Rochester, Minnesota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

654
FXUS63 KARX 231811
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1211 PM CST Mon Dec 23 2024

.KEY MESSAGES...

- Low Confidence (<20%) In Freezing Drizzle Occurrence Today As
  Low Level Dry Air Has Abated Precipitation Early This Morning.
  Highest PoPs In Central Wisconsin Later This Morning Through
  The Afternoon With Snow As Main P-Type.

- Overcast Skies, Daytime Highs In The Mid 30s, and Light South-
  Southeast Winds Expected Christmas Day.

- Ongoing Widespread Preciptiation Chances For Latter Half Of
  The Week; All Liquid Expected At Current Forecast Hour.

&&

.DISCUSSION...
Issued at 317 AM CST Mon Dec 23 2024

Ongoing Early Morning Preciptiation:

The near term forecast has only become more tricky if anything;
continually decreasing confidence (<20%) for freezing drizzle.
Overnight observations have had the low level dry air winning
out over incoming moisture and accompanying feint  returns.
Given these trends, have delayed onset of southern half of the
Winter Weather Advisory (Richland, La Crosse, Monroe, Juneau,
Adams, Jackson) counties in southwest/south-central Wisconsin
from 23.09Z to 23.15Z. Monitoring morning ceiling observations
may provide the best lead time for precipitation onset. Given
the presence of upper level ice nuclei and the limitation being
the drier air, confidence for snow given any saturation has
increased. Ice and dry air ingest is intermittent though so not
as clear as one would hope. Could warrant an AFD Update section
later this morning as well, depending on how things saturate.

Precipitation Today:

Given the decrease in moisture compared to previous forecasts,
precipitation confidence has also decreased for today. As the low
exits to the southeast, potential wraparound moisture remains
the concern. Besides the dry air winning out early this
morning, a lack of forcing (limited frontogenesis and a only a
very narrow filament of isentropic upglide) has resulted in a
drier forecast. Have reduced ice accumulations to only a Trace
in limited spots as overachieving surface temperatures place the
surface freezing isotherm into central Wisconsin.

Select high resolution models continue freezing drizzle concerns
through northeast Iowa tonight. Nevermind the incessantly mentioned
drying trend, there is quite a large spread in near freezing
surface temperatures ab. Again, given the overachieving surface
temperatures, and the colder, drier air inherently removing the
increased moisture, haven`t trended into FZDZ. But will be
subsequent detail to monitor.

Christmas Day:

An amplified upper level trough still expected to rapidly lift
north-northeast through Christmas. Forecast trends have
separated northern and southern streams of this upper level
forcing, keeping us in upper level diffluence and calm weather.
The higher precipitation signal remains tied to the better
moisture to our southeast. Above freezing surface temperatures
are expected within this moisture return, i.e., rain. Little to
no confidence in the exact location of the surface freezing
isotherm locally, will be tied to moisture plume. Current
National Blend forecast calls for overcast skies, daytime highs
in the mid 30s, and light south-southeast winds.

Widespread Precipitation Chances Latter Half Of The Week:

Precipitation chances cover the latter half of the week as an
amplified synoptic upper level trough sends multiple bouts of
energy through the Central Plains. Initial precipitation chances
are slightly delayed over previous forecasts, reaching the
local area Thursday night. Precipitation type expected to be
liquid as above normal temperatures place the freezing isotherm
well to the north in long term global ensembles (100%
confidence - EPS/GEFS).

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1206 PM CST Mon Dec 23 2024

As wintry precipitation exits to the east over the next few
hours, attention turns to ceilings. A brief period of IFR
conditions, already ongoing at RST/AUM/ONA, should occur,
including at LSE. As these depart to the east, MVFR is favored
until the overnight hours, when IFR and potentially LIFR
ceilings are expected. There is a smaller chance (30%) for
IFR/LIFR fog to occur as well. Either way, widespread flight
rules restrictions are expected tonight into Tuesday morning to
round out the period.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 3 PM CST this afternoon for
     WIZ029-034-041>044-053-055.
MN...None.
IA...None.

&&

$$

DISCUSSION...JAR
AVIATION...Ferguson