249
FXUS63 KMPX 211926
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
226 PM CDT MON APR 21 2025
KEY MESSAGES
- WEATHER PATTERN TO REMAIN ACTIVE, WITH ADDITIONAL RAIN CHANCES
TONIGHT, THURSDAY, AND EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 220 PM CDT MON APR 21 2025
REST OF TODAY/TONIGHT...ANY LINGERING PRECIPITATION ACROSS WESTERN
WISCONSIN HAD CONCLUDED AS OF MIDDAY. CLOUD COVER ASSOCIATED WITH
THE DEPARTING WEATHER SYSTEM CONTINUES TO CLEAR FROM WEST TO EAST,
WITH SUNNY SKIES OVER WEST/CENTRAL MINNESOTA CAPTURED ON GOES-EAST
VISIBLE SATELLITE. THE WESTERN EXTENT OF THE CLOUD DECK WILL SERVE
AS THE DIVIDING LINE FOR THIS AFTERNOON'S HIGH TEMPERATURE GRADIENT.
HIGHS ARE ON TRACK TO REACH THE MID 60S ACROSS WESTERN MINNESOTA,
THOUGH WILL LIKELY STRUGGLE TO BREAK OUT OF THE LOW 50S ACROSS
PORTIONS OF WESTERN WISCONSIN. SURFACE RIDGE WILL KEEP THINGS
CLEAR AND QUIET THROUGH EARLY EVENING, HOWEVER THE ADVANCE OF A
COMPACT SURFACE LOW OVER THE DAKOTAS WILL PUSH A WARM FRONT
ACROSS THE REGION TONIGHT. SUPPORTED BY MODEST MID-LEVEL FLOW,
HREF'S CAM PAINTBALL ENSEMBLE CAPTURES AN ARC OF SCATTERED
SHOWERS (AND PERHAPS A FEW THUNDERSTORMS) DEVELOPING ACROSS
WESTERN MINNESOTA AFTER SUNSET. THIS ACTIVITY WILL MOVE FROM
WEST TO EAST OVERNIGHT, LIKELY PERSISTING INTO THE EARLY MORNING
COMMUTE ACROSS WESTERN WISCONSIN. GIVEN THAT THE LOW-LEVEL JET
AXIS IS FORECAST TO BE POSITIONED ACROSS CENTRAL IOWA, THERE ARE
SOME QUESTIONS ABOUT HOW WIDESPREAD THIS NOCTURNAL CONVECTION
WILL BE LOCALLY. NONETHELESS, A FEW HUNDREDTHS TO A TENTH OF TWO
OF PRECIPITATION WILL BE POSSIBLE (HIGHEST AMOUNTS WILL BE
LOCALIZED).
TUESDAY...A SWIFT MID-LEVEL JETSTREAK WILL PUSH THE NOCTURNAL
CONVECTION EASTWARD THROUGH EARLY TOMORROW MORNING. SKIES WILL AGAIN
CLEAR FROM WEST TO EAST, ALLOWING FOR SUNSHINE DURING THE AFTERNOON.
THIS SHOULD SET THE STAGE FOR RELATIVELY EFFICIENT MIXING, WHICH MAY
MEAN THE NBM'S WIND FORECAST IS CURRENTLY UNDERDONE. FOR REFERENCE,
THE 15Z RAP DISPLAYED WIDESPREAD GUSTS UPWARDS OF 25 KNOTS (MIXING
TO ~5K FEET) TOMORROW AFTERNOON. THIS PROCESS SHOULD YIELD A MILD
AFTERNOON, WITH HIGHS IN THE UPPER 60S TO LOWER 70S ACROSS MUCH OF
THE REGION (COOLER IN WESTERN WI). HOWEVER, WE'LL NEED TO KEEP AN
EYE ON THE DEGREE OF MIXING ACROSS WESTERN MN (WHERE LITTLE TO NO
RAIN FELL SUNDAY NIGHT) AS RH'S ARE FORECAST TO DROP TO BETWEEN 25-
35%. FOR NOW, OUR WIND FORECAST SUGGESTS THAT FIRE WEATHER CONCERNS
ARE ONLY "ELEVATED" TOMORROW AFTERNOON. HOWEVER, SHOULD CONDITIONS
MIX IN THE MANNER THE RAP SUGGESTS, FIRE WEATHER CONCERNS MAY
INCREASE ACROSS SOUTH/WEST MN.
RAIN CHANCES RETURN LATE WEEK...AS HAS BEEN THE TREND WITH PREVIOUS
FORECASTS, WEDNESDAY CONTINUES TO LOOK LIKE A NICE DAY WITH HIGHS IN
THE UPPER 60S AND LOWER 70S. HOWEVER, THE 12Z GUIDANCE HAS TRENDED
IN A SLIGHTLY WETTER DIRECTION COMPARED TO PREVIOUS FORECASTS. THE
REASON FOR THIS TREND IS TIED WARM ADVECTION BENEATH LARGE SCALE
ZONAL FLOW (FROM SOUTHWEST TO NORTHEAST) ACROSS THE CENTRAL CONUS.
IT STILL APPEARS THAT MUCH OF WEDNESDAY WILL BE DRY FOR I-94 AND
NORTH, HOWEVER WARM ADVECTION DRIVEN SHOWERS/STORMS COULD IMPACT
SOUTHERN MN WEDNESDAY AFTERNOON/EVENING. NBM HAS INTRODUCED 30-40%
POPS ACROSS THIS PORTION OF THE FORECAST AREA TO REFLECT THESE
CHANCES. THE ADVANCE OF A SHORTWAVE TROUGH WITHIN THE ZONAL FLOW
WILL SEND A SURFACE LOW THROUGH THE MIDWEST THURSDAY INTO FRIDAY.
MINNESOTA/WISCONSIN WILL BE ON THE NORTHERN SIDE OF THE SYSTEM, SO
NOT EXPECTING MUCH OF A SEVERE WEATHER THREAT, THOUGH ENSEMBLES HINT
THAT THIS COULD BE ANOTHER ROUND OF SOAKING RAINFALL ACROSS THE
REGION. AS STATED BY THE OVERNIGHT SHIFT, EACH DETERMINISTIC AND
ENSEMBLE COUNTERPART FEATURE VARIANCE IN RAINFALL EXPECTATIONS FROM
WEDNESDAY PM - EARLY FRIDAY, THOUGH BASELINE EXPECTATIONS BETWEEN
0.25-0.5" SEEM REASONABLE. HIGHER AMOUNTS (CLOSER TO AN INCH)
CERTAINLY APPEAR POSSIBLE, BUT CONFIDENCE IS TOO LOW TO IDENTIFY
FAVORED LOCATIONS AT THIS TIME.
EXTENDED PERIOD...FRIDAY IS TRENDING DRIER AND SLIGHTLY COOLER
FOLLOWING THE DEPARTURE OF THURSDAY'S RAINFALL. BREEZY NORTHERLY
WINDS WILL KEEP HIGHS IN THE UPPER 50S/NEAR 60. SATURDAY LOOKS DRY
AND SLIGHTLY WARMER, WITH HIGHS IN THE LOW TO MID 60S. PERHAPS IT'S
NOT MUCH OF A SURPRISE THAT OUR UNSETTLED PATTERN WILL SEND ANOTHER
ROUND OF WET WEATHER INTO THE UPPER MIDWEST TO CLOSE THE WEEKEND.
THIS TIME THE CULPRIT WILL BE THE ADVANCE OF A LONGWAVE TROUGH SET
TO COME ASHORE OVER THE WEEKEND. GLOBAL GUIDANCE IS ALREADY IN
FAIRLY GOOD AGREEMENT WITH THE DEVELOPMENT OF WIDESPREAD PRECIPITATION
ACROSS THE REGION AHEAD OF THE ADVANCING TROUGH, THOUGH THERE ARE
TIMING DIFFERENCE TO RESOLVE. NEARLY ALL GRAND ENSEMBLE MEMBERS SHOW
PRECIPITATION BETWEEN SUNDAY PM-TUESDAY AM, SO CONFIDENCE IN
MEASURABLE PRECIPITATION DURING THIS TIMEFRAME IS ALREADY HIGH
(NBM ALREADY HAS POPS > 60%). ON ANOTHER NOTE...WHILE IT IS TOO
SOON TO DISCUSS SPECIFICS WITH REGARDS TO SEVERE WEATHER POTENTIAL
NEXT WEEK, BOTH THE CSU/NSSL ML HIGHLIGHT LOWER END SEVERE PROBS
CREEPING INTO THE UPPER MIDWEST IN ADVANCE OF THE AFOREMENTIONED
TROUGH.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1232 PM CDT MON APR 21 2025
CLOUDS HAVE BEEN SLOW TO EXIT FAR EASTERN MN AND WESTERN WI,
PARTICULARLY LOW STRATUS, BUT STRATUS IS GRADUALLY BEING
REPLACED BY MID-LVL FAIR WX CUMULUS CLOUDS ACROSS THE AREA.
THUS, BY LATER THIS AFTERNOON, ALL SITES WILL HAVE VFR
CONDITIONS. AN APPROACHING FRONTAL SYSTEM TONIGHT WILL BRING
ANOTHER ROUND OF RAIN SHOWERS, BUT THIS SYSTEM WILL WEAKEN AS IT
PASSES ACROSS THE AREA. THUS, NO TSRA IS EXPECTED BUT
SCATTERED/INTERMITTENT -SHRA IS LIKELY DURING THE OVERNIGHT TO
MORNING HOURS. CONDITIONS WILL LIKELY DROP TO MVFR DURING AND
AFTER THE RAIN SHOWERS MOVE THROUGH THE REGION, WITH VFR
CONDITIONS EXPECTED TO RETURN LATE MORNING THROUGH LATE
AFTERNOON ACROSS THE SPAN OF WFO MPX TAFS. NW WINDS INTO THIS
EVENING WILL GO LIGHT/VARIABLE THEN PICK UP FROM THE SE
OVERNIGHT THROUGH MUCH OF TUESDAY WITH SPEEDS 10KTS OR LESS.
KMSP...VFR CONDITIONS HAVE FINALLY BEEN REALIZED AT MSP BUT
MID-LEVEL CEILINGS ARE STILL IN PLACE AT INITIALIZATION. CLOUDS
WILL DIMINISH THROUGH THE AFTERNOON HOURS, WITH CEILINGS
DISSIPATING, FOLLOWED BY CLEARING SKIES THIS EVENING INTO THE
EARLY MORNING HOURS. MID-LEVEL CEILINGS RETURN OVERNIGHT IN
CONJUNCTION WITH LIGHT RAIN MOVING INTO THE AREA. MVFR
CONDITIONS, MORE LIKELY FOR CEILINGS THAN VISIBILITY, DEVELOP
JUST BEFORE SUNRISE AND WILL REMAIN UNTIL LATE MORNING TUESDAY.
VFR WITH RISING CEILINGS ARE THEN EXPECTED FOR TUESDAY
AFTERNOON.
/OUTLOOK FOR KMSP/
WED...VFR. CHC -SHRA/MVFR OVERNIGHT. WIND VARIABLE AROUND 5
KTS.
THU...-SHRA/MVFR LIKELY, MAINLY P.M. WIND NE 10 KTS.
FRI...VFR. WIND N 10-15 KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...STRUS
AVIATION...JPC
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