Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 181838
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
135 PM CDT Sun Apr 18 2021

.SHORT TERM...(Tonight through Tuesday)
Issued at 135 PM CDT Sun Apr 18 2021

Cold front still on track to sweep eastward across the region this
evening, with parent upper level shortwave trough lagging behind it.
With saturation holding mostly post the front, so will the
associated shower chances. Models a bit faster with this system,
bringing the showers in early/mid evening. Higher chances/qpf still
lies more northward where the added influence of the upper level
energy will be felt. Could be more of a broken line of light pcpn
locally, and what falls won`t amount to much - around 1/10" or so.

While rainfall promises to be meager with the front, the cold air
does not. There will be wintry feel to the air for the start of the
new work week. 850 mb temps still looking to drop to around -8 C
with NAEFS 850 mb temp anomalies nearing -2. Highs might not reach
40 for some Monday with freezing temps for lows expected into Thu
morning.

The front will continue to sag southward Mon/Tue, and where it ends
up continues to be of keen interest as it will be the focus for a
(heavy) snow band. Latest EC and NAM runs look more like the GFS
now, which favored a southern solution for front placement and
eventual shortwave interaction. Bulk of the EC ensemble members
favor this, as does the GFS. Could still see the northern fringes of
the snow band clip parts of northeast IA/southwest WI, but
confidence increasing that the local area will be spared the
indignity of accumulating snows for late April. All said, something
to keep an eye on.

.LONG TERM...(Wednesday through Sunday)
Issued at 135 PM CDT Sun Apr 18 2021

The GFS and EC remain in good agreement with sliding shortwave
ridging a loft across the region for Thu/Fri, with a corresponding
bump up in temperatures (expecting a return to near normal). The
weekend holds the potential for various bits of shortwave energy to
spin across the Upper Mississippi river valley. While models
continue to be at odds in strength, positioning and timing, there is
some agreement that later Fri into Sat could see some chances as
ridges slides east and ripples in the flow work in. Will stay the
course with the blend for chances.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1202 PM CDT Sun Apr 18 2021

VFR conditions will continue this afternoon with west winds around
10 kts with some gusts to 20 kts. A strong cold front will shift
winds to the NW this evening with a period of gusts up to 25-30 kts
possible behind the front, and gusts around 20 kts continuing into
Monday. A band of showers will also move through for a few hour
period between 02Z and 07Z. MVFR ceilings will develop behind the
front with potential for SCT/BKN MVFR ceilings to persist into
Monday in the cooler air behind the front.

&&


.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION.....JM


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