102
FXUS63 KARX 291949
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
149 PM CST WED JAN 29 2025
KEY MESSAGES
- NEAR RECORD/RECORD HIGH TEMPERATURES EXPECTED THURSDAY. HIGHS
EXPECTED TO BE IN THE MID 50S.
- CHANCES FOR RAIN (20-50%) THURSDAY NIGHT INTO FRIDAY MORNING,
MAINLY SOUTH OF I-90. QPF AMOUNTS UP TO 1/4" ARE EXPECTED,
WITH THE HIGHEST AMOUNTS ACROSS NORTHEAST IOWA AND SOUTHWEST
WISCONSIN.
- ADDITIONAL PRECIPITATION CHANCES SATURDAY AFTERNOON INTO
SUNDAY MORNING (30-50%) IN THE FORM OF A SNOW/RAIN-SNOW MIX,
MAINLY NORTH OF I-90. TEMPERATURES COOL FRIDAY AND SATURDAY,
WARMING AGAIN SUNDAY.
DISCUSSION
ISSUED AT 149 PM CST WED JAN 29 2025
NEAR RECORD/RECORD TEMPERATURES THURSDAY
A SIMILAR SET-UP TO THE WARMTH THIS PAST TUESDAY IS EXPECTED
THURSDAY SUCH THAT NEAR RECORD TO RECORD HIGH TEMPERATURES ARE
EXPECTED. WINDS BECOMING SOUTHWEST THIS AFTERNOON AND EVENING BEGIN
TO USHER WARM AIR INTO THE REGION AS WE HEAD INTO THURSDAY
WITH 850-925HPA TEMPS EXPECTED TO REACH 6-8C THURSDAY AFTERNOON
ACROSS THE REGION, WHICH IS SIMILAR BUT PERHAPS A DEGREE OR TWO
COOLER THAN WHAT WAS EXPERIENCED TUESDAY. A STRONGER LOW LEVEL
JET IS ALSO EXPECTED TO BE EAST OF OUR AREA AND CLOSER TO LAKE
MICHIGAN BY THURSDAY AFTERNOON SUCH THAT MECHANICAL MIXING IS
EXPECTED TO BE LESS THAN TUESDAY.
DESPITE THIS, STILL THINKING THAT A WELL MIXED BOUNDARY LAYER WILL
DEVELOP AS A DRY COLUMN SHOULD ALLOW FOR CLEARING SKIES
OVERNIGHT AND THROUGHOUT THE DAY THURSDAY COMBINED WITH AT LEAST
SOME MECHANICAL MIXING GIVEN WINDS ALOFT OF 20-25KT. THERE IS
MORE UNCERTAINTY IN TEMPERATURES FURTHER SOUTH INTO NORTHEAST
IOWA AND SOUTHWEST WISCONSIN AS CLOUD COVER SHOULD BE INCREASING
STARTING THURSDAY AFTERNOON, AND AS SUCH WAS NOT AS AGGRESSIVE
WITH TEMPERATURES IN THESE AREAS. HOWEVER, THINKING WE SHOULD BE
ABLE TO TAP INTO THE TEMPERATURES ALOFT AND PUSH OUR HIGHS
TOMORROW INTO THE RECORD TERRITORY. CONFIDENCE IS INCREASED IN
THIS SCENARIO AS THE EFI IS IN AGREEMENT WITH THIS ANALYSIS, SHOWING
A 90%+ PROBABILITY OF UNUSUAL WARMTH ACROSS OUR AREA.
PRECIPITATION CHANCES THURSDAY NIGHT INTO FRIDAY MORNING
A 500HPA LOW PRESSURE AREA CURRENTLY SITUATED ACROSS THE DESERT
SOUTHWEST WILL BEGIN TO LIFT NORTHWARD TONIGHT. IN RESPONSE A
MATURE FRONTAL CYCLONE WILL DEVELOP ACROSS THE CENTRAL UNITED
STATES THURSDAY AND APPROACH THE MIDWEST THURSDAY EVENING.
WHILE THE BULK OF THIS SYSTEM IS PROGGED TO REMAIN SOUTH OF OUR
AREA, SOME MODEL GUIDANCE, MOST NOTABLY THE GEFS, CONTINUES TO
BRING THE DEFORMATION ZONE OF THE SYSTEM INTO OUR AREA, SOUTH OF
I-90.
THE 29.00Z NAEFS AND EFI SUGGEST THE HIGHEST MOISTURE CONTENT WILL
REMAIN TO OUR SOUTH ACROSS MR. MIMAL'S NOSE, A CONSISTENT
SIGNAL OVER THE LAST SEVERAL RUNS, ALTHOUGH A SLIGHT NORTHWARD
SHIFT HAS BEEN NOTED IN RECENT RUNS. THE NAEFS INDICATES
MOISTURE IN THE 99TH PERCENTILE OR ABOVE AND THE EFI CONTINUES
TO SHOW A 90%+ PROBABILITY OF UNUSUAL MOISTURE WITH A NON-ZERO
SHIFT-OF- TAILS. THIS SUGGESTS THAT ANY HIGHER IMPACTS FROM THIS
EVENT SHOULD REMAIN ACROSS IOWA AND ILLINOIS.
WHILE THE HIGHEST MOISTURE CONTENT IS EXPECTED TO REMAIN TO OUR
SOUTH, THIS DOESN'T MEAN THAT WE WILL END UP WITH NOTHING IN TERMS
OF PRECIPITATION. THE 29.13Z NBM CONTINUES TO SUGGEST A 20-50%
PROBABILITY OF MEASURABLE PRECIPITATION AND A 10-30% PROBABILITY OF
GREATER THAN 1/4" ACROSS AREAS SOUTH OF I-90 ASSOCIATED WITH THE
AFOREMENTIONED DEFORMATION BAND. PRECIPITATION TYPE CURRENTLY LOOKS
TO BE ALL RAIN, AS RECENT MODEL RUNS HAVE TRENDED WARMER IN THE
LOWEST 5KFT, WITH SURFACE-850HPA TEMPERATURES REMAINING ABOVE
FREEZING. COULD STILL STILL SEE A FEW FLAKES MIX IN ON THE NORTHWEST
SIDE OF THE SYSTEM AS IT MOVES EASTWARD ON FRIDAY AS COLD AIR
ADVECTION BEGINS TO RAMP UP (10-20%), BUT THIS APPEARS TO BE AT
LEAST SOMEWHAT DEPENDENT ON HOW FAST THE SYSTEM MOVES THROUGH THE
AREA. A LITTLE SLOWER AND A MORE MIXED-PRECIP TYPE SCENARIO WILL BE
MORE LIKELY GIVEN COLD AIR ADVECTION WILL COME MORE INTO PLAY
WHEREAS IF IT FOLLOWS CURRENT ENSEMBLE GUIDANCE OR EVEN A LITTLE
FASTER, ALL RAIN WILL RESULT. OVERALL, THINKING THAT RAIN WILL
BE THE DOMINANT PRECIPITATION TYPE. HIGHEST QPF AMOUNTS WILL BE
ACROSS NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN WITH AMOUNTS
GENERALLY UP TO 1/4". ANY SNOWFALL IS NOT EXPECTED TO
ACCUMULATE.
TEMPERATURES AND PRECIPITATION CHANCES THIS WEEKEND
TEMPERATURES APPEAR TO MODERATE SOMEWHAT FRIDAY AND SATURDAY AS
WE DIP BACK INTO THE UPPER 30S AND LOW 40S AS COOLER AIR IS
USHERED IN BEHIND THE PREVIOUSLY TALKED ABOUT SYSTEM.
TEMPERATURES THEN WARM BACK INTO THE UPPER 40S AND LOW 50S AGAIN
BY SUNDAY, NEARLY 20 DEGREES ABOVE NORMAL. HOWEVER, THERE IS A
FAIRLY LARGE SPREAD IN THE ENSEMBLES REGARDING TEMPERATURES THIS
WEEKEND (5-10 DEGREES), SO THIS IS SOMEWHAT LOW CONFIDENCE AT
THE MOMENT AND THESE WILL BE FINE-TUNED IN FURTHER RENDITIONS
OF THE FORECAST.
ANOTHER SUBTLE SHORTWAVE TROUGH SINKS SOUTH INTO THE REGION SATURDAY
INTO SUNDAY BRINGING OUR NEXT BOUT OF PRECIPITATION (20-50%),
PRIMARILY NORTH OF I-90. WITH COLD AIR ADVECTION IN PLACE THROUGHOUT
THE COLUMN, TEMPERATURES SHOULD FALL BELOW FREEZING DURING THIS
TIMEFRAME LEADING TO SNOW BEING THE PRIMARY PRECIPITATION TYPE,
ALTHOUGH A RAIN SNOW MIX IS POSSIBLE CLOSER TO I-90. STILL A
LITTLE EARLY TO REALLY HAMMER OUT SNOW AMOUNTS, ALTHOUGH THE
29.13Z NBM DOES SUGGEST A 30-60% CHANCE OF GREATER THAN 1" AND A
10-30% CHANCE OF GREATER THAN 3", ASSUMING AT 10:1 SNOW-LIQUID
RATIO. MODEL SOUNDINGS ALSO INDICATE SOME DRY AIR INTRUDING INTO
THE ATMOSPHERE ABOVE 700HPA SUNDAY MORNING, DRYING OUT THE DGZ.
GIVEN VARIOUS AREAS OF LOW LEVEL FRONTOGENESIS WITHIN A STILL
SATURATED AND BELOW FREEZING SURFACE-700HPA LAYER, MAY NEED TO
KEEP AN EYE OUT FOR POSSIBLE FREEZING DRIZZLE.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1144 AM CST WED JAN 29 2025
PATCHY MVFR/VFR CEILINGS FL015-045 AT KRST/KLSE SHOULD
GRADUALLY BREAK UP LATER THIS AFTERNOON WITH A BAND OF MID
CLOUDS SHIFTING NORTHEAST ACROSS PARTS OF WI WITH VFR
CONDITIONS TONIGHT AND THURSDAY MORNING. NORTHWEST SURFACE FLOW
6 TO 12KTS SHOULD SHIFT TO THE WEST THEN SOUTHWEST OVERNIGHT.
MEANWHILE, A LOW LEVEL JET IS FORECAST TO DEVELOP AT KRST BY 10Z
AND KLSE 12Z AND LAST FOR A FEW HOURS THURSDAY MORNING BEFORE IT
SHIFTS EASTWARD THURSDAY AFTERNOON. INCREASING CLOUDS ARE
FORECAST FROM THE SOUTH FOR NORTHEAST IOWA, ESPECIALLY AFTER 18Z
THURSDAY.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FALKINHAM
AVIATION...ZAPOTOCNY
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