027
FXUS63 KMPX 261749
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1249 PM CDT SAT APR 26 2025
KEY MESSAGES
- SHOWERS AND A FEW THUNDERSTORMS LATE TONIGHT AND EARLY SUNDAY.
- THUNDERSTORMS REDEVELOP SUNDAY NIGHT INTO MONDAY MORNING.
SOME STORMS MAY BE SEVERE WITH LARGE HAIL.
- MAJOR SEVERE WEATHER OUTBREAK LIKELY ACROSS SOUTHERN/EASTERN
MN AND WI MONDAY AFTERNOON AND EARLY EVENING. THERE IS A LEVEL
4 OUT OF 5 SEVERE RISK. ALL SEVERE HAZARDS ARE POSSIBLE,
INCLUDING STRONG TORNADOES.
DISCUSSION
ISSUED AT 403 AM CDT SAT APR 26 2025
TODAY THROUGH SUNDAY...
A TRANQUIL MORNING WILL LEAD TO A PLEASANT DAY WITH HIGH
PRESSURE OVERHEAD. SOUTHEAST SURFACE FLOW WILL BEGIN TO BRING IN
WARMER AIR. HIGHS IN THE LOW TO MID 60S ARE EXPECTED TODAY,
MAKING THIS THE BETTER PICK OF WEEKEND DAYS FOR OUTDOOR
ACTIVITIES.
AS THE HIGH CONTINUES EAST TONIGHT, MOISTURE RETURN WILL BEGIN
TO REACH MINNESOTA THIS EVENING. A SOUTH-NORTH 40-45 KT 850 MB
JET ACROSS THE DAKOTAS WILL BEGIN TO CURVE MORE TO THE EAST
OVERNIGHT AND A BAND OF SHOWERS AND A FEW THUNDERSTORMS WILL
DEVELOP ON THE LEADING EDGE OF THE BETTER MOISTURE ADVECTION.
SEVERE WEATHER IS NOT EXPECTED WITH THIS ROUND. THE BATCH OF
SHOWERS SHOULD WEAKEN SUNDAY MORNING AS IT REACHES WESTERN
WISCONSIN. A FEW ADDITIONAL SHOWERS AND STORMS ARE POSSIBLE
AMIDST MODEST INSTABILITY SUNDAY AFTERNOON AND CONTINUED
MOISTURE ADVECTION.
SUNDAY NIGHT INTO MONDAY NIGHT...
AN UPPER LOW OVER THE SOUTHWESTERN U.S. WILL EJECT NORTHEAST
WHILE BECOMING AN OPEN TROUGH BY EARLY MONDAY. THE RESULT WILL
BE AN ELONGATED TROUGH TO THE SOUTHWEST AND A 70-80 KT MID LEVEL
JET STRETCHING FROM TEXAS TO MINNESOTA LATE SUNDAY NIGHT. STEEP
MID LEVEL LAPSE RATES WILL OVERSPREAD THE UPPER MIDWEST SUNDAY
EVENING AND SHOULD KEEP A CAP IN PLACE. HOWEVER, WHILE AN 850 MB
JET INTENSIFIES TO 50-60 KTS AND ADVANCES NORTHEAST TO SOUTHERN
MINNESOTA AFTER MIDNIGHT, ISENTROPIC LIFT WILL ERODE THE CAP
ENOUGH TO GET WHAT COULD BE FAIRLY WIDESPREAD THUNDERSTORM
DEVELOPMENT OVERNIGHT. DEEP LAYER SHEAR MAY BE SUFFICIENT FOR
ELEVATED SUPERCELLS CAPABLE OF PRIMARILY LARGE HAIL, ALTHOUGH A
FEW DAMAGING WIND GUSTS MAY ALSO OCCUR.
THE LLJ WILL CONTINUE NORTHEAST MONDAY MORNING AND THE NOSE OF
IT SHOULD REFOCUS CONVECTION NORTH OF THE AREA. THE ELEVATED
MIXED LAYER WILL RETURN (MID LEVEL LAPSE RATES AROUND 9C/KM) AND
WILL CAP THE WARM SECTOR INTO THE EARLY AFTERNOON HOURS. THIS
WILL ALLOW THE BOUNDARY LAYER TO RECOVER FROM EARLIER CONVECTION
AS A PRISTINE WARM SECTOR AIRMASS OVERSPREADS THE REGION. BY
EARLY AFTERNOON, THE COLD FRONT MAY SPARK INITIAL CONVECTION
ACROSS WESTERN MN. LIFT WILL EXPAND EAST INTO MID AFTERNOON
WITH THE APPROACH OF THE LOW PRESSURE SYSTEM. THIS WILL EASE
THE EML/CAP AND THUNDERSTORM DEVELOPMENT IS EXPECTED TO OCCUR
RAPIDLY MID AFTERNOON OFF THE FRONT TO THE EAST. UNLIKE MANY
SEVERE EVENTS HERE THAT ARE LARGELY TIED TO A COLD FRONT WHICH
TEND TO PRODUCE QLCSS, A POSITIVELY-TILTED TROUGH WITH LIFT
EXTENDING DEEP INTO THE WARM SECTOR WILL LEAD TO SCATTERED TO
NUMEROUS SEMI-DISCRETE SUPERCELLS. WITH AN 850 MB JET REMAINING
QUITE STRONG AT NEARLY 55 KTS AND A MID LEVEL 500 MB JET OF
70-80 KTS, DEEP LAYER SHEAR WILL BE VERY IMPRESSIVE. GIVEN SEMI-
DISCRETE SUPERCELLS DEVELOPING IN AN UNTOUCHED WARM SECTOR WITH
60 KTS OF DEEP LAYER SHEAR, THIS APPEARS LIKELY TO EVOLVE INTO
A MAJOR SEVERE WEATHER OUTBREAK CAPABLE OF ALL HAZARDS,
INCLUDING STRONG OR EVEN INTENSE TORNADOES. SPC OUTLOOK FOR DAY
3 HAS ALREADY PLACED A LARGE MODERATE RISK FROM THE METRO SOUTH
AND EAST. IT IS THERE THE PRESENCE OF DISCRETE SUPERCELLS IS
MOST LIKELY, AS IS THE POTENTIAL FOR STRONG TORNADOES.
THE INITIAL CONVECTION ALONG THE COLD FRONT EARLY AFTERNOON WILL
CONTINUE EAST, PROBABLY BECOMING A QLCS WHICH WILL BE THE FINAL
ROUND OF CONVECTION WITH THIS SYSTEM. UNFORTUNATELY, AREAS
ALREADY HIT WITH SUPERCELLS MAY HAVE TO CONTEND WITH THIS FINAL
ROUND AS WELL. ALL HAZARDS ARE LIKELY WITH THE LINE, INCLUDING
THE POTENTIAL FOR SOME WEAKER TORNADOES THAN FARTHER EAST.
MONDAY IS SHAPING UP TO BE A DANGEROUS DAY AND IS NOT A TYPICAL
SEVERE WEATHER SETUP FOR THIS REGION. 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.
LATE MONDAY NIGHT AND BEYOND...
THE PATTERN WILL BECOME MORE TRANQUIL AGAIN NEXT WEEK FOLLOWING
MONDAY'S SYSTEM. A SPLIT FLOW PATTERN WILL GRADUALLY BECOME MORE
DOMINATED BY THE NORTHERN STREAM LATE WEEK WITH A POSSIBLE
OMEGA BLOCK FORMING. THE RIDGE PORTION OF THAT BLOCK WOULD BE
ACROSS THE CENTRAL U.S. WHICH SHOULD LEAD TO A SIGNIFICANT
WARMING TREND IN EARLY MAY.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1249 PM CDT SAT APR 26 2025
THE FORECAST STILL LOOKS ON TRACK FOR INCREASING MID LEVEL
CLOUDS LATER THIS AFTERNOON/EVENING AND THEN SHOWERS LIKELY
LATE TONIGHT. VFR EXPECTED THROUGH THE PERIOD, EXCEPT THERE
MAY BE SOME MVFR THAT DEVELOPS WITH ANY HEAVIER SHOWERS IN
PARTS OF SOUTHERN AND CENTRAL MN. ESE WINDS AT MIDDAY WILL
BECOME MORE SOUTHEAST AND INCREASE TOMORROW, WITH SOME GUSTS
OVER 20 KTS. THERE IS A SMALL CHANCE OF THUNDER LATE TONIGHT,
BUT IT DID NOT LOOK TO BE ENOUGH TO INCLUDE IT IN THE FORECAST.
KMSP...NO ADDITIONAL CONCERNS.
/OUTLOOK FOR KMSP/
SUN AFTN/NIGHT...TSRA LIKELY SUNDAY NIGHT. WIND SE 10-20G25KTS.
MON...TSRA WITH IFR/MVFR CIGS EARLY, THEN VFR. TSRA REDEVELOPING
IN THE AFTERNOON. WIND S 15-20G30KTS.
TUE...CHC MVFR CIGS IN THE MORNING. WIND NW 10-20KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...BORGHOFF
AVIATION...TDK
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