958
FXUS63 KARX 162312
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
612 PM CDT TUE SEP 16 2025
KEY MESSAGES
- A GRADUAL INCREASE IN RAIN CHANCES, AREAL COVERAGE, AS WE MOVE INTO
THE WEEKEND.
- SUMMERY TEMPS PERSIST INTO THURSDAY (80+ HIGHS FOR MOST), DROPPING
TO MORE SEASONABLE LEVELS FOR THE WEEKEND (70S).
DISCUSSION
ISSUED AT 135 PM CDT TUE SEP 16 2025
> OVERVIEW: GEFS AND EPS CONTINUE TO FAVOR A SLOWER, RETROGRADING
UPPER LEVEL FLOW FOR THE NEXT FEW DAYS - BUILDING THE BENT OVER
RIDGE (ACROSS THE EASTERN GREAT LAKES) WESTWARD AS SHORTWAVES DROP
SOUTH OUT OF CANADA INTO THE PLAINS TROUGH. THE RIDGE EASES EAST
OVER THE WEEKEND AS THE TROUGH GETS A PUSH FROM A SERIES OF
SHORTWAVES MOVING OUT OF THE PAC NW/WESTERN CANADA.
LONG RANGE GUIDANCE ALSO CONTINUES TO HINT AT A MORE DEVELOPED
SHORTWAVE TROUGH/COLD FRONT TO TRACK FROM CANADA TO ACROSS PORTIONS
OF THE REGION MON/TUE. SOME DIFFERENCES IN TIMING/LOCATION - BUT HAS
THE POTENTIAL TO PACK MORE OF A PUNCH.
> TEMPERATURES: THE SUMMER TEMPS PERSIST THROUGH AT LEAST THU WITH
80+ DEGREE HIGHS PROGGED IN THE GRAND ENSEMBLE FOR MOST OF THE LOCAL
AREA. SOME TEMPERING WHERE/IF PCPN DEVELOPS - WITH LOW POPS HOLDING
MOSTLY WEST OF THE MISSISSIPPI RIVER AND NORTH OF I-94.
CLOUDS AND MORE WIDESPREAD SHOWERS WILL BE USHERED IN WITH THE UPPER
LEVEL LOW/TROUGH FOR THE WEEKEND WHILE COOLER AIR FOLLOWS IN THE
WAKE OF THE LOW. IT'S NOT A BIG DROP OFF BUT HIGHS BACK INTO THE
70S, MORE SEASONABLE FOR MID SEP, ARE CURRENTLY EXPECTED. AGAIN,
WHERE MORE RAIN IS REALIZED TEMPS WILL HOLD A FEW DEGREES COOLER
(60S FOR HIGHS CERTAINLY POSSIBLE).
> RAIN CHANCES: WEAK UPPER LEVEL SHORTWAVE AND DIFFERENTIAL HEATING
WORKING WITH 1.5-2+ K J/KG MUCAPE TO FIRE SCATTERED SHOWERS/STORMS
ACROSS CENTRAL IA, BUILDING NORTHEAST. THIS SHOULD CONTINUE THROUGH
LATE AFTERNOON, DIMINISHING IN THE EVENING WITH THE LOSS OF DAYTIME
HEATING. LOCALLY NE IA LIKELY TO BE IMPACTED BY SOME CONVECTION. HOW
FAR NORTH/NORTHEAST OF THAT IS NOT CERTAIN. EXPECT SOME UPDATES TO
RAIN CHANCES WITH FOCUS ON NEAR TERM TRENDS.
WED COULD BE SIMILAR TO TODAY WITH LINGERING, WEAK MICRO SCALE
BOUNDARIES, RIBBON OF INSTABILITY, AND CONVECTIVE INDUCED/ENHANCED
AREAS OF UPPER LEVEL DIVERGENCE PROVIDE SOME LIFT FOR SCATTERED
SHOWERS/STORMS. A LOT OF UNCERTAINTY WITH HOW RAIN CHANCES
COULD/WILL LAYOUT - WITH A CLOSE EYE ON ENVIRONMENT/NEAR TERM TRENDS
LEADING TO ADJUSTMENTS TO THE FORECAST. WILL LEAN INTO THE NBM FOR
CHANCES FOR NOW, WHICH HOLD MOST WEST OF THE MISSISSIPPI RIVER/NORTH
OF I-94 (INFLUENCE OF THE RIDGE HOLDING SPREADING CHANCE FURTHER
EAST/SOUTHEAST). THU COULD BE A REPEAT OF WED.
RAIN CHANCES WILL BE ON THE INCREASE AS THE AREA COMES MORE DIRECTLY
UNDER THE INFLUENCE OF THE UPPER LEVEL LOW/TROUGH. MUCH OF FRI
THROUGH SUN THEN LOOKS SHOWERY - PERHAPS MORE SO FRI/SAT. MIGHT GET
A 24 HOUR BREAK FROM THE RAIN BEFORE ANOTHER SHORTWAVE TROUGH SLIDES
ACROSS/NEAR THE AREA MON/TUE.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 608 PM CDT TUE SEP 16 2025
VFR CONDITIONS CURRENTLY PRESENT ACROSS THE AREA OUT SIDE OF
SOME THUNDERSTORMS ACROSS NORTHEASTERN IOWA. THIS IS PROVIDING
SOME CLOUD COVER FOR THE TERMINALS BUT ITS WELL OVER VFR
CRITERIA. SOME FOG WILL BE POSSIBLE TOMORROW MORNING, MAINLY
EAST OF THE MISSISSIPPI RIVER. VALLEY FOG FOR LSE LOOKS UNLIKELY
DUE TO STRONGER WINDS JUST OFF THE SURFACE AND THE POTENTIAL
FOR CLOUD COVER. HAVE INCLUDED SOME MVFR BR FOR NOW TOMORROW
MORNING TO ACCOUNT FOR THE MIST/FOG POTENTIAL BUT TRENDS WILL
NEED TO BE MONITORED GOING FORWARD WITH DEGRADATIONS POSSIBLE IN
FUTURE UPDATES. SHOWERS AND STORMS ARE EXPECTED TO MOVE IN FROM
THE WEST LATE TOMORROW MORNING INTO THE AFTERNOON. HAVE
INCLUDED A PROB30 AT RST FOR THE END OF THE PERIOD AS CONFIDENCE
IN TIMING IS STILL TOO LOW TO CREATE ITS OWN PREVAILING GROUP.
WINDS THROUGH THE PERIOD WILL BE LIGHT OUT OF THE SOUTH AT LESS
THAN 10 KTS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FERGUSON
AVIATION...BARENDSE
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