Rare October ‘moderate severe risk’ Friday, Tropical Storm Karen threatens Gulf

Early October in Minnesota is usually all about crisp blue skies and vivid fall colors. Not this year.

The opening act of our four-day fall storm has already brought lightning, thunder and downpours. The second act looks even more dramatic.

Our potent low pressure system winds up Friday, and spins toward Omaha. An active warm front ahead of the system will trigger waves of showers and  thunderstorms, and there’s a good chance some of those will be severe, capable of producing tornadoes in southern Minnesota and Iowa.

NOAA’s Storm Prediction Center has issued a slight risk for severe storms that includes the Twin Cities, and a rare October ‘moderate risk’ along the Interstate-90 corridor in southern Minnesota into northern Iowa.

Image: NOAA SPC

Friday’s weather maps show another unusual element for October in Minnesota –favorable low-level wind shear for tornadoes. The most severe storms — and those capable of producing a tornado — will probably be in southern Minnesota along the I-90 corridor. Here’s the wording from the National Oceanic and Atmospheric Administration’s SPC. Yes NOAA sends these in ALL CAPS. I don’t think they mean to shout.

THE MOST PROBABLE/CERTAIN FOCUS FOR DEEP CONVECTIVE DEVELOPMENT AND ASSOCIATED SEVERE POTENTIAL FRIDAY AFTERNOON/EVENING WILL LIKELY BE FOCUSED NEAR/EAST OF THE SURFACE TRIPLE POINT…INCLUDING AREAS FROM EASTERN NEB/SOUTHEAST SD INTO IA AND SOUTHERN MN/SOUTHWEST WI…ALTHOUGH THIS FOCUS COULD BE SHUNTED A BIT SOUTH PENDING EARLY DAY OUTFLOW/EFFECTIVE WARM FRONTAL LOCATION.

THE EXACT EXTENT OF STORM COVERAGE NEAR THE COLD FRONT AND WITHIN THE WARM SECTOR IS A BIT UNCERTAIN. BUT IN GENERAL…NEAR/JUST SOUTH OF THE WARM FRONT AND AHEAD OF THE SURFACE LOW IS WHERE LARGE LOOPING HODOGRAPHS AND SUPPORT RISK FOR SUPERCELLS INCLUDING LARGE HAIL AND TORNADOES /ONE OR TWO POSSIBLY STRONG/ SHOULD BE MAXIMIZED…WITH POTENTIAL FOR DAMAGING WINDS AS WELL.

Bottom line? Keep an eye out for severe weather watches and warnings, especially Friday afternoon and evening.

Main storm tracks in Friday into Saturday

The storm track favors a warm front pushing onto southern Minnesota Friday. Look for thunderstorms to become more numerous as the day wears on, and move in from the southwest. Here’s the storm track and rainfall outlook from the National Weather Service in the Twin Cities.

Image: Twin Cities NWS

The heaviest waves of rain with this storm will likely come late Friday afternoon and night. Another inch to as much as 3 inches could fall in the Upper Midwest by Sunday.

Image: NOAA Weather Prediction Center

Storm lingers into Sunday

All indications are the storm will linger into Sunday. The worst of the rain will come Friday and Friday night, but a few showers could linger into Sunday. Here’s the chilly Euro weekend solution via Weatherspark. The good news? 70s could be back next week!

Image: Weatherspark

Twin Cities Marathon: Chilly and wet?

Sunday’s running of the Medtronic Twin Cities Marathon looks to be chilly — and potentially wet. I’m not a runner (I prefer my sweat on hockey skates) but I understand runners like it cool. I’m just not sure this kind of chill will be ideal. Temps look to be in the lower 40s, with a potentially raw northwest wind at times during the race. There may also be some scattered showers or drizzle.

Here’s a closer breakdown of Sunday’s Euro model depiction, which suggests some bracing temperatures in the lower 40s at race time. Dress appropriately!

Image: Euro data via Weatherspark

Hurricane Karen?

Tropical Storm Karen blew up pretty quickly in the Gulf, and will likely become a Category 1 hurricane. The target zone appears to be near Pensacola, which is like a hurricane magnet for recurving storms in the Gulf.

Image: NOAA National Hurricane Center

Intensity forecast indicate 75 mph winds likely Friday before landfall this weekend. But intensity forecasts are notoriously tough with hurricanes. Oil rigs have been evacuated in the Gulf.

 

 

 

  • Pappy

    Here is the Mexican forecast: chili today, hot tamale.