Thursday, May 20, 2010

5/20/10: Thursday's Weather Report

Issued at 3:38 PM CDT, Thursday, May 20th, 2010

Weather History:

On this date last year, a record high temperature of 88 degrees occurred at Duluth, MN.

On this date in 1986, a record low temperature of 26 degrees occurred at Duluth, MN.

Here are some high temperatures that occurred in Northern Minnesota and Northwest Wisconsin on Wednesday, May 19th, 2010. Source: NWS Duluth, MN. High temperatures that occurred on Wednesday were running some 10-20 degrees Above Normal for this time of year.

Duluth MN: 79 degrees

International Falls MN: 82 degrees

Hibbing MN: 81 degrees

Sky Harbor MN: 79 degrees

Silver Bay MN: 81 degrees

Orr MN: 82 degrees

Eveleth MN: 81 degrees

Ashland WI: 81 degrees

Hayward WI: 81 degrees

Superior WI: 81 degrees

Siren WI: 80 degrees

Phillips WI: 81 degrees

Cass Lake MN: 80 degrees

Littlefork MN: 82 degrees

Madeline Island WI: 83 degrees

Gordon WI: 83 degrees

Upson WI: 80 degrees

Butternut WI: 81 degrees

Weather tidbits:

*Average monthly temperature (thru the 19th) at Duluth, Minnesota: 47.7 degrees
Departure: 2.1 degrees Below Normal

*So far this month we've had 6 days with a high temperature of at least 70 degrees at Duluth, Minnesota.

*May 2009 featured 5 days with a high temperature of at least 70 degrees with 1 day of an 80 degree or warmer high temperature at Duluth, Minnesota.

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Some subtle changes took place Today thanks to a cold front which has now turned stationary over Central Lake Superior. This boundary as it entered the lake earlier Today caused a lake breeze front to develop which then moved rapidly toward the south/west This Morning. A sudden wind shift to the east took place once this boundary moved through, wind speeds also picked up to between 10-25 mph near Lake Superior, temperatures also dropped from the 70s This Morning to the 50s This Afternoon. Farther Inland, another warm day occurred Today with high temperatures in the middle 70s to lower 80s! 850 mb temperatures as of 3 PM ranged from +14/+15 degrees C across Northern Minnesota and Northwest Wisconsin. Mostly sunny-sunny skies covered most of our local area Today, but there has been some stratus clouds moving onshore from Lake Superior, generally affecting portions of Lake/Cook Counties in Northeast Minnesota Today. Surface map as of mid-Afternoon featured high pressure of 1026 mb centered in Southern Hudson Bay Canada. Low pressure of 1008 mb was centered in Eastern Kansas.

Today's 500 mb analysis:

Northwest flow aloft covered Northeast Canada and the Northeast U.S. Today per water vapor satellite imagery as an upper level low spins around up in that area. (570 meter) upper level low was tracking east through Kansas Today with plenty of mid/high level moisture streaming north into the Northern Plains and Upper Midwest per water vapor satellite imagery. A narrow ridge of high pressure continued to cover the Upper Great Lakes Today per RUC model analysis while a cold and potent upper level trough with 500 mb temperatures from -25/-32 degrees C covered the Pacific Northwest and Western Canada Today.

Tonight:

Clear-partly cloudy skies will continue across our area Tonight with high pressure centered well to our northeast along with a stationary front which will run from Central Ontario Province to Northern Lake Superior. Lows Tonight will be in the 40s to around 50 degrees with some 30s especially closer to Lake Superior. Winds Tonight will be out of the south or east under 15 mph with some higher gusts near Lake Superior This Evening.

Friday and Friday Night:

The low pressure disturbance over Kansas Today will head east-northeast during this period. An increase in moisture will occur in our area Tomorrow with PWS which were around one half inch Today climbing to .75"-1.00" on Friday while dewpoints which have been generally in the 30s the past few days rise into the 40s for portions of our area during this period. The bulk of the steadier rain associated with that Plains system is expected to pass off to our south/southeast, but there will be a risk for some showers Friday and Friday Evening across our area, although rainfall amounts should be light, generally under 0.10". Partly sunny-mostly cloudy skies are forecast on Friday with highs in the 60s and 70s but it will be cooler near Lake Superior. Lows Friday Night will be in the 40s and 50s. Winds will be out of the south or east under 20 mph during this period.

Extended Forecast:

An upper level trough will develop across the Western U.S. with a southwesterly flow aloft becoming established to the east of this trough across the Plains and Upper Midwest this weekend through most of next week.

An increase in moisture thanks to southerly winds will take place across our area this weekend with dewpoints climbing into the 50s and 60s by Sunday while PWS increase to 1.00"-1.25" with 850 mb td's soaring to between +12/+16 degrees C by Sunday! Needless to say there will be quite a bit of moisture in the atmosphere by late this weekend.

Instability will also be on the rise, first in the form of elevated CAPE for Saturday/Saturday Night with a mix bag of surface based and elevated CAPE overhead on Sunday. By Sunday, the forecast models indicate that CAPES could reach the 1500-3000 j/kg range in our area which is plenty of fuel for a thunderstorm to tap into.

An area of low pressure is expected to pass well to our west/northwest this weekend. A warm front and cold front attached to this low will move north/east into Minnesota from Saturday Night through Sunday Night. As this is happening, a surge of warm air aloft will also move overhead with 850 mb temperatures rising to +12/+20 degrees C while 700 mb temperatures climb to between +8/+12 degrees C! If the cap holds, then little if any thunderstorm activity will occur across our local area from Saturday Night into Sunday Night, but if this cap breaks, then scattered thunderstorms and a threat for some severe weather would occur especially Sunday and Sunday Evening.

The threat for a few showers/thunderstorms and possibly some severe weather could then carry over at least off an on through most of next week as an upper level trough remains anchored to our west while a southwest flow of warm/moist/unstable air continues in the Upper Midwest while some low pressure disturbances embedded within that Western U.S. trough lift northeast through the Northern Plains helping to trigger this convection.

High temperatures for Saturday and Sunday will be in the 70s and 80s but it will be cooler near Lake Superior. Lows Saturday Night and Sunday Night will be in the 50s and 60s.

5 Day Forecast for Duluth/Superior

.Tonight... Mostly clear. Low 40 to 45. Wind east at 5 to 15 mph with gusts to 25 mph This Evening.

.Friday... Mostly cloudy. A few showers possible. High 65 to 70 but cooler near Lake Superior. Wind east to southeast at 5 to 15 mph. Chance of rain 30%.

.Friday Night... Mostly cloudy. A few showers possible early. Low 45 to 50. Wind east at 5 to 15 mph. Chance of rain 30%.

.Saturday... Partly sunny. High 68 to 73 but cooler near Lake Superior.

.Saturday Night... Partly cloudy. Low 50 to 55.

.Sunday... Partly sunny. Showers or thunderstorms possible. Humid. High 75 to 80 but cooler near Lake Superior. Chance of rain 20%.

.Sunday Night... Partly cloudy. Showers or thunderstorms possible. Low 50 to 55. Chance of rain 20%.

.Monday... Partly sunny. Showers or thunderstorms possible. High 73 to 78. Chance of rain 20%.

Normal High Temperature Today 65 degrees

Normal Low Temperature Today 42 degrees

Tim