Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/25/21

Area Forecast Discussion

National Weather Service La Crosse WI

 528 PM CST Wed Nov 24 2021

.SHORT TERM...(This evening through Thursday)
Issued at 130 PM CST Wed Nov 24 2021

A cold front completes its sweep across the region this evening
with polar air streaming in overnight and setting the stage for a
relatively chilly Thanksgiving day.

As of 2pm, a well-advertised cold front was knocking on La
Crosse`s doorstep and should complete its passage through the
Upper Mississippi River Valley by early this evening. Temperatures
steadily fall in its wake back into the 30s this evening with
lows plummeting into the upper teens west to mid-20s east. With
the surface low pressure cell filling over the next 12-18 hours,
winds behind the front have only been gusting into the 20-30kt
range upstream in northern Minnesota. Thus, have not deviated too
far from the NBM deterministic wind speeds for tonight with a
leaning towards the HRRR to capture the higher wind gusts.

Low-level moisture wrapping around the lower tropospheric low may
experience enough synoptic lift ahead of the H500-300 trough to
generate light flurries during the overnight hours. However, low-
level omega plots show little support within the region of
100-150mb deep moisture plume/low static stability in the BL,
thus stuck with flurries versus explicit snow mention.

Low clouds linger to start Thanksgiving Day, but drier air scours
out the clouds during the morning hours and should result in a
sunny, albeit cold afternoon. With the thermal trough over the
region during this timeframe, highs will struggle to reach the mid
20s west to low 30s east. Northwesterly winds remain in place
through the day, but lessen in the afternoon/evening as a surface
ridge approaches from the west.

.LONG TERM...(Thursday night through Wednesday)
Issued at 130 PM CST Wed Nov 24 2021

After the passage of the mid-week cold front, a high pressure
system will settle into the area Friday, warming temperatures
slightly. Highs Friday will be in the high 20s to low 30s. Once
the ridge moves through the area, a low pressure system will move
into the area late Friday night to early Saturday morning. Its
associated cold front could bring some light rain/sprinkles (south
of I-90) and flurries (north of I-90) to the area Saturday
afternoon to Saturday evening. However, due to limited moisture
availability from the northwest flow aloft and timing uncertainty
between the GFS and European models, kept pops lower. High temps
Saturday should be mainly in the 30s, with some areas reaching low
40s. The end of Thanksgiving weekend is expected to be dry with
temps again in the high 30s to low 40s.

For Monday, GFS and European models suggest a short time of
precip in the morning in central Wisconsin. PWATs across the area
of about 0.47 inches could help supply that precip, but model
certainty is relatively low at this time, so have kept pops out of
the forecast for now. Tuesday and Tuesday night look to be dry
with highs in the mid 30s to low 40s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 528 PM CST Wed Nov 24 2021

MVFR ceilings move into the area tonight lasting until tomorrow
morning. Skies will clear out well as drier air advects into the
region. VFR conditions are then expected through the end of the
period. Overnight, there is a possibility for some accompanying snow
flurries with the lower ceilings. However, little to no impacts are
expected. Northwesterly winds will persist through the TAF period,
but the gusts will lessen tomorrow afternoon as a surface ridge
builds in from the west.

&&

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

$$

SHORT TERM...Skow
LONG TERM...Dahl
AVIATION...Peters