Sunday, April 9, 2017

Showers, few t-storms tonight. Low confidence forecast for Monday with rain/snow possible (Narrow band of heavy snow?) Snowfall map in this post

/Issued 5:39 PM CDT, Sunday, April 9, 2017/

Kept going back and fourth with my snowfall map as to the location of the heaviest snowfall band, but in the end this is what I have come up with.

Source:  18z RAP model;

Thunderstorm potential through tonight per Storm Prediction Center.  A few strong to severe thunderstorms could affect parts of eastern Minnesota and northwest Wisconsin.

Surface analysis from late Sunday afternoon, April 9, 2017.

Tonight's low temperature forecast.  Source:

Monday's high temperature forecast.  Source:

30-day precipitation total.  Source:

Drier than average here in the Northland while above average precipitation has occurred south of the Northland during the past 30 days.

Temperature departure map for the week of April 2, 2017.  Source:

Precipitation departure map for the week of April 2, 2017.  Source:

Temperature and precipitation report for Duluth, Minnesota (Airport location)

April 2-8, 2017

High temperatures

4/2:  57 F/+15 degrees above normal
4/3:  53 F/+10 degrees above normal
4/4:  56 F/+13 degrees above normal
4/5:  51 F/+7 degrees above normal
4/6:  50 F/+6 degrees above normal
4/7:  58 F/+13 degrees above normal
4/8:  62 F/+17 degrees above normal

Low temperatures:

4/2:  33 F/+9 degrees above normal
4/3:  38 F/+13 degrees above normal
4/4:  36 F/+11 degrees above normal
4/5:  33 F/+7 degrees above normal
4/6:  28 F/+2 degrees above normal
4/7:  24 F/-2 degrees below normal
4/8:  36 F/+9 degrees above normal

Total precipitation:  0.11"
Normal:  0.46"
Departure:  -0.35" below normal

Note:  Today is the 10th day in a row with a high temperature of at least 50 degrees at the Duluth Airport, and the 2nd day in a row with a high temperature of at least 60 degrees.  This streak will end on Monday.

Weather Synopsis for northeast Minnesota and northwest Wisconsin

An area of low pressure was over extreme northwest Iowa at 4 PM today with a warm frontal boundary stretching from south central Minnesota to central Wisconsin to southern Upper Michigan.  There's been some showers today over parts of east central and northeast Minnesota while stronger thunderstorms have erupted closer to the warm front across north central Wisconsin.  Quite a contrast in temperatures this afternoon with 30s in northwest Minnesota with mid 60s/low 70s in south central Minnesota -- Here in the Northland highs were above average once again today with 50s and 60s.

Low confidence forecast through Monday night.

Expect showers and scattered thunderstorms to continue tonight from east central Minnesota through northwest Wisconsin.  A few of the storms could become strong to severe with enough instability and shear present in those areas.  Elevated CAPE ~500 j/kg along with steep mid level lapse rates combined with 50-60 knots of 0-6 KM shear supports a risk of stronger convection especially this evening with hail being the main hazard with storms over southern portions of the Northland.

The period from Monday morning through early Tuesday morning is still a mystery.  Low pressure is forecast to be somewhere between southern Wisconsin/northern Illinois while a potent mid/upper trough now over northern Rockies tracks E/NE into the upper Midwest.

There will be precipitation Monday in northwest Wisconsin and east central Minnesota with rain early in the morning likely mixing with and switching over to wet snow by Monday afternoon.  A narrow band of heavy wet snow is expected to develop but where this band sets up is still uncertain.  Computer models especially the NAM continue to shift the band NW-SE every new model run while the EURO has been more consistent the past couple of runs with its further SE location of the heavier snowfall.  I'm riding more with the EURO model which results in not much snow for the Twin Ports Monday and Monday night, this is backed up further with the 18z models of the GFS and RGEM which have shifted the main snow band farther southeast compared to earlier model runs.

Lows tonight and highs Monday will be in the 30s and 40s with the coldest temperatures Monday where the heavier rain/snow will be falling.

Forecast for Duluth and Superior

.Tonight...  Occasional showers.  Mostly cloudy.  Low 34 to 38.  Wind becoming north at 10 to 20 mph.

.Monday...  Mostly cloudy.  Breezy.  Occasional rain or wet snow possible.  Snowfall less than one inch.  High 34 to 38.  Wind north to northeast at 15 to 25 mph.

Normal temperatures for Monday

High:  46
Low:   28

Sunrise Monday:  6:30 AM CDT
Sunset Monday:   7:50 PM CDT