606
FXUS63 KARX 181059
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
559 AM CDT SAT JUL 18 2026
KEY MESSAGES
- AIR QUALITY CONCERNS RETURN TONIGHT THROUGH SUNDAY AS
NORTHERLY WINDS BRING WILDFIRE SMOKE BACK TO THE AREA.
- MONDAY CONTINUES TO SHOW PROMISE FOR SEVERE WEATHER POTENTIAL,
BUT DETAILS REMAIN UNCERTAIN.
- COOLER TEMPERATURES AND MOSTLY DRY WEATHER ARE EXPECTED
TUESDAY THROUGH THE END OF NEXT WEEK.
DISCUSSION
ISSUED AT 1240 AM CDT SAT JUL 18 2026
TODAY - SUNDAY: AIR QUALITY CONCERNS RETURN
A COLD FRONT CURRENTLY MOVING SOUTHWARD THROUGH THE UPPER
MISSISSIPPI RIVER VALLEY WILL CONTINUE SPARKING SHOWERS AND
STORMS OVER THE NEXT FEW HOURS. MODEL GUIDANCE IS STRUGGLING TO
HANDLE THE ONGOING CONVECTION, THOUGH MOST SOLUTIONS SUGGEST
THESE STORMS SHOULD WEAKEN AND DISSIPATE WITH TIME AS THEY TEND
TO OUTRUN THE GREATER INSTABILITY AND SHEAR ALONG THE FRONT.
AFTER THE FRONT FULLY MOVES SOUTH OF THE AREA SATURDAY MORNING,
WINDS VEER TO THE NORTH AND USHER IN A DRIER AND SLIGHTLY
COOLER AIRMASS. RATHER BENIGN WEATHER IS EXPECTED FOR THE
REMAINDER OF THE WEEKEND AS A RESULT, ALTHOUGH THE NORTHERLY
WINDS LEAVE US OPEN TO THE RETURN OF NEAR-SURFACE WILDFIRE
SMOKE. THE 18.00Z HRRR SUGGESTS HIGHER CONCENTRATIONS OF NEAR-
SURFACE SMOKE BEGIN TO MOVE INTO WESTERN WISCONSIN SATURDAY
EVENING, EVEN REACHING THOSE ALONG THE MISSISSIPPI RIVER IN
SOUTHEAST MINNESOTA AND NORTHEAST IOWA, AND LINGERS THROUGH
SUNDAY. BECAUSE OF THE INCREASE IN NEAR-SURFACE SMOKE DENSITY,
AIR QUALITY CONCERNS INCREASE SATURDAY EVENING THROUGH SUNDAY.
UNCERTAINTY DOES REMAIN REGARDING EXACT FIRE AND SMOKE BEHAVIOR
OVER THE WEEKEND THOUGH, SO FUTURE AIR QUALITY ALERTS WILL HAVE
TO WAIT UNTIL CONFIDENCE IN LOCATION AND IMPACTS INCREASES.
MONDAY - MONDAY NIGHT: STRONG TO SEVERE STORM POTENTIAL
MONDAY CONTINUES TO LOOK LIKE THE NEXT MOST FAVORABLE DAY FOR
STRONG TO SEVERE STORM POTENTIAL AS AN UPPER LEVEL SHORTWAVE
TROUGH DIVES SOUTHEASTWARD INTO THE UPPER MIDWEST ALONG WITH AN
ASSOCIATED MID-LATITUDE CYCLONE AT THE SURFACE. THE UPPER
MISSISSIPPI RIVER VALLEY WILL BE WELL WITHIN THE WARM SECTOR
MONDAY WITH SOUTHERLY WINDS ADVECTING A MOISTURE RICH AIRMASS
INTO THE REGION, INCREASING MUCAPE TO 1500-2500 J/KG WITH A
GRADIENT OF INSTABILITY SETTING UP GENERALLY ALONG THE
MISSISSIPPI RIVER WHILE A 500HPA JET STREAK OVERSPREADS THE
REGION, INCREASING 0-6KM SHEAR TO 40-50KTS RESULTING IN
IMPRESSIVE ELONGATION IN MODEL HODOGRAPHS BY THE AFTERNOON.
THERE REMAINS QUITE A BIT OF VARIATION AMONGST THE MODEL
GUIDANCE AND THEIR SOLUTIONS RUN-TO-RUN AS FAR AS THE EVOLUTION
OF THIS EVENT IS CONCERNED, THOUGH LOOKING AT THE INDIVIDUAL
MEMBERS OF THE 17.18Z GEFS/EPS/AIGEFS/AIFS ENS THERE IS AN
OVERALL CONSENSUS OF CONVECTION DEVELOPING MONDAY MORNING,
LIKELY IN THE FORM OF AN MCS THAT TRAVELS SOUTHWARD ALONG THE
INSTABILITY GRADIENT. THAT SAID, THERE IS QUITE A BIT OF
DISCREPANCY AS FAR AS TIMING AND LOCATION IS CONCERNED BUT THE
17.19Z NBM SUGGESTS PROBABILITIES FOR PRECIPITATION MONDAY
MORNING ARE AROUND 60-80%.
ANOTHER ROUND OF STORMS MAY BE ABLE TO DEVELOP IN THE AFTERNOON
ALONG THE COLD FRONT AS IT MOVES THROUGH, BUT THIS IS THE MAIN
POINT OF UNCERTAINTY CURRENTLY DUE TO AFTERNOON DEVELOPMENT
BEING DEPENDENT ON HOW MORNING STORMS EVOLVE. THAT SAID, CURRENT
PROBABILITIES FOR PRECIPITATION MONDAY AFTERNOON SIT AT 40-50%
PER THE 17.19Z NBM. ALL HAZARDS CONTINUE TO LOOK PROBABLE WITH
STORMS THAT DEVELOP MONDAY WITH LARGE HAIL, DAMAGING WINDS, A
FEW TORNADOES, AND HEAVY RAINFALL.
TUESDAY - END OF NEXT WEEK: COOLER TEMPERATURES AND MOSTLY DRY
ONCE THE COLD FRONT PASSES AND THE STORMS CLEAR OUT LATE MONDAY
NIGHT, THERE SHOULD BE A NOTICEABLE DIFFERENCE ACROSS THE AREA
WITH AN OVERALL MUCH COOLER AIRMASS EXPECTED FOR MID NEXT WEEK.
TEMPERATURES TUESDAY AND WEDNESDAY WILL FINALLY DROP BELOW
AVERAGE INTO THE UPPER 70S TO LOW 80S WITH DRY CONDITIONS
EXPECTED AS A WEAK SURFACE HIGH PRESSURE MOVES IN BEHIND THE
FRONT. WHILE A QUICK MOVING DISTURBANCE MAY BRING SOME LOW RAIN
CHANCES TO THE AREA BY LATE WEEK, EXPECT GENERALLY DRY
CONDITIONS AND NEAR NORMAL TEMPERATURES TO ROUND OUT THE NEXT
WORK WEEK.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 559 AM CDT SAT JUL 18 2026
SCATTERED SHOWERS AND STORMS CONTINUE TO MAKE THEIR WAY THROUGH
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN THIS MORNING. THESE
SHOWERS AND STORMS WILL MOVE OUT OVER THE NEXT FEW HOURS AND
THE REST OF THE TAF PERIOD IS EXPECTED TO BE DRY. MVFR CIGS ARE
POSSIBLE AFTER THESE SHOWERS AND STORMS MOVE THROUGH FOR A
COUPLE OF HOURS. SMOKE MOVES BACK INTO THE REGION THIS EVENING
AND MAKES ITS WAY TO KLSE AFTER MIDNIGHT. NORTHERLY WINDS TODAY
SHIFT TO LIGHT AND VARIABLE OVERNIGHT.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BARENDSE/FALKINHAM
AVIATION...CECAVA
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