Monday, August 30, 2010

8/30/10: Monday's Weather Report

Issued at 4:32 PM CDT, Monday, August 30th, 2010

Weather Tibits:

*Today marks the 4th day in a row with a maximum temperature of at least 80 degrees at Duluth, Minnesota.

*Today's high temperature of at least 80 degrees at Duluth, Minnesota marks the 14th day this month with a high temperature at or above 80 degrees.

*Since June 1st, 2010 there's been measurable rain (trace or greater) on 52 of those days in Duluth, Minnesota.

Weather History:

On this date in 2009... A record low temperature of 38 degrees occurred at Duluth, Minnesota.

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

A very humid and warm day with dewpoints in the middle 60s to lower 70s with PWS of 1.40-1.70"! High temperatures Today were in the middle 80s to lower 90s which is way above average for late August by some 10-20 degrees! There were some showers over portions of Northeast/Eastcentral Minnesota and far Northwest Wisconsin earlier Today, but that activity diminished by the Afternoon leaving behind a partly-mostly cloudy sky across our area along with gusty south winds of 10-25 mph. Surface map late This Afternoon has a stationary front extending from Westcentral Ontario Province Canada through Northwest Minnesota to Eastern North Dakota to Central South Dakota with low pressure averaging 1002 mb centered over Northern South Dakota.

Today's Upper Level Analysis:

A very active weather pattern has evolved as we begin to close out the month of August. A strong upper level trough covered the Northern Rockies and Pacific Northwest Today per water vapor satellite imagery with late Afternoon RUC model analysis showing an 80-90 knot upper level jet on the south/east side of this 500 mb trough. A vigorous disturbance was heading N-NE out of the Northern Rockies and into the Northern Plains late Today and it's this disturbance combined with the front along with ample instability, shear and moisture in place that will lead to a severe weather outbreak Tonight across portions of the Northern Plains and Upper Midwest. A southwest flow aloft continued Today across our area out ahead of this trough with a plume of deep tropical moisture lifting north from Texas through the Central Plains into the Upper Midwest per water vapor satellite imagery. A large upper level ridge continued to dominate areas to our south/east, while Hurricane Earl a category 4 storm with 135 mph winds heads away from the Virgin Islands This Afternoon with movement toward the west-northwest.


Low pressure will deepen to around 998 mb as it lifts N/NE out of Northern South Dakota. A stationary front near the Red River Valley (NW MN) will turn into a cold front during the night, but this boundary will remain to our west the entire night. Our immediate area will remain in the warm sector of this storm Tonight with a strong 850 mb jet out of the S-SW at 30-55 knots which will continue to pump warm and muggy air north into our area. Lows Tonight will only drop into the 60s and 70s once again with dewpoints in the 65-72 degree range while those south winds vary in speeds between 10-25 mph. Partly-mostly cloudy skies will cover our area Tonight with scattered showers and thunderstorms developing, first in far Northern-Western parts our area, then spreading into Eastern-Northeast Minnesota and far Northwest Wisconsin Overnight.

CAPES should remain around 1000-1500 j/kg Tonight across portions of our area with Lifted Indices of -2/-5 degrees C. SHEAR of around 30 knots combined with mid level winds increasing to 30-40 knots could lead to a few severe thunderstorms before 2 AM CDT, mainly west of a line from Ely to McGrath Minnesota, including the Counties of Northern-Western St. Louis, Koochiching, Itasca, Cass, Crow Wing and Aitkin. Damaging wind and possibly some large hail will be the main threats in our area with a risk for a couple tornadoes This Evening in Western Minnesota and the Eastern Dakotas. Locally heavy rainfall and dangerous lightning strikes will also occur with any thunderstorm Tonight.

Tuesday and Tuesday Night:

Strong low pressure will deepen to around 990 mb as it heads N/NE through Eastern Manitoba Province/Western Hudson Bay Canada during this period while a cold front trailing southwest of the surface low moves through our local area Tomorrow and Tomorrow Evening before it exits to our south/east later Tomorrow Night.

At this time it appears that the greater threat for a few severe thunderstorms for Tuesday Afternoon/Evening would be over Northwest Wisconsin with a lesser risk in Northeastern-Eastern Minnesota. CAPES of 1000-2000 j/kg with Lifted Indices from -2/-6 degrees C are forecast to cover those above mentioned areas Tuesday Afternoon with dewpoints along and ahead of the front ranging from 68-75 degrees with PWS around 1.30-1.75". The low level jet on Tuesday looks much weaker compared to Tonight, however, thanks in part to the main surface low lifting into Central Canada and away from our area, but SHEAR of 30-40 knots will be in place along with 35-45 knot mid level winds and these factors could help to trigger a few severe storms with damaging wind and large hail being the main threats along with heavy rainfall and dangerous lightning.

Partly-mostly cloudy skies will cover Northern Minnesota and Northwest Wisconsin with highs Tomorrow in the 70s and 80s with lows Tomorrow Night in the 50s to around 60 degrees. Southwest winds will turn westerly at 10-20 mph during this period.

Extended Forecast:

A temporary area of high pressure will move through the Upper Midwest on Wednesday before the next low pressure system and it's upper level trough and cold front dig into the Upper Midwest/Western Great Lakes region from Wednesday Night into early Friday. Instability and moisture with this next event looks skimpy, but the dynamics of this system combined with the colder temperatures moving in aloft Thursday Afternoon will lead to areas of rain and embedded thunderstorm activity across Northern Minnesota and Northwest Wisconsin from Wednesday Night into Thursday Night. All in all it looks like a much cooler and less humid weather pattern from Wednesday into this Labor Day holiday weekend as a northwest flow develops by the end of the week. High temperatures on Wednesday will be in the 60s and 70s with lows Wednesday Night mainly in the 50s. Highs for Thursday will be in the 50s and 60s with lows Thursday Night in the 40s and 50s.

5 Day Forecast for Duluth/Superior

.Tonight... Unseasonably warm. Humid. Variable cloudiness. Scattered showers or thunderstorms possible after Midnight. Low 68 to 73. Wind south at 10 to 20 mph. Chance of rain 40%.

.Tuesday... Muggy. Scattered showers or thunderstorms. Variable cloudiness. High 78 to 83. Wind south at 10 to 20 mph. Chance of rain 40%.

.Tuesday Night... Turning cooler and less humid. Showers or thunderstorms possible early. Becoming partly cloudy. Low 55 to 60. Wind becoming west at 10 to 20 mph. Chance of rain 40%.

.Wednesday... Cooler and less humid. Partly cloudy. High 70 to 75.

.Wednesday Night... Becoming mostly cloudy. Showers possible late. Low 50 to 55. Chance of rain 30%.

.Thursday... Mostly cloudy. Occasional showers. High 65 to 70. Chance of rain 50%.

.Thursday Night... Mostly cloudy. Showers possible. Low 47 to 52. Chance of rain 30%.

.Friday... Partly sunny. High 60 to 65.

Normal High Temperature Today 70 degrees

Normal Low Temperature Today 50 degrees