184
FXUS63 KGRR 291947
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
347 PM EDT SAT MAR 29 2025
KEY MESSAGES
- OCCASIONAL SHOWERS THIS EVENING INTO SUNDAY MORNING
- SEVERE WEATHER POSSIBLE SUNDAY AFTERNOON AND EVENING
- ANOTHER SYSTEM MID NEXT WEEK BRINGS A MIXTURE OF PRECIPITATION
DISCUSSION
ISSUED AT 347 PM EDT SAT MAR 29 2025
- OCCASIONAL SHOWERS THIS EVENING INTO SUNDAY MORNING
LOW PRESSURE IS SITUATED IN THE CENTRAL PLAINS THIS EVENING WITH A
WARM FRONT THAT STRETCHES INTO LOWER MICHIGAN FROM NEAR MUSKEGON
TO LANSING. THE FRONT WILL REMAIN A FOCUS FOR RAIN SHOWER
DEVELOPMENT THIS EVENING AND INTO SUNDAY MORNING. AN 850MB LOW
LEVEL JET THAT REMAINS AIMED AT THE AREA WILL PROVIDE THE LIFT
NEEDED WHEN COMBINED WITH THE WARM FRONT ALOFT. INSTABILITY
REMAINS NEGLIGIBLE TONIGHT SO WE ARE EXPECTING RAIN SHOWERS.
THUNDERSTORMS SHOULD HOLD OFF UNTIL AFTER SUNRISE ON SUNDAY.
- SEVERE WEATHER POSSIBLE SUNDAY AFTERNOON AND EVENING
THE MAIN FORECAST FOCUS IS THE SEVERE THREAT SUNDAY AFTERNOON AND
EVENING. THE MAIN TIME FRAME OF CONCERN IS FROM ROUGHLY 200PM
THROUGH 1000PM. THE LOW IN THE PLAINS MOVES OUR DIRECTION TOMORROW
AND THROUGH THE FORECAST AREA TOMORROW NIGHT. AS THE LOW DRAWS
CLOSER THE WARM FRONT WILL PUSH NORTHWARD PLACING THE BULK OF
SOUTHWEST LOWER MICHIGAN IN THE WARM SECTOR. SURFACE DEW POINTS
WILL SURGE TOWARDS 60F WITH 850MB DEW POINTS INCREASING TO +11C.
WITH A SPRING TIME SYSTEM AND COLD AIR ALOFT, THIS IS MORE THAN
ENOUGH LOW LEVEL MOISTURE TO DRIVE INSTABILITY UP. MUCAPE VALUES
WILL LIKELY SURGE INTO THE 1000-2000 J/KG RANGE WITH 2000+ J/KG
POSSIBLE IF WE CAN SEE SOME BREAKS IN THE OVERCAST AND HEATING.
BOTH MOISTURE AND INSTABILITY ARE IN PLACE. DEEP LAYER SHEAR WILL
BE PROVIDED BY STRENGTHENING WIND FIELDS AS THE DEEPENING LOW
MOVES OUR DIRECTION. 50 KNOT LOW LEVEL JET SPEEDS AND 60 KNOTS IN
THE MID LEVELS WILL PROVIDE DEEP LAYER SHEAR VALUES (0-6KM) OF
MORE THAN ENOUGH FOR ROTATING UPDRAFTS. AGREE WITH THE PRIOR
DISCUSSION THAT THE BENT BACK HODOGRAPHS IN THE MID LEVELS COULD
BE A HINDRANCE TO LONG LIVED SUPERCELLS. THAT SAID, THE WRF-ARW
DOES SHOW SOME LONG UPDRAFT HELICITY SWATHS IN OUR CWA.
BOTTOM LINE WE HAVE A SEVERE WEATHER POTENTIAL SUNDAY AFTERNOON
AND EVENING ACROSS THE ENTIRE AREA WITH LOCATIONS NEAR AND SOUTH
OF M-46 BEING MOST LINED UP FOR STRONG TO SEVERE STORMS. BIGGEST
THREAT WILL BE STRONG DAMAGING WINDS WITH PLENTY OF WIND IN THE
PROFILE MOST OF WHICH IS UNIDIRECTIONAL. HAIL WOULD BE THE NEXT
THREAT BUT SLIGHTLY LOWER. ROTATING UPDRAFTS AND COLD MID LEVEL
WILL SET THE STAGE FOR HAIL PRODUCTION. A TORNADO THREAT WILL
EXIST WITH BOTH SUPERCELLS THAT CAN MAINTAIN THEMSELVES AS WELL AS
QLCS MODES GIVEN WHAT MAY BECOME A BROKEN LINE WITH EMBEDDED BOWS
AT TIMES.
THE PRECIPITATION MAY END AS A BIT OF SNOW IN SPOTS AS THE COLD
AIR RAPIDLY SWEEPS INTO THE SYSTEM BEHIND THE LOW SUNDAY NIGHT.
- ANOTHER SYSTEM MID NEXT WEEK BRINGS A MIXTURE OF PRECIPITATION
A MID WEEK SYSTEM WILL BRING THE THREAT OF MULTIPLE PRECIPITATION
TYPES TUESDAY NIGHT THROUGH WEDNESDAY NIGHT OF NEXT WEEK. SOME
SNOW AND FREEZING RAIN MAY OCCUR AT THE ONSET BEFORE THE
PRECIPITATION CHANGES TO RAIN AS THE LOW SWEEPS THROUGH THE
WESTERN GREAT LAKES.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 123 PM EDT SAT MAR 29 2025
A FAIRLY DYNAMIC NEXT 24 HRS IS TAKING SHAPE. A FRONTAL BOUNDARY
CURRENTLY IS DRAPED ACROSS CENTRAL LOWER AND HAS BEEN MOVING BACK
AND FORTH ACROSS MKG WHICH HAS IMPACTED CEILINGS A BIT. IT'S
POSSIBLE THIS BOUNDARY COULD IMPACT GRR AND/OR LAN AS WELL.
RADAR SHOWS SCATTERED SHOWERS MOVING ACROSS THE STATE WHICH HAS
RESULTED IN MIXED CEILINGS AND VISIBILITIES. OVERALL, MVFR
CONDITIONS WILL DECREASE TO IFR TONIGHT. MKG MAY SEE SOME LLWS DUE
TO LIGHTER SURFACE WINDS COUPLED WITH THE STRONGER WINDS ALOFT.
THUNDERSTORMS ARE POSSIBLE NEAR/NORTH OF MKG SUNDAY MORNING AND
ACROSS THE REST OF THE TERMINALS AFTER 18Z.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...DUKE
AVIATION...04
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