Wednesday, July 20, 2016

July 20, 2016: Scattered strong to severe t'storms possible late tonight; Hot and muggy Thursday with record or near record warmth possible in Duluth

/Issued 8:21 PM CDT, Wednesday, July 20, 2016/

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

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

NWS Duluth headlines map.

More information about the heat advisory at this link:

Tonight's low temperature forecast.  Source, National Weather Service Duluth, Minnesota.

Thursday's high temperature forecast.  Source, National Weather Service Duluth, Minnesota.

Weather Summary for NE Minnesota and NW Wisconsin
Date:  July 20, 2016

A very warm and more importantly a very muggy day as high temperatures climbed into the 80s with a few locations making it into the low 90s.  Dew points were generally in the 70s which is oppressive especially for our area.  A lake breeze continued today around Lake Superior which kept temperatures in the 70s although it was still very muggy with dew points in the 60s to lower 70s.  Partly to mostly cloudy skies were common today with very warm temperatures aloft helping to keep thunderstorms from developing despite a very unstable atmosphere.  Winds today were out of the south or east at 10 to 20 mph.

Heat index (Feels like temperature) from 4 PM today, July 20, 2016

Hinckley, MN:  102 F
Ashland, WI:  100 F
International Falls, MN:  97 F
Two Harbors, MN:  97 F
Silver Bay, MN:  96 F
McGregor, MN:  96 F
Siren, WI:  96 F
Aitkin, MN:  95 F
Cloquet, MN:  95 F
Ely, MN:  94 F
Hayward, WI:  93 F
Phillips, WI:  91 F
Duluth, MN (Airport)  91 F

Forecast Discussion for NE Minnesota and NW Wisconsin

Confidence:  Medium.

Tonight (July 20)

Very warm and muggy under partly to mostly cloudy skies.  Low temperatures will only settle into the 70s which is the average HIGH temperature for this time of year.  Dew points will remain close to the 70 degree mark though the night in most of the Northland.  Winds will be out of the south, east or southwest at 5 to 15 mph.

Low pressure will move east out of the northern Plains tonight while a warm front lifts northeast into central Minnesota.

An incredible amount of instability will remain over the Northland tonight with CAPE values of 2000-4000+ j/kg along with very steep lapse rates of 7.0-8.5 c/km.  A strong cap consisting of +14 degree Celsius 700mb temperatures remain over the area this evening and its possible that the H7 temperatures won't cool much through the night -- This may keep convection from developing or moving very far into the Northland.  On the other hand, should thunderstorms be able to initiate, then they certainly could become strong to severe with a threat for damaging wind and large hail.  Frequent cloud to ground lightning and torrential rainfall will also occur if storms can develop.

Thursday (July 21)

Hot and muggy, in fact high temperatures Thursday should end up warmer than what we saw on Wednesday.

Low pressure along with a warm front and cold front will pass through the area on Thursday.  Very unstable airmass will remain in place especially over east central Minnesota into northwest Wisconsin.

There could be some lingering showers and thunderstorms early in the morning, then if any storms redevelop during the afternoon-evening they should be confined to northwest Wisconsin the way it looks now.

High temperatures are forecast to be in the 80s and 90s with the 90 degree temperatures probably more widespread compared to Wednesday.

Dew points are forecast to range from the 60s in far northern Minnesota with 70s and perhaps near 80 degree dew points over the rest of the Northland.

Winds will be out of the west or southwest at 10 to 20 mph.

Note:  The potential for a lake breeze on Thursday is much lower although one can't be completely ruled out..Just never know what that big lake will do sometimes.  As long as we get some sun in Duluth on Thursday I see no reason why temperatures won't climb to at least 90 degrees, possibly as warm as 95 degrees by late afternoon.  But, if clouds stick around then temperatures will likely stay below 90 degrees.

Forecast for Duluth and Superior

Timing:  Until 9 PM CDT Thursday

Tonight - Muggy.  Partly to mostly cloudy.  Showers and thunderstorms possible after midnight.  Low 68 to 73.  Wind southeast at 5 to 15 mph.

Thursday - Hot and muggy.  Partly to mostly sunny.  Showers and thunderstorms possible mainly early.  High 90 to 95.  Afternoon heat index of 95 to 100.  Wind west to southwest at 10 to 20 mph.  Note:  *Record high temperature is 93 degrees last set in 1960*

Normal temperatures for Thursday

High:  77
Low:  56

Sunrise Thursday:  5:36 AM CDT
Sunset Thursday:   8:53 PM CDT