More heat, humidity; cool front arrives tonight

A cool front was draped over far northern Minnesota resulting in a rather larget cluster of thunderstorms early this morning.  Debris clouds from the decaying storms will hold the tempreatures down in that region this afternoon.

Screen capture of radar around 610 a.m. CDT. Source:Wunderground.com The colder cloud tops of the thundestorms showed up nicely on this IR satellite image. Source:Intellicast.com

In central and southern Minnesota and into northeast Iowa and Wisconsin, very warm temperatures with high dew points will result in heat index values approaching or exceeding 100 degrees this afternoon and early evening.

NWS Heat Advisory in shaded area.

From the National Weather Service in Chanhassen:

A HEAT ADVISORY REMAINS IN EFFECT THROUGH THIS EVENING FOR MUCH OF SOUTHERN AND CENTRAL MINNESOTA AND WEST CENTRAL WISCONSIN. DANGEROUS HEAT INDICES OF 100 TO 103 DEGREES WILL OCCUR THIS AFTERNOON ACROSS THE ADVISORY AREA.

HIGH TEMPERATURES TODAY WILL CLIMB INT0 THE LOWER TO MIDDLE 90S…AND COMBINE WITH DEWPOINTS AROUND 70 DEGREES TO YIELD DANGEROUS HEAT INDEX VALUES. THIS DANGEROUS HEAT IS OCCURRING IN RESPONSE TO A LARGE AREA OF HIGH PRESSURE THAT IS NEARLY STATIONARY OVER THE MIDWEST. A COLD FRONT WILL DROP SOUTH ACROSS THE REGION TONIGHT.

Highs expected today.

For southeast Minnesota and portions of Wisconsin, the Heat Advisory extends through 7 p.m. Friday as the cool front arrives later in the day.

Follow basic heat safety. Avoid the midday sunshine if at all possible. Being in direct sunshine can add as much as 15 degrees to the heat index value.

There is a difference between the two US forecast models for the intensity and coverage of thunderstorms later tonight.  It is likely that the strongest storms, with the greatest threat of severe weather, is  over northern Minnesota and into the UP of Michigan.

 

The Storm Prediction Center’s severe hail outlook for the next 24 hours.

The locally-run NWS Weather and Research Forecasting (WRF) paints a line of thunderstorms through central Minnesota at 10 p.m. this evening.

Forecast of a line of thunderstorms (simulated radar) valid at 10 p.m. Source:NWS Chanhassen

The NAM (North American Mesocale) model is not as generous with the rainfall amounts this evening and into the overnight hours.

Rainfall from the NAM 1 a.m. CDT ending at 4 am. CDT Friday. Source:NOAA/College of DuPage

The Global Forecast System (GFS) prediction of precipitation for later tonight shows a chance for some locally heavy rain in east central Minnesota into western Wisconsin.

GFS model rainfall from 1 a.m. CDT to 4 a.m. CDT. Considerable rainfall nearby the Twin Cities. Source:NOAA/College of DuPage

The cool front is expected to lose some punch as it sags to northern Iowa and northern Illinois on Friday.  High temperatures are likely to drop a few degrees in central Minnesota on Friday. Noticeably cooler temperatures are on tap  for Saturday afternoon and  Sunday.

 

Highs expected on Saturday.

Showers and thunderstorms may return as early as Sunday.  We’ll sort out the details of that Sunday chance for rainfall in the afternoon blog.

Craig Edwards

 

 

 

 

 

 

 

 

  • raflw

    How about that morning ‘low’ of 80 today? Ugh.

    • Starquest

      Love it! Ties the record set in 2011.