870
FXUS63 KGRR 281816
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
216 PM EDT FRI MAR 28 2025
KEY MESSAGES
- WARMER WITH SHOWERS AND CHANCE OF STORMS THROUGH SUNDAY
- RAIN TRANSITIONS TO SNOW AND DIMINISHES SUNDAY NIGHT INTO MONDAY
- ADDITIONAL PRECIPITATION MID-NEXT WEEK
UPDATE
ISSUED AT 1151 AM EDT FRI MAR 28 2025
A STATIONARY FRONT IS SITUATED ACROSS THE AREA AS WE APPROACH
MIDDAY STRETCHING FROM CENTRAL WISCONSIN EASTWARD ACROSS LAKE
MICHIGAN TO ALONG I-96. DEW POINTS ARE IN THE 30S TO THE NORTH OF
THE FRONT AND 40S TO THE SOUTH. OCCASIONAL SHOWERS AND
THUNDERSTORMS THIS MORNING HAVE BEEN MOVING EAST NEAR THE
BOUNDARY. FURTHER SOUTH A WARM FRONT STRETCHES FROM NORTHERN
ILLINOIS INTO CENTRAL INDIANA. MUCAPE VALUES OVER SOUTHWEST LOWER
MICHIGAN AND NEARBY IN PROXIMITY TO THE AFOREMENTIONED FRONTAL
BOUNDARIES REMAINS MODEST, ONLY ON THE ORDER OF 500 J/KG. THIS IS
DUE TO THE EXTENT OF CLOUDS AND SHOWERS WHICH IS CURTAILING
INSTABILITY.
GOING FORWARD THIS AFTERNOON THE HREF IS SHOWING THE SHOWERS AND
STORMS CLEARING TO THE EAST WITH NOTHING ELSE FORMING IN ITS WAKE.
THIS MAKES SENSE FOR TWO REASONS, 1) SATELLITE AND RADAR IMAGERY
WOULD CONFIRM THIS WITH CLEARING AND NO ADDITIONAL PRECIPITATION
PRODUCTION IMMINENT AND 2) FLAT RIDGING IS FORECAST TO BUILD
OVERHEAD WHICH WILL PROVIDE SUBSIDENCE AND NO IMPETUS FOR FURTHER
CONVECTION.
CHANCES FOR RAIN THIS AFTERNOON TREND DOWNWARD WITH TIME. WE WILL
TURN AT LEAST PARTLY SUNNY THIS AFTERNOON WITH A BREEZY SOUTHWEST
WIND DEVELOPING. HIGHS WILL PUSH TO AROUND 70 ALONG I-94. FOR
REFERENCE THE RECORD HIGH IN AZO TODAY IS 79 WITH A NORMAL HIGH OF
51. ROUGHLY 20 DEGREES ABOVE NORMAL IS OUR FORECAST HIGH
TEMPERATURE DOWN THERE TODAY.
DISCUSSION
ISSUED AT 304 AM EDT FRI MAR 28 2025
- WARMER WITH SHOWERS AND CHANCE OF STORMS THROUGH SUNDAY
ELEVATED SHOWERS AND THUNDERSTORMS ARE ON TRACK TO ARRIVE IN THE
COMING HOURS ASSOCIATED WITH A WARM FRONT SURGING NORTH ACROSS THE
STATE. CAPE LOOKS TO BE SUFFICIENT FOR GENERAL THUNDER, ON THE ORDER
OF A FEW HUNDRED JOULES, BUT NOT ANYTHING MORE THAN THAT. POOR MID-
LEVEL MOISTURE QUALITY WILL LIMIT WIDESPREAD PRECIPITATION TO UNDER
ONE-QUARTER INCH, THROUGH THE HREF LPMM SUGGESTS ISOLATED POCKETS UP
TO ONE-HALF INCH ARE POSSIBLE. BEST COVERAGE WILL BE ACROSS
SOUTHWEST LOWER MICHIGAN BECOMING MORE SPOTTY AS THE FRONT CROSSES
THE AREA GIVEN A DIMINISHED FRONTOGENETICAL RESPONSE. HIGHS WILL
RANGE FROM THE 50S NEAR US10 WHERE THE FRONT STALLS TO NEAR 70
ACROSS THE I94 CORRIDOR.
SATURDAY WILL INITIALLY FEATURE PRECIPITATION LIMITED TO THE
NORTHERN CWA NEAR THE FRONT, EXPANDING SOUTH THROUGH THE DAY AS THE
FRONT DRIFTS TO THE SOUTH. THERE WILL BE A NOTABLE TEMPERATURE
GRADIENT ACROSS LOWER MICHIGAN AS A RESULT OF THE FRONT. UNCERTAINTY
IS HIGHEST ACROSS THE NORTHERN CWA DUE TO HIGH DEPENDENCE ON
SPECIFIC FRONTAL POSITIONING. THE NORTHERN CWA IS FAVORED TO START
IN THE 50S, BUT FALL BACK INTO THE 40S/UPPER 30S BY EVENING. HIGHS
NEAR AND SOUTH OF I96 (WHICH IS APPROXIMATELY WHERE THE FRONT WILL
STALL SATURDAY NIGHT) ARE FAVORED TO REMAIN INTO THE 60S
SUNDAY, INCREASING SOUTHERLY FLOW DRIVES THE BAROCLINIC ZONE BACK TO
THE NORTH WITH 850MB TEMPS CLIMBING TO NEAR 10C. ACROSS SOUTHERN
MICHIGAN, TEMPERATURES WILL CLIMB WELL INTO THE 60S AGAIN. CENTRAL
MICHIGAN WILL BE MUCH MORE UNCERTAIN, REACHING THE FIFTIES IF THE
FRONTAL BOUNDARY MOVES NORTH OF THEM (FAVORED BY THE ECMWF/CMC
FAMILIES) OR STAYING IN THE THIRTIES IF IT STALLS ACROSS LOWER MI
(FAVORED BY THE GFS/NAM FAMILIES). THE GEFS HAS TRENDED SLIGHTLY
WARMER IN THE 00Z SUITE WHICH WOULD FAVOR MORE RAIN AND LESS OF AN
ICY MIX RISK. INSTABILITY ALSO RE-ENTERS THE PICTURE SUNDAY LEADING
TO A ATTENDANT THUNDER RISK WITH WIDESPREAD RAIN AS THE SURFACE LOW
APPROACHES. ONE THING WE WILL NEED TO WATCH IS THE POTENTIAL FOR A
FEW STRONGER STORMS ON SUNDAY. 30-45 KNOTS OF SHEAR WITH MUCAPE
VALUES LIKELY EXCEEDING 500-1000 J/KG MAY BE ENOUGH FOR SOME
ORGANIZATION OF STORMS, PARTICULARLY GIVEN BACKED WINDS ALONG THE
WARM FRONTAL BOUNDARY WHEREVER IT SETS UP.
- RAIN TRANSITIONS TO SNOW AND DIMINISHES SUNDAY NIGHT INTO MONDAY
AS THE SURFACE LOW DEPARTS SUNDAY NIGHT INTO MONDAY, COLD AIR
ADVECTION WILL TAKE HOLD LEADING TO RAIN MIXING WITH/CHANGING OVER
TO SNOW AS IT DIMINISHES. SOME UNCERTAINTY EXISTS IN HOW LONG
PRECIPITATION LINGERS GIVEN THE GFS SUITE FAVORS A QUICKLY DEPARTING
LOW, WHILE THE ECMWF AND CMC SUITES HOLD THE LOW AND ASSOCIATED
TROUGHING LONGER KEEPING PRECIPITATION INTO MONDAY. ACCUMULATION
CHANCES LOOK TO BE LOW, WITH AREAS NEAR AND NORTH OF US10 HAVING THE
BEST SHOT AT SEEING ANY ACCUMULATION. SURFACE AND UPPER-LEVEL
RIDGING THEN DRIES OUT THE AREA FOR TUESDAY.
- ADDITIONAL PRECIPITATION MID-NEXT WEEK
OUR NEXT SYSTEM ARRIVES WEDNESDAY AS A MID-LEVEL WAVE EJECTS A
SURFACE LOW THROUGH THE REGION ONCE AGAIN WITH HIGH CONFIDENCE IN
SOME FORM OF PRECIPITATION. ENSEMBLE CLUSTERS SUGGEST UNCERTAINTY IN
HOW THIS TROUGH INTERACTS WITH THE DOWNSTREAM RIDGING AFFECTING HOW
MUCH WARM AIR IS ADVECTED INTO LOWER MICHIGAN. IF WE END UP ON THE
COOLER END OF THE SYSTEM HIGHS TOWARDS THE 40S AND LIGHT SNOW OR A
RAIN/SNOW MIX ARE FAVORED. HOWEVER IF WARM AIR ADVECTION IS MORE
ROBUST HIGHS INTO THE SIXTIES AND RAIN ARE EXPECTED ONCE AGAIN.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 217 PM EDT FRI MAR 28 2025
THE TAF PERIOD BEGINS WITH IFR CIGS CONTINUING AT THE EASTERN
SITES OF LAN AND JXN. SATELLITE SHOWS CLOUDS CLEARING FROM THE
WEST SO THESE CIGS WILL LIFT OVER THE NEXT FEW HOURS. BEHIND THE
FRONT WINDS WILL MIX OUT THIS AFTERNOON WITH GUSTY SW WINDS AFTER
19Z. THE NEXT AVIATION CONCERN WILL BE LLWS THIS EVENING. A LOW
LEVEL JET WILL MOVE OVER THE REGION AROUND SUNSET. WITH SURFACE
WINDS DROP, THE WINDS ALOFT WILL REMAIN STRONG WITH SW WINDS GOING
TO 50KTS BY 2Z FRIDAY AND INCREASING TO 60KTS AT 2KFT AFTER 5Z.
THE LLWS WILL DROP DOWN TO 55KTS AROUND 12Z AND CONTINUE UNTIL
AROUND 14Z. TAF SITES WILL THEN MIX DOWN THE WINDS WITH WIND GUSTS
OF 35KTS POSSIBLE AFTER 14Z. MVFR CIGS WILL MOVE IN LATE IN THE
TAF PERIOD WITH SCATTERED SHOWERS POSSIBLE LATE SATURDAY MORNING.
SO HAVE PUT VCSH IN APPROPRIATE TAF SITES.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM EDT
SATURDAY FOR LMZ844>849.
UPDATE...DUKE
DISCUSSION...THOMAS
AVIATION...CERU
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