404
FXUS63 KARX 170655
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
155 AM CDT SUN MAY 17 2026
KEY MESSAGES
- TODAY HAS TRENDED TOWARD COOLER AND CLOUDY WITH PERIODIC RAIN
SHOWERS AND NON-SEVERE STORMS. HAVE COOLED HIGH TEMPERATURES BY
5-6F EXCEPT FOR NERN IA AND SWRN WI.
- SUNDAY NIGHT BRINGS SEVERE STORM POTENTIAL AFTER ABOUT 9 OR 10
PM. THERE IS STILL UNCERTAINTY ON HOW THIS PLAYS OUT AND THE
INTENSITY OF STORMS MOVING IN FROM THE WEST IN THE LATE
EVENING. CONFIDENCE IS HIGHER FOR THE SEVERE STORM POTENTIAL
FURTHER WEST (MN/IA), WITH A WEAKENING TREND IN THE STORMS
MOVING INTO WI AFTER MIDNIGHT. DAMAGING WIND IS THE MAIN
THREAT.
- MONDAY'S SEVERE STORM POTENTIAL COMES WITH UNCERTAINTY. THE
HIGHEST RISK WILL BE TO THE SOUTHWEST OF THE LOCAL AREA, WITH
THE (MID?) EVENING AND NIGHT FAVORED AGAIN FOR STORMS TO MOVE
IN. IT DOES APPEAR A DAMAGING WIND THREAT EXISTS, WITH STORMS
AGAIN WEAKENING AS THEY MOVE EAST (SIMILAR TO TONIGHT).
- PATTERN CHANGE COMES TUESDAY WITH A COLD FRONT: COOLER AND
DRY WEATHER FOR THE REST OF THE WEEK.
DISCUSSION
ISSUED AT 154 AM CDT SUN MAY 17 2026
TODAY'S CLOUDY AND SHOWERY DAY
A MASSIVE AREA OF CONVECTIVE STORMS OVERNIGHT FROM NEBRASKA
THROUGH IOWA THAT IS ONGOING AT 05Z WILL BRING A CONVECTIVELY-
ENHANCED SHORTWAVE TROUGH THROUGH THIS MORNING. THIS VORTICITY
MAX, SEEN ALREADY WITH BROAD CYCLONIC ROTATION IN THE STORM
REGION IN SERN NEB AT 05Z WILL LIFT A RAIN/STORM COMPLEX
THROUGH WI THIS MORNING. THIS IS IN CONCERT WITH THE ENERGY
SLIPPING INTO THE HIGH PLAINS AND OVERALL EVOLUTION OF A WARM
FRONTAL SURGE ACROSS THE AREA TODAY. STRONG WARM ADVECTION WILL
BEGIN THIS MORNING ABOVE THE SURFACE PROVIDING A CAPPED
ENVIRONMENT WITH ABUNDANT LOW-LEVEL MOISTURE RETURN AND CLOUDS.
THIS WARM FRONT WILL SHIFT ACROSS THE AREA FROM SOUTH TO NORTH
THROUGH THE FIRST PART OF THE DAY WITH STRONG MOISTURE TRANSPORT
CONVERGENCE AT 850 MB SEEN ISENTROPICALLY LIFTING NORTHWARD FOR
RAIN SHOWERS AND SOME STORMS. THINKING THE CAMS LOOK PRETTY DRY
THIS AFTERNOON FOR THIS FORCING NEAR/NORTH OF I-90 AND HAVE KEPT
RAIN CHANCES. ANY STORMS SHOULD REMAIN BELOW SEVERE LIMITS WITH
MARGINAL CAPE. WITH THE SUGGESTION OF WIDESPREAD CLOUDS AS THE
WARM SECTOR TO THE SOUTH LIFTS NORTH, HAVE COOLED HIGH
TEMPERATURES 5-6F, EXCEPT SWRN WI/NERN IA WHERE LATE DAY SUN
LOOKS TO BREAK OUT IN THE WARM SECTOR. IT REMAINS TO BE SEEN
HOW THE ONGOING LARGE REGIONAL MCC WILL IMPACT THE WARM FRONT
WORKING NORTH TODAY...IT COULD WORK TO SLOW THE PROGRESSION.
SUNDAY NIGHT SEVERE STORM POTENTIAL
GOOD CONSENSUS EXISTS IN THE MODEL GUIDANCE THAT ONCE THE WARM
FRONT LIFTS NORTH, BY EARLY EVENING A WARM SECTOR WITH ABOUT
1500-2000 J/KG OF MLCAPE EXISTS OVER MN/IA...HIGHER FURTHER WEST
AND LOWER INTO WI. THIS POOL SHOULD BE PRETTY HEAVILY CAPPED BY
WARM AIR ALOFT SOUTH OF ABOUT I-90 OR I-94 DEPENDING ON ITS
NORTHERN PROGRESS TODAY. SEVERE STORMS DEVELOP IN WESTERN IA/MN
IN THE EARLY EVENING AND ARRIVE IN THE MID-LATE EVENING IN SERN
MN AND NERN IA. THE CHALLENGE IS HOW THIS WARM AIR ALOFT WILL
INTERACT WITH THE STORMS AS THEY PROGRESS EAST WITH DIMINISHING
INSTABILITY AS WELL. THE 17.00Z NAMNEST, MOST AGGRESSIVE WITH
THE WARM DRY AIR ALOFT KILLS THE STORMS BEFORE THEY MAKE IT IN.
ALL OF THE 17.00Z CAMS DECAY THE SYSTEM EAST OF I-35, WHICH
WOULD SEEM TO FAVOR A DAMAGING WIND THREAT FOR THOSE CLOSER TO
I-35 IN MN/IA, AND DIMINISHING SEVERE STORM PROBABILITIES
EASTWARD. THUS THE SHIFTING SPC RISK AREA WESTWARD.
THUS, THERE IS UNCERTAINTY IN THIS PATTERN LEADING INTO THE VERY
SHORT FORECAST TIME FRAMES. BASED ON THE WARM AIR ALOFT IN THE
700-850MB LAYER, AND THE NOCTURNAL TIMING OF THE STORM COMPLEX
MOVING IN, IT WOULD SEEM THAT STORMS SHOULD BE ON THE DECREASE
COMING INTO THE LOCAL AREA TONIGHT. WIND DAMAGE WOULD BE THE
MAIN THREAT WITH THIS LINE OF STORMS COMING IN.
MONDAY'S SEVERE STORM POTENTIAL
WITH THE LARGE SCALE REMAINING FAIRLY STAGNANT WITH UPPER
SOUTHWEST FLOW UNTIL TUESDAY, MONDAY IS A RINSE AND REPEAT OF
SUNDAY: DAYTIME CAPPING WITH WARM AIR ALOFT AND INSTABILITY
BUILDING TO OVER 2000 J/KG MLCAPE. WITH A STRONGER SHORTWAVE
EJECTING OUT OF THE LONGWAVE TROUGH, IN THE HIGH PLAINS BY 7 PM
MONDAY, ANOTHER SURGE OF MOISTURE TRANSPORT WILL CAUSE STORMS
AGAIN TO FORM FURTHER WEST OF THE LOCAL AREA IN THE EVENING.
THIS IS IN ASSOCIATION WITH THE LOW-LEVEL LOW PRESSURE CENTER
AHEAD OF THE MID-LEVEL SHORTWAVE TROUGH, AND ENHANCED THETA-E
CONVERGENCE AT 925 MB. THIS AREA MOVES IN DURING THE MID/LATE
EVENING WITH A LINE OF STORMS. MLCAPE IS AROUND 1500 J/KG AND
WANING AGAIN IN THE NOCTURNAL REGIME.
A LOWER PROBABILITY SCENARIO THAT COULD OCCUR IS LATER
AFTERNOON DEVELOPMENT ALONG A STATIONARY FRONT WEST AND NORTH OF
LA CROSSE (MOST LIKELY). THERE IS QUITE A BIT OF SPREAD ON THE
LOCATION OF THIS FRONT FROM MCW-LSE-MDZ TO NORTHWEST OF THE
AREA. IF THIS BOUNDARY IS IN THE AREA MONDAY LATE AFTERNOON,
LOW-LEVEL THETA-E CONVERGENCE IS SUGGESTED IN A FEW OF THE MODEL
FORECASTS WHICH MAY BE ENOUGH TO BREAK THE CAP. SHOULD THIS
HAPPEN, HODOGRAPHS WOULD FAVOR SMALL TORNADO CHANCES NEAR THE
BOUNDARY AND POSSIBLY A SUPERCELL STORM. RIGHT NOW, CONFIDENCE
IS NOT HIGH IN THIS BOUNDARY INITIATING STORMS.
SO, AGAIN SOME UNCERTAINTY AND IT WOULD APPEAR THE TIMING IS
AGAIN NOT IDEAL FOR A HIGHER RISK. HOWEVER, THERE ARE GOOD
DYNAMICS (300-500MB QG CONVERGENCE) WITH THE MONDAY NIGHT
STORMS, BUT MAINLY THROUGH MINNESOTA IN THE SOUTHWEST FLOW.
OVERALL, IT WOULD APPEAR MONDAY NIGHT'S THREAT IS AGAIN MAINLY
DAMAGING WIND WITH HIGHER RELATIVE CHANCES FOR LOCATIONS FURTHER
WEST.
RAINFALL TOTALS THROUGH THE PERIOD ARE AS CHALLENGING AS THE
SEVERE STORM RISK. THE FAVORED AREAS FOR MORE THAN 2 INCHES
WOULD BE FURTHER WEST WHERE THE CONVECTIVE SYSTEMS COME IN TO
DIE - WITH WI SEEING AMOUNTS CLOSER TO 1 INCH THROUGH MONDAY
NIGHT. AREAS WEST OF I-35 IN MN/IA WILL BE THE HIGHER REGIONAL
TOTALS THROUGH TUESDAY. THUS, IT SEEMS RIVER RISES BUT NO
LARGER FLOODING THREAT IS PRESENTING ITSELF.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 106 AM CDT SUN MAY 17 2026
ONGOING SCATTERED THUNDERSTORMS THREATENING BOTH LOCAL TAF SITES
AT 17.06Z TAF ISSUANCE REQUIRE TAF INCLUSION FOR POTENTIAL
IMPACTS. MORE FREQUENT LIGHTNING OBSERVATIONS SEEN ALONG AND
EAST OF THE MISSISSIPPI RIVER VALLEY IN NEAREST TERM COMPARED TO
SCATTERED OBSERVATIONS TO THE WEST. WHILE EXPECT A SHORT
REPRIEVE THROUGH THE EARLY MORNING, SHOULD STORM COVERAGE
CONTINUE AND FILL IN, FURTHER AMENDMENT WILL BE REQUIRED.
WIDESPREAD SHOWERS WITH EMBEDDED SCATTERED THUNDER LIFT
NORTHEAST THROUGH THE LOCAL AREA TODAY, USHERING IN IFR-MVFR
CEILINGS AND VISIBILITIES. A SHORT REPRIEVE IN WIDESPREAD,
HEAVIER RAINFALL THROUGH THE AFTERNOON CEASES THIS EVENING INTO
TONIGHT NEAR THE END OF THE 17.06Z TAF. HAVEN'T INCLUDED MENTION
FOR ADDITIONAL STORM POTENTIAL AS TIMING REQUIRES FURTHER
DETAIL.
HYDROLOGY
ISSUED AT 106 AM CDT SUN MAY 17 2026
ONE TO TWO INCH TOTALS ARE STILL FORECAST ACROSS THE AREA, WITH
AREAS FURTHER WEST MORE FAVORED FOR THE 2 INCH TOTALS. THIS WILL
LIKELY NOT CAUSE RIVER FLOODING, ONLY WITHIN BANK RISES.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BAUMGARDT
AVIATION...FALKINHAM
HYDROLOGY...BAUMGARDT
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page