Friday, May 27, 2011

5/27/11: Friday's Weather Report

Issued at 3:14 PM CDT, Friday, May 27th, 2011

Low temperature report for Friday, May 27th, 2011.  Source:  NWS Duluth, Minnesota.

Grand Marais, MN:  31 degrees
Hibbing, MN:  26 degrees
Ashland, WI:  28 degrees
Hayward, WI:  32 degrees
Silver Bay, MN:  27 degrees
Ely, MN:  27 degrees
Crane Lake, MN:  28 degrees
Embarrass, MN:  28 degrees
Floodwood, MN:  29 degrees
4 miles east of Island Lake, MN:  29 degrees
3 miles east of Orr, MN:  26 degrees
2 miles south of Tower, MN:  30 degrees
Finland, MN:  32 degrees
Gurney, WI:  26 degrees
Madeline Island, WI:  28 degrees
Upson, WI:  29 degrees
Solon Springs, WI:  32 degrees

Weather History:

On this date in 2008:  A record low temperature of 31 degrees occurred at Duluth, Minnesota.

WEATHER HEADLINES:

-Rain overspreads the area Tonight
-Scattered showers/thunderstorms for Saturday
-Isolated risk for severe weather Saturday Afternoon
-Dry Sunday
-Memorial Day severe weather threat?

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Sunshine during the Morning gave way to increasing cloudiness from southwest to northeast This Afternoon.  A rather large area of light rain and drizzle was pushing E-NE out of the Eastern Dakotas and Western Minnesota Today and the leading edge of this rain as of 3 PM extended from near International Falls to Aitkin.  High temperatures Today were in the 40s around the head of Lake Superior with 50s and a few lower 60s elsewhere.  Winds were out of the south or east at 5-15 mph with a few higher gusts.

Today's Upper Level Analysis:

Southwest flow aloft has developed in the Upper Midwest as an upper level trough heads slowly east out of the Northern Rockies and Northern Plains, a large area of 60-90 meter 12 hour H5 height falls covered those areas Today underneath this upper trough.  A powerhouse jet stream with speeds greater than 140 knots extends from the Central Pacific, east to the Central Rockies and Western High Plains Today per RUC model analysis.  A blazing heat wave is developing south of that jet with temperatures Today in the 90s and low 100s from Southwest Oklahoma to Central-Western Texas into parts of Arizona and New Mexico.

Tonight:

Low pressure will be nearly stationary in Southeast Saskatchewan Province.  A 25-35 knot SW low level jet will advect moisture north into the Upper Midwest and this will cause areas of rain in  Northern Minnesota and Northwest Wisconsin.  An isolated thunderstorm or two is also possible Overnight toward the Walker and Brainerd Lakes areas as elevated CAPE rises to around 100 j/kg.  Overcast skies can be expected Tonight with lows mainly in the 40s.  Winds will be out of the south or east under 20 mph.

Saturday and Saturday Night:

Low pressure will remain off to our northwest during this period.  An upper level low/trough will pull into the Upper Midwest with a pool of cold air aloft (500mb temperatures of -20 to -25 degrees C) Any leftover showers from Tonight should end Tomorrow Morning, then partial sunshine should take place into early Afternoon which will allow temperatures to climb into the 50s and 60s.  The milder air near the surface combined with the cold air aloft will make the atmosphere somewhat unstable Tomorrow Afternoon and Evening.  Latest model data suggests that CAPES will climb to around 500 j/kg with Lifted Indicies of zero to -3 degrees C.  This will likely result in the development of scattered showers and thunderstorms Saturday Afternoon and Evening.  A very strong jet stream with winds greater than 110 knots will be located just to our south with fast winds in the mid levels in place across our area, and this combined with around 30 knots of shear could lead to an isolated severe thunderstorm risk Saturday Afternoon into the early Evening hours with large hail and damaging winds being the main hazards.  A greater risk for severe weather would likely occur if there was more moisture in place on Saturday, as it stands now it looks like dewpoints will stay mostly in the 40s with PWS generally around 1/2".  Partly sunny to mostly cloudy skies are on tap Tomorrow with partly to mostly cloudy skies Saturday Night...Looks mainly dry in our area by late Saturday Night with lows in the 40s.  Winds will be out of the south, east or west Tomorrow under 20 mph with southwest or west winds Tomorrow Night under 15 mph.

Extended Forecast:

Sunday and Sunday Night, May 29th:  Low pressure will pass by to our N-NE on Sunday while a warm front takes shape across the Central Plains.  A few showers can't be ruled out in far Northern Minnesota on Sunday, otherwise it looks generally dry for the area Sunday and Sunday Night with highs mainly in the 60s and lows in the 40s.

Monday and Monday Night, May 30th:  Deep low pressure of 991-995mb will track from Eastern Colorado to the Central Dakotas.  A warm front will extend E-NE of that low and this boundary will push north while a strong cold front plows NE out of the Northern Plains.  A 40-60 knot southerly low level jet will develop ahead of this storm on Monday with deep moisture streaming into the area.  By Monday Afternoon and Evening dewpoints are expected to range from 55-65 degrees, highest values away from Lake Superior.  PWS of 1.25-1.50" and 850mb td's of +10 to +14 degrees C are also expected on Monday.  As the warm front lifts north, there will probably be an area of showers and elevated thunderstorms marking it's arrival as MUCAPES climb to around 500 j/kg through midday Monday. 

Surface based instability will then develop Monday Afternoon-Evening, at least for Southern parts of our area where CAPES of 1000-2000 j/kg and Lifted Indicies of -2 to -6 degrees C are forecast to develop.  How far north the warm front advances by late Monday Afternoon-early Monday Evening is still uncertain and that will be important since there could be a risk for severe thunderstorms including supercells and possible tornadoes near that warm frontal boundary.  If storms don't form near the warm front, or if the warm front lifts well to the north, near the Ontario border, then will likely have to wait for the forcing associated with the cold front to trigger some storms in our area sometime Monday Night.  Another critical aspect to this forecast will be the cap and the models Today are handling the cap differently.  The 12z GFS has 700mb temperatures approaching +12 degrees C through Monday Evening, while the 12z NAM has H7 temperatures of +6 to +8 degrees C, in other words the NAM shows a much weaker cap compared to the GFS.

The mid and upper level winds with this system look very strong.  60-80 knot SW mid level winds with an upper level jet of around 100 knots approaching from the Northern Plains.  Shear will be very high across the entire area, and the 1KM Helicity and EHI (energy helicity index) look to max out somewhere in Western or Central Minnesota.  The bottom line is that there could be a severe threat Monday and or Monday Evening in portions of Minnesota with all modes of severe weather possible, this would include hail, high winds, and the risk for a few tornadoes..The tornado risk seems greatest in Western and Central Minnesota late Monday Afternoon-early Monday Evening the way it looks now.

High temperatures on Monday will be in the 70s in Southern areas with 40s near Lake Superior and 50s and 60s elsewhere.  Lows Monday Night will be in the 50s with 40s near Lake Superior.

5 DAY FORECAST FOR DULUTH/SUPERIOR

.Tonight...  Mostly cloudy.  Scattered showers developing This Evening with showers Overnight.  Low 40 to 45.  Wind east to southeast at 10 to 20 mph.

.Saturday...  Scattered Afternoon showers or thunderstorms.  Partly sunny.  High 61 to 66.  Wind southwest at 10 to 15 mph.

.Saturday Night...  Mostly cloudy.  Showers possible during the Evening.  Low 45 to 50.  Wind west to southwest at 10 to 15 mph.

.Sunday...  Partly sunny.  High 63 to 68.

.Sunday Night...  Partly cloudy.  Low 40 to 45.

.Memorial Day...  Breezy.  Mostly cloudy.  Occasional showers or thunderstorms.  High 50 to 55 but cooler near Lake Superior.  East winds could occasionally gust to 25 mph.

.Monday Night...  Mostly cloudy.  Showers or thunderstorms possible.  Low 45 to 50.

.Tuesday...  Breezy.  Partly cloudy.  High 65 to 70.  West to southwest winds could occasionally gust to 30 mph.

Normal temperatures for Today

High:  67
Low:  44

Saturday's Pollen Forecast:

Tree:    High
Grass:  None
Weed:  None

Sunrise Tomorrow:  5:21 AM CDT
Sunset Tomorrow:   8:51 PM CDT

Tim