120
FXUS63 KARX 190308
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1008 PM CDT WED MAR 18 2026
KEY MESSAGES
- WARMER, MORE MOIST AIRMASS RAISES NIGHTLY FOG CONCERNS FOR
MUCH OF THE AREA THROUGH LATE WEEK.
- CONFIDENCE (60%) IN ANOMALOUS WARMTH INITIALLY REACHES THE
FORECAST AREA FRIDAY, INCREASING (70%) FOR SATURDAY.
- MODERATE CONFIDENCE (50-70%) FOR LIGHT PRECIPITATION SATURDAY
NIGHT THROUGH SUNDAY. LOW CONFIDENCE IN EXACT LOCATION OR
POTENTIAL FOR HIGHER AMOUNTS (0.1"+).
DISCUSSION
ISSUED AT 957 PM CDT WED MAR 18 2026
WARMING INTO EARLY WEEKEND, POTENTIAL NIGHTLY FOG:
OUTSIDE OF NIGHTLY FOG, A RELATIVELY QUIET PERIOD OF SENSIBLE
WEATHER IS EXPECTED AFTER ONGOING MIXED PRECIPITATION POTENTIAL
IN CENTRAL WISCONSIN EXITS EAST OF THE LOCAL FORECAST AREA
TONIGHT. MAIN FORECAST DETAIL WILL BE ADVECTION OF ANOMALOUSLY
WARM TEMPERATURES INTO THE EARLY WEEKEND AND SUBSEQUENT
POTENTIAL PRECIPTIATION.
THE TWO MAIN PHENOMENA THAT WILL HAVE THE LARGEST IMPACT ON
SENSIBLE WEATHER LOCALLY WILL BE THE DENSE, CLIMATOLOGICALLY
THICK SNOWPACK OBSERVED AND EXACT LOCATION OF A RELATIVELY
DIFFUSE BAROCLINIC BOUNDARY STREWN NORTHWEST TO SOUTHEAST WEST
OF THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT, FLIRTING
EAST/WEST OVER THE FORECAST AREA AS MEAGER WAVES MEANDER ALONG
IT INTO THIS WEEKEND. A FARTHER NORTHEAST ADVECTION OF THE WARM,
MOIST AIRMASS WILL INCREASE NIGHTLY FOG POTENTIAL AND DEGREE OF
HOTTEST TEMPERATURES INTO SATURDAY.
CONFIDENCE IN WARMEST TEMPERATURES:
WHILE OUR ON DOORSTEP FOR THURSDAY, NBM (18.19Z) PROBABILITIES FOR
THE 60 DEGREE ISOTHERM GREATLY INCREASE (25-75%) INITIALLY FRIDAY
ALONG OUR WESTERN PERIPHERAL COUNTIES AND INTO SOUTHWEST WISCONSIN.
FURTHER WARMING INTO THE WEEKEND USHERS IN SIMILAR PROBABILITIES FOR
THE 70 DEGREE ISOTHERM LOCALLY. ALTHOUGH, HIGH INTERQUARTILE SPREAD
(25TH-75TH PERCENTILE) OF 10-15 DEGREES OVER SOUTHEAST MINNESOTA ON
FRIDAY SPREADS ACROSS THE FORECAST AREA ON SATURDAY. AGAIN, AMOUNT
OF MELTING AND RESULTANT ALBEDO WILL BE CRUCIAL, ULTIMATE FACTOR TO
MONITOR THURSDAY AND FRIDAY AS THE BAROCLINIC BOUNDARY ATTEMPTS TO
ADVECT NORTHEAST THROUGH THE FORECAST AREA WITH PASSING WAVES.
LOW CONFIDENCE IN LATE WEEKEND PRECIPITATION:
THE SYNOPTIC PATTERN BREAKS THROUGH THE END OF THE WEEKEND, USHERING
IN MORE NORMAL DAYTIME HIGHS IN THE 40S TO 50S THROUGH SUNDAY AND
LOW CONFIDENCE IN WIDESPREAD PRECIPITATION POTENTIAL WITH THE
PASSING COLD FRONTAL BOUNDARY SATURDAY NIGHT THROUGH SUNDAY. AS POTENTIAL
CYCLOGENESIS PASSES NEAR THE FORECAST AREA, CONFIDENCE IN PRECIPITATION
POTENTIAL (50-70%) AGREES BETWEEN LONG TERM GLOBAL ENSEMBLES
WHILST DISAGREEING WITHIN RESPECTIVE ENSEMBLE RUNS. THE GEFS
(18.18Z) INCREASED PROBABILITIES FOR 0.01" OF QPF IN 24 HOURS
COMPARED TO PREVIOUS RUN (18.12Z), 50-70% ALONG AND EAST OF THE
MISSISSIPPI RIVER, WHILE THE MOST RECENT EPS (18.18Z) DECREASED
TO SIMILAR PROBABILITIES IN MOST RECENT RUN. INTERENSEMBLE
CONFIDENCE FOR HIGHER AMOUNTS (0.1"/24HR) INCREASES NORTHEAST
OF THE FORECAST AREA, LOWEST (<15%) IN MOST RECENT EPS (18.18Z).
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 636 PM CDT WED MAR 18 2026
A MIX OF LIGHT RAIN AND FREEZING RAIN WILL IMPACT LOCALLY
NORTHERN SMALLER AIRPORTS IN CENTRAL WISCONSIN (KMDZ) TONIGHT.
INCREASING LOW LEVEL MOISTURE OVER SNOW COVERED, COLD GROUND
WILL CAUSE WIDESPREAD FG ELSEWHERE, INCLUDING BOTH TAF SITES
(KLSE & KRST). THEREFORE, HAVE INCLUDED 1/4SM MENTION OVERNIGHT
AT 19.00Z ISSUANCE. DIFFICULTY DISCERNING DURATION OF LARGEST
IMPACTS THROUGH THURSDAY AND HAVE INCLUDED LINGERING LIFTING
THROUGH THE LATE MORNING BUT WILL REQUIRE FURTHER ADJUSTMENT IN
COMING 19.06Z TAF ISSUANCE.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...JAR
AVIATION...JAR
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