Cool and breezy

The official high temp at Minneapolis-St. Paul International Airport hit 81 degrees yesterday. That was 8 degrees above average.

Today we'll have the meteorological equivalent of a "market correction", with cooler than normal highs.

Northwestern Minnesota will have highs in the upper 50s, with 60s over the remainder of Minnesota. The Twin Cities should top out in the upper 60s this afternoon. Morning sunshine will give way to a cloud/sun mix this afternoon.

It'll also be breezy today.

Areas of frost tonight

A high pressure system will settle over Minnesota tonight, which will result in very light winds. When the air is calm or winds are very light, radiational cooling takes place under clear skies.

Temperatures in central and northern Minnesota will drop into the 30s overnight, and areas of frost are possible:

Official temperatures are measured two meters (6.56 feet) above the ground. When winds are very light, the official temp at two meters could be around 36  or 37, and the ground level temp could be around 32.

The National Weather Service has issued a frost advisory, valid from 3 a.m. to 8 a.m. Wednesday, for much of north-central Minnesota and part of central Minnesota:

Here are the frost advisory details:

NATIONAL WEATHER SERVICE DULUTH MN

258 AM CDT TUE SEP 13 2016

...FIRST FROST OF THE SEASON ACROSS PARTS OF NORTH CENTRAL

MINNESOTA...

.AN AREA OF HIGH PRESSURE BUILDING IN ACROSS NORTH CENTRAL

MINNESOTA TONIGHT WILL RESULT IN CLEAR SKIES...CALM WIND...AND

TEMPERATURES FALLING TO NEAR FREEZING. THESE CONDITIONS WILL BE

FAVORABLE FOR FROST WHICH COULD DAMAGE SENSITIVE VEGETATION.

MNZ010-018-025-026-033-131800-

/O.NEW.KDLH.FR.Y.0004.160914T0800Z-160914T1300Z/

KOOCHICHING-NORTH ITASCA-NORTH CASS-SOUTH ITASCA-SOUTH CASS-

INCLUDING THE CITIES OF...INTERNATIONAL FALLS...BIGFORK...

WALKER...GRAND RAPIDS...PINE RIVER

258 AM CDT TUE SEP 13 2016

...FROST ADVISORY IN EFFECT FROM 3 AM TO 8 AM CDT WEDNESDAY...

THE NATIONAL WEATHER SERVICE IN DULUTH HAS ISSUED A FROST

ADVISORY...WHICH IS IN EFFECT FROM 3 AM TO 8 AM CDT WEDNESDAY.

* LOCATION...NORTH CENTRAL MINNESOTA INCLUDING KOOCHICHING ITASCA

AND CASS COUNTIES.

* TEMPERATURES...LOWS 32 TO 36.

* IMPACTS...FROST MAY DAMAGE OR KILL SENSITIVE OUTDOOR VEGETATION

IF PRECAUTIONS ARE NOT TAKEN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FROST ADVISORY MEANS THAT WIDESPREAD FROST IS EXPECTED.

SENSITIVE OUTDOOR PLANTS MAY BE KILLED IF LEFT UNCOVERED.

Frost isn't real unusual in northern Minnesota as we approach mid September. Here are the average dates of the first 32 degree readings in late summer/early fall for northern Minnesota:

And remember, you can have frost with an official temp above 32 degrees, when winds are light and skies are clear. Specific frost information is not available, but it is safe to say that the average date of the first frost would be a few days earlier than the average date of the first 32 degree reading.

Cool Wednesday, rain chance Thursday

The cool high pressure system doesn't move away until Wednesday night:

The final frame shows showers moving into western Minnesota Thursday morning. We'll have a chance of showers in the Twin Cities later in the day.

Highs in the 60s are expected tomorrow:

Lower 70s return to southeastern Minnesota on Thursday:

Showers, possibly storms on Friday

The National Weather Service Global Forecast System model shows that periods of rain are a good bet on Friday:

A few thunderstorms will also be possible Friday and Friday night.

A few showers could linger into early Saturday, but most of the weekend looks dry.

High temps could be slightly below normal on Saturday, then into the lower 70s in many spots on Sunday.

That would be nice!