Saturday, May 7, 2011

5/7/11: Saturday's Weather Report

Issued at 3:24 PM CDT, Saturday, May 7th, 2011

Weather History:

One year ago Today, 4.4" of snow fell at Duluth, Minnesota.

Weather headlines:

-A few showers for parts of the area thru Sunday Night
-Arrowhead and most of Northwest Wisconsin should stay rain-free into Sunday Night
-Next week continues to look unsettled at times
-Strong/severe thunderstorm potential Tuesday and possibly on Wednesday?

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Partly to mostly cloudy skies were found in our area Today with a few showers at times in Northcentral Minnesota.  Highs Today ranged from the 40s in Superior and Downtown Duluth with mid 50s to mid 60s elsewhere.  Winds Today were out of the east around 12 mph with higher gusts near Lake Superior.  Surface map as of 3 PM featured low pressure of 1002mb in Eastern Wyoming.  Low pressure of 1004-1008mb were off to our northwest with a stationary front stretching from Southern Alberta Province to the Minnesota-Ontario border.

Today's Upper Level Analysis:

West-northwest 500mb flow covered the Upper Midwest Today per RUC model analysis and water vapor satellite imagery.  H5 trough was in place from Western Canada to the Pacific Northwest...Downstream of this trough, an upper level ridge was beginning to take shape over the Southern U.S.  Another 500mb trough remained over the Northeast U.S. and Eastern Canada Today.  Lots of warm air covered parts of Oklahoma, Texas, and the Southwest U.S. Today with Afternoon temperatures in the 90s to low 100s with 850mb temperatures of +22 to +28 degrees C!

Tonight:

Stationary front will be located in far Northern Minnesota...This boundary will keep a few showers around in Northcentral Minnesota Tonight.  There might be a thunderstorm or two as well through 9 PM This Evening, although instability isn't the best with CAPE generally around 100 j/kg.  Partly to mostly cloudy skies will cover the area Tonight with lows in the 30s and 40s.  Winds will be out of the south or east under 15 mph.

Sunday and Sunday Night:

Stationary front remains over Northern Minnesota while strong low pressure of around 992mb pulls out into the Western High Plains with a developing warm front attached to that low remaining well to our south during this period.  Partly to mostly cloudy skies can be expected Tomorrow and Tomorrow Night.  Scattered showers are possible as well, mainly in western-southern areas.  The Arrowhead of Minnesota into most of Northwest Wisconsin should remain generally dry during this period.  Highs Tomorrow will be in the 50s and 60s, except for cooler temperatures near Lake Superior.  Lows Sunday Night will be in the 30s and 40s.  South or east winds up to 20 mph are forecast during this period.

Extended Forecast:

Strong low pressure of around 990mb will remain over the Western High Plains on Monday before it lifts N-NE into mid-week.  A warm front attached to this low will advance slowly north into Wednesday, but that boundary should not make it much farther north than Southern Minnesota the way it looks now.  An upper level trough and cold front tied with this whole weather system is forecast to push east into the Upper Midwest and Central Plains from mid to late week.  Note:  There continues to be some uncertainty with the timing of this storm, and also with the placement of the warm front for Tuesday and Wednesday.

Monday and Monday Night, May 9th:  Southerly flow out ahead of the low and upper level trough will pump moist air north into our area with dewpoints climbing into the 40s with PWS nearing 1.00".  Overrunning showers will likely occur at times in our area north of a warm front.  Isolated thunderstorms are possible as well, especially by Monday Night when MOST UNSTABLE CAPE climbs to 150-500 j/kg.  Any thunderstorm that does develop this far north will be elevated, and should stay below severe levels.  High temperatures on Monday will be in the 40s and 50s with lows Monday Night generally in the 40s.

Tuesday and Tuesday Night, May 10th:  Low pressure averaging 993mb will move into Northwest Iowa or Western Minnesota during this period with a warm front heading into Southern Minnesota.  Warm/moist advection pattern will be occurring in our area during this period with dewpoints away from Lake Superior reaching the 50s with 850mb td's increasing to +8 to +14 degrees C while PWS remain at around 1.00".  MOST UNSTABLE CAPE could also become quite strong during this period, perhaps reaching the 1000-2000 j/kg range.  It does appear that the potential for thunderstorms will increase Tuesday and Tuesday Night, but the storms that form in our area should stay elevated north of the warm front.  If the instability does get as strong as what the models show, then there will be an isolated severe thunderstorm risk with large hail being the main threat.  Note:  The greatest risk for seeing possible surface based convection would be along or south of the I94 corridor in Central Minnesota and points south from there late Tuesday Afternoon/Tuesday Evening with isolated supercells and a chance for a tornado possible in those areas based on latest model data.  High temperatures on Tuesday will be in the 50s and 60s with 40s near Lake Superior.  Lows Tuesday Night will be in the 40s to around 50 degrees.  High temperatures in Southern Minnesota could get into the 80s on Tuesday depending on the placement of the warm front.

Wednesday and Thursday, May 11th-12th:  Model differences become quite large during this period with the EURO slower than the GFS with the eastward movement of the cold front, surface low, and upper level trough.  The risk for strong to severe thunderstorms would occur on Wednesday based on Today's 12z GFS model run, while the EURO would support a risk for showers/thunderstorms both Wednesday and Thursday, but little in the way of severe potential for this area.  The risk for some rain could linger into Friday, May 13th as an upper level low/trough covers the Great Lakes, Upper Midwest, and Central Plains.

5 Day Forecast for Duluth/Superior

.Tonight...  Partly to mostly cloudy.  Light showers or sprinkles possible between 6-8 PM.  Low 37 to 41.  Wind east at 10 to 15 mph.

.Sunday...  Partly sunny.  High 55 to 60 but cooler near Lake Superior.  Wind east at 10 to 15 mph.

.Sunday Night...  Mostly cloudy.  Showers possible.  Low 40 to 43.

.Monday...  Mostly cloudy.  Showers possible.  High 50 to 55 but cooler near Lake Superior.

.Monday Night...  Mostly cloudy.  Showers or thunderstorms possible.  Low 40 to 45.

.Tuesday...  Mostly cloudy.  Showers or thunderstorms possible.  High 50 to 55 but cooler near Lake Superior.

.Tuesday Night...  Mostly cloudy.  Showers or thunderstorms possible.  Low 40 to 45.

.Wednesday...  Mostly cloudy.  Showers or thunderstorms possible.  High 50 to 55 but cooler near Lake Superior.

Normal temperatures for Today

High:  60
Low:  37

Sunday's pollen forecast:

Tree:    High
Grass:  None
Weed:  None

Sunrise Tomorrow:  5:43 AM CDT
Sunset Tomorrow:   8:28 PM CDT

Tim