105
FXUS63 KARX 300547
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1247 AM CDT SUN AUG 30 2026
KEY MESSAGES
- LIMITED CONFIDENCE (<5%) IN STRONG TO SEVERE STORMS THROUGH
SUNDAY.
- PERIODIC STORM CHANCES THROUGH THE WEEK WITH ANOMALOUS WARMTH
THROUGH MIDWEEK.
DISCUSSION
ISSUED AT 1247 AM CDT SUN AUG 30 2026
STORM POTENTIAL SUNDAY:
AN UPSTREAM PHASED LOW LEVEL TROUGH OVER THE NORTHERN PLAINS
WILL SPREAD ACCOMPANYING ANOMALOUS LOW LEVEL MOISTURE (SPC RAOB
CLIMATOLOGY: BIS, ABR) EAST THROUGH THE OVERNIGHT HOURS INTO SUNDAY
MORNING ALONG A LOW LEVEL JET EVIDENT IN CENTRAL PLAINS VWPS OF 40
TO 50KTS. WHILE INCREASING MOISTURE AND STEEPENED MID LEVEL LAPSE
RATES INCREASE LOCAL AIRMASS INSTABILITY, ACCOMPANYING ANOMALOUS LOW
LEVEL TEMPERATURES ASSOCIATED WITH AN ELEVATED MIXED LAYER FROM
850MB TO 700MB POKING NORTHEAST TOWARDS THE UPPER MISSISSIPPI RIVER
VALLEY LIMITS CONFIDENCE IN WIDESPREAD STORM CHANCES THROUGH SUNDAY.
FURTHERMORE, GIVEN THE LOWER LATE-SUMMMER SUN ANGLE, DURATION AND
STRENGTH OF SURFACE DIURNAL HEATING DECREASES CONFIDENCE IN REACHING
SURFACE CONVECTIVE TEMPERATURES. THEREFORE, GIVEN A LACK OF A
WIDESPREAD, STRONG ATMOSPHERIC FORCING MECHANISM AND WEAK PASSING
UPPER LEVEL PERTURBATION PULSES, A LIMITED WINDOW OF STORM POTENTIAL
IS SEEN IN HIGH RESOLUTION MODEL SOUNDINGS THROUGH LATE SUNDAY
AFTERNOON INTO SUNDAY NIGHT. WHILE ELEVATED NATURE OF STORMS WOULD
LIMIT SEVERE HAZARDS TO LARGE HAIL AND DAMAGING WINDS, OVERALL
CONFIDENCE IN STORMS BECOMING SEVERE REMAINS LOW (<5%).
STORM POTENTIAL MONDAY:
PHASING AND SUBSEQUENT PROGRESSION OF THE SYNOPTIC PATTERN
PROGRESSES THE LOW LEVEL TROUGH AXIS OF DRIER AIR THROUGH MONDAY
MORNING. WHILE THE FRONTAL BOUNDARY COULD POTENTIALLY PROVIDE
ADDITIONAL FORCING, AGEOSTROPHIC SUBSIDENCE IN THE EQUATORIAL EXIT
REGION OF QUASI-ZONAL AMPLIFYING UPPER LEVEL JET STREAK LIMITS
WIDESPREAD STORM/PRECIPITATION CHANCES THROUGH MONDAY LOCALLY.
THEREFORE, WHILE TREND IN MEDIUM-RANGE REAL-TIME AI CONVECTIVE
HAZARD FORECASTS LOCALLY PEAKS MONDAY (5-25%), EXPECT A DOWNWARD
TREND BASED ON MORE RECENT, HIGH RESOLUTION MODEL FORECASTS.
PERIODIC STORM CHANCES, ABOVE NORMAL TEMPERATURES THIS WEEK:
OTHER THAN PERIODIC STORM CHANCES THROUGH THE WEEK, MAIN FORECAST
IMPACT WILL BE ABOVE NORMAL TEMPERATURES AS LONG TERM GLOBAL
ENSEMBLES AND THEIR AI/DETERMINISTIC COUNTERPARTS SUGGEST PERSISTENT
SYNOPTIC RIDGING CAUSING REPEAT RETURN FLOW INTO THE UPPER MIDWEST.
CURRENT NBM CONFIDENCE SUGGESTS UPPER 80 TO LOW 90 MAXIMUM
TEMPERATURES AS THE 70 DEGREE ISODROSOTHERM BRUSHES THE FORECAST
AREA CAUSING 50-70% PROBABILITIES FOR 95+ DEGREE APPARENT
TEMPERATURES ACROSS THE SOUTHERN HALF OF THE FORECAST AREA FROM
TUESDAY TO THURSDAY. ALTHOUGH, AFOREMENTIONED STORM POTENTIAL
INCREASING CLOUD COVER CAUSING LOWER TEMPERATURES TO BE REALIZED
SHOULD ALSO BE TAKEN INTO ACCOUNT AS FORECAST HOUR NEARS.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1247 AM CDT SUN AUG 30 2026
AS MOISTURE TRANSPORT INCREASES OVERNIGHT THERE MIGHT BE A FEW
STORMS IN WESTERN WISCONSIN OVERNIGHT. OTHERWISE CEILINGS AND
VISIBILITIES WILL BE VFR.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...JAR
AVIATION...BOYNE
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