406
FXUS63 KARX 181820
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
120 PM CDT MON MAY 18 2026
KEY MESSAGES
- THE SEVERE WEATHER THREAT LOOKS LOWER FOR TONIGHT. AS A
RESULT, THE STORM PREDICTION CENTER HAS SHIFTED THE SLIGHT
RISK FURTHER SOUTH. THE NORTHERN EXTENT OF THE SLIGHT RISK NOW
ONLY EXTENDS NORTH TO INTERSTATE 90 WHERE BEFORE IT EXTENDED
AS FAR NORTH AS NORTHEAST MINNESOTA.
- PATCHY TO AREAS OF FROST POSSIBLE IN NORTH-CENTRAL AND CENTRAL
WISCONSIN ON TUESDAY NIGHT AND WEDNESDAY NIGHT.
DISCUSSION
ISSUED AT 120 PM CDT MON MAY 18 2026
THIS AFTERNOON AND TONIGHT
THE SQUALL LINE THAT MOVED THROUGH OUR AREA LAST NIGHT HAS MOVED
SOUTH INTO THE INTERSTATE 70 CORRIDOR. SOUTH OF THIS LINE, THE
TEMPERATURES ARE IN THE LOWER 80S AND DEW POINTS RANGING FROM
THE MID-60S TO LOWER 70S. WITH RAIN COOLED AIR NORTH OF THIS
BOUNDARY, THIS AIR MASS WILL REMAIN SOUTH OF OUR FORECAST AREA
FOR TONIGHT. AS A RESULT, WE HAVE SEEN A REDUCTION IN THE
INSTABILITY AVAILABLE FOR THE STORMS ALONG THE COLD FRONT
TONIGHT. SURFACE-BASED CAPES WHICH LOOKED TO BE IN THE 1500 TO
2500 J/KG RANGE YESTERDAY ARE NOW ONLY UP TO 750 J/KG. IN
ADDITION, THE STRONGER 0-3 KM AND 0-6 KM SHEAR REMAINS POST
FRONTAL. THE CAMS ARE PROGRESSIVELY MOVING THE SQUALL LINE
FURTHER AND FURTHER SOUTH. MUCH OF THE CONSENSUS IN THE CAMS HAS
THIS SQUALL LINE MOVING EAST ACROSS SOUTHERN IOWA AND NORTHERN
MISSOURI. FURTHER NORTH, THERE ARE MORE SCATTERED THUNDERSTORMS.
THIS HAS REDUCED THE SEVERE WEATHER THREAT BECAUSE THERE WOULD
BE LESS COALESCING OF THE COLD POOLS.
DUE TO THIS, WE REACHED OUT TO THE STORM PREDICTION CENTER AND
WAS ABLE TO GET A MORE SOUTHERN SHIFT IN THE DAY 1 SLIGHT RISK.
IT IS NOW SOUTH OF INTERSTATE 90. THERE IS NOW A MARGINAL RISK
FROM INTERSTATE 90 NORTH INTO UPPER MICHIGAN. IF THERE IS SEVERE
WEATHER, IT WOULD OCCUR BETWEEN 19.03Z AND 19.07Z. THE PRIMARY
THREAT WOULD BE DAMAGING WINDS.
TUESDAY
A NORTHERN STREAM SHORTWAVE TROUGH WILL MOVE NORTHEAST ACROSS
WESTERN AND NORTHERN MINNESOTA AND NORTHERN WISCONSIN. THIS WILL
RESULT IN SOME SCATTERED MORNING SHOWERS. THE STRONG COLD AIR
ADVECTION IN THE WAKE OF THE COLD FRONT WILL CONTINUE INTO THE
DAY. HIGH TEMPERATURES FOR THE DAY WILL OCCUR AROUND MIDNIGHT IN
THE MID- AND UPPER 60S. TEMPERATURES DURING THE DAY WILL BE IN
THE 50S AND 60S.
TUESDAY NIGHT AND WEDNESDAY NIGHT
THE COMBINATION OF MOSTLY CLEAR TO PARTLY CLOUDY SKIES AND LIGHT
WINDS WILL ALLOW TEMPERATURES TO FALL INTO THE 30S AND 40S. THERE
COULD BE THE POTENTIAL FOR EVEN COLDER TEMPERATURES IN CENTRAL AND
NORTH-CENTRAL WISCONSIN. THIS COULD RESULT IN SOME PATCHY TO
AREAS OF FROST IN OUR TRADITIONAL COOLER AREAS OF CENTRAL AND
NORTH- CENTRAL WISCONSIN.
FRIDAY INTO THE WEEKEND
A NORTHERN STREAM SHORTWAVE WILL MOVE SLOWLY EAST THROUGH THE
REGION. AS THIS OCCURS, THERE WILL BE PERIODIC SHOWERS AND STORMS.
LIKE YESTERDAY, BOTH THE 0-3 AND 0-6 KM SHEAR REMAIN LESS THAN
30 KNOTS. AS A RESULT, THE PROBABILITIES FOR ORGANIZED SEVERE
WEATHER LOOK LOW.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1257 PM CDT MON MAY 18 2026
VFR TO MVFR CONDITIONS CURRENTLY PRESENT ACROSS THE REGION WITH
SOUTH TO SOUTHWEST WINDS AT OR BELOW 12 KTS. MOST LOCATIONS
CURRENTLY SEEING MVFR CIGS IN SOUTHEAST MINNESOTA AND NORTHEAST
IOWA WILL LIKELY NOT SEE IMPROVEMENT THROUGH THE AFTERNOON AS
THE STRATUS DECK SHOULD PERSIST. ANOTHER ROUND OF SHOWERS AND
STORMS IS EXPECTED TO MOVE IN FROM THE WEST/SOUTHWEST THIS
EVENING, WITH IMPACTS AT THE TERMINALS BEGINNING BETWEEN 01-03Z
TONIGHT. THIS LINE WILL GRADUALLY MOVE EAST WITH LINGERING
SHOWERS CONTINUING INTO THE EARLY MORNING HOURS. WIDESPREAD IFR
CIGS ARE EXPECTED TO BUILD IN BEHIND THE SHOWERS FOR TOMORROW
MORNING BEFORE GRADUALLY LIFTING TO MVFR LATE IN THE PERIOD. VFR
CONDITIONS ARE NOT EXPECTED TO RETURN UNTIL AFTER 18Z TOMORROW.
WINDS BEHIND THE SHOWERS WILL TURN TO THE NORTHWEST AND PICK UP
TO BETWEEN 10-20 KTS WITH GUSTS IN THE 20-30 KT RANGE BY LATE
MORNING.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BOYNE
AVIATION...BARENDSE
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