438
FXUS63 KARX 210806
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
300 AM CDT MON APR 21 2025
KEY MESSAGES
- MORNING RAINS EXIT NORTH OF THE AREA BY NOON. ANOTHER ROUND OF
SHOWERS/A FEW STORMS LATER TONIGHT INTO TUE.
- MORE RAIN CHANCES FROM WED NIGHT INTO FRI. THU/THU NIGHT HOLDS THE
HIGHER THREAT WITH 60-70% CHANCES.
- NEED A DRY DAY? WEDNESDAY MORNING INTO THE AFTERNOON LOOKS LIKE A
DECENT BET FOR MOST ALONG WITH FRIDAY AFTERNOON INTO SATURDAY NIGHT.
DISCUSSION
ISSUED AT 200 AM CDT SUN APR 21 2025
OVERVIEW: QUICK MOVING, ZONAL-ISH FLOW WITH INCREASING HEIGHTS STILL
ON THE DOCKET FOR THE NEW WEEK. STEADY SIGNAL IN THE LONG RANGE
GUIDANCE. VARIOUS BITS OF SHORTWAVE ENERGY WILL TAKE AIM AT THE
UPPER MISSISSIPPI RIVER BRINGING SHOWER/STORMS CHANCES ON ALMOST A
DAILY BASIS. THERE IS A DRY PERIOD IN THE GEFS AND EPS WITH RIDGE
BUILDING FOR FRI NIGHT-SAT NIGHT. ALL WPC CLUSTERS FAVOR THIS TOO,
WITH ONLY SMALL DIFFERENCES IN AMPLITUDE AND POSITIONING. IF YOU ARE
LOOKING FOR A "DRY" PERIOD, THIS IS PROBABLY IT. MUCH WED ALSO
TRENDS DRY.
AS FOR THOSE RAIN CHANCES...
> THIS MORNING: WIDESPREAD RAIN, ASSOCIATED WITH AN UPPER LEVEL
SHORTWAVE TROUGH/SFC LOW AND VERY FAVORABLE LOW LEVEL MOISTURES
TRANSPORT, CONTINUES TO LIFT NORTHEAST EARLY THIS MORNING. CAMS
MODELS SUGGEST THE SOUTHERN, BACK-EDGE OF THE RAIN WILL PULL NORTH
OF I-90 BY 12Z, LIFTING NORTHEAST OF TAYLOR COUNTY IN NC WI BY NOON.
ADDITIONAL RAINFALL BETWEEN 12-18Z THIS MORNING WILL BE LIGHT -
GENERALLY UNDER 1/10".
> LATER TONIGHT/TUE: ANOTHER SHORTWAVE TROUGH STILL ON TRACK TO SPIN
ACROSS THE NORTHERN PLAINS THIS EVENING, LIFTING NORTHEAST ACROSS
NORTHERN PORTIONS OF THE REGION LATER TONIGHT. WHILE THE MODELS HAVE
BEEN CONSISTENT IN KEEPING THE BRUNT OF THE UPPER LEVEL FORCING
NORTH, THEY HAVE ALSO BEEN CONSISTENT WITH SLIPPING A RELATED WARM
FRONT WEST-EAST ACROSS THE REGION, WITH WARM AIR ADVECTION
ALONG/AHEAD OF IT ALONG WITH SOME FGEN. PERHAPS MORE IMPORTANTLY FOR
LOCAL RAIN CHANCES, THE LOW LEVEL JET/850 MB MOISTURE TRANSPORT
LOOKS TO NOSE INTO NORTHEAST IA OVERNIGHT. THIS MIX OF FORCING
SHOULD SPARK AN AREA OF SHOWERS/ELEVATED STORMS. SCATTERED SHOWERS
COULD EXTEND NORTHWARD ALONG THE FRONT.
THE FRONT WILL CONTINUE TO SINK SLOWLY SOUTHEAST TUE. LOW LEVEL
MOISTURE WILL POOL ALONG IT WHILE DAYTIME HEATING RESULTS IN FETCH
OF INCREASING INSTABILITY (UPWARDS OF 1500 J/KG SBCAPE IN THE RAP)
SOUTH OF IT. COULD BE SOME LOW LEVEL CAPPING TO INHIBIT CONVECTION
INITIALLY, BUT EVENTUALLY THE FRONT SHOULD SPARK SHOWERS/STORMS
ALONG IT. THE DEEPER SHEAR WILL LIE NORTHWARD OF THE FRONT, BUT
ENOUGH IN THE LOW LEVELS TO SUPPORT CONVECTIVE UPDRAFTS. COULD BE A
FEW STRONGER STORMS - CAN'T RULE OUT SEVERE EITHER. LOCAL IMPACTS
ALL DEPEND ON WHERE THAT FRONT LAYS OUT IN THE AFTERNOON AND LATEST
CAMS RUNS SUGGEST IT WILL BE JUST SOUTH OF THE LOCAL AREA.
> WED NIGHT/FRI: A MESSY WEATHER SCENARIO WITH BITS OF SHORTWAVE
ENERGY IN THE NORTHERN AND SOUTHERN BRANCHES OF THE UPPER LEVEL
FLOW, LOW LEVEL JET/MOISTURE TRANSPORT INTERACTIONS, VARIOUS SURFACE
BOUNDARIES, AND WEAK/MARGINAL INSTABILITY FROM TIME TO TIME. NO
CLEAR SIGNALS IN THE LONG RANGE GUIDANCE IN HOW THESE WILL "SETUP".
HOWEVER, WHAT THEY DO CONCUR IS DROPPING QPF ACROSS THE REGION OVER
THIS PERIOD - WITH AGREEMENT FROM ALL THEIR ENSEMBLE MEMBERS.
CURRENTLY, THE FAVORED PERIOD IS THU/THU NIGHT. THE MODEL BLEND WILL
CONTINUE TO PAINT RAIN CHANCES WITH BROAD STROKES, AND GIVEN THE
SETUP, DON'T SEE ANY REASON TO STRAY FOR NOW.
TEMPERATURES: TEMPS THIS WEEK WILL SEE AN UPTICK THANKS TO THE
INCREASE IN HEIGHTS AND BROAD/SHORTWAVE RIDGING. HOWEVER, WITH A MIX
OF CLOUDS AND PERIODIC PCPN CHANCES, THOSE TEMPS WILL BE TEMPERED
FROM TIME TO TIME. THE WARMEST DAY STILL LOOKING LIKE WED - THE ONE
MOSTLY "RAIN FREE" DAYTIME PERIOD IN THE FORECAST. STILL, IT'S A
BUSY WEATHER PATTERN AND EVEN SUBTLE FEATURES COULD PULL A MILD DAY
BACK TO SEASONABLE EXPECTATIONS. ALL IN ALL, THE TRENDS IN THE GEFS
AND EPS CONTINUE TO PAINT AT OR ABOVE NORMAL TEMPS - WITH AGAIN THE
CAVEAT OF RAIN/CLOUD COOLING.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 640 PM CDT SUN APR 20 2025
MVFR AND IFR CONDITIONS CONTINUE FOR MUCH OF THE NEXT 15-21 HOURS AS
ONGOING RAIN KEEPS CONDITIONS LESS THAN IDEAL. CURRENT THINKING IS
THAT VFR CONDITIONS WILL EVENTUALLY OCCUR BY MONDAY AFTERNOON, BUT
WILL NEED TO KEEP A CLOSE EYE ON POTENTIAL FOR LINGERING MVFR
CUMULUS TOMORROW, PARTICULARLY IN OUR NORTHEAST. OTHERWISE WINDS,
INITIALLY OUT OF THE EAST, WILL BECOME OUT OF THE NORTHWEST BETWEEN
06 AND 12Z.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...RIECK
AVIATION...FERGUSON
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