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2/17/09: Tuesday’s Weather Report

Issued at 4:05 PM CST, Tuesday, February 17th, 2009

Surface Analysis at 21z:

Low pressure averaging 994 mb was centered along the Southern Nebraska/Northern Kansas state line…Or between the cities of Holdrege Nebraska and Phillipsburg Kansas. 3 mb per 2 hour pressure falls were occurring ahead of this low This Afternoon from Central-Eastern Kansas through Southeast Nebraska into Southern Iowa and Missouri. In the warm sector of this storm, temperatures were up into the 60s, 70s, and 80s This Afternoon from far Southern Nebraska down across Kansas, Oklahoma, and Texas. A cold front stretched from Northeastern Lake Superior to north and west of Duluth Minnesota down into Southwest Minnesota.

Upper Air Analysis at 21z:

Seeing the flow aloft transition briefly toward the southwest around Minnesota Today as the pattern starts to amplify. This is occurring thanks to a few things. First, an H5 low which was over Northern Ontario… Second, an upper level trough which is digging south-southeast from Manitoba into the Northern Plains and Upper Midwest. Third, a low pressure system coming out of the Plains. All three of these features will begin to phase somewhat during the next 24 hours, but the phasing process won’t occur until they shift east of Minnesota. Forecast models always have major difficulties when we have pieces of energy in both branches (northern) (southern) of the jet stream, and if or when these seperate pieces of energy can phase. A similar set-up may occur around our area next week, but there’s plenty of time to deal with that possible mess. Back to Today’s event… Seeing a nice H5 and H3 jet max of 80-90 knots and 120-140 knots respectively running from the Southwest U.S. out into the Southern/Central Plains with 12 hour H5 height falls of 90 meters over Northern Kansas into Central/Southern Nebraska. With most storms, there’s always a nice temperature gradient…And this one is no different as H85 temperatures ranged from -20 to -24 degrees C from Northern and Central Ontario to Eastern Manitoba to +6 to +14 degrees C across the Plains. In Minnesota, 3 PM 850 mb temperatures ranged from +2 degrees C in the Southwest half of the state to -8 degrees C from far Northwest Minnesota into Northeast Minnesota.

Today’s Weather:

Snow has been falling most of the day in Northern Minnesota with anywhere from 1 to as much as 5 inches of new snow coming down Today thanks to some pretty good frontogeneis and convergence taking place near the aforementioned cold front. Additional radar echoes mostly in the form of virga have been expanding in aerial coverage This Afternoon across Southern, Central, and Eastern areas of Minnesota in response to the low over Southern Nebraska and Northern Kansas. Skies around Minnesota were partly sunny to mostly cloudy Today with high temperatures generally in the teens, 20s, and 30s with a few 40s South. Winds across the state were out of the south, north, or east at 5 to 15 mph with gusts of 15 to around 25 mph.

Here are some snowfall totals from Northern Minnesota Today:

Kabetogama (St. Louis County) 5.5″

Little Marais (Lake County) 1.2″

International Falls (Koochiching County) 3.6″

3 miles West of Indus (Koochiching County) 2.8″

10 miles West-Southwest of Gunflint Trail Lake (Cook County) 2.5″

Temperatures around Minnesota at 4 PM ranged from 40 degrees at St Paul to 18 degrees at Warroad to 28 degrees at Detroit Lakes to 18 degrees at International Falls to 36 degrees at Grand Rapids to 23 degrees at Ely to 23 degrees at Wheaton to 36 degrees at Willmar to 34 degrees at Brainerd to 27 degrees at Cloquet to 37 degrees at Redwood Falls to 41 degrees at Mankato to 41 degrees at Red Wing.

Tonight through Wednesday Night:

*Winter Weather Advisory* remains in effect until 6 AM CST Wednesday for parts of Northern/Northeast Minnesota.

Upper level trough will continue to dig and deepen over the Upper Midwest through Wednesday as low pressure heads east-northeast from it’s current position along the Nebraska/Kansas state line to south-southeast of Chicago Illinois on Wednesday, then toward Southeastern Lower Michigan by Wednesday Evening. Pressures near the surface low will fall to around 988 mb during the next 24 hours.

For Tonight…Look for snow or a mixture of rain and snow to develop across Southern Minnesota with all precipitation turning over to snow during the night. Some snow will also develop across Central and Eastern Minnesota, while Northern areas of the state continue to see some snow, but the snow up North should be tapering off from northwest to southeast Overnight. Western Minnesota will also see a bit of snow Tonight, but this snow will also end from northwest to southeast toward Midnight. Snow accumulations Tonight will range from 1 to 3 inches with the higher totals across Northern, Southcentral, and Eastern Minnesota. Lows Tonight will be in the teens and 20s South and East to the single digits below to above zero North and West. Winds will be out of the north or east at 10 to 20 mph with some higher gusts possible. Areas of blowing and drifting snow could develop over parts of the state Tonight, and wind chills could fall into the 5 below to 20 below range toward dawn over Western and Northern parts of Minnesota.

Concerning the lake effect snow potential along the North Shore of Lake Superior Tonight…

As of 4 PM, temperatures had fallen into the 20s near Lake Superior with H85 temps of -8 to -10 degrees C over Western, Central, Northern, and Eastern Lake Superior. Winds were out of the east as of late Afternoon. Haven’t seen any lake effect activity yet, but as temperatures both at the surface and aloft continue to cool during the night and surface winds turn more to the E/NE, some lake effect snow should develop. The problem is that the winds aloft which were out of the W/SW late Today, will turn briefly toward the E/NE late Tonight, then back toward the N/NE, and eventually north by Wednesday Morning. So there’s quite a bit of shear noted for lake effect snow bands to become well organized This Evening…Then as the shear relaxes, we could see a flare up of lake effect snow for a time late Tonight around the head of Lake Superior…From around Two Harbors down toward Duluth and Superior, this threat probably won’t last very long though as the winds both at the surface and aloft switch to the N/NE which will end the lake effect snow threat for the North Shore of Lake Superior by Wednesday Morning.

As we move into Wednesday and Wednesday Night, look for the deepening low pressure and upper level trough to shift east of Minnesota as arctic high pressure builds into Minnesota from the west/northwest. Lingering snow showers and flurries will end across the state on Wednesday, then mainly dry conditions are expected for Wednesday Night. Skies will be partly to mostly cloudy Tomorrow, and mostly clear Tomorrow Night. High temperatures Wednesday will be in the single digits below to above zero North and West to the teens and 20s with near steady or slowly falling temperatures South and East. Lows Tomorrow Night will range from zero to around 20 below. North to northwest winds are expected Wednesday and Wednesday Night at 10 to 20 mph with some higher gusts. Wind chills will fall to between 10 below to 25 below over parts of Minnesota by Wednesday Night.

Extended Forecast:

Dry weather is forecast across Minnesota Thursday with high pressure beginning to push off toward our south/east. High temperatures will be in the single digits, teens, and 20s. The period from Thursday Night through Friday Night will feature a potent upper level trough and area of low pressure which will dig south-southeast from Saskatchewan and Manitoba, down into the Northern Plains and Upper Midwest. The main lift associated with this system should be over Western and Southern areas of the state where some snow is expected to fall from late Thursday Night into Friday, may see a few inches of snow over those areas during that time. The rest of the state should see some flurries or snow showers with little accumulation. High pressure will once again build into Minnesota by this weekend as the late week trough and low pressure area exits to our southeast. Low temperatures around Minnesota Thursday Night and Friday Night will be in the single digits and teens below to above zero with highs on Friday in the teens and 20s.

Forecast for Duluth/Superior:

.Tonight… Light snow and flurries developing. Snow accumulations up to an inch possible. Mostly cloudy. Low 10 to 15. Wind east at 10 to 20 mph, becoming northeast to north late.

.Wednesday… Snow showers and flurries around during the Morning… Snow accumulations less than one inch. Partly sunny. High 15 to 20 with near steady or slowly falling temperatures. Wind north to northwest at 15 to 25 mph.

.Wednesday Night… Mostly clear. Low 3 below to 9 below. Wind northwest at 10 to 20 mph. Wind chills ranging from 15 below to 30 below.

.Thursday… Mostly sunny. High 10 to 15.

.Thursday Night… Partly to mostly cloudy. Low 2 above to 7 below.

.Friday… A few snow showers or flurries possible. High 15 to 20. Chance of snow 20%.

.Friday Night… Partly cloudy. Low 3 below to 4 above.

4 PM Thompson Hill Observation:

Current Temperature: 24.5 degrees

Dewpoint: 23 degrees

Humidity: 97%

Wind: E at 9 mph G 19 mph

Max Temperature Today: 33.1 degrees

Max Humidity Today: 97%

Min Temperature Today: 23.6 degrees

Min Humidity Today: 52%

Normal High Temperature Today 25 degrees

Normal Low Temperature Today 6 degrees

Tim

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