Sunday, September 18, 2016

A few showers/t-storms tonight; Gusty west winds-mild high temperatures Mon-Tue; Potentially wet pattern Sep 21-25

/Issued 3:55 PM CDT, Sunday, September 18, 2016/

Source, Weather Prediction Center.

Mild high temperatures and a gusty west wind Monday-Tuesday will be replaced by a gusty east wind and cooler temperatures in the Twin Ports starting on Wednesday, and these conditions could linger for several days as the weather pattern becomes stagnant with strong high pressure off to the north while low pressure covers the Rockies and northern Plains -- A warm front will also develop by midweek but should remain south of northeast Minnesota and northwest Wisconsin...This boundary will be one area where periods of rain will occur, and some of this rain could be heavy at times which may lead to flooding.  Note:  There is uncertainty on the placement of the warm front later this week but I think there's a decent chance that it will remain over northern Iowa or southern Minnesota thanks to the high north of Minnesota, as a result the corridor of heavier rainfall would also remain south of the Northland with light to moderate rainfall possible in our local area from mid to late week.

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

Tonight's low temperature forecast.

Monday's high temperature forecast.

Temperature departure map for the week of September 11.  Generally above average to near normal temperatures in most of northeast Minnesota and northwest Wisconsin with an area of below average temperatures in a part of northern Minnesota (Green and blue area on map)

Precipitation departure map for the week of September 11.  Most of the Northland had below average precipitation totals last week with the exception being along parts of the North Shore of Lake Superior which had near to slightly above average rain totals.

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

September 11-17, 2016

High temperatures:

9/11:  76 F/+9 degrees above normal
9/12:  72 F/+5 degrees above normal
9/13:  62 F/-4 degrees below normal
9/14:  64 F/-2 degrees below normal
9/15:  70 F/+5 degrees above normal
9/16:  69 F/+4 degrees above normal
9/17:  65 F/Normal

Low temperatures:

9/11:  50 F/+2 degrees above normal
9/12:  56 F/+8 degrees above normal
9/13:  44 F/-3 degrees below normal
9/14:  40 F/-7 degrees below normal
9/15:  45 F/-1 degree below normal
9/16:  59 F/+13 degrees above normal
9/17:  51 F/+5 degrees above normal

Total precipitation:  0.26"
Normal:  1.00"
Departure:  -0.74" below normal

Weather Summary for northeast Minnesota and northwest Wisconsin
Date:  September 18, 2016

Mild temperatures today with highs in the upper 60s to mid 70s which is 5-10 degrees warmer than normal for today's date.  It was slightly cooler though around Lake Superior due to an easterly breeze.  Partly to mostly sunny skies were found over the area today with southerly winds in the 5-15 mph range.

Forecast Discussion for northeast Minnesota and northwest Wisconsin

.Short Term Forecast...

Tonight (September 18)

A warm front and cold front will move through the Northland tonight.  Low level moisture has been increasing ahead of this front today with late afternoon dew points in the upper 50s to lower 60s in north central and east central Minnesota and northwest Wisconsin.  Instability has also been on the increase with CAPE around 500 j/kg as of 3 PM -- This number might increase this evening, possibly peaking at around 1000 j/kg.  Impressive jet stream dynamics in place with a 100-140 knot jet moving into North Dakota this evening which is setting up a decent amount of divergence across the Northland.

Although the chances for showers and thunderstorms isn't very high for tonight convection could develop but should remain isolated to scattered in overall coverage.  A 30-40 knot SW low level jet will linger ahead of the cold front tonight which should help to increase the amount of instability and moisture which may help to trigger a few storms.  Deep layer wind shear will be on the increase this evening as stronger mid/upper level winds approach from the west -- Isolated strong to severe thunderstorms with hail and gusty winds are possible tonight if thunderstorms can develop.

Partly to mostly cloudy skies will be found over the Northland tonight with lows in the 50s to lower 60s.  South or southeast winds will shift to the southwest at 10 to 20 mph.

Monday (September 19)

Breezy but temperatures will remain above average with highs generally in the 70-75 degree range.  Partly to mostly cloudy skies are expected with tonight's cold front moving well to the south of the area while weak high pressure builds into the Upper Midwest.  Low temperatures Monday night will be in the 40s and 50s.  West or southwest winds on Monday at 10 to 20 mph with gusts to around 30 mph.

.Extended Forecast...

Tuesday (September 20)

Should remain dry on Tuesday with highs in the 60s and 70s.  Lows Tuesday night in the 50s to around 60 degrees with 40s in far northern Minnesota.

September 21-26:

This period could turn rainy from time to time as a large upper level trough moves slowly E/NE across the Rockies and Plains while a couple areas of low pressure lift northeast out of the western High Plains -- It likely won't rain continuously from the 21st-26th but expect periods of rain the way it looks now.  Temperatures will also turn cooler especially near Lake Superior thanks to a stronger east wind which should develop by mid to late week.

Forecast for Duluth and Superior

.Tonight...  Partly to mostly cloudy.  A few showers or thunderstorms possible mainly before 1 AM.  Low 53 to 58.  Wind southeast at 10 to 20 mph becoming southwest late.

.Monday...  Breezy.  Partly to mostly sunny.  High 69 to 74.  Wind southwest at 15 to 25 mph.

Normal temperatures for Monday

High:  64
Low:   45

Sunrise Monday:  6:52 AM CDT
Sunset Monday:   7:11 PM CDT