Tuesday, July 13, 2010

7/13/10: Tuesday's Weather Report

Issued at 7:49 PM CDT, Tuesday, July 13th, 2010

Weather History:

On this date in 1990... A record low temperature of 39 degrees occurred at Duluth, MN.

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Partly-mostly sunny skies were found in our area Today with high temperatures in the middle 70s to lower 80s away from Lake Superior and generally around 70 degrees closer to Lake Superior. Dewpoints climbed into the 50s and 60s over most areas Today with early Evening 850 mb td's ranging from +8/+13 degrees C over all but Northeast Minnesota. PWS ranged from around 0.90" in extreme Northeast Minnesota to between 1.00-1.40" over the remainder of our area. Winds Today were out of the south or east at 10-20 mph with some higher gusts. Surface map early This Evening features an area of low pressure averaging 1000 mb centered in the Western High Plains. A cold front extended from Central North Dakota back through Northwest South Dakota with a warm front centered in Central Minnesota.

This Evening's Upper Level Analysis:

A powerful upper level low (552 meters) was tracking east through Southern Saskatchewan Province early This Evening per water vapor satellite imagery. Unusually strong upper level winds (100-110 knots) covered areas from Central Idaho through Northwest North Dakota with strong mid level winds (60-80 knots) in place over parts of the Northern Rockies/Northern Plains per RUC model analysis.

Tonight:

Warm/moist advection pattern will occur through the night across Northern Minnesota and Northwest Wisconsin thanks to a southerly low level jet of 30-45 knots which will help advect warmth and moisture north into our area. Partly-mostly cloudy skies will occur Tonight with scattered showers and thunderstorms, mainly affecting Northern and Eastcentral Minnesota and far Northwest Wisconsin. Instability will be on the rise Tonight with CAPES climbing to 1000-2000 j/kg Overnight with Lifted Indices of -2/-4 degrees C. Wind shear will also be present along with increasing winds aloft.

...CONCERNING TONIGHT'S SEVERE POTENTIAL...

The potential does exist for a few severe thunderstorms Overnight, mainly west of a line from Crane Lake to Pine City, including International Falls, Bigfork, Grand Rapids, Hill City, Walker, Brainerd, Cass Lake, Leader, Aitkin, and Hinckley. Large hail and damaging winds would be the main threats if severe weather does develop Tonight. Locally heavy rainfall and dangerous lightning strikes will also occur. Lows Tonight will be in the 50s and 60s with south or east winds at 10-20 mph.

Wednesday and Wednesday Night:

...SEVERE WEATHER OUTBREAK POSSIBLE WEDNESDAY AND WEDNESDAY EVENING...

Ingredients appear to be coming together for what could be a rather significant outbreak of severe thunderstorms for the Upper Midwest with all modes of severe weather a distinct possibility.

Very strong winds aloft (around 100 knots at 300 mb) and 60-80 knots at (500 mb) will spread into the Upper Midwest on Wednesday while low pressure passes by to our west-northwest with a cold front heading east out of the Dakotas and through our local area Wednesday Afternoon and Wednesday Evening. A very potent upper level low will also be in place near the Manitoba Lakes area with strong lift occurring to the south/southeast of that upper low.

Scattered showers and thunderstorms will occur at times across Northern/Eastern Minnesota and Northwest Wisconsin on Wednesday before ending from west to east Wednesday Evening.

CAPES from 1500-3500 j/kg along with Lifted Indices of -3/-7 degrees C in conjunction with a change in wind direction with height along with ample amounts of shear (50-60 knots) could result in the development of severe thunderstorms and supercells in parts of our area on Wednesday.

There is also a risk for tornadoes Wednesday Afternoon/early Wednesday Evening in Northwest Wisconsin and Eastern Minnesota as 1 km Helicities increase to 100-200 m2/s2. Note: The past few SREF model runs have been showing some high values for tornadoes (4-6) in Eastern Minnesota/Northern-Western Wisconsin Tomorrow Afternoon/early Evening.

One thing that may hinder thunderstorm development will be the presence of a rather strong cap. The latest forecast models indicate that 700 mb temperatures will rise to between +10/+12 degrees C basically from Brainerd to Duluth and points south of here while 850 mb temperatures soar toward +20 degrees C especially in Southern parts of our local area. An even stronger cap will be in place the farther south you go in Southern Minnesota/Northern Iowa/Southwestern Wisconsin on Wednesday. The forcing and lift associated with this strong system should be able to overcome this cap which will lead to the development of scattered convection and possible severe weather on Wednesday.

High temperatures Tomorrow will be in the 70s and 80s while dewpoints will be in the 60s and 70s. PWS will range from 1.25"-2.00" with 850 mb td's of +12/+20 degrees C! With all this moisture in the atmosphere, there will be a risk for very heavy rainfall. Note: High temperatures will likely soar into the 90s, possibly even into the low 100's on Wednesday in parts of Iowa and even into Southern Minnesota where dewpoints could reach 80 degrees on Wednesday!

Drier air will start to spread into our area Wednesday Night with lows in the 50s and 60s.

Winds Tomorrow will be out of the south, southwest, or east at 10-20 mph with winds Tomorrow Night out of the west or southwest at 10-20 mph.

Extended Forecast:

Calmer weather will return to our area Thursday and Friday with low pressure at the surface and aloft centered well to our north. High temperatures both days will be in the 70s and 80s with lows Thursday Night and Friday Night in the 50s and 60s.

5 Day Forecast for Duluth/Superior

.Tonight... Partly to mostly cloudy. Late night showers or thunderstorms possible. Low 56 to 61. Wind east to southeast at 10 to 20 mph. Chance of rain 30%.

.Wednesday... Humid. Scattered showers and thunderstorms. A few storms could be severe with large hail and damaging winds. Heavy rain also possible. Variable cloudiness. High 72 to 77. Wind south to southeast at 10 to 20 mph. Chance of rain 60%.

.Wednesday Night... Turning less humid. Becoming partly cloudy. Showers or thunderstorms possible early. Low 57 to 62. Wind southwest at 10 to 20 mph. Chance of rain 30%.

.Thursday... Less humid. Partly cloudy. High 78 to 83.

.Thursday Night... Mostly clear. Low 58 to 63.

.Friday... Partly cloudy. High 78 to 83.

.Friday... Partly cloudy. Low 57 to 62.

.Saturday... Partly cloudy. High 80 to 85.

Normal High Temperature Tomorrow 76 degrees

Normal Low Temperature Tomorrow 55 degrees

Tim