033
FXUS63 KARX 121226 CCA
AFDARX
AREA FORECAST DISCUSSION...CORRECTED FOR AVIATION DISC
NATIONAL WEATHER SERVICE LA CROSSE WI
602 AM CDT THU JUN 12 2025
KEY MESSAGES
- FLOODING THREAT HAS GREATLY LOWERED DUE TO THE GREATER
INSTABILITY REMAINING OVER SOUTHERN AND WESTERN IOWA THROUGH
FRIDAY AND EASTERLY WINDS ADVECTING DRIER AIR INTO THE REGION
TONIGHT. RAINFALL AMOUNTS FROM LAST NIGHT THROUGH FRIDAY NIGHT
WILL BE UP TO A HALF-INCH IN CENTRAL WISCONSIN AND RANGE FROM
A HALF TO 2 INCHES ELSEWHERE ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY.
- PERIODIC SHOWERS AND STORMS EXPECTED NEXT WEEK.
DISCUSSION
ISSUED AT 243 AM CDT THU JUN 12 2025
THIS MORNING
SHOWERS AND STORMS ARE CONTINUING TO DEVELOP ALONG NORTH OF A
SURFACE FRONT NEAR INTERSTATE 80. MOST UNSTABLE CAPES ARE UP TO
500 J/KG ACROSS NORTHEAST AND NORTH-CENTRAL IOWA AND BETWEEN 500
AND 1000 J/KG JUST SOUTH IN CENTRAL IOWA AND THE EFFECTIVE
SHEAR IS UP TO 35 KNOTS IN NORTH-CENTRAL IOWA. WITH DOWNDRAFT
CAPES UP TO 1300 J/KG AND INVERTED-V SOUNDING, MIGHT SEE SOME
GUSTS UP TO 50 MPH. THE CAPE PROFILE LOOKS SUFFICIENT TO PRODUCE
AROUND 1-INCH DIAMETER HAIL. WITHIN THE NEXT 2 TO 4 HOURS, THE
EFFECTIVE SHEAR IS FORECAST TO FALL BELOW 25 KNOTS AND THE DEEP
MOISTURE CONVERGENCE ALSO WEAKENS. AS THIS OCCURS, THIS
CONVECTION IS FORECAST TO GRADUALLY WEAKEN.
FURTHER NORTH, THERE IS ANOTHER BAND OF SHOWERS AND SCATTERED
STORMS ALONG THE MINNESOTA/IOWA BORDER. THIS BAND IS ASSOCIATED
WITH MODERATE TO STRONG 850 MB FRONTOGENESIS AND WEAK TO
MODERATE 850 MB MOISTURE CONVERGENCE. THE CAMS CONTINUE TO SHOW
THAT THIS 850 MB FRONTOGENESIS WILL GRADUALLY SHIFT NORTH AND
WEAKEN. IN ADDITION WITH THE LOW-LEVEL JET WEAKENING AND VEERING
THIS MORNING, THE MOISTURE CONVERGENCE WILL WEAKEN ALONG THIS
FRONT. AS A RESULT, THIS CONVECTION SHOULD GRADUALLY WEAKEN AND
BECOME MORE SCATTERED THIS MORNING.
THIS AFTERNOON
A STATIONARY FRONT WILL LINGER ALONG THE SOUTHERN BORDER OF THE
FORECAST AREA. MOST UNSTABLE CAPES WILL BE UP 1500 J/KG IN
NORTHEAST IOWA. SURFACE-BASED STORMS WILL INITIALLY DEVELOP
ALONG THE FRONT BETWEEN 12.19Z AND 12.21Z DUE TO VERY STEEP
950-850 MB LAPSE RATES AND WEAK CONVERGENCE. SOUNDING PROFILES
SHOW WINDS ALOFT GENERALLY LESS THAN 15 KNOTS AND SKINNY CAPE
PROFILES. IF SEVERE STORMS HAPPENED TO DEVELOP, THEY WOULD BE
SHORT-LIVED. MAIN THREATS WOULD BE HAIL UP TO QUARTERS AND
GUSTY WINDS. AS THESE STORMS MOVE NORTH IN NORTHEAST IOWA, THEY
WILL QUICKLY BECOME ELEVATED AND WEAKEN.
FURTHER NORTH, SCATTERED CONVECTION WILL BE FOUND ALONG AND
NORTH OF THE INTERSTATE 90 CORRIDOR AS THE 850 FRONT MOVES
SLOWLY NORTH.
THIS EVENING
ONE NEW DEVELOPMENT IN THE CAMS IS THAT EAST WINDS WILL ADVECT
DRY AIR (DEW POINTS IN THE MID- AND UPPER 40S) INTO THE REGION
FROM THE GREAT LAKES. AS A RESULT, WE HAVE SEEN A REDUCTION IN
OUR RAINFALL AMOUNTS IN THE UPPER MISSISSIPPI RIVER VALLEY. AT
THIS TIME, THE HEAVIEST RAIN (1.5 TO 4 INCHES) LOOKS TO FALL
FROM THE NORTHWEST SUBURBS OF THE TWIN CITIES NORTHWEST INTO
CENTRAL MINNESOTA.
FRIDAY AND FRIDAY NIGHT
A WEAK SURFACE LOW AND UPPER LEVEL SHORTWAVE TROUGH WILL MOVE
EAST ACROSS THE AREA. WHILE THERE WILL GRADUALLY RECOVER INTO
THE LOWER 60S IN THE WARM SECTOR OF THIS SYSTEM, LOW-LEVEL
CONVERGENCE WILL BE MAINLY FOUND NORTH OF THE WARM FRONT OVER
NORTHERN WISCONSIN AND ALONG A COLD FRONT THAT WILL BE MOVING
EAST THROUGH THE UPPER MISSISSIPPI RIVER VALLEY.
RAINFALL AMOUNTS FROM LAST NIGHT THROUGH FRIDAY NIGHT WILL BE UP
TO A HALF-INCH IN CENTRAL WISCONSIN AND RANGE FROM A HALF TO
2 INCHES ELSEWHERE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY.
EARLY AND MID WEEK NEXT WEEK
AN UPPER-LEVEL RIDGE WILL BUILD NORTHWARD TOWARD THE REGION.
HOWEVER, IT LOOKS LIKE WILL STAY SOUTHWEST AND SOUTH OF THE
UPPER MISSISSIPPI RIVER. THERE WILL BE PERIODIC THREATS OF
SHOWERS AND STORMS AS SHORTWAVE TROUGHS ON THE NORTHERN
PERIPHERY OF THIS RIDGE MOVE THROUGH THE REGION.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 600 AM CDT THU JUN 12 2025
SHOWERS WILL MOVE THROUGH THE AREA THROUGHOUT MUCH OF THE MORNING
BRINGING SOME AREAS OF MVFR REDUCTIONS, ESPECIALLY SOUTH OF I-90.
THESE SHOWERS WILL EVENTUALLY LIFT NORTH OF THE AREA LATER INTO THE
MORNING LEAVING SOME LOW-VFR CIGS FOR THE AFTERNOON. AS WE HEAD
LATER INTO THE EVENING, SHOWERS AND STORMS WILL DEVELOP ALONG A
STATIONARY BOUNDARY ACROSS NORTHEAST IA AND SOUTH-CENTRAL MN AND
WILL PROGRESS NORTHWARD. THESE SHOWERS AND STORMS WILL LIKELY WEAKEN
BY THE TIME THEY APPROACH I-90 BUT DID INCLUDE A PROB30 FOR -TSRA AT
KRST AS A FEW OF THE CAMS SUGGEST THIS POSSIBILITY LATER THIS
EVENING. MVFR TO IFR VSBYS WILL LIKELY OCCUR WITHIN ANY MORE ROBUST
SHOWERS AND STORMS THAT OCCUR THIS EVENING. THERE REMAINS SOME HINTS
IN GUIDANCE FOR SOME MVFR CIGS TO DEVELOP NEAR AND AFTER 06Z, HAVE
OPTED TO INCLUDE SOME MENTION AT KRST GIVEN THE SOMEWHAT HIGHER
PROBABILITIES (40-60%) IN THE 12.06Z HREF. WINDS WILL REMAIN
PRIMARILY FROM THE EAST AT AROUND 8-12 KTS THROUGH THE TAF
PERIOD.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BOYNE
AVIATION...NAYLOR
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