058
FXUS63 KARX 071735
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1135 AM CST FRI MAR 7 2025
KEY MESSAGES
- SNOW HAS MOVED INTO NORTHEAST IOWA OVERNIGHT AND WILL CONTINUE
THROUGHOUT THE MORNING AND INTO THE AFTERNOON ACROSS NORTHEAST
IOWA AND SOUTHWEST WI. ACCUMULATIONS OF 1 TO 2 INCHES ARE
LIKELY SOUTH OF A CHARLES CITY, IA TO PRAIRIE DU CHIEN, WI
LINE.
- SMALL CHANCE (15-30%) FOR LIGHT SNOW IN CLARK/TAYLOR COUNTIES
ON SATURDAY. LITTLE TO NO ACCUMULATIONS EXPECTED.
- MILDER TEMPERATURES TO START NEW WEEK WITH HIGHS IN THE 50S
AND 60S TO START THE UPCOMING WEEK.
DISCUSSION
ISSUED AT 332 AM CST FRI MAR 7 2025
TODAY: ACCUMULATING SNOW FOR NORTHEAST IA AND SOUTHWESTERN WI
SNOW IS CURRENTLY MOVING INTO PORTIONS OF NORTHEAST IOWA THIS
MORNING WITH SEVERAL SITES REPORTING LIGHT SNOW IN IOWA. AS WE HEAD
THROUGH THE REST OF THE MORNING, THE SURFACE LOW AND ACCOMPANYING
500MB SHORTWAVE WILL TREK EASTBOUND WITH PIECES OF MID-LEVEL
FRONTOGENESIS DEVELOPING THROUGHOUT THE DAY. THE RECENT RAP KEYS IN
ON A SLIGHTLY MORE ENHANCED 500-700MB FRONTOGENETIC SIGNAL BY LATE
MORNING INTO THE AFTERNOON WHICH HAS SOME LOW PROBABILITIES (10-20%)
FOR 1/2"/HR RATES IN THE 07.00Z HREF. OVERALL THOUGH PROBABILITIES
(40-70%) FAVOR RATES OF 1/4"/HR OR LESS IN THE 07.00Z HREF. AS WE
HEAD INTO THE AFTERNOON, MUCH OF THE CAMS AGREE ON SHIFTING THE BAND
EASTWARD OF THE AREA BY LATE AFTERNOON. A SWITCH OVER TO RAIN CANNOT
BE RULED OUT AT TIMES FOR THE AFTERNOON AS 07.06 RAP/HRRR SOUNDINGS
SHOWING BOTH A LOSS OF CLOUD ICE AND WARMING OF THE NEAR-SURFACE
LAYER TO ABOVE FREEZING TO GREATER THAN 1KFT.
AS FAR AS AMOUNTS ARE CONCERNED, GENERALLY EXPECTING 1 TO 2
INCHES SOUTH OF A LINE FROM CHARLES CITY, IA TO PRAIRIE DU
CHIEN, WI WITH THIS EVENT. WITH LITTLE DENDRITIC GROWTH ZONE
RESIDENCY AND WARM PROCESSES DOMINATING THERMAL PROFILES UNDER
700MB, THINKING THAT SLRS AROUND 10-11:1 ARE LIKELY APPROPRIATE.
OVERALL PROBABILITIES FOR AN INCH OR GREATER IN THE 07.00Z HREF
ARE VERY HIGH (50-100%) FROM FLOYD COUNTY, IA EASTBOUND TO
GRANT COUNTY, WI. ALTHOUGH PROBABILITIES FOR AMOUNTS IN EXCESS
OF 3 INCHES REMAIN VERY LOW (10-30%) IN THESE SAME LOCATIONS IN
THE 07.00Z HREF. AS A RESULT, CURRENTLY NOT GOING WITH ANY
WINTER WEATHER ADVISORY AT THIS TIME AS ANY HIGHER AMOUNTS WOULD
BE LOCALIZED IN NATURE. HOWEVER GIVEN THAT THE CAMS HAVE
TRENDED NORTH AND MAY CONTINUE TO DO SO OVER THE COMING HOURS,
MAY NEED TO ISSUE A SHORT-FUSED ADVISORY IF CONDITIONS WARRANT
IT. REGARDLESS, MOTORISTS SHOULD EXPECT SOME SLIPPERY ROADS AND
GIVE THEMSELVES EXTRA TIME TO REACH THEIR DESTINATION IN
NORTHEAST IA AND SOUTHWESTERN WI THIS MORNING.
THIS WEEKEND: WARMING TREND, LIGHT SNOW CHANCES FAR NORTH SATURDAY
LOOKING TOWARDS THE WEEKEND, UPPER-LEVEL NORTHWESTERLY FLOW
DOMINATES THE SYNOPTIC FLOW PATTERN OVER THE LOCAL AREA INITIALLY.
ON SATURDAY MORNING, A SHORTWAVE DESCENDS FROM CENTRAL CANADA INTO
NORTHERN PARTS OF THE REGION PROVIDING SOME WEAK FORCING IN THE FORM
OF SOME LOW-LEVEL FRONTOGENESIS AND FRONTAL BOUNDARY PASSAGE. AS A
RESULT, NOTING A FEW OF THE CAMS SUGGESTING SOME SNOW SHOWER
ACTIVITY. HOWEVER, GIVEN THAT THE 07.00Z HREF HAS FAIRLY LOW
PROBABILITIES (20-50%) IN CLARK/TAYLOR COUNTIES FOR MEASURABLE SNOW
WITH THIS SYSTEM SO REALLY NOT EXPECTING MUCH FOR ANY IMPACTS.
OTHERWISE, IN THE WAKE OF THIS BOUNDARY FAIRLY DECENT DIURNAL MIXING
WILL ENABLE SOME MORE BREEZY CONDITIONS FOR SATURDAY AFTERNOON WITH
MOMENTUM TRANSFER IN THE RAP SUGGESTING THAT WIND GUSTS OF UP TO
AROUND 25-30 MPH COULD BE POSSIBLE IN AREAS OF WEST-CENTRAL WI.
ADDITIONALLY, IF SKY COVER CLEARS OUT WELL COULD OVERACHIEVE ON
TEMPERATURES SLIGHTLY BUT LIKELY WILL KEEP HIGHS IN THE MIDDLE
TO UPPER 40S FOR SATURDAY. TEMPERATURES WILL LIKELY WARM FURTHER
FOR SUNDAY WITH A UPPER-LEVEL RIDGE OUT WEST BEGINNING TO PUSH
EAST INTO THE AREA ENABLING SOME WARM AIR ADVECTION.
CONSEQUENTLY EXPECTING HIGHS GENERALLY IN THE MIDDLE 40S TO
MIDDLE 50S FOR SUNDAY WITH MINIMAL SKY COVER, CERTAINLY A GREAT
DAY TO BE OUTDOORS TO ROUND OUT THE WEEKEND!
NEXT WEEK: MILD TEMPERATURES FOR THE UPCOMING WEEK
AS WE START THE NEXT WEEK, THE UPPER-LEVEL RIDGE ATTEMPTS TO
MOVE OVERHEAD ON MONDAY WHICH WILL LIKELY BE OUR WARMEST DAY FOR
NEXT WEEK WITH THE 07.00Z EFI HAVING A 60 TO 80% CHANCE TO
EXCEED MODEL CLIMATOLOGY FOR HIGHS ON MONDAY. ALL INDICATIONS
SUGGEST PORTIONS OF THE AREA WILL REACH INTO THE MIDDLE 50S TO
LOWER 60S ON MONDAY, MAINLY THOSE WHO HAVE NO REMAINING SNOW
COVER. FOR EXAMPLE, THE 10TH TO 90TH PERCENTILE RANGE OF 60 TO
73 AT LA CROSSE, WI IN THE NBM WITH A MEDIAN OF 66. THERE STILL
REMAINS SOME SOLUTIONS WHICH TRY TO AMPLIFY THE RIDGE FURTHER
WHICH WOULD TREND TO THE WARMER PERCENTILES OF ENSEMBLE
GUIDANCE. HOWEVER, THIS APPEARS TO BE BECOMING LESS LIKELY (LESS
THAN 20% CHANCE IN THE GEFS/EC/CANADIAN ENSEMBLE) AS AN
UPSTREAM WAVE FROM CENTRAL CANADA WILL EJECT SOUTH ON TUESDAY
TURNING THE FLOW MORE ZONAL AND SUPPRESSING THE RIDGE. CONSEQUENTLY,
TUESDAY AND WEDNESDAY WILL LIKELY BE SLIGHTLY COOLER BUT STILL
MILD WITH THE NATIONAL BLEND KEEPING TEMPERATURES RANGING FROM
THE MIDDLE 40S TO UPPER 50S ACROSS THE LOCAL AREA. LATE WEEK
FEATURES A PRONOUNCED UPPER-LEVEL TROUGH OVER THE WESTERN CONUS
THAT ATTEMPTS TO WORK ITS WAY EASTWARD. MAJORITY OF
DETERMINISTIC AND ENSEMBLE GUIDANCE DEVELOP A ROBUST SURFACE LOW
WITH IT AS IT PULLS EASTWARD INTO THE CENTRAL CONUS. HOWEVER,
PREDICTABILITY WITH THIS SYSTEM REMAINS LOW AT THIS TIME. SO
SOMETHING TO KEEP AN EYE ON, HOWEVER TOO EARLY TO ASCERTAIN ANY
DETAILS.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1122 AM CST FRI MAR 7 2025
FLIGHT RESTRICTIONS (IFR/LIFR) AFFECTING SOUTHERN HALF OF THE
FORECAST AREA FROM NORTHEAST IOWA THROUGH SOUTHWEST WISCONSIN
THROUGH THIS AFTERNOON. THE RESPONSIBLE LOW PRESSURE SEEN MOVING
EAST THROUGH NORTHERN MISSOURI. AS THE LOW CONTINUES EAST,
EXPECT THE RESPONSIBLE SNOWFALL TO SHUNT SOUTHEAST. SUBSEQUENT
VFR CONDITIONS EXPECTED AREA WIDE.
FOLLOWUP FLIGHT IMPACTS WILL BE INCREASED WINDS THROUGH
SATURDAY. INITIALLY INCREASING DURING THE MORNING HOURS AND
HIGHEST DURING THE AFTERNOON CONCURRENT WITH PEAK DIURNAL
HEATING. WINDS WILL BE OUT WEST.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...JAR
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