789
FXUS63 KARX 121843
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
143 PM CDT MON MAY 12 2025
KEY MESSAGES
- ELEVATED FIRE WEATHER CONDITIONS INTO THE EARLY EVENING.
- SHOWERS AND THUNDERSTORMS WILL INCREASE IN PROBABILITY ACROSS
THE AREA AS WE HEAD THROUGH THE WEEK. SEVERE STORMS CONTINUE
TO LOOK POSSIBLE FOR THURSDAY AFTERNOON AND IT IS A DAY THAT
YOU SHOULD REMAIN WEATHER AWARE AND MONITOR FUTURE FORECASTS.
DISCUSSION
ISSUED AT 142 PM CDT MON MAY 12 2025
ELEVATED FIRE CONDITIONS INTO THE EVENING
TEMPERATURES WERE INTO THE 80S ACROSS MUCH OF THE AREA THIS
AFTERNOON WITH SOUTHERLY WINDS GUSTING TO NEAR 20 MPH. THE
LOWEST RELATIVE HUMIDITIES WILL BE NORTH AND WEST OF LA CROSSE
AND AT 18Z, THESE VALUES WERE IN THE LOWER 20%S. THUS, ELEVATED
FIRE DANGER THROUGH THE EARLY EVENING IS EXPECTED.
INCREASING CLOUDS, MOISTURE AND RAIN CHANCES
AN UPPER LEVEL LOW PRESSURE SYSTEM LOCATED OVER MISSISSIPPI WILL
SLOWLY MOVE TOWARD THE OHIO VALLEY AND INTO THE EASTERN GREAT
LAKES BY WEDNESDAY. ON TUESDAY, EAST/SOUTHEAST WINDS AHEAD OF
THE LOW WILL BRING MOISTURE EAST ACROSS IL/WI AND INTO THE
AREA. BY TUESDAY AFTERNOON, SOME MARGINAL INSTABILITY WILL BE
PRESENT WITH BROKEN SUNSHINE ALLOWING FOR THE DEVELOPMENT OF
SHOWERS AND A FEW THUNDERSTORMS DURING PEAK HEATING. COVERAGE
WILL INCREASE TOWARD THE SOUTHEAST, WITH THOSE FURTHER NORTH AND
WEST SEEING MORE SUN AND LESS/NO SHOWER ACTIVITY (NEAR/WEST OF
A MEDFORD-ROCHESTER-CHARLES CITY LINE). WOULD EXPECT SOUTHWEST
WI TO EXPERIENCE SIMILAR TO WHAT CENTRAL/NRN IL ARE SEEING TODAY
WITH SHOWERS ON RADAR. SOME CHANCES WILL AGAIN BE PRESENT
ACROSS WI /BORDERING IA/MN WEDNESDAY AFTERNOON AS THE AREA
REMAINS ON THE WESTWARD EXTENT OF THE INFLUENCE OF THE LOW
CENTERED NEAR MICHIGAN. PLENTY OF DRY HOURS ARE EXPECTED BOTH
DAYS WITH HARD TO PREDICT, TRANSIENT SHOWERS/STORMS MOVING FROM
EAST TO WEST.
SEVERE THUNDERSTORMS POSSIBLE THURSDAY
SYNOPTIC SCALE INGREDIENTS STILL LOOK TO BE COMING TOGETHER OVER
THE UPPER MISSISSIPPI RIVER VALLEY FOR THE POTENTIAL FOR SEVERE
THUNDERSTORMS ON THURSDAY. GOOD CONSENSUS EXISTS ON AMPLE LOW-LEVEL
MOISTURE AHEAD OF AN EJECTING, NEGATIVELY TILTED TROPOSPHERIC-DEEP
LOW PROGRESSING ACROSS THE THE AREA. FORECAST GUIDANCE REALLY
STRUGGLES THIS TIME OF YEAR WITH LOW-LEVEL DEWPOINT FORECASTS
HOWEVER, SO THE MAGNITUDE/ABUNDANCE OF THE MOISTURE, AND THUS
INSTABILITY, IS STILL A BIT UNCLEAR. AS EVIDENCE OF THE
STRUGGLES, MODEL DEWPOINT FORECASTS IN THE 60S ARE FORECAST FOR
7 PM TONIGHT ACROSS THE AREA IN THE 12.12Z NAM/GFS, NEARLY
10-15F TOO HIGH IN A 12 HOUR FORECAST. IT APPEARS AMPLE MLCAPE
WILL BE PRESENT WITH EVEN CONSERVATIVE MEASURES (25TH PERCENTILE
1000-1500 J/KG) AHEAD OF AN APPROACHING MID-LEVEL WIND MAX OF
60-70KTS AND STRONG DYNAMICAL LIFT. A STRONGER CAPPING
INVERSION LOOKS LIKE IT WOULD LIMIT PRE-FRONTAL STORMS AND
INITIATION WOULD OCCUR RIGHT ON THE FRONT. BUT DETAILS IN THE
CAP STRENGTH SOUTHWARD AND MAYBE MOST IMPORTANT, THE TIMING OF
THE WAVE AND COLD FRONT, STILL NEED TO BE RESOLVED. IT APPEARS
THE HIGHER PROBABILITIES SUGGEST MAINLY A WISCONSIN RISK, WHILE
THERE IS A 20% CHANCE FOR A SLOWER FRONTAL TIMING, BRINGING
SEVERE STORM RISKS WESTWARD INTO MN/IA FURTHER /BASED ON THE
12.00Z GRAND ENSEMBLE, 12.12Z NAM/GFS. A CONSISTENT ECMWF
DETERMINISTIC SIGNAL IS A SLOWER TIMING IN THE LAST THREE RUNS
/12.00-12.12Z/.
THE RISK PROBABILITIES FOR THIS EVENT WILL INCREASE FROM WEST
TO EAST ACROSS THE AREA AND MAINLY TARGET THU AFTERNOON. THE AI
PROBABILITIES HAVE A BIT OF SPREAD IN THEM TOO BUT DO INDICATE
THIS DAY NEEDS TO BE MONITORED. SPC IS CURRENTLY HIGHLIGHTING
MUCH OF WI AND BORDERING MN/IA COUNTIES WITH A 15% RISK WHICH
WOULD LIKELY TRANSLATE INTO A LEVEL 2-3 OF 5 RISK WHICH STILL
LOOKS APPROPRIATE FOR THE LATEST MODEL GUIDANCE. LARGE HAIL,
DAMAGING WIND AND TORNADOES WOULD BE POSSIBLE WITH ORTHOGONAL
STORM MOTION TO THE FRONT FAVORING MORE DISCRETE STORMS /
SUPERCELLS. WITH DETAILS YET TO BE RESOLVED, BUT CONSISTENT
LARGER SCALE INGREDIENTS, WILL CONTINUE ONGOING LEVEL OF
MESSAGING.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1150 AM CDT MON MAY 12 2025
VFR CONDITIONS ARE AGAIN EXPECTED THROUGH THE PERIOD. SOME
SHOWER AND THUNDERSTORM ACTIVITY WILL BE AROUND TUESDAY
AFTERNOON AS INSTABILITY GROWS. COVERAGE LOOKS TO BE ISOLATED
NORTH AND WEST OF LA CROSSE, WITH SCATTERED COVERAGE SOUTH AND
EAST OF LA CROSSE.
FIRE WEATHER
ISSUED AT 142 PM CDT MON MAY 12 2025
RELATIVE HUMIDITIES WILL SEE SOME RECOVERY OVERNIGHT, AND WITH
INCREASING DEWPOINTS ON TUESDAY, MIN RH VALUES SHOULD INCREASE
INTO THE 30S TO 40% NORTH AND WEST OF LA CROSSE, HIGHER
ELSEWHERE. THERE ARE PERIODIC WETTING RAIN CHANCES AS THE WEEK
PROGRESSES.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BAUMGARDT
AVIATION...BAUMGARDT
FIRE WEATHER...BAUMGARDT
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