Thursday, September 2, 2010

9/2/10: Thursday's Weather Report

Issued at 2:55 PM CDT, Thursday, September 2nd, 2010

Rainfall report from earlier Today, Thursday, September 2nd, 2010. Source: NWS Duluth, MN.

Duluth MN: 0.29"

Brainerd MN: 0.29"

Hibbing MN: 0.14"

Ashland WI: 0.19"

Hayward WI: 0.42"

Two Harbors MN: 0.35"

Aitkin MN: 0.27"

Hinckley MN: 0.34"

Cloquet MN: 0.40"

Superior WI: 0.35"

Siren WI: 0.47"

Bruno MN: 0.53"

8 miles South of Bigfork MN: 0.51"

Kabetogama MN: 0.41"

Park Falls WI: 0.22"

Upson WI: 0.40"

Gordon WI: 0.41"

Sarona WI: 0.58"

Note: A wake low developed in the Twin Ports This Morning as an area of thunderstorms weakened. A wake low is a sudden drop in surface pressure in a short amount of time which can lead to a period of intense wind. This wake low produce a 6.1 millibar surface pressure drop in Duluth in 28 minutes between 5:38-6:06 AM CDT Today per NWS Duluth, MN.

Local Storm Report from This Morning, Thursday, September 2nd, 2010. Source: NWS Duluth, MN.

*6:10 AM CDT 9/2/10: 6 miles Northwest of Duluth, MN (St. Louis County) Non-Thunderstorm Wind Gust: 52 mph. Measured at the Duluth International Airport.

*6:14 AM CDT 9/2/10: 2 miles Northeast of Superior, WI. Non-Thunderstorm Wind Gust: 44 mph. Gusts to 38 knots measured at Sky Harbor Airport.

*6:15 AM CDT 9/2/10: 2 miles South-Southeast of Duluth, MN. Non-Thunderstorm Wind Gust: 58 mph. 50 knot wind gust report at the MNDOT site on the Blatnik Bridge.

*6:18 AM CDT 9/2/10: 1 mile South-Southeast of Duluth, MN. Non-Thunderstorm Wind Gust. 44 mph. 38.1 knot wind gust reported at the Great Lakes Marine Water Level Observation Site.

*6:20 AM CDT 9/2/10: 3 miles Southeast of Duluth, MN. Non-Thunderstorm Wind Gust. 44 mph measured at Park Point.

*8:02 AM CDT 9/2/10: Devils Island WI (Ashland County) Non-Thunderstorm Wind Gust. 37 knot peak wind gust.

*Gale Warning* has been issued for Lake Superior, this includes the North Shore and South Shore along with the Duluth/Superior Harbor area. The warning is in effect from 4 AM CDT Friday until 12 AM CDT Friday. The largest waves >11 feet will occur over the open waters and along the South Shore of Lake Superior, east of the Twin Ports Harbor as winds will be out of the west or northwest.

Forecast Discussion for Northeast Minnesota and Northwest Wisconsin

Today's Weather:

Dual low pressure centers with one covering Northeast Wisconsin (1006 mb) and the other over Southeastern Manitoba Province Canada (1006 mb) has resulted in a rather gray and cool day around our local area with occasional showers and isolated thunderstorms. There has been some breaks in the clouds from time to time allowing for some partial sunshine over parts of our area, but overall skies were on the cloudy side Today. High temperatures were mainly in the 60s with winds turning to the southwest or west at 10-20 mph.

Today's Upper Level Analysis:

A potent upper level trough continued to move east out of the Northern Rockies and into the Northern Plains/Upper Midwest This Afternoon per water vapor satellite imagery. This is a very dynamic system with a 100 knot upper level jet extending from Northwest Iowa through Southern Minnesota to Westcentral Wisconsin per RUC model analysis while a strong upper level disturbance/vort associated with cold temperatures aloft (H5 temps around -19 degrees C) heads east into Minnesota This Afternoon per water vapor satellite imagery/RUC model analysis.


Low pressure will phase together near Central Lake Superior or a little more northwest of that area. As the lows merge, look for pressures to drop to around 996 mb during the night. A vigorous disturbance will continue to move east and through our local area This Evening with scattered showers along with a few thunderstorms with favorable instability and cold air aloft in place. CAPES of 500-1000 j/kg with Lifted Indices of -1/-4 degrees C along with Lapse Rates of 6.0-7.5 c/km will be in place over parts of our area This Evening as that disturbance passes by. Although widespread severe weather is not expected, an isolated stronger storm could drop quarter to half inch diameter hail and wind gusts to 35 mph along with brief heavy downpours and occasional lightning strikes. Some lingering showers could occur during the Overnight hours, otherwise skies will remain mostly cloudy with lows in the 40s and 50s. Winds will be out of the west or southwest at 10-20 mph with gusts to 30 mph.

Friday and Friday Night:

Strong low pressure (991-994 mb) will be centered to the north/northeast of Lake Superior during this period. An 850 mb jet is forecast to increase to between 35-50 knots on the west-southwest side of the low from late Tonight through Friday Afternoon...This will lead to some strong northwest or west winds on Friday with wind speeds of 15-30 mph while gusts reach 35-45 mph! Wind speeds will decrease Friday Night to 10-25 mph. Mostly cloudy skies along with areas of showers and drizzle are expected on Friday with highs only in the 50s to around 60 degrees. Partly-mostly cloudy skies with lows in the 30s and 40s are forecast Tomorrow Night.

Extended Forecast:

Saturday and Sunday look dry and cool across Northern Minnesota and Northwest Wisconsin with high pressure passing through the Northern Plains/Upper Midwest/Central Plains. High temperatures will be in the 50s and 60s on Saturday with lows in the 30s and 40s. Highs for Sunday will be in the 60s to around 70 degrees with lows Sunday Night in the 40s to around 50 degrees. Our next chance for showers or thunderstorms will occur early next week as low pressure deepens as it lifts northeast out of the Western High Plains.

5 Day Forecast for Duluth/Superior

.Tonight... Scattered showers. A thunderstorm possible before 9 PM. Mostly cloudy. Breezy. Low 47 to 52. Wind southwest to west at 10 to 20 mph with gusts to 30 mph. Chance of rain 50%.

.Friday... Windy and cool. Mostly cloudy with showers at times. High 55 to 60. Wind west to northwest at 20 to 30 mph with gusts to 40 mph. Chance of rain 50%.

.Friday Night... Becoming partly cloudy. Low 40 to 45. Wind northwest decreasing to 10 to 20 mph.

.Saturday... Partly cloudy. High 60 to 65.

.Saturday Night... Mostly clear. Low 40 to 45.

.Sunday... Partly cloudy. High 63 to 68.

.Sunday Night... Partly cloudy. Low 45 to 50.

.Labor Day... Mostly cloudy. Showers possible. High 60 to 65. Chance of rain 20%.

Normal High Temperature Today 69 degrees

Normal Low Temperature Today 49 degrees