U.S./Southern Rockies Today per water vapor satellite imagery.


High pressure will begin to ease off to our north/east while a couple areas of low pressure averaging 1000 mb head into the Northcentral Rockies/Western High Plains. Clear-partly cloudy skies during the Evening will become partly-mostly cloudy Overnight. Lows will be in the 30s and lower 40s Tonight, but some 20s can't be ruled out in the typical cold spots. Patchy frost could develop Overnight, especially away from Lake Superior. Winds Tonight will become easterly under 15 mph.

Monday and Monday Night:

Strong warm/moist advection pattern will overspread our area during this period as low pressure of around 996 mb heads northeast from the Northern Plains to Southern Ontario Province. A warm front currently over the Central Plains will lift north-northeast during this period with a cold front heading east out of the Dakotas and through most of our local area Monday Night. A very strong southerly low level level jet of 40-65 knots will develop Tomorrow and Tomorrow Night over our area which will result in a rapid influx of deep moisture. Dewpoints which will start the day in the 30s and lower 40s are expected to climb into the 55-64 degree range by Monday Evening while 850 mb td's increase to between +8/+12 degrees C Monday Afternoon/Evening with PWS coming up to around 1.00-1.25". Warm advection will be just as impressive with 850 mb temperatures of +2/+6 degrees C early Monday Morning surging to between +12/+20 degrees C by Monday Afternoon/Night.

Instability will increase Monday Afternoon and Monday Night due to the strong low level jet and warm/moist advection pattern. Elevated CAPE is forecast to range from 500-1200 j/kg during that aforementioned time period with Lifted Indices falling to between zero/-3 degrees C. There will also be plenty of SHEAR in place with 40-50 knots of 0-6 KM BULK SHEAR and around 30 knots of EFFECTIVE BULK SHEAR per 15z SREF model run. The negative continues to be the very strong cap that is expected to spread northeast into Minnesota Tomorrow and Tomorrow Night as 700 mb temperatures soar to between +8/+12 degrees C which is very strong for mid-September.

Scattered showers or thunderstorms should develop at times across Northern Minnesota and Northwest Wisconsin by Monday Afternoon into Monday Night as this low pressure system and it's warm front/cold front move through. There should be enough forcing and lift near this system and also near the low level jet to overcome the cap which should allow for some thunderstorm development. At this time it appears that hail will be the main risk from these storms and some of that hail could reach severe criteria (1" in diameter)

High temperatures on Monday will be mainly in the 50s with lows Monday Night in the 40s and 50s. Winds will be out of the east at 10-25 mph on Monday and from the south, east or west at 10-20 mph Monday Night.

Extended Forecast:

Low pressure will exit to our northeast on Tuesday with high pressure building into the Upper Midwest from Tuesday Afternoon into Wednesday. Some showers could linger on Tuesday, mainly in Northwest Wisconsin and possibly in far Northeast Minnesota, otherwise it looks mainly dry for Tuesday Night and Wednesday. Highs will be in the 50s and lower 60s on Tuesday with lows Tuesday Night in the 30s and 40s. Highs for Wednesday will be in the 50s to near 60 degrees with lows Wednesday Night mainly in the 40s. The storm for late this coming week continues to be on track per latest model runs. Low pressure is expected to lift northeast out of the Rockies and Western High Plains with widespread rain which could be heavy along with a few thunderstorms spreading into our area during the late Wednesday Night into Thursday Night time frame.

5 Day Forecast for Duluth/Superior

.Tonight... Mostly clear during the Evening with skies becoming partly to mostly cloudy late. Low 38 to 43. Wind east at 5 to 15 mph.

.Monday... Breezy. Considerable cloudiness. Showers or thunderstorms possible during the Afternoon. High 55 to 60. Wind east at 15 to 25 mph. Chance of rain 30%.

.Monday Night... Scattered showers or thunderstorms. Mostly cloudy. Low 48 to 53. Wind east at 10 to 20 mph becoming southwest Overnight. Chance of rain 50%.

.Tuesday... A few showers possible early. Variable cloudiness. High 58 to 63. Chance of rain 30%.

.Tuesday Night... Partly cloudy. Low 38 to 43.

.Wednesday... Partly cloudy. High 55 to 60.

.Wednesday Night... Partly to mostly cloudy. Low 43 to 48.

.Thursday... Occasional rain. Isolated thunderstorms also possible. Mostly cloudy. High 53 to 58. Chance of rain 70%.

Normal High Temperature Tomorrow 63 degrees

Normal Low Temperature Tomorrow 43 degrees