Friday, July 9, 2010

7/9/10: Friday's Weather Report

Issued at 7:52 PM CDT, Friday, July 9th, 2010

Weather History:

On this date in 1997... A record low temperature of 42 degrees occurred at Duluth, Minnesota.

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Our streak of pleasant Summer weather continued Today with partly cloudy-sunny skies throughout our area with high temperatures in the upper 70s to lower 80s with comfortable dewpoints which were generally in the 50s along with westerly winds under 20 mph. Surface map early This Evening featured a stationary front over far Northeast Minnesota into Central Lake Superior. High pressure of 1020 mb was centered over Northeastern Kansas.

This Evening's Upper Level Analysis:

West-northwest flow aloft covered the Upper Midwest This Evening per water vapor satellite imagery and RUC model analysis. An upper level disturbance was passing just north of Lake Superior while it tracks E-SE. A few other disturbances were moving E-SE out of the Southern Saskatchewan and Southern Manitoba Province and also the Northern Plains. 850 mb temperatures as of 7 PM ranged from +15/+16 degrees C across Northern Minnesota and Northwest Wisconsin.


A weak warm advection pattern will spread east into our area during the night while high pressure moves off to our southeast later in the night which will cause a southerly flow to develop which will result in a weak advection of deeper moisture into our area during the Overnight hours. A few showers and thunderstorms have developed late This Afternoon over parts of Northern-Eastern North Dakota and also in Northwest Minnesota with movement of this activity toward the east-southeast. Instability is higher out in these areas early This Evening and there is also more moisture out in this area which is helping to support this isolated convection. As these spotty showers and thunderstorms move closer and possibly into our local area they may loose some of there intensity due to weaker amounts of moisture and instability. With that said, there is the possibility for a few showers or isolated thunderstorms Tonight, mainly in Western-Northern areas. Clear-partly cloudy skies will be found across our area Tonight with lows in the 50s and 60s. Winds will be out of the west or south under 15 mph.

Saturday and Saturday Night:

A cold front will sag southeast into the Northern Plains and Northwest Minnesota late Saturday Afternoon or Evening. A southerly flow will be found out ahead of this boundary which will result in warm temperatures and increasing amounts of moisture and instability across Northern Minnesota and Northwest Wisconsin. High temperatures on Saturday should be mostly in the 80s with lows Saturday Night in the 50s and 60s. Dewpoints are expected to climb into the 57-65 degree range during this period with PWS climbing to between 1.00"-1.25" while 850 mb td's increase to between +8/+12 degrees C. A few showers or thunderstorms are possible on Saturday as some warm advection continues out ahead of the cold front to our northwest. Additional showers or thunderstorms could develop Saturday Night as the cold front begins to approach our local area during the night.

An 850 mb jet out of the southwest of 20-35 knots will be in place along and ahead of this boundary during this period, but winds aloft and shear look rather weak at the moment, generally around 20-30 knots at best. Instability will certainly be in place, however, as CAPES build to between 1000-2500 j/kg while Lifted Indices decrease to around -2/-5 degrees C by Saturday Afternoon and Evening.

The threat for a widespread severe weather event looks low at this time, but isolated strong to severe thunderstorms could develop especially Saturday Night for areas along and west of a line from International Falls to McGrath Minnesota. Hail to one inch in diameter and damaging wind gusts to 60 mph would be the main threats if severe thunderstorms develop. Locally heavy downpours and dangerous lightning will be a threat in any thunderstorm that does develop during this period.

Extended Forecast:

A cold front is expected to reach Northeast and Central Minnesota Sunday Morning before it drops southeast into Northern Wisconsin and Eastern Minnesota early Sunday Afternoon, this boundary will then continue to settle south and should clear the Southern parts of our local area Sunday Afternoon the way it looks now. Scattered showers or thunderstorms will be possible on Sunday over Northern Minnesota and Northwest Wisconsin, the threat for rain will then shift south and out of our area from northwest to southeast by Sunday Afternoon or early Sunday Evening. Prospects for severe weather look low for Sunday with generally weak instability in place, but the shear and winds aloft look to increase a bit compared to Saturday, so if the instability can increase and the front can slow down a bit, then some severe weather could develop Sunday Afternoon or early Sunday Evening, mainly over Northwest Wisconsin and Eastcentral Minnesota, the chances for this to happen are pretty low at this time.

High pressure will build into the Upper Midwest Sunday Night through Monday Night with cooler temperatures and lowering humidity.

High temperatures Sunday and Monday will be mainly in the 70s with lows Sunday Night and Monday Night in the 40s and 50s.

The middle to end of next week could become quite active over portions of the Northern Plains and Upper Midwest, but there are pretty significant timing and track differences between the models at this time so nothing is set in stone quite yet.

The overall weather pattern will feature an upper level low off to our northwest while strong winds aloft set-up to our west while nosing into the Upper Midwest. Meanwhile an upper level ridge of high pressure will develop next week over the Central and Southern Plains where a heat-wave will develop. A couple of disturbances/surface areas of low pressure could rotate south-east around that upper low off to our northwest and also to the north of the building hot dome which will become established across the Central-Southern U.S. Those systems interacting with favorable wind energy, instability, and moisture could spark a couple rounds of severe weather across the Northern Plains and Upper Midwest around the middle or end of next week the way it looks now.

5 Day Forecast for Duluth/Superior

.Tonight... Mostly clear. Low 56 to 61. Wind west at 5 to 15 mph.

.Saturday... Warm. Partly cloudy. Showers or thunderstorms possible. High 80 to 85. Wind south to southwest at 10 to 20 mph. Chance of rain 20%.

.Saturday Night... Showers or thunderstorms possible. Variable cloudiness. Low 60 to 65. Wind southwest at 10 to 20 mph. Chance of rain 30%.

.Sunday... Showers or thunderstorms possible. Mostly cloudy. High 70 to 75. Chance of rain 30%.

.Sunday Night... Decreasing cloudiness. Low 51 to 56.

.Monday... Mostly sunny. High 70 to 75.

.Monday Night... Mostly clear. Low 50 to 55.

.Tuesday... Partly cloudy. High 70 to 75.

Normal High Temperature Tomorrow 76 degrees

Normal Low Temperature Tomorrow 54 degrees