663
FXUS63 KARX 301739
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1139 AM CST THU JAN 30 2025
KEY MESSAGES
- RECORD/NEAR RECORD TEMPS EXPECTED FOR A FEW LOCATIONS TODAY AS
HIGHS CLIMB INTO THE UPPER 40 TO MID 50S.
- INCREASING CHANCES FOR ACCUMULATING SNOW NORTH OF I-94 SAT
AFT/NIGHT (40-70%). WINTRY MIX SOUTH OF THERE.
DISCUSSION
ISSUED AT 200 AM CST THU JAN 30 2025
OVERVIEW: QUICK MOVING ZONAL TO BROAD UPPER LEVEL RIDGING WILL
DOMINATE THE WEEKEND, THROUGH MUCH OF THE NEXT WEEK. BUT, AS WE MOVE
INTO THE NEW WEEK, THE LONG RANGE GUIDANCE STARTS TO STRAY FROM EACH
OTHER - WITH IMPACTS ON TEMPS AND PCPN CHANCES. WPC CLUSTERS BEAR
THIS OUT WITH A COUPLE OF THE CLUSTERS SUGGESTING BROAD TROUGHING BY
TUE/WED WHILE THE OTHERS FAVOR AN AMPLIFICATION OF THE RIDGING. THE
GEFS IS SOLIDLY IN THE TROUGH BASKET WHILE THE THE EPS CONTINUES TO
RIDE THE RIDGE. CONSISTENT SIGNAL IN THE ENSEMBLE SUITES OVER THE
PAST COUPLE DAYS. FORECAST CONFIDENCE LOWER BECAUSE OF THESE
DIFFERENCES, ALTHOUGH THE EPS DID HAVE A BETTER HANDLE ON THE
CURRENT MILD/WARM CONDITIONS. WILL STICK WITH THE MODEL BLEND FOR
NEXT WEEK FOR NOW.
TEMPERATURES: DESPITE CLIMATOLOGY SAYING THIS IS THE COLDEST PART OF
THE YEAR FOR THE REGION, MOTHER NATURE HAS BROUGHT A SPATE OF VERY
MILD/WARM DAYS. THIS CONTINUES TODAY - WITH SOME RECORD HIGHS LIKELY.
BUFKIT SOUNDINGS SUGGEST MIXING WILL BE SOMEWHAT SHALLOW TODAY,
MOSTLY UPWARDS OF 925 MB (1.5-2 KFT). THAT SAID, THE NAM/GFS/EC WARM
IT FROM NEAR -2 C AT 925 MB AT 00Z THU TO AROUND +6 C BY 00Z FRI.
RAP EVEN MORE BULLISH JUMPING IT CLOSER TO 8 TO 9 C. EFIS SLIGHTLY
LESS COMPARED TO THE PREVIOUS 4 DAYS FOR TMAX, BUT STILL FROM 0.8 TO
0.9 WITH A NON ZERO SOT. OBSERVED HIGHS OVER THE PAST FEW DAYS HAVE
OUTPACED THE MODEL BLEND, AND EXPECT A SIMILAR OUTCOME TODAY. NO
SNOW COVER TO TEMPER TEMPS, BUT INCREASING HIGH CLOUDS ACROSS PARTS
OF NE IA/SW WI TODAY COULD CUT INTO HIGHS A FEW DEGREES FOR THOSE
LOCATIONS. 90+ % OF THE EPS MEMBERS HAVE HIGHS IN THE UPPER 40S TO
MID 50S FOR THE LOCAL FORECAST AREA. GEFS REMAINS A FEW DEGREES
COOLER. SHOULDN'T HAVE TOO DIFFICULT A TIME CLIMBING ABOVE 50 FOR
MANY LOCATIONS CONSIDERING WE ARE GOING TO START THE DAY OUT WITH
TEMPS MORE LINE WITH THE NORMAL HIGH FOR LATE JAN RATHER THAN LOW.
THE MILD CONDITIONS WILL PERSIST FRI/SAT, ALTHOUGH NOT NEARLY AS
WARM AS TODAY. HOWEVER, GEFS AND EPS SUGGEST ANOTHER BUMP IN TEMPS
AHEAD OF A SHORTWAVE TROUGH FOR SUNDAY - COULD GET BACK TO 50
DEGREES FOR SOME LOCATIONS.
HOW TEMPS PLAYOUT NEXT WEEK AREN'T AS CLEAR DUE TO DIFFERENCES IN
THE LONG RANGE GUIDANCE - ALTHOUGH TRENDS STILL LEAN INTO AT/ABOVE
NORMAL.
PRECIPITATION CHANCES: INCREASING CHANCES FOR WIDESPREAD LIGHT PCPN
SAT AFTERNOON/NIGHT.
TODAY/FRIDAY: UPPER LEVEL SHORTWAVE TROUGH REMAINS ON TRACK TO SHIFT
EASTWARD OUT OF THE SOUTHERN PLAINS TODAY, MOVING ACROSS THE MID
MISSISSIPPI RIVER VALLEY TONIGHT AND THEN OVER THE TN RIVER VALLEY
FRI. TRACK OF THE LOW CONTINUES TO PLACE THE NORTHERN FRINGES OF ITS
ASSOCIATED DEFORMATION PCPN BAND AS FAR NORTH AS NE IA/SW WI TONIGHT
INTO FRI MORNING. MODELS/ENSEMBLES HAVE SHIFTED A BIT SOUTH WITH THE
NORTHERN REACH WITH ROUGHLY 20-60% CHANCES IN A FAIRLY NARROW RIBBON
ACROSS THE FAR SOUTH. TEMPS FAVOR MOSTLY RAIN, ALTHOUGH SOME MIX IN
WITH SNOW IS POSSIBLE. ACCUMULATIONS EITHERWAY SHOULD BE MINOR (HREF
0-20% FOR UP TO 1/10" LIQUID)
SAT AFTERNOON/SUNDAY: A MORE INTERESTING PERIOD FOR PCPN CHANCES
WITH THE THREAT FOR ACCUMULATING SNOW AND A WINTRY MIX (SNOW,
DRIZZLE, PERHAPS FREEZING PCPN) GROWING IN LIKELIHOOD.
BITS OF SHORTWAVE ENERGY PROGGED TO SPRING EASTWARD FROM THE PAC NW
TO ACROSS THE UPPER MISSISSIPPI RIVER VALLEY FOR SAT AFTERNOON INTO
SUN. STRONGER FGEN RESPONSE IN A MOSTLY WEST-EAST FASHION LAID OUT
ACROSS CENTRAL MN/NORTHERN WI WITH GOOD QG CONVERGENCE THROUGH THE
LAYERS, ALSO MOSTLY LOCATIONS ACROSS NORTHERN PORTIONS OF THE
REGION. THAT SAID, A RATHER ROBUST LOW LEVEL THERMODYNAMIC SIGNAL
PRECEDES THE SHORTWAVE ENERGY ACROSS THE REGION WITH HEFTY
ISENTROPIC UPGLIDE ALONG THE 280:295K SFCS AREAWIDE SAT,
PERSISTING INTO SAT NIGHT.
DEPTH OF SATURATION WILL PLAY A BIG ROLE IN WHAT PTYPE IS MORE
LIKELY/WHERE. FORECAST SOUNDINGS AND TIME/HEIGHT X-SECTIONS HOLD THE
DEEPEST SATURATION NORTHWARD, SHALLOWING IT OUT AS WE MOVE SOUTH OF
I-94. ICE IN CLOUD CONCERNS CROP UP AS A RESULT. SOME SUGGESTIONS
THE A SEEDER-FEEDER PROCESS COULD OVERCOME ANY LOSS IN ICE FROM A
LOW CLOUD DECK, BUT MOSTLY NORTH OF I-94.
AS IT SITS RIGHT NOW, ACCUMULATING SNOWS ARE MORE LIKELY NORTH OF I-
94 WITH LREF CHANCES FROM 40 TO 70% FOR MORE THAN 1" (AROUND 3" SITS
AT 10%) USING A 10:1 RATIO. SOUTH OF THERE, CONCERNS FOR ICE IN THE
CLOUD RAISE THE POTENTIAL FOR LIQUID PCPN. NAM SET UP "SCREAMS"
WIDESPREAD DRIZZLE FOR THE AFTERNOON AND NIGHT - THE KIND THAT
REDUCES VSBY AND ACCUMULATES. THE GFS HAS SIGNALS BUT NOT AS
BULLISH. SFC TEMPS TRENDING WARM ENOUGH TO KEEP IT LIQUID, BUT GEFS
MEMBERS PAINT ABOUT A 20% FOR FREEZING PCPN FROM I-94 NORTHWARD SAT
NIGHT.
A SOMEWHAT MESSY SCENARIO AT THIS TIME WITH A MIXED BAG OF FORCING
AND SATURATION QUESTIONS. CONFIDENT IN AREAS OF PCPN, ESPECIALLY
NORTH OF I-94, WITH SOME SNOW ACCUMS IN THAT SAME LOCATION. HOW
WIDESPREAD PCPN IS SOUTH OF THERE ISN'T CERTAIN.
FOR NOW WILL LET THE MODEL BLEND DICTATE PCPN CHANCES AND PTYPE.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1126 AM CST THU JAN 30 2025
VFR CONDITIONS THROUGH THE TAF PERIOD AT KRST/KLSE WITH SOME
VARIABLE HIGH CLOUDS. A STORM SYSTEM WILL PASS TO THE SOUTH TODAY
AND TONIGHT, WITH MVFR CONDITIONS AND LIGHT RAIN OR A RAIN/SNOW MIX
CLIPPING OUR SOUTHERN AREAS TOWARD KDBQ TONIGHT INTO FRIDAY MORNING.
MEANWHILE, A SURFACE TROUGH WILL BE MOVING THROUGH THE AREA.
SOUTHWEST WINDS WILL INCREASE FOR A TIME THROUGH EARLY TO MID
AFTERNOON (6 TO 12KTS WITH SOME GUSTS 15 TO 20KTS), THEN BECOME
LIGHT WEST THEN NORTHWEST. NORTHEAST WINDS INCREASE TONIGHT 6 TO
12KTS AFTER 04Z THIS EVENING.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...RIECK
AVIATION...ZAPOTOCNY
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