597
FXUS63 KARX 081657
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1155 AM CDT MON SEP 8 2025
KEY MESSAGES
- MOSTLY DRY, RETURN TO NEAR SEASONABLE WITH DAYTIME HIGHS IN
THE 70S FOR MOST TODAY.
- PRECIPITATION CHANCES GRAZE NORTHWESTERN PERIPHERAL COUNTIES
IN SOUTHEAST MINNESOTA AND CENTRAL WISCONSIN OVERNIGHT.
MODERATE PRECIPITATION CHANCES THROUGH TUESDAY (20-60%).
- WARMING THROUGH THE WEEK WITH ABOVE NORMAL TEMPERATURES
EXPECTED THIS WEEKEND.
DISCUSSION
ISSUED AT 240 AM CDT MON SEP 8 2025
WARMER, MOSTLY DRY THROUGH TODAY:
THE WEEKEND'S SURFACE HIGH PRESSURE HAS BEEN SHIFTING EAST
THROUGH THE OHIO RIVER VALLEY TO SOUTHERN GREAT LAKES ON EARLY
MORNING SATELLITE IMAGERY, ALLOWING RETURN FLOW TO BUILD THROUGH
THE MISSOURI RIVER VALLEY. CENTRAL PLAINS VWPS (ICT,TOP,GID,OAX)
EXHIBITED AMPLIFICATION OF THE NOCTURNAL LOW LEVEL JET,
ADVECTING A PLUME OF HIGHER MOISTURE, BRINGING MORE MOISTURE TO
THE UPPER MISSISSIPPI RIVER VALLEY WITH 0.75" GOES-DERIVED PWATS
ENCROACHING ON LOCALLY WESTERN COUNTIES IN SOUTHEAST MINNESOTA
AND NORTHEAST IOWA EARLY THIS MORNING.
THE RESULTANT 5-10 DEGREE SWING IN TEMPERATURES BRINGS NEAR-NORMAL
DAYTIME HIGHS ACROSS THE FORECAST AREA; IN THE 70S FOR MOST.
HAVE CONTINUED PREVIOUS MENTION OF SHOWERS THROUGH THE MORNING
HOURS ON THE LOBE OF THE INCREASED MOISTURE TRANSPORT MOST EVIDENT
IN SATELLITE IMAGERY.
WHILE HIGHER PRECIPITATION CHANCES REMAIN ALONG AND WEST OF THE
LOCAL FORECAST AREA THROUGH TODAY DUE TO CONTENTION BETWEEN THE
FORCING SYNOPTIC WAVE AND THE AFOREMENTIONED HIGH PRESSURE
(LREF CONFIDENCE IN 579DAM HEIGHTS AT 500MB), A MEAGER EAST
SHIFT IN THE PATTERN DOES GRAZE LIMITED PRECIPITATION CHANCES
ALONG NORTHWESTERN PERIPHERAL COUNTIES IN SOUTHEAST MINNESOTA
OVERNIGHT.
EXPECT QUITE A TIGHT POP & QPF BOUNDARY DUE TO LOCAL SYNOPTIC
CONFLUENCE, WITH HREF AND LREF MEMBERS EXHIBITING LOW LEVEL DRY
AIR PLUMES ENTRAINED WITHIN THE ANTICYCLONIC FLOW (SOUTHEAST OF
THE BOUNDARY). THEREFORE CONFIDENCE IN LOCAL IMPACTS AND
PRECIPITATION REMAINS LOW TO MODERATE (20-40%) FOR MUCH OF THE
FORECAST AREA UNTIL TUESDAY WHEN THE MORE MOIST AIRMASS ADVECTS
EAST (20-60% POPS).
WARMING THROUGH THE WEEK:
THE WARMING TREND CONTINUES THROUGH THE WEEK AS ANOMALOUS MID
LEVEL HEIGHTS (90TH PERCENTILE IN SPC CLIMATOLOGY) BUILD
THROUGH THE CENTRAL PLAINS (LREF). CURRENT FORECAST HOUR LEAVES
MUCH TO BE DESIRED IN THE WAY OF CONFIDENCE FOR EXACT DETAILS AS
GFS/GEFS WARM BIAS FORECASTS A HIGH OF 88F/85F AT LA CROSSE,
CONTENDING WITH A 68F/73F HIGH IN THE ECMWF/EPS. RESULTANT NBM
25TH TO 75TH PERCENTILE SPREAD IS 5 TO 15 DEGREES THIS WEEKEND,
LARGEST ON SUNDAY.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1155 AM CDT MON SEP 8 2025
CIGS: SKC/SCT CONDITIONS INTO TONIGHT WITH AN INCREASE IN A MID
LEVEL VFR DECK AS AN UPPER LEVEL SHORTWAVE TROUGH APPROACHES FROM
THE WEST. ONCE IN THE CIGS SHOULD HOLD THROUGH TUE NIGHT INTO THE
EARLY PART OF WED.
WX/VSBY: SCATTERED TO AREAS OF -SHRA WILL ACCOMPANY THE SHORTWAVE
BUT WILL HAVE TO BATTLE DRIER SUB CLOUD LAYER/SFC INVERSION OVER THE
LOCAL AREA INITIALLY. HIGHER RAIN THREAT MOVES IN LATER TUE NIGHT,
PERSISTING INTO WED. MOST CAMS AND OTHER SHORT TERM GUIDANCE SUGGEST
SCATTERED COVERAGE WITH QPF ALSO ON THE LOWER END (< 1/4"). THUNDER
THREAT ALSO LOW (<30%). GIVEN EXPECTED TIMING, WON'T ADD TO THE
FORECAST NOW.
WINDS: SOUTHERLY THROUGH THE PERIOD AND LOOKING TO STAY "UP"
TONIGHT (10+ KTS). AFTERNOON GUSTS IN THE MID 20 KTS TODAY.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...JAR
AVIATION.....RIECK
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