715
FXUS63 KARX 142332
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
632 PM CDT THU AUG 14 2025
KEY MESSAGES
- SEVERE WEATHER THREAT HAS INCREASED TO A LEVEL 2 OUT OF 5 ON
FRIDAY FOR AREAS ALONG AND NORTH OF INTERSTATE 90. IN
ADDITION, THE THREAT FOR SEVERE WEATHER LOOKS TO HAVE
INCREASED FROM SATURDAY INTO MONDAY TOO.
- HEAVY RAIN LOOKS TO BE A THREAT FROM FRIDAY NIGHT INTO MONDAY.
THIS COULD RESULT IN SOME FLASH FLOODING. HOWEVER,
UNCERTAINTY REMAINS HIGH ON LOCATION AND AMOUNTS.
- HEAT INDICES ON SATURDAY WILL RANGE FROM THE MID-90S TO AROUND
100F SOUTH OF INTERSTATE 94.
DISCUSSION
ISSUED AT 202 PM CDT THU AUG 14 2025
LATE THIS AFTERNOON AND TONIGHT
AS WARM AIR ADVECTION SLOWLY INCREASES AHEAD OF A DECAYING MCS
LATE THIS AFTERNOON AND TONIGHT, SHOWERS AND STORMS WILL
DEVELOP ACROSS THE REGION. THE 0-3 AND 0-6 KM SHEAR CONTINUES TO
LOOK WEAK FOR THE REGION. AS A RESULT, ORGANIZED CONVECTION IS
NOT EXPECTED.
FRIDAY IN THE WEEKEND
THE MODELS REMAIN IN GOOD AGREEMENT THAT SEVERAL MESOSCALE
CONVECTIVE COMPLEXES WILL AFFECT THE AREA FROM FRIDAY NIGHT
INTO MONDAY. THESE CONVECTIVE COMPLEXES WILL EITHER TRACK ALONG
THE PERIPHERY OF 700 MB CAP OR DIVE INTO THE INSTABILITY AND
WEAKEN AS THEY MOVE INTO THIS CAP. IT CONTINUES TO LOOK LIKE THE
STRONGEST CAP (12-14C) WILL BE LOCATED OVER NORTHEAST IOWA. MEANWHILE,
THE REMAINDER OF THE AREA WILL LIKELY SEE 700 MB TEMPERATURES
BETWEEN 11 AND 13C AND THIS RESULTS IN MUCH UNCERTAINTY ON HOW
THE MESOSCALE COMPLEXES WILL MOVE ACROSS MINNESOTA AND
WISCONSIN. THE DETERMINISTIC RUNS OF THE GFS, NAM, AND ECMWF
CONTINUE TO SUGGEST THAT THE FRIDAY NIGHT AND SATURDAY MORNING
MESOSCALE CONVECTIVE SYSTEM WOULD LIKELY DEVELOP JUST NORTHWEST
OF THE AREA AND THEN TRACK ACROSS THE NORTHERN TWO-THIRDS OF THE
AREA, THE SATURDAY NIGHT INTO SUNDAY MESOSCALE COMPLEX LOOKS TO
TRACK ACROSS EITHER THE NORTHERN THIRD OR NORTHERN HALF OF THE
AREA ON SATURDAY NIGHT AND SUNDAY MORNING, AND THE ONE ON SUNDAY
NIGHT AND MONDAY COMPLEX LOOKS TO MOVE ACROSS MUCH OF THE
FORECAST AREA.
PRECIPITABLE WATER VALUES CLIMB TO AROUND 2 INCHES ON FRIDAY NIGHT
AND INTO THE 2 TO 2.5 INCH RANGE FOR THE WEEKEND AND MONDAY. THESE
ANOMALOUS (175 TO 200 PERCENT OF NORMAL) VALUES ALONG WITH WARM
CLOUD LAYER DEPTHS BETWEEN 4 AND 4.5 KM AND 0-1 KM MIXED-LAYER
CAPES RANGING FROM 1500 TO 3500 J/KG UNDERNEATH THE CAP WILL
RESULT IN SHOWERS AND STORMS WHICH ARE HIGHLY EFFICIENT AT
PRODUCING HEAVY RAIN. WPC CURRENTLY HAS INCREASED THEIR MARGINAL
(THREAT 1 OUT OF 4) RISK TO A SLIGHT RISK (THREAT 2 OUT OF 4)
RISK OF EXCESSIVE RAIN FOR FRIDAY/FRIDAY NIGHT AND
SATURDAY/SATURDAY NIGHT. IT REMAINS AS A MARGINAL RISK FOR
SUNDAY/SUNDAY NIGHT AND MONDAY AND MONDAY NIGHT. WPC IS
CURRENTLY FORECASTING 2 TO 5 INCHES ALONG AND NORTH OF
INTERSTATE 94. HOWEVER, WHEN ONE LOOKS AT THE RAIN TOTALS IN THE
ENSEMBLES, THE SPREAD REMAINS LARGE, SO UNCERTAINTY REMAINS
HIGH ON THE POSITIONING OF THIS HEAVY RAIN. IN ADDITION, THERE
WILL BE A POTENTIAL FOR LOCALIZED RAIN TOTALS HIGHER THAN 5
INCHES. THIS WILL BE ESPECIALLY WHERE MULTI-DAY HEAVY RAIN
EVENTS CAN OVERLAP.
UNLIKE YESTERDAY, THE MID-LEVEL WESTERLIES (30-40 KNOTS) ARE MUCH
FURTHER SOUTH FOR THIS TIME PERIOD. AT THE SAME TIME, WE ARE SEEING
THE 850 MB WINDS INCREASING FROM THE SOUTHWEST INTO THE 30 TO 40
KNOT RANGE AT TIMES. THIS INCREASES THE HODOGRAPH LENGTH. AS A
RESULT, THERE HAS BEEN INCREASE IN THE 0-3 KM AND 0-6 KM SHEAR AT
TIMES. SPC HAS INCREASED THE DAY 2 (FRIDAY/FRIDAY NIGHT) SEVERE
WEATHER THREAT TO A SLIGHT RISK (THREAT LEVEL 2 OUT OF 5) ALONG AND
NORTH OF INTERSTATE 90 AND MARGINAL (THREAT LEVEL 1 OUT OF 5) FOR
THE REMAINDER OF THE AREA. THE INITIAL THREAT WILL BE LARGE HAIL.
WITH THE 0-1 KM SHEAR INCREASING AT OR ABOVE 20 KNOTS, THERE MIGHT
BE EVEN A POTENTIAL FOR A TORNADO OR TWO. IF THE STORMS ARE
ABLE TO COALESCE THEIR COLD POOLS, THERE COULD BE AN INCREASING
THREAT FOR DAMAGING WINDS. ADDITIONAL SEVERE WEATHER WILL BE
POSSIBLE DURING THE WEEKEND PRIMARILY ALONG AND NORTH OF
INTERSTATE 90. THE MAIN THREAT WILL BE DAMAGING WINDS.
LIKE THE PAST SEVERAL DAYS, HEAT INDICES ON SATURDAY WILL BE IN THE
80S NORTH OF INTERSTATE 94 AND RANGE FROM THE MID-90S TO AROUND
100F. THE HIGHEST HEAT INDICES WILL BE IN THE RIVER VALLEYS. WHILE
THIS HAS BEEN A CONSISTENT SIGNAL, THERE REMAINS A CONCERN THAT
CLOUD DEBRIS AND COLD POOL FROM A DECAYING MCS MAY LIMIT SOME OF
THIS HEAT POTENTIAL.
WEDNESDAY INTO THURSDAY
THE 14.00Z MODEL ENSEMBLES REMAIN IN GOOD AGREEMENT THAT 500 MB
RIDGE AXIS RETROGRADES WEST AND FLATTENS WITH TIME AS THE POLAR JET
INCREASES IN AMPLITUDE. A CANADIAN SURFACE HIGH BUILDS OVER THE AREA
ON WEDNESDAY AND REMAINS IN CONTROL OF THE AREA INTO THURSDAY. THIS
WILL RESULT IN NEAR-NORMAL TEMPERATURES AND BELOW-NORMAL
PRECIPITATION. NORMAL HIGH TEMPERATURES ARE NEAR 80 AND LOW
TEMPERATURES ARE NEAR 60.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 632 PM CDT THU AUG 14 2025
MOSTLY VFR CONDITIONS EXPECTED. SCATTERED SHOWERS CONTINUE TO
MAKE THEIR WAY EASTWARD. THERE IS ALSO A LOW CHANCE (10 TO 20%)
OF THUNDER OCCURRING. THIS WILL CONTINUE THROUGH THE EVENING,
THEN CONFIDENCE ON WHEN AND WHERE RAIN OCCURS AFTER MIDNIGHT IS
LOWER. CURRENT FORECAST IS HAVING THE HIGHER RAIN CHANCES (20 TO
30%) IN PORTIONS OF SOUTHEAST MINNESOTA AND WESTERN WISCONSIN,
ROUGHLY ALONG A LINE FROM KAUM TO KMDZ. THERE IS BETTER MODEL
AGREEMENT ON THE NEXT SHOWER AND THUNDERSTORM CHANCES, WHICH
ARE POSSIBLE LATER FRIDAY AFTERNOON AND EVENING ACROSS MUCH OF
THE AREA (20 TO 40%). LIGHT SOUTH WINDS OVERNIGHT THEN, INCREASE
TO 10 AND 15 MPH FRIDAY MORNING.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BOYNE
AVIATION...CECAVA
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