183
FXUS63 KARX 161755
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1255 PM CDT SUN AUG 16 2026
KEY MESSAGES
- DRIER CONDITIONS ARE EXPECTED TODAY INTO MONDAY WITH NEAR-
NORMAL HIGHS IN THE UPPER 70S TO LOW 80S.
- SHOWER AND STORM POTENTIAL RETURNS MONDAY NIGHT INTO TUESDAY MORNING
(30-50%) AND TUESDAY AFTERNOON INTO WEDNESDAY (30-60%),
THOUGH BETTER CHANCES HAVE BEGUN TO TREND SOUTHWARD.
- PERIODIC CHANCES FOR SHOWERS AND STORMS EXIST THROUGH THE END
OF NEXT WEEK.
DISCUSSION
ISSUED AT 1245 AM CDT SUN AUG 16 2026
TODAY - MONDAY: DRIER, NEAR NORMAL TEMPERATURES
A WEAK COLD FRONT MOVING THROUGH THE REGION OVERNIGHT SHOULD SHIFT
EASTWARD BY THE MID-MORNING HOURS TODAY. SOME ISOLATED TO SCATTERED
LIGHT SHOWERS ARE POSSIBLE (20-40%) ALONG THE FRONT OVERNIGHT,
MAINLY NORTH OF I-94, WHERE STRONGER CONVERGENCE ALONG SAID
FRONT EXISTS. AREAS OF PATCHY FOG HAVE ALSO BEGUN TO DEVELOP
GIVEN THE HUMID CONDITIONS IN PLACE, BUT WILL BEGIN TO DISSIPATE
AFTER SUNRISE THROUGH AROUND 9AM.
DRY CONDITIONS ARE THEN EXPECTED THROUGHOUT THE REST OF THE DAY AS
DRIER AIR IS USHERED INTO THE REGION ASSOCIATED WITH NORTHWEST WINDS
BEHIND THE FRONT. SOME SLIGHTLY STRONGER WIND GUSTS ARE EXPECTED
THROUGH THE AFTERNOON, GENERALLY 15-20MPH GIVEN STEEPENING 0-1KM
LAPSE RATES IN RESPONSE TO SOME WEAK COLD AIR ADVECTION. BENIGN
CONDITIONS CONTINUE INTO MONDAY AS HIGH PRESSURE REMAINS THE
DOMINANT FEATURE ACROSS THE UPPER MIDWEST, THOUGH ANOTHER SURFACE
COLD FRONT BEGINS TO MOVE SOUTHWARD INTO THE REGION MONDAY NIGHT AS
MID-UPPER LEVEL TROUGHING ACROSS CANADA DEEPENS WHILE WARM
AND MOIST SOUTHERLY FLOW ACROSS THE CENTRAL PLAINS NOSES NORTHWARD.
TUESDAY - WEDNESDAY: INCREASING SHOWER AND STORM POTENTIAL
THE AFOREMENTIONED FRONT CONTINUES MOVING SOUTHWARD OVERNIGHT MONDAY
INTO TUESDAY, LEADING TO SOME PRECIPITATION POTENTIAL AS IT DOES (30-
50%). INSTABILITY ALONG THE FRONT WILL BE LACKING GIVEN THE
OVERNIGHT TIMEFRAME, THOUGH SOME ELEVATED INSTABILITY UPWARDS OF 500
J/KG PER 15.18Z GFS SOUNDINGS SUGGESTS A FEW RUMBLES OF THUNDER
CAN'T BE RULED OUT.
THE FRONT LAYS OUT GENERALLY WEST TO EAST ACROSS NORTHERN IOWA INTO
SOUTHERN WISCONSIN TUESDAY AFTERNOON WHILE ANOTHER SHORTWAVE MAKES
ITS WAY ACROSS ZONAL UPPER LEVEL FLOW. BECAUSE OF THIS FRONTAL
PLACEMENT, SHOWER AND STORM POTENTIAL HAS TRENDED SOUTHWARD OVER THE
PAST 24 HOURS. DEWPOINTS IN THE LOW TO MID 60S LOOK TO POOL TO THE
SOUTH OF THE BOUNDARY, GREATEST ACROSS NORTHEAST IOWA INTO SOUTHWEST
WISCONSIN ALLOWING MLCAPE TO BUILD TO 1500-2000 J/KG DURING THE
AFTERNOON. 500HPA FLOW BEGINS TO INCREASE AS WELL AS A JET STREAK
ASSOCIATED WITH THE AFOREMENTIONED WAVE OVERSPREADS THE AREA,
INCREASING 0-6KM BULK SHEAR TO 35-45KTS. WHILE THE PRIMARY
INGREDIENTS FOR STRONG TO SEVERE STORMS LOOK TO BE IN PLACE FOR
THOSE SOUTH OF THE BOUNDARY, SOME UNCERTAINTY REGARDING THE
INFLUENCE OF MORNING SHOWER/STORM ACTIVITY ON THE AFTERNOON EXISTS
AS WELL AS SOME POTENTIAL TIMING ISSUES BETWEEN THE STRONGEST
INSTABILITY AND WIND SHEAR. REGARDLESS, AI/ML GUIDANCE CONTINUES TO
SUGGEST SEVERE CONVECTION IS POSSIBLE WHICH IS ALSO REFLECTED BY THE
SPC WHICH CURRENTLY HIGHLIGHTS OUR SOUTHERN COUNTIES AS A FAVORABLE
AREA FOR SEVERE WEATHER. WILL NEED TO CONTINUE TO WATCH FOR ANY
ADDITIONAL POSITIONAL AND TEMPORAL TRENDS AS THESE WILL INFLUENCE
WHAT AREAS WILL HAVE THE MOST FAVORABLE THERMODYNAMIC AND KINEMATIC
ENVIRONMENT FOR STRONG TO SEVERE CONVECTION.
OUTSIDE OF STRONG/SEVERE POTENTIAL, HEAVY RAINFALL LOOKS TO BE
POSSIBLE WITH STORMS THAT DEVELOP. CURRENT PROBABILITIES IN THE
16.01Z NBM SUGGEST AMOUNTS AROUND 1 INCH ARE NOT OUT OF THE
QUESTION, GENERALLY 10-30%, THOUGH THE EXPECTED PLACEMENT OF THE
FRONT AND THE SOUTHWARD TREND PREVIOUSLY DISCUSSED SUGGESTS THE
HIGHEST AMOUNTS SHOULD REMAIN ACROSS CENTRAL IOWA.
THURSDAY - NEXT WEEKEND: PERIODIC SHOWERS AND STORMS
NORTHWEST UPPER LEVEL FLOW REMAINS SITUATED ACROSS THE UPPER MIDWEST
FROM THE MIDDLE TO THE END OF THE NEW WEEK, ALLOWING SEVERAL
SHORTWAVE IMPULSES TO MOVE THROUGH THE REGION. PERIODS OF SHOWERS
AND STORMS ARE POSSIBLE IN RESPONSE TO THESE UPPER LEVEL FEATURES
THOUGH VARIATIONS AMONGST THE ENSEMBLE MEMBERS KEEPS PROBABILITIES
FOR SAID SHOWERS AND STORMS ON THE LOWER SIDE FOR A GIVEN DAY,
GENERALLY 10-30%.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1231 PM CDT SUN AUG 16 2026
PRIMARY FOCUS OVER THE NEXT 24 HOURS IS POTENTIAL FOR IFR/LIFR
FOG/STRATUS OVERNIGHT TONIGHT AS RELATIVELY DAMP POST-FRONTAL
CONDITIONS ARE PRESENT AT ISSUANCE, AS EVIDENCED BY THE
WIDESPREAD STRATOCUMULUS AT OR AROUND 3500 FT, AND WINDS
OVERNIGHT WILL DECREASE CONSIDERABLY. LATEST GUIDANCE SUGGESTS
LIGHT WIND LAYER WILL BE DEEP ENOUGH TO FAVOR FOG RATHER THAN
STRATUS WITH THIS MORE PROBABLE TO DEVELOP ACROSS WISCONSIN,
INCLUDING AT LSE. HAVE ONLY INCLUDED A FEW HOURS IN THE TAF AS
LIGHT WIND LAYER IS SHALLOWER THAN OPTIMAL FOR A CLASSIC RIVER
VALLEY FOG EVENT. CONFIDENCE THAT THIS WOULD SPREAD AS FAR WEST
AS RST WAS TOO LOW (20%) FOR INCLUSION WITH THIS CYCLE.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FALKINHAM
AVIATION...FERGUSON
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