Sunday, August 28, 2016

August 28, 2016: Occasional strong to severe thunderstorms possible in parts of the Northland tonight through Monday evening

/Issued 10:50 AM CDT Sunday, August 28, 2016/

Heads up for tonight - Could turn a little stormy at times as a warm front lifts north out of southern Minnesota.

Here's the severe thunderstorm outlook for tonight from the Storm Prediction Center (8 AM update)

Excessive rainfall outlook from the Weather Prediction Center.  This is valid through 7 AM CDT Monday.

This was the setup for Saturday, August 27, 2016.  Cold temperatures aloft with just enough warming near the surface making the atmosphere unstable, this combined with a strong upper level low pressure system helped to produce scattered severe thunderstorms Saturday afternoon in far eastern North Dakota and far western Minnesota.  Source,

Filtered storm reports map for August 27th, 2016.  Source, Storm Prediction Center.

Several reports of large hail and a couple reports of tornadoes on Saturday in extreme eastern North Dakota and far western Minnesota.  Biggest hail size was 2.00 inches in diameter (Larger than golf balls)

Rainfall reports for August 27, 2016
Source:  National Weather Service Duluth, Minnesota; CoCoRaHs; MesoWest

Kabetogama, MN 1.5 NW:  0.85"
Kabetogama, MN:  0.72"
International Falls, MN:  0.59"
Littlefork, MN:  0.57"

Iron Junction, MN 3.4 NNW:  0.49"
Bigfork, MN:  0.43"
Duluth, MN 4.2 NNE:  0.40"
Spooner, WI 10.6 WNW:  0.39"

Duluth, MN 3.0 NE:  0.37"
Hibbing, MN:  0.34"
Winton, MN 0.1 WSW:  0.34"
3 E of Orr, MN:  0.33"

Duluth, MN (Airport)  0.32"
Cook, MN:  0.32"
Siren, WI:  0.29"
Hayward, WI:  0.27"
Barnes, WI 2.2 S:  0.26"

Cloquet, MN 3.1 ENE:  0.25"
Hayward, WI:  0.27"
Embarrass, MN:  0.24"
4 W of Clam Lake, MN:  0.22"

Mellen, WI 18.6 SW:  0.22"
Hovland, MN 0.1 NE:  0.21"
Iron River, WI 7.2 SE:  0.17"
Hayward, WI 9.2 NNE:  0.16"

Stone Lake, WI 2.0 NW:  0.15"
Grand Rapids, MN:  0.13"
Park Falls, WI 1.3 N:  0.12"
Ashland, WI 0.5 WNW:  0.12"

Two Harbors, MN:  0.11"
Superior, WI (Airport)  0.07"

Mostly cloudy skies continue over most of the Northland late this morning but I do think will see these clouds slowly erode this afternoon which should lead to at least partially sunny skies in most of the area during the afternoon hours.  Highs today will warm into the 70s with a few locations possibly nearing 80 degrees if skies clear soon enough.

-Focus for tonight and also on Monday will be the potential for a couple rounds of strong to severe thunderstorms which could affect parts of the Northland.

-A warm front approaching from the southwest along with a reservoir of unstable air with CAPE >2000 j/kg will be found over western and central Minnesota with steep mid level lapse rates also in place.  We should see thunderstorms develop this evening or overnight tonight across western, central and northern Minnesota with a threat for large hail and damaging winds...Heavy rain is also possible which could lead to flash flooding.

-Monday could also turn stormy at times as a cold front approaches the Northland from the northwest during the afternoon/evening hours.  If the atmosphere can recover after tonight's round of storms, then there could be another round of strong to severe thunderstorms in portions of the Northland especially from late Monday afternoon through Monday evening.  Hail and gusty winds appear to be the main threats from this activity later Monday.