Sunrise 6:11 AM   Sunset 7:58 PM Moonrise 3:54 PM   Moonset 4:04 AM

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FXUS63 KARX 201055 AFDARX

Area Forecast Discussion National Weather Service La Crosse WI 555 AM CDT Sat Apr 20 2024

KEY MESSAGES

- Freeze warning continues for eastern MN, northeast IA, and parts of western WI through early morning.

- Continued below normal temperatures today with some flurries/flurry-rain mix today and freeze headlines expected again for Sunday morning.

- Shower chances Monday night and Tuesday (80% chance less than 0.25"); how cold Wednesday morning? Current probabilities for lows <32 degrees F are 70% near Medford to 30-40% toward New Hampton and Elkader IA.

- More seasonable to end the week, but shower and thunderstorm chances return.

DISCUSSION
Issued at 330 AM CDT Sat Apr 20 2024

Overview:

It felt more like March than April Friday as several locations were held to the 40s. Combined with gusty northwest winds mostly 38 to 48 mph; it felt quite blustery. Rochester topped out at 56 mph!

Water vapor satellite imagery and heights early this morning showed a seasonably strong, broad trough encompassing much for the U.S. and was centered over Hudson Bay. A 500mb ridge was located over the West Coast. The surface map showed west to northwest winds with a re-inforcing cold front upstream. By 3am, temperatures were in the 30s area-wide with a few upper 20s. Winds were northwest mostly 5 to 15 mph with gusts 15 to 25 mph. Nighttime microphysics satellite imagery and radar showed considerable clouds across the region with flurries/flurry-rain mix and trace reports of precipitation. Some of the snow showers were working into Wabasha County and Medford had dropped to less than 3 miles for a time.

Continued below normal temperatures today with some flurries/flurry- rain mix today and freeze headlines expected for Sunday morning:

We remain under the influence of cyclonic flow today as re-inforcing cold air arrives this morning. Light snow/flurries have been noted on the upstream obs and a few snow showers have been steadily dropping southeast toward the forecast area with some visibility restrictions 2 to 5 miles. Forecast soundings show convective temperatures in the mid 30s with increasing moisture 1500-3800ft AGL during the day with low freezing levels. Thus, expect areas of clouds to re-develop today. There is better warm air aloft early this morning and again some weaker warm air aloft this afternoon with some upper level jet support this afternoon. The HRRR had some hints at snow showers from 18Z on, but the most recent 20.07Z run had backed off on this somewhat. The RAP more from 21Z on. The Hi-res models have not picked up on the current activity well, thus this lowers confidence. Did add low pops to the forecast today for flurries or a flurry/rain mix. Continued brisk northwest winds today, but not as strong as Friday with gusts mostly 15 to 25 mph. Temperatures remain below normal with highs in the 40s.

The skies clear tonight with diminishing winds. With the chilly airmass in place, low temperatures look to fall into the mid-20s to lower 30s. With these freezing temperatures again forecast, we'll likely need another freeze warning headline for Sunday morning.

Mid-level ridging builds in for Sunday. Northwest winds continue with a relatively dry airmass. Weekend precipitable water values are 50 to 75% of normal, but with the warmer temperatures Sunday, lowest relatively humidities lower to 20 to 30%. Northwest winds again gusting 15 to 30 mph. East of the Mississippi river Monday, it will be dry with strengthening winds area-wide with gusts 25 to 40 mph. Dewpoints gradually increase west of the Mississippi River. Highs Monday top out in the 60s with rain chances increasing during the afternoon.

Attention turns to fire weather concerns. With the recent snow/rains, there has been some progress on green-up and the Fine Fuel Moisture is mostly in the 80s Sunday and Monday. With low RH values and stronger winds gusts, we'll continue to coordinate with local officials each day related to fire weather concerns.

Shower chances Monday night and Tuesday; how cold Wednesday morning?

Monday afternoon/Monday night, an area of low pressure will track through the U.P. of Michigan with a surface cold front passing through the local area. This will bring a good chance for light rain especially Monday night and again Tuesday afternoon with a re-inforcing cold front. There is a 30-50% chance of 0.1" or more with an 80% chance of the rain being less than 0.25".
Behind the cold front Tuesday afternoon, temperatures could again be below freezing Wednesday morning. This far out, there is not good agreement with a large spread in solutions. The current GEFS/EC/Canadian ensembles means are 29-35 for the local area for Wednesday morning.

More Seasonable to end the week, but shower and thunderstorm chances return:

Temperatures are currently forecast to moderate into the 60s for the end of the week with the potential for another storm system to bring showers/thunderstorms to the region Thursday night/Friday.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
Issued at 547 AM CDT Sat Apr 20 2024

Mostly cloudy skies today with ceilings skirting the MVFR/VFR threshold this afternoon. West winds blow 10-15 knots with periodic gusts up to 20-25 knots west of the Mississippi River.
Patches of flurries/sprinkles are likely today, but impacts at the terminals are not anticipated.

ARX WATCHES/WARNINGS/ADVISORIES
WI...Freeze Warning until 8 AM CDT this morning for WIZ032-033-041- 053>055-061.
MN...Freeze Warning until 8 AM CDT this morning for MNZ079-086>088- 094>096.
IA...Freeze Warning until 8 AM CDT this morning for IAZ008>011-018- 019-029-030.

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