Saturday, September 17, 2016

Risk of a few showers/t-storms Sunday PM; Mild high temperatures the next few days; Stormy pattern possible Sep 21-26; Turning colder Sep 26-28 (Flurries in N MN?)

/Issued 5:25 PM CDT, September 17, 2016/

Impressive jet stream dynamics developing on Sunday - Here's the 250mb forecast for Sunday evening per 18z NAM.  Source,

Note:  Could get a few thunderstorms to pop up Sunday afternoon or evening over parts of the Northland if there is enough moisture and instability, and also if the cap can break.  Something to watch!

Things could change from what these maps below are showing but potential is there for some interesting weather beginning around September 21.

Tonight's low temperature forecast.

Sunday's high temperature forecast.

7-day precipitation forecast valid thru September 24, 2016.  Source, Weather Prediction Center.

*Local Storm Reports for September 16, 2016*
Source:  National Weather Service Duluth, Minnesota

*8:15 PM CDT:  HAIL.  0.25 inch diameter.  WNW Beroun, MN (Pine County)

Rainfall reports for September 16-17, 2016
Source:  National Weather Service Duluth, Minnesota; MesoWest

Note:  Totals listed below are from 7 AM Friday thru 7 AM Saturday.

Brainerd, MN:  0.97"
Grand Marais, MN:  0.97"
Wright, MN 3E:  0.92"
Aitkin, MN:  0.86"
Hibbing, MN:  0.83"

Island Lake, MN 4E:  0.83"
Eveleth-Virginia, MN:  0.71"
Hinckley, MN:  0.57"
Moose Lake, MN:  0.44"
Saginaw, MN:  0.40"

Embarrass, MN:  0.34"
Tower, MN 2S:  0.32"
Isabella, MN:  0.32"
Cass Lake, MN:  0.31"
Cloquet, MN:  0.31"

Isle, MN 12N:  0.31"
Kabetogama, MN:  0.24"
Washburn, WI:  0.22"
Barnes, WI:  0.21"
Minong, WI:  0.21"

Duluth, MN (NWS)  0.19"
Siren, WI:  0.17"
Grand Rapids, MN 12N:  0.16"
Duluth, MN (Airport)  0.14"
Two Harbors, MN:  0.13"

Superior, WI:  0.13"
Littlefork, MN:  0.13"
Hayward, WI:  0.13"
Clam Lake, WI 4W:  0.12"
Ely, MN 25E:  0.12"

Walker, MN:  0.12"
Ashland, WI:  0.05"

Here's a look at when the first fall freeze occurred at the Duluth Airport dating back to 2000.

Note:  Temperature equal to or less than 32 degrees.

2000:  September 23 (30 degrees)
2001:  September 24 (30 degrees)
2002:  September 24 (32 degrees)
2003:  September 28 (31 degrees)
2004:  October 1 (30 degrees)
2005:  October 6 (32 degrees)
2006:  October 10 (28 degrees)
2007:  September 12 (29 degrees)
2008:  October 3 (28 degrees)
2009:  October 8 (32 degrees)
2010:  September 26 (31 degrees)
2011:  September 15 (30 degrees)
2012:  October 6 (27 degrees)
2013:  October 19 (32 degrees)
2014:  October 6 (32 degrees)
2015:  October 7 (31 degrees)
2016: ???

Earliest since 2000:  September 12, 2007.
Latest since 2000:  October 19, 2013

Weather Summary for northeast Minnesota and northwest Wisconsin
Date:  September 17, 2016

Moist cyclonic flow occurring today with low pressure centered northeast of Lake Superior late this afternoon - Partly sunny to mostly cloudy skies were common throughout the area with spotty showers occurring this afternoon mainly over the Arrowhead of Minnesota and in far northern Wisconsin.  Highs today were in the 60s with west winds at 10 to 20 mph.

Forecast Discussion for northeast Minnesota and northwest Wisconsin

.Short Term Forecast...

Tonight (September 17)

Lingering spotty showers early this evening otherwise clearing skies tonight with patchy fog possible late.  Lows in the 40s to around 50 degrees with 30s possible in the typical cold spots.  West winds becoming south later in the night.

Sunday (September 18)

Strong moisture advection will be occurring on Sunday.  Dew points starting out in the 40s tomorrow morning rising to between 60-65 degrees by early Sunday evening.  PWATS ~0.50" increasing to ~1.25".  Southwest low level jet of 25-40 knots is forecast to develop tomorrow which will help increase the moisture in our area.

Low pressure will be centered to our northwest while a warm front and cold front push through the Northland Sunday night.  The computer models continue to show the atmosphere becoming unstable with CAPE increasing to around 1000 j/kg Sunday night, this combined with steep mid level lapse rates of around 7.0 c/km; Increasing winds aloft 35-45 knot mid level winds and a 60 knot upper level jet to our north while a 120+ knot wind max spreads east into North Dakota.

Partly to mostly cloudy skies are expected on Sunday and there is a chance for scattered showers and thunderstorms especially from Sunday afternoon through Sunday night.

A few of these storms could become strong to severe mainly Sunday evening with a threat of large hail and gusty winds.

Highs on Sunday will be in the 70s with 60s along the North Shore of Lake Superior.  Lows Sunday night will be in the 50s and 60s.  Winds tomorrow will be out of the south at 10 to 20 mph with winds turning to the southwest tomorrow night.

.Extended Forecast...

Monday (September 19)

Mainly dry weather is expected on Monday as a cold front pushes well to the south/east of our area.  Highs are forecast to be in the 60s and 70s with lows in the 40s and 50s.

Tuesday (September 20)

Dry weather should continue on Tuesday with highs mainly in the 70s.

Note:  The period from September 21-25 could be wet at times as a strengthening baroclinic zone/warm front develops south of the Northland -- Depending on how far north things setup will determine just how much rain will get in northeast Minnesota and northwest Wisconsin.  There is potential of a few inches of rain somewhere in Minnesota and Wisconsin during the aforementioned time frame.

Forecast for Duluth and Superior

.Tonight...  Decreasing cloudiness.  Patchy fog possible late.  Low 45 to 50.  Wind west at 5 to 15 mph.

.Sunday...  Partly to mostly cloudy.  Late afternoon-evening showers or thunderstorms possible.  High 68 to 73.  Wind south at 10 to 20 mph.

Normal temperatures for Sunday

High:  64
Low:   45

Sunrise Sunday:  6:51 AM CDT
Sunset Sunday:   7:13 PM CDT