402
FXUS63 KARX 310342
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
942 PM CST THU JAN 30 2025
KEY MESSAGES
- RAIN EXPECTED OVERNIGHT INTO FRIDAY MORNING, MAINLY ACROSS
NORTHEAST IOWA AND FAR SOUTHWESTERN WISCONSIN. AMOUNTS
GENERALLY UP TO 0.1" EXPECTED IN FAR SOUTHWEST WISCONSIN.
- WINTRY PRECIPITATION CHANCES SATURDAY NIGHT INTO SUNDAY
(20-75%). HIGHER CONFIDENCE IN ACCUMULATING SNOW NORTH OF
I-94, BUT LESS CONFIDENCE IN PRECIPITATION TYPE FURTHER SOUTH.
DISCUSSION
ISSUED AT 216 PM CST THU JAN 30 2025
RAIN OVERNIGHT INTO FRIDAY MORNING
A MATURING MID-LATITUDE CYCLONE ACROSS THE CENTRAL UNITED STATES AS
SEEN ON CURRENT WATER VAPOR IMAGERY CONTINUES MOVING NORTHWARD
THIS AFTERNOON. VARIOUS ENSEMBLE BLENDS, INCLUDING THE 30.13Z
NBM, 30.12Z HREF, AND 30.06Z EPS, SUGGEST PRECIPITATION CHANCES
OF 20-40% ACROSS OUR FAR SOUTH AS THIS SYSTEM MOVES TOWARDS THE
UPPER MIDWEST. THE 30.06Z GEFS/GEPS HOWEVER, BRINGS THE SYSTEM
A LITTLE FURTHER NORTH AND INTO OUR AREA, WITH THE ENSEMBLE
MEANS SUGGESTING ROUGHLY 1/4" OF QPF. THIS SOLUTION SEEMS TO BE
AN OUTLIER ON THE HIGH END, AND THINKING A "GLANCING BLOW" IS
THE MOST APPROPRIATE FOR THIS SCENARIO. DETERMINISTIC QPF IS
LIGHT, WITH AROUND 0.1" EXPECTED, MAINLY IN FAR SOUTHWEST
WISCONSIN. THE LOW MOVES EAST OF THE AREA TONIGHT INTO FRIDAY,
WITH CLEARING SKIES.
WINTRY PRECIPITATION THIS WEEKEND
ANOTHER 700-500HPA TROUGH SWINGS THROUGH THE UPPER MIDWEST SATURDAY
INTO SUNDAY. ASSOCIATED WITH IT ARE SEVERAL AREAS OF FRONTOGENESIS
AS A SURFACE LOW BEGINS TO DEVELOP IN THE NORTHERN GREAT PLAINS.
WITH COLD AIR ADVECTION ON THE BACKSIDE OF TONIGHT'S LOW,
TEMPERATURES TREND BACK TO NEAR OR BELOW FREEZING AS WE GET TOWARDS
SATURDAY NIGHT, ESPECIALLY IN AREAS NORTH OF I-94.
GIVEN MODEST MOISTURE TRANSPORT AND A SATURATED COLUMN IN AREAS
NORTH OF I-94 COINCIDING WITH THE AFOREMENTIONED SHORTWAVES AND
FRONTOGENESIS ENERGY AS WELL AS MID LEVEL WARM AIR ADVECTION, THERE
IS A HIGHER CONFIDENCE THAT ACCUMULATING SNOWFALL WILL OCCUR IN
THESE AREAS GIVEN THE AMPLE FORCING DURING THE SATURDAY EVENING INTO
SUNDAY MORNING TIMEFRAME. THE 30.13Z NBM INDICATES A 30-70%
PROBABILITY OF GREATER THAN 1 INCH OF SNOW AND A 20-40% PROBABILITY
OF GREATER THAN 3 INCHES, WITH EVEN SOME SMALL CHANCES (10-20%) TO
EXCEED 5 INCHES OF SNOW, ASSUMING A 10:1 RATIO.
HOWEVER, CONFIDENCE IN SNOWFALL AND OVERALL PRECIPITATION TYPE
DECREASES FURTHER SOUTH, CLOSER TO I-90. THERE CONTINUES TO BE THE
INDICATION OF DRYING MID-LEVELS ACROSS THE AREA AS THESE FORCING
MECHANISMS MOVE THROUGH THE REGION WHILE LEAVING THE LOWEST ~6KFT
SATURATED AND BELOW FREEZING. THIS SETS UP THE POTENTIAL FOR
FREEZING DRIZZLE ACROSS THE AREA MAINLY DURING THE
SATURDAY EVENING INTO SUNDAY MORNING TIMEFRAME.
MODEL SOUNDINGS VARY IN THEIR TEMPERATURE AND MOISTURE PROFILES
DURING THIS TIMEFRAME, SPECIFICALLY BETWEEN THE GFS AND NAM. THE GFS
SOUNDINGS SUGGEST DRIER MID TO UPPER LEVELS (700HPA AND ABOVE) WHILE
THE LOW LEVELS REMAIN SATURATED AND BELOW FREEZING INDICATING
FREEZING DRIZZLE WOULD BE THE DOMINANT PRECIPITATION TYPE. THE NAM
SOUNDINGS KEEP UPPER LEVELS (600HPA AND ABOVE) DRY SATURDAY
AFTERNOON AND OVERNIGHT (INDICATIVE OF FREEZING DRIZZLE) BEFORE
BECOMING SATURATED BUT LEAVING A ~5KFT DRY LAYER LEAVING THE LOW
LEVELS SATURATED. THIS WOULD SUGGEST THE POSSIBILITY OF A MORE
SEEDER-FEEDER SETUP AND A FAR MORE MESSY SCENARIO PRECIPITATION TYPE
WISE. HOWEVER, THIS DRY LAYER IS FAIRLY DEEP AND WOULD BE
CHALLENGING TO PRECIPITATE ALL THE WAY THROUGH TO ALLOW THIS
SCENARIO. IT IS INTERESTING TO NOTE THAT THE 30.00Z LREF IS THE
ONLY ENSEMBLE SUGGESTING FREEZING PRECIPITATION PROBABILITIES
AT THIS TIME ARE 10-20%.
REGARDLESS OF THE ULTIMATE PRECIPITATION TYPE, CONFIDENCE REMAINS IN
THE OCCURRENCE PRECIPITATION SATURDAY NIGHT INTO SUNDAY, WITH
SNOW ACCUMULATIONS NORTH OF I-94.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 940 PM CST THU JAN 30 2025
IFR TO LIFR CEILINGS/VISIBILITIES MOVE AS FAR NORTH AS AN HPT
TO LNR LINE AFTER 06Z BEFORE SINKING BACK TO THE SOUTH AROUND
12Z. VFR CONDITIONS ARE FORECAST FOR THE REMAINDER OF THE
PERIOD. WINDS WILL BE FROM THE NORTH AROUND 5-10 KTS THROUGH THE
DAY, GUSTING UP TO 15-20 KTS FROM MIDDAY TO MID-AFTERNOON.
WINDS BACK MORE TO THE EAST AFTER SUNSET.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FALKINHAM
AVIATION...SKOW
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