Issued at 4:42 PM CDT, Friday, July 15th, 2011
Weather History:
On this date in 2006: A record high temperature of 96 degrees occurred at Duluth, Minnesota.
WEATHER HEADLINES:
-Low confidence forecast through early next week
-Thunderstorm timing and where they occur is very uncertain
-Marine layer may come and go near Lake Superior into early next week
-Dangerous combination of heat/humidity for Inland locations thru at least early next week
Forecast Discussion for Northeast Minnesota and Northwest Wisconsin
Today’s Weather:
Warm front has remained in Southern Minnesota Today due in part to a complex of strong to severe thunderstorms which formed early This Morning in Westcentral Minnesota, this complex of storms then tracked E-SE through portions of Central, Southern and Eastern Minnesota through early Afternoon…Convection near this warm front has prevented it from shifting farther north Today. A weak surface trough was analyzed over Northern-Western Minnesota late Today, but abundant cloud-cover had been in place until mid-late Afternoon which has kept the air marginally unstable but rather capped due to a limited amount of surface heating Today near this trough. High temperatures Today were in the 60s near Lake Superior with 70s and 80s farther inland. Dewpoints Today have climbed into the 60s to lower 70s with PWS of 1.30-1.60″ as of 4 PM. Winds across our area were out of the south or east Today under 20 mph.
Today’s Upper Level Analysis:
RUC model analysis and water vapor satellite imagery shows 500mb troughs over the Western U.S. and in Eastern Canada/Northeast U.S. with an upper level ridge over the Central-Southern U.S. Morning complex of storms which affected parts of the Upper Midwest continued to weaken This Afternoon as it drops into Southwest Wisconsin, but a new round of storms has been forming late Today in Southern Minnesota behind this first complex.
Tonight:
A weak surface trough will settle south-east into our area. A very moist, somewhat unstable but capped airmass will be in place near this boundary Tonight. CAPE will generally be in the 500-1500 j/kg range with Lifted Indices of -1 to -4 degrees C. Dewpoints should hold in the 60s to around 70 degrees with PWS averaging 1.50″. A few showers and thunderstorms could develop Tonight, first in Northcentral Minnesota…Then possibly in Northwest Wisconsin and Eastcentral Minnesota Overnight. Late Afternoon 0-6 KM and EFFECTIVE BULK SHEAR of 30-40 knots with 1KM HELICITY around 200 m2/s2 is more than enough to cause severe weather, but the shear and helicity are both forecasted to weaken during the Evening, so the main threats from thunderstorms would be from heavy rain and dangerous lightning. Partly to mostly cloudy skies with lows in the 60s to around 70 degrees are expected Tonight with 50s for some communities near Lake Superior. Note: Patchy fog could also occur at times Tonight. Winds will be out of the south or east under 15 mph.
Saturday and Saturday Night:
Surface trough washes out with the main surface front setting up well to our west-north through this period. Temperatures will heat up this period thanks to more sun Tomorrow compared to Today. Highs will be in the 80s and 90s with cooler temperatures possible near Lake Superior. Lows Saturday Night will be in the 60s and 70s. Dewpoints will be in the 60s and 70s with PWS of 1.00-1.25″. Afternoon and Evening heat indices are forecasted to range from 95-105 degrees, especially away from Lake Superior. Winds during this period will be out of the south or east under 15 mph. Expect partly cloudy skies Tomorrow and Tomorrow Night with a few showers and thunderstorms possible in the Morning, especially in Northwest Wisconsin. A few showers and thunderstorms could then move into far Northern Minnesota late Saturday Night. There will be plenty of instability in place during this period with CAPE of 1500-3000 j/kg and Lifted Indices of -3 to -7 degrees C, so if thunderstorms are able to develop they could become severe with a large hail and damaging wind threat…The greatest severe potential would be along the Minnesota/Ontario border for late Saturday Night.
Extended Forecast:
Quite a bit of uncertainty with the forecast for Sunday and Monday. Computer models are not in the best agreement pertaining to a cold front, and how far south it gets early next week. The NAM drops the front farthest south, while the GFS hangs it up much closer-if not in our local area early next week. Should the NAM verify, then there would be a break in the heat and humidity for early next week, especially near Lake Superior as the marine layer would strengthen. A very strong cap will be in place across our area with 700mb temperatures of +13 to +16 degrees C for Sunday and Monday, even with this cap in place the computer models seem to be generating an awful lot of QPF (precipitation) in our area for late this weekend and early next week which seems kinda fishy. The atmosphere will be very unstable on Sunday with CAPE >3000 j/kg and Lifted Indices from -4 to -9 degrees C. 0-6 KM and EFFECTIVE BULK SHEAR are forecasted to be in the 40-50 knot range which combined with the amount of energy in the air would support a severe thunderstorm risk with damaging wind and large hail for Sunday and Sunday Night. High temperatures on Sunday will be in the 80s and 90s with cooler temperatures possible near Lake Superior. Lows Sunday Night will be in the 60s and 70s. A frontal boundary should be near us or farther to our west-south for next Monday, this boundary will then lift back north as a warm front early next week. May see a few showers and thunderstorms at times between Monday-Wednesday of next week and another round of heat/humidity may build into the area sometime Tuesday-Wednesday of next week. Highs on monday will be in the 70s and 80s with cooler temperatures near Lake Superior. Lows Monday Night will mainly be in the 60s.
5 DAY FORECAST FOR DULUTH/SUPERIOR
“EXCESSIVE HEAT WATCH”
Timing: Saturday Afternoon through Tuesday Evening.
.Tonight… Humid. Partly to mostly cloudy. Low 60 to 65. Wind south to southeast at 5 to 15 mph.
.Saturday… Warm and humid. Partly cloudy. High 82 to 87 but cooler at times closer to Lake Superior. Wind south at 5 to 15 mph.
.Saturday Night… Warm and humid. Partly cloudy. Low 67 to 72. Wind south to southeast at 5 to 15 mph.
.Sunday… Warm and humid. Partly sunny. Showers and thunderstorms possible. High 83 to 88 but it may be cooler at times near Lake Superior. Chance of rain 20%.
.Sunday Night… Humid. Variable cloudiness. Showers and thunderstorms possible. Low 63 to 68. Chance of rain 20%.
.Monday… Humid. Partly sunny. Showers and thunderstorms possible. High 80 to 85 but cooler near Lake Superior. Chance of rain 20%.
.Monday Night… Partly cloudy. Low 60 to 65.
.Tuesday… Partly cloudy. High 80 to 85 but cooler near Lake Superior.
Normal temperatures for Tomorrow
High: 77 degrees
Low: 55 degrees
Saturday’s Pollen Forecast:
Grass: Moderate
Tree: None
Weed: None
Sunrise Tomorrow: 5:30 AM CDT
Sunset Tomorrow: 8:59 PM CDT
Tim