Nice through Friday; cold rain may mix with snow Saturday

Chalk up another nice spring day Thursday. Believe it or not, April temperatures in the Twin Cities are now running near average for the month so far.

Temperatures ran about 10 degrees warmer than average Thursday afternoon across Minnesota. The average high in the Twin Cities is now 63 degrees. But blue-tinted colder air is pooling upstream across the northern Rockies.

Temperatures Thursday afternoon, via Oklahoma Mesonet

Friday brings cool but sunny weather. Then comes Saturday.

Saturday: cold rain and snow

Thursday’s computer runs still suggest roughly the same Saturday weather scenario I’ve been talking about all week. A cold rain moves in Saturday, that may mix with snow across southern Minnesota at times.

I still expect little if any accumulation across most of central and southern Minnesota including the Twin Cities. But it may be just cold enough to produce several inches of slushy slop across southeast Minnesota and southern Wisconsin Saturday night.

Here are some of the factors working against significant accumulations around the Twin Cities Saturday.

  • Time of day: The bulk of rain (and any mixed snow) falls during daylight hours when temperatures will be warmest.
  • Late April sun angle: It’s strong enough to add a few critical degrees even through the clouds.
  • Warm ground: Any flakes that do fall will want to melt quickly on warm ground.

The American, Canadian, and European models keep precipitation mostly as rain Saturday in and near the Twin Cities, then change it over to wet snow across southeast Minnesota and Wisconsin by Saturday night.

The National Oceanic and Atmospheric Administration’s Global Forecast System captures the essence of the transition. A few wet flakes mixed with mostly rain in the Twin Cities, then accumulating snows across southeast Minnesota and Wisconsin.

NOAA GFS model Saturday via tropical tidbits

NOAA’s GFS snowfall output seems reasonable. A few sloppy inches across southeast Minnesota with some 6 inches-plus totals possible across southern Wisconsin.

NOAA GFS snowfall output, via pivotal weather

Let’s see what changes Friday’s model runs bring.

Milder air returns

The good news in this whiplash Minnesota spring? Milder air returns late next week. Highs hit the 60s again, and some models suggest 70 degrees again the weekend of May 4 and 5.

NOAA, via Weather Bell

The longer range upper-air maps still suggest even milder air as we move deeper into May.

NOAA upper-air map for 7 pm CDT Thursday, May 9.

Hang in there Minnesota.