942
FXUS63 KMPX 270847
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
347 AM CDT SUN APR 27 2025
KEY MESSAGES
- THUNDERSTORMS DEVELOP TONIGHT INTO MONDAY MORNING. SOME STORMS
MAY BE SEVERE WITH LARGE HAIL.
- AN OUTBREAK OF SEVERE THUNDERSTORMS REMAINS LIKELY MONDAY
AFTERNOON AND EARLY EVENING. A LEVEL 4 OUT OF 5 SEVERE RISK
REMAINS IN PLACE ACROSS MUCH OF THE UPPER MIDWEST. ALL SEVERE
HAZARDS ARE POSSIBLE, INCLUDING STRONG TORNADOES AND VERY
LARGE HAIL.
DISCUSSION
ISSUED AT 347 AM CDT SUN APR 27 2025
NUMEROUS SHOWERS HAVE DEVELOPED ACROSS SOUTHERN AND WESTERN
MINNESOTA EARLY THIS MORNING. THE SHOWERS ARE TIED TO A
MOISTURE GRADIENT THAT WILL CONTINUE EASTWARD DURING THE NEXT
SEVERAL HOURS. DRY BOUNDARY LAYER AIR HAS KEPT AMOUNTS VERY
LIGHT AND POOR LAPSE RATES HAVE KEPT THE CHANCE FOR THUNDER LOW.
BY MID MORNING, MOST OF THE ACTIVITY WILL HAVE DISSIPATED, BUT
EXTENSIVE CLOUD COVER EXTENDING ACROSS ALMOST THE ENTIRETY OF
THE PLAINS SHOULD REMAIN FOR THE REST OF THE DAY UNDERNEATH A
MOIST INVERSION.
A DEEP TROUGH OVER THE SOUTHWESTERN U.S WILL BEGIN TO EMERGE
OVER THE WESTERN PLAINS TONIGHT AND SPAWN AN AREA OF LOW
PRESSURE OVER THE CENTRAL PLAINS TONIGHT. THE 850 MB JET WILL
STRENGTHEN MARKEDLY OVER THE CENTRAL AND SOUTHERN PLAINS TO 55
TO 60 KTS EARLY THIS EVENING. THE NOSE OF THAT JET WILL REACH
SOUTHWESTERN MINNESOTA AROUND MIDNIGHT WHICH WILL BE THE IMPETUS
FOR THUNDERSTORM INITIATION FROM WEST CENTRAL TO SOUTH CENTRAL
MINNESOTA. FORECAST SOUNDINGS ARE LESS CAPPED ABOVE 850 MB THAN
IN EARLIER FORECASTS AND THE ECMWF LIGHTNING FLASH DENSITY
PRODUCT SHOWS FAIRLY ROBUST GROWTH THROUGH THE REST OF THE
NIGHT ACROSS CENTRAL MINNESOTA AND PARTS OF WESTERN WISCONSIN.
ADDITIONAL CLUSTERS OF THUNDERSTORMS FROM THE DAKOTAS MAY ALSO
REACH WESTERN MINNESOTA TOWARD DAWN. ACTIVITY WILL BUILD NORTH
WITH TIME AS THE NOSE OF THE LOW LEVEL JET CONTINUES TO LIFT
NORTH INTO NORTHERN MINNESOTA. IN ADDITION, A STOUT EML WILL
ALSO BE BUILDING IN FROM THE SOUTHWEST, LEADING TO A
STRENGTHENING CAP MONDAY MORNING. THE STRONGEST STORMS ARE
LIKELY TO OCCUR ALONG THE LEADING EDGE OF THE EML WHERE ELEVATED
CAPE IS MAXIMIZED AND CINH IS STILL MINIMAL. THOSE STORMS MAY
CONTAIN LARGE HAIL.
THE WARM FRONT WILL LIFT NORTH MONDAY MORNING AND THERE SHOULD
BE A BREAK IN CONVECTION UNTIL ABOUT MIDDAY. THE EML/CAP WILL
RELAX AROUND THAT TIME AS A DRYLINE BEGINS TO REACH THE WESTERN
MINNESOTA BORDER. NUMEROUS THUNDERSTORMS WILL DEVELOP ALONG IT
AND COULD BRING A HEIGHTENED TORNADO RISK INITIALLY IF STORMS
CAN REMAIN SOMEWHAT DISCRETE. THIS WINDOW MAY NOT LAST LONG
THOUGH AS A SQUALL LINE SHOULD FILL IN RELATIVELY QUICKLY.
DESPITE THAT, ALL HAZARDS ARE POSSIBLE WITH IT, INCLUDING LARGE
HAIL, DAMAGING WINDS, AND TORNADOES. A SECOND LINE OF STORMS
COULD FIRE ALONG THE COLD FRONT WEST OF THE FIRST LINE AN HOUR
OR TWO LATER. THE LINE(S) WILL TRACK EASTWARD ACROSS MINNESOTA
THROUGH THE AFTERNOON AND REACH WESTERN WISCONSIN BY EARLY
EVENING.
SOME UNCERTAINTY REMAINS WHETHER DISCRETE SUPERCELLS CAN FORM
IN AN UNDISTURBED WARM SECTOR AHEAD OF THE LINE(S) OF STORMS.
CAMS ARE NOT TOO OPTIMISTIC, BUT THIS COULD BE A FUNCTION OF THE
PHYSICS OF THE MODELS AND ALSO THE LACK OF A SPARKING MECHANISM
LIKE A FRONT. THE FACT IS, MID LEVEL HEIGHT FALLS WILL
OVERSPREAD THE WARM SECTOR IN A VERY UNSTABLE, HIGHLY SHEARED
ENVIRONMENT WHICH SHOULD RESULT IN AT LEAST A FEW DISCRETE
SUPERCELLS DEVELOPING ACROSS SOUTHERN AND EASTERN MINNESOTA
DURING THE MID TO LATE AFTERNOON. THESE CELLS WOULD POSE THE
GREATEST RISK FOR STRONG TORNADOES (EF2+) AND VERY LARGE HAIL.
THE TORNADO THREAT WILL MAXIMIZE DURING THE EARLY EVENING AS THE
LLJ STRENGTHENS FROM 50 KTS TO 60 KTS, ELONGATING LOW LEVEL
HODOGRAPHS FURTHER.
IT IS WORTH REPEATING - MONDAY IS LIKELY TO BE A DANGEROUS
WEATHER DAY. IT IS IMPORTANT TO HAVE SEVERE WEATHER SAFETY
PLANS IN PLACE NOW SO QUICK AND DECISIVE ACTION CAN BE TAKEN
WHEN STORMS APPROACH AND WARNINGS ARE ISSUED.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1049 PM CDT SAT APR 26 2025
MAIN CHANGE TO THE TAFS THIS EVENING IS THE RAIN OVER WESTERN
MN HAS BEEN STRUGGLING WITH THE ANTECEDENT DRY AIRMASS. AS A
RESULT, HAVE DELAYED THE RAIN ONSET AT MOST LOCATIONS AND EVEN
REMOVED IT FROM EAU. WE'RE STILL ANTICIPATING SCATTERED SHOWERS
TO MOVE EAST THROUGH THE NIGHT, THOUGH COVERAGE OF WHAT ACTUALLY
REACHES THE GROUND MAY END UP BEING LESS THAN ORIGINALLY
THOUGHT. NOT MUCH AS CHANGED WITH THOUGHTS FOR SUNDAY, WITH A
STOUT INVERSION BUILDING IN AS MOISTURE SURGES INTO WESTERN MN,
WHERE MVFR CIGS ARE EXPECTED, LIKELY TRENDING TOWARD IFR BY THE
END OF THE PERIOD. ALSO HAPPENING AT THE END OF THE PERIOD IS A
50 KT LLJ WILL START NOSING UP INTO SOUTHERN MN, WHICH WILL
BRING THE TREAT FOR THUNDERSTORMS OVERNIGHT. THIS THUNDER THREAT
LOOKS TO BE JUST GETTING GOING AS WE HIT THE END OF THIS TAF
PERIOD FOR THE 24 HOUR TAFS (6Z MON), WITH CIGS ALSO DROPPING AS
THE WARM FRONT BEGINS ITS TREK TO THE NORTH ACROSS THE MPX AREA
SUNDAY NIGHT.
KMSP...HI-RES MODELS HAVE BEEN TRENDING DRY FOR THE SHOWERS
TRYING TO PUSH EAST TONIGHT, THOUGH WE DO STILL ANTICIPATE A
LITTLE LIGHT RAIN IN THE METRO AROUND SUNRISE. SUNDAY LOOKS
QUIET, WITH MAYBE EVEN SOME PEAKS OF SUN BEFORE MVFR CIGS MOVE
IN PRETTY QUICK SUNDAY EVENING, THAT MAY BE IFR COME MONDAY
MORNING. WITH THE WARM FRONT MOVING ACROSS THE METRO SUNDAY
NIGHT, WE STILL ANTICIPATE FAIRLY WIDESPREAD THUNDERSTORMS TO BE
MOVING NORTH WITH THAT FEATURE, WITH 8Z TO 10Z MONDAY LOOKING
TO CURRENTLY HAVE THE BEST CHANCE OF TS AT MSP.
/OUTLOOK FOR KMSP/
MON...TSRA WITH IFR/MVFR CIGS EARLY, THEN VFR. TSRA REDEVELOPING
IN THE AFTERNOON. WIND S 15-20G30 KTS.
TUE...CHC MVFR CIGS IN THE MORNING. WIND NW 10-20 KTS.
WED...VFR, CHC MVFR/-SHRA LATE. WIND SSE 10-15 KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...BORGHOFF
AVIATION...MPG
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