Sunday, August 28, 2016

Warm and muggy on Monday with dew points approaching 70 degrees, highs around 80; Risk for strong to severe thunderstorms in parts of the Northland through Monday evening

/Issued 4:57 PM CDT, Sunday, August 28, 2016/

Visible satellite image from 4:30 PM today.  Source,

Warm front extends from northern and eastern North Dakota southeast toward the Twin Cities late afternoon, this front will lift north/northeast through the night.  Scattered thunderstorms should erupt near and north of this boundary tonight, some of these storms could become strong to severe.

Tonight's severe weather outlook.  Source, Storm Prediction Center.

Severe thunderstorm outlook for Monday, August 29, 2016.  Source, Storm Prediction Center.

Tonight's low temperature forecast.

Monday's high temperature forecast.

Last week's temperature departure map.  The greatest departures from normal last week were once again found closer to Lake Superior where above average temperatures occurred.  Southern portions of northwest Wisconsin had below average temperatures last week while most of northern Minnesota had near to slightly below normal temperatures for the week of August 21st.

Below average precipitation in most of the Northland for the week of August 21st.  The only exception to this was far eastern portions of northwest Wisconsin from Ashland and Hurley south to Park Falls -- Those areas had near normal precipitation totals last week.

Temperature and precipitation report for Duluth, Minnesota - Airport location.

August 21-27, 2016

High temperatures:

8/21:  70 F/-4 degrees below normal
8/22:  81 F/+8 degrees above normal
8/23:  85 F/+12 degrees above normal
8/24:  82 F/+9 degrees above normal
8/25:  72 F/-1 degree below normal
8/26:  73 F/Normal
8/27:  64 F/-8 degrees below normal

Low temperatures:

8/21:  50 F/-4 degrees below normal
8/22:  55 F/+1 degree above normal
8/23:  66 F/+12 degrees above normal
8/24:  57 F/+4 degrees above normal
8/25:  55 F/+2 degrees above normal
8/26:  53 F/Normal
8/27:  57 F/+4 degrees above normal

Total precipitation:  0.33"
Normal:  0.86"
Departure:  -0.53" below normal

Note:  Only a few more days left of August and for Meteorological summer 2016

Stats for Duluth, Minnesota

Total precipitation for August (thru the 27th)  3.24"
Departure:  +0.04" above normal

Precipitation total since June 1st:  12.09"
Departure:  +0.81" above normal

Average temperature for August (thru the 27th)  67.6 degrees
Departure:  +2.9 degrees above normal

24 days so far this month with a high temperature of at least 70 F (Average is 23 days)
11 days so far this month with a high temperature of at least 80 F (Average is 7 days)

72 days so far this summer with a high temperature of at least 70 F (Average is 65 days)

28 days so far this summer with a high temperature of at least 80 F (Average is 23 days)

Note:  The average temperature so far for the summer of 2016 (thru Aug 27) 65.4 degrees which is +2.0 degrees warmer than normal.

Weather Summary for northeast Minnesota and northwest Wisconsin
Date:  August 28, 2016

Widespread low clouds and some fog this morning gave way to increasing amounts of sunshine during the afternoon hours.  High temperatures were generally in the 70s with late afternoon dew points in the 50s in far northeast Minnesota and in the 60s over the rest of the area.  Winds today were out of the south or east at 5 to 15 mph.

Forecast Discussion for northeast Minnesota and northwest Wisconsin

...Short Term Forecast...

Tonight (August 28)

Showers and thunderstorms should increase in coverage in western-northern areas this evening...Storms should then move toward the east or east-southeast reaching eastern Minnesota and far northwest Wisconsin well after midnight.

Some of the storms could be strong to severe tonight especially across north central Minnesota but there is at least a marginal risk for storms to be strong to severe as far east as far northwest Wisconsin overnight.

The setup in place tonight will feature a warm front lifting slowly N/NE into the Northland.  CAPE has increased to 1000-2000 j/kg late this afternoon over most of the Northland with Lifted Indices of about -2 to -6 degrees Celsius.  An area of higher CAPE 3000-5000 j/kg covered the eastern Dakotas and western Minnesota late this afternoon and storms should develop on the nose of this higher instability gradient this evening.

Large hail and strong winds will be the main threats from storms that become severe tonight in parts of the Northland.

There is a chance for a few tornadoes mainly before Midnight generally along and near a Grand Forks to Fargo line east toward Moorhead, Crookston, Detroit Lakes and Park Rapids -- Storm relative helicity values have increased to around 300 m2/s2 late this afternoon per mesoanalysis in that area...If storms can develop this evening they will have a chance to produce a tornado.

Low temperatures tonight will be in the 60s with 50s along the North Shore of Lake Superior.  Winds will be out of the south or east at 5 to 15 mph.

Monday (August 29)

Warm front is forecast to lift north into Ontario Province but a cold front will move through the Northland during the afternoon/evening hours.  If the atmosphere can recover after tonight's storms, then a chance for more strong to severe thunderstorms exists in northeast Minnesota and northwest Wisconsin during the afternoon and evening.

The amount of instability over our area could be higher tomorrow with CAPE possibly in the 3000-4000 j/kg range with Lifted Indices of -4 to -9 degrees Celsius along with mid level lapse rates around 7.0 c/km.

Low level jet although not as strong as tonight (30-40 knots) should still be in the 25-35 knot range on Monday with mid level winds around 30 knots.  Deep layer wind shear is forecast to be at around 30 knots or so.  Note:  The winds aloft and amount of deep layer wind shear that is forecast tomorrow isn't the best but should still be enough to get the job done assuming there is enough clearing before late Monday afternoon.

High temperatures on Monday will be in the 70s and 80s with dew points in the 60s to lower 70s.  Lows Monday night will be in the 50s and 60s.  South or southwest winds tomorrow at 10 to 20 mph will become west or northwest tomorrow night.

...Extended Forecast...

Tuesday and Wednesday (August 30-31)

High pressure builds into the Upper Midwest resulting in dry weather with cooler temperatures and much less humid conditions.  Highs Tuesday and Wednesday are forecast to be in the 70s with lows Tuesday night in the 40s and 50s.

Forecast for Duluth and Superior

.Tonight...  Partly to mostly cloudy.  Showers and thunderstorms possible mainly after Midnight.  Low 62 to 66.  Wind southeast at 5 to 15 mph.

.Monday...  Muggy.  Partly to mostly cloudy.  Showers and thunderstorms possible early and again by late afternoon.  High 79 to 84.  Wind south at 10 to 20 mph.  Dew point around 70 degrees.

Normal temperatures for Monday

High:  72
Low:   52

Sunrise Monday:  6:25 AM CDT
Sunset Monday:   7:53 PM CDT