Sunshine today, Friday flakes; wet on Christmas

Be ready for anything when it comes to weather in Minnesota.

Other than a direct hit from a hurricane, we see it all.

Warmth and sunshine are on tap for today, and our high temps will be unusually warm, with upper 30s over much of central and southern Minnesota:

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Our average high temperature is only 25 degrees in the Twin Cities this time of year.

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I'm hoping that we don't lose too much of our snowcover before Christmas!

Friday flakes

A fresh batch of flakes is expected on Friday, with an inch or two possible in the Twin Cities and much of central, southwestern, and northeastern Minnesota.

Southeastern Minnesota and parts of southwestern Wisconsin could see 3 or more inches.

NOAA’s Global Forecast System model shows the snow area Friday and Friday night:

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NOAA GFS model Friday and Friday night, via tropicaltidbits

Friday's highs will be slightly cooler than today's highs:

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Christmas mix changes to rain

You've heard the news: Santa's reindeer will need rain gear.

A wintry mix of rain, sleet and snow Christmas morning is likely to change to all rain over much of southern and central Minnesota Christmas afternoon.

NOAA’s Global Forecast System model shows the precipitation pattern from Christmas Day through noon on Monday:

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NOAA GFS model Christmas andChrisrmas night, via tropicaltidbits

Northwestern Minnesota and eastern North Dakota could see heavy snow on Christmas,  so you'll want to check later forecasts if you're planning to be in those areas.

Here's the big picture, courtesy of the Twin Cities office of the National Weather Service:

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NWS Twin Cities

In the Twin Cities, the temperatures at or near the ground when the rain begins will be very important.  Temps are expected to be slightly above freezing when the rain begins, but if surface temps are cold enough some areas could see an icy mess on Christmas Day.

Significant rain is possible on Christmas Day, which could cause some localized flooding if storm drains are clogged or if the rain seeps into basements due to ponding on frozen ground.

Rain on Christmas is unusual, but it has happened before.

I remember rain and lightning as I carried presents into a celebration late on Christmas Eve in 1982.

The Minnesota State Climatology Office had this description of our 1982 weather:

One of the more bizarre weather conditions on Christmas Eve and Christmas Day happened in 1982. Heavy rains accompanied with thunder and lightning hit the Twin Cities after dusk on the 24th and continued into the early morning hours of the 25th. The rain changed over to a slushy 1.4 inches of snow later in the morning of the 25th, but officially 1982 was a brown Christmas since the snow depth was measured at 6am and the change-over occurred after that.

Some additional context, from the NWS Twin Cities office:

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NWS Twin Cities

Freezing rain vs. rain

I've heard people say "the temperature is supposed to be 38 degrees, why are they saying it will snow?"

I've also heard "why are they saying it will rain if the temperature is supposed to be 29?"

The key to remember is that our official temperatures are measured about 6 feet above the ground.

If there is a warm layer above us, precipitation in the form of rain can make it through the shallow cold layer near the ground and freeze when it hits roads, sidewalks and power lines.

Here's a description of freezing rain vs sleet, from the National Weather Service:

Freezing rain occurs when the layer of freezing air is so thin that the raindrops do not have enough time to freeze before reaching the ground.  Instead, the water freezes on contact with the surface, creating a coating of ice on whatever the raindrops contact.

Sleet is simply frozen raindrops and occurs when the layer of freezing air along the surface is thicker.  This causes the raindrops to freeze before reaching the ground.

If there is no significant warm layer, we see all snow. If the warm layer extends from the ground to great heights, we see all rain:

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NWS

Meteorologists will be closely watching that temperature profile as we go into Christmas Day.