Metro severe risk fades this afternoon, but severe watch possible just south and east
Weather cliches seem to be apt today.
Timing is everything. A watched pot won’t boil.
The timing of a passing cool front before “max heating” in the metro means the best chances for developing thunderstorms is south and east of the Twin Cities. I can’t rule out a stray storm over the metro this afternoon, but the best chance for storms is rapidly shifting south and east of the Twin Cities.
Check out the early PM GOES 1km visible shot, with wind “streamlines” and dew points overlaid. You can see the 70 degree dew points right over the metro…and the wind shift line, or front, moving in with much drier air.
The best chances for a line of strong to severe storms has now shifted to areas just southeast of the Twin Cities. Mankato, Waseca, Rochester, Winona, La Crosse and Eau Claire should keep an eye out for strong storms and possible watches and warnings this afternoon and evening.
Here’s the latest from NOAA’s SPC on the chances for a watch this afternoon.
Here’s the latest Twin Cities radar loop from Weather Underground.
Summer Pause Button?
This is going to be a very different weather week in Minnesota.
We (enjoyed?) what was probably the hottest week of the year in Minnesota last week. Temps ran 6 to 13 degrees above average…and we logged three consecutive days at or above 92 in the metro during the “heat wave” last week.
A cool front sweeps through Minnesota today bringing scattered thunderstorms, then a noticeably cooler and refreshing air mass. From 3 days in the 90s with high humidity last week… to 3 days in the 70s with lows in the 50s this week? Welcome to “summer” in Minnesota.
Look for scattered thunderstorms to favor southeast Minnesota and southwest Wisconsin as the front sweeps through today. A few of the storms could be severe packing high winds and hail.
Twin Cities: Nip and tuck
It will be a race against time to see if storms are able to fire today before the front moves through the Twin Cities metro area around midday. The most unstable air will be ahead of the front, and storms will tend to develop this afternoon as more heat kicks in. If the front clears the metro before storms can develop or become severe, then some (metro) areas may escape storms and beneficial rainfall. Here’s the GOES 1km visible shot from this morning as the front approaches.
NOAA: Slight risk for severe storms
Dew points are in the upper 60s to near 70 near the front, and that will provide enough fuel for the possibility of severe storms. Biggest threats? High winds and hail.
Here’s the risk area from Storm Prediction Center:
Here’s the weather geek speak verbiage in the “convective outlook.”
…UPPER MS VALLEY…
AN UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS THE UPPER MS VALLEY ON MONDAY. AT THE SFC…A LOW WILL MOVE EWD ACROSS NRN MN WITH A TRAILING COLD FRONT ADVANCING SEWD ACROSS CNTRL AND SRN MN INTO NRN WI AND NW IA. THE NAM/GFS/ECMWF MODELS SUGGEST THAT ELEVATED THUNDERSTORMS MAY BE ONGOING ALONG THE FRONT AT THE BEGINNING OF THE PERIOD. THE MODELS DEVELOP NEW THUNDERSTORMS ALONG AND AHEAD OF THE FRONT EARLY MONDAY AFTERNOON WITH CONVECTION MOVING SEWD ACROSS THE UPPER MS VALLEY DURING THE LATE AFTERNOON AND EARLY EVENING.
FORECAST SOUNDINGS AT 21Z FOR MINNEAPOLIS SHOW SFC DEWPOINTS IN THE UPPER 60S TO NEAR 70 F ALONG WITH MLCAPE VALUES IN THE 2000 TO 2500 J/KG RANGE. THIS COMBINED WITH 40 TO 50 KT OF DEEP LAYER SHEAR AND STEEP MID-LEVEL LAPSE RATES SHOULD BE SUPPORTIVE OF SUPERCELLS WITH LARGE HAIL. STEEP LOW-LEVEL LAPSE RATES AND ABUNDANT LOW-LEVEL MOISTURE MAY ALSO RESULT IN A WIND DAMAGE THREAT ESPECIALLY IF A TRANSITION TO LINEAR MODE CAN OCCUR. THE SEVERE THREAT SHOULD EXTEND SWWD INTO NW IA WHERE THE MODELS DEVELOP THE STRONGEST INSTABILITY SO WILL EXTEND THE SLIGHT RISK INTO THAT AREA.
The cool front will clear the metro area by around 3 p.m. or so and push any thunderstorms into Wisconsin and southeast Minnesota later in the day and evening.
September Preview: Cooler week ahead
We may be searching for July later this week.
You can give the AC a rest for sure by tonight. Temps as cool as the 50s have been lurking in southern Canada behind the front. Don’t be shocked if temps dip into the upper 50s in the metro suburbs Tuesday morning. Upper 40s up north near International Falls to the Boundary Waters Canoe Area will feel downright “Septemberish.”
Hopefully the extra blanket is still close at hand?
Highs may not climb out of the 70s later this week. Here are forecast highs for Tuesday. Note the 80s getting shoved well south,and no 90s on the map.
“Canadian High” builds in
Here’s the National Ocean and Atmospheric Administration’s NAM model showing today’s front sweeping through — as cooler Canadian high pressure builds in with a north wind this week. (click to animate)
Here’s the meteogram this week from Iowa State as temps crash about 15 degrees from last week.
Keep an eye out for storms today…and keep the long sleeves handy later this week!