469
FXUS63 KGRR 260549
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
149 AM EDT SAT APR 26 2025
KEY MESSAGES
- EVENING STORMS THEN DRYING OUT FOR THE WEEKEND
- FROST POTENTIAL SATURDAY NIGHT
- THUNDERSTORM POTENTIAL MONDAY NIGHT AND TUESDAY
UPDATE
ISSUED AT 928 PM EDT FRI APR 25 2025
LITTLE IF ANY INSTABILITY REMAINS OVER THE CWA NOW THAT THE FRONT
HAS MOVED THROUGH. AS SUCH, WE REMOVED THE MENTION OF THUNDER
TONIGHT. RADAR SHOWS THE LAST BAND OF SHOWERS POISED TO MOVE
ACROSS THE LAKE SHORE. ONCE THAT MOVES THROUGH, THE REST OF THE
NIGHT WILL BE DRY. NO CHANGES TO THE REMAINDER OF THE FORECAST.
DISCUSSION
ISSUED AT 341 PM EDT FRI APR 25 2025
- EVENING STORMS THEN DRYING OUT FOR THE WEEKEND
CONVECTION HAS COMMENCED THIS AFTERNOON, POISED JUST OFF TO OUR
SOUTH ACROSS THE FAR SOUTHERN ROW OF MICHIGAN COUNTIES. MUCAPE
VALUES ARE ON THE ORDER OF 1000-2000 J/KG SO WE HAVE PLENTY OF
INSTABILITY. DEEP LAYER SHEAR IS ON THE ORDER OF 30 KNOTS, SO WE
HAVE HAD OCCASIONAL CORES ALOFT THAT HAVE BEEN WORTH MONITORING,
BUT NOTHING SEVERE YET. GIVEN SOLID INSTABILITY AND MARGINAL SHEAR
THERE WILL BE PERIODS THIS EVENING WHERE A STRAY CORE MAY PULSE
TOWARDS SEVERE LEVELS. OVERALL THOUGH, OUR SEVERE THREAT IS QUITE
LOW. STORMS WILL CONTINUE FROM NOW THROUGH 7-8PM BEFORE MOVING
EAST AND/OR DIMINISHING. THERE MAY BE SOME WRAP AROUND SHOWERS ON
THE BACKSIDE OF THE DEPARTING LOW TONIGHT, BUT SCATTERED POPS
(30-40 PCT) AT BEST SHOULD COVER THAT THREAT.
OTHERWISE, WE ARE LOOKING AT DRY WEEKEND AS HIGH PRESSURE SLIDES
EAST ACROSS THE GREAT LAKES. NEXT CHANCE FOR PRECIPITATION SHOULD
NOT COME UNTIL MONDAY NIGHT.
- FROST POTENTIAL SATURDAY NIGHT
THERE WILL BE THE POTENTIAL FOR SOME PATCHY FROST IN THE COUNTIES
WE HAVE ACTIVE FOR FROST/FREEZE HEADLINES FOR SATURDAY NIGHT. THE
COUNTIES WE ARE ISSUING HEADLINES FOR ARE FROM THE
MUSKEGON/KENT/MONTCALM/GRATIOT ROW TO THE SOUTH. AT THIS TIME
THOUGH WE ARE HOLDING OFF ON ANY HEADLINES AT ALL AND WE WILL
ASSESS THE THREAT FURTHER TONIGHT AND INTO SATURDAY. AS IT STANDS
NOW LOW TEMPERATURES LOOK TO BE 34 TO 36 DEGREE RANGE THAT WOULD
EQUATE TO AN ADVISORY IF THESE FORECAST LOW TEMPERATURES HOLD. THE
CENTRAL LOWER MICHIGAN COUNTIES ARE COLDER, BUT THE GROWING SEASON
HAS NOT PROGRESSED ENOUGH UP THERE AT LAST CHECK TO BRING THEM
INTO THE FOLD. BOTTOM LINE IS THERE IS A CHANCE OF FROST SATURDAY
NIGHT BUT WE WILL HOLD OFF FOR NOW AND ISSUE GOING FORWARD IF
CONFIDENCE INCREASES.
- THUNDERSTORM POTENTIAL MONDAY NIGHT AND TUESDAY
THE GRR FORECAST AREA IS IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS
BOTH MONDAY NIGHT AND AGAIN ON TUESDAY. MONDAY NIGHT THE
CONVECTION WILL BE COMING IN LIKELY IN A DECAYING PHASE AFTER
GENERATING EARLY ON MONDAY UPSTREAM. ON TUESDAY, THE CONVECTION
WILL GO UP ON AN ADVANCING FRONT IN OUR SOUTH AND EAST, SO IT WILL
ONLY BE A PORTION OF THE AREA THAT WILL HAVE A THREAT FOR SEVERE
WEATHER. THE UPPER WAVE DRIVING THE COLD FRONT LOOKS FAIRLY
POTENT. MONDAY NIGHT CONVECTION LOOKS ELEVATED WITH MARGINAL SHEAR
VALUES SO CANNOT RULE OUT SOME NEAR SEVERE HAIL.
THE TIME FRAME OF CONCERN WILL BE TUESDAY AFTERNOON AS THE
MOISTURE CONSOLIDATES ALONG THE FRONT AND INSTABILITY JUMPS TO IN
EXCESS OF 2000 J/KG. DEEP LAYER SHEAR ON TUESDAY IS HIGH AROUND 50
KNOTS PER THE GFS. THE COMBINATION OF CAPE/SHEAR IS SUFFICIENT FOR
ALL HAZARDS. THE QUESTION MARK AS IS ALWAYS THE CASE IN THESE
EVENTS IS WHETHER OR NOT THE CLOUDS AND PRECIP CLEAR OUT ENOUGH ON
TUESDAY TO BUILD THE INSTABILITY TO FORECAST LEVELS. BOTTOM LINE
WE ARE WATCH MONDAY NIGHT AND ESPECIALLY TUESDAY CLOSELY.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 149 AM EDT SAT APR 26 2025
AN AREA OF LIGHT RAIN IS MOVING THROUGH AND SHOULD BE EAST OF ALL
TAF SITES BY 8Z. CEILINGS WILL GRADUALLY LOWER TO LOW MVFR TO IFR
VALUES INTO SATURDAY MORNING. IFR TO MVFR CEILINGS WILL SCATTER
OUT DURING THE AFTERNOON. BREEZY NORTHERLY WINDS WITH GUSTS AROUND
20 KNOTS WILL CONTINUE BEFORE BECOMING LIGHT AND VARIABLE
SATURDAY NIGHT.
MARINE
ISSUED AT 341 PM EDT FRI APR 25 2025
NORTH WINDS ARE BEGINNING TO FILL IN ACROSS LAKE MICHIGAN THIS
AFTERNOON. LOW PRESSURE CONSOLIDATES THIS AFTERNOON ACROSS THE
SOUTHERN GREAT LAKES AND MOVES EAST THIS EVENING. PEAK WINDS WILL
OCCUR THIS EVENING BUT A STRONGER NORTH FLOW WILL PERSIST INTO
SATURDAY. NORTH WINDS OF 15 TO 30 KNOTS WILL BE COMMON TONIGHT
AND SATURDAY MORNING. WE HAVE A SMALL CRAFT ADVISORY (SCA) IN
EFFECT THROUGH 800PM WHICH LOOKS GOOD. WE MAY NEED TO EXTEND THE
SCA FOR AN HOUR OR TWO IN THE FAR SOUTH SATURDAY EVENING, BUT AT
THIS POINT THINKING IS IT LOOKS GOOD.
WINDS AND WAVES WILL BE BELOW ADVISORY CRITERIA SATURDAY NIGHT AND
SUNDAY AS HIGH PRESSURE DRIFTS THROUGH THE REGION. SUNDAY NIGHT
INTO MONDAY SOUTH WINDS TAKE HOLD AND WE MAY NEED HEADLINES ONCE
AGAIN.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ844>849.
UPDATE...04
DISCUSSION...DUKE
AVIATION...RAH
MARINE...DUKE
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