875
FXUS63 KGRR 192327
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
727 PM EDT MON MAY 19 2025
KEY MESSAGES
- COOL AND WET THROUGH THURSDAY.
- WEEKEND WARMING TREND
DISCUSSION
ISSUED AT 228 PM EDT MON MAY 19 2025
- COOL AND WET THROUGH THURSDAY.
LATEST VISIBLE LOOP SHOWS STRATOCU FLOWING SOUTHWESTWARD ACROSS
THE CWA AND COVERS ALL BUT THE SOUTHWEST CWA. ABUNDANT HIGH CLOUDS
COVER THE SOUTHWEST CWA. AS WE GO THROUGH THE EVENING, SOME OF THE
STRATOCU MAY DISSIPATE LEAVING PARTLY CLOUDY SKIES FOR A FEW
HOURS. HOWEVER, CLOUDS WILL INCREASE LATER TONIGHT FROM LOW
PRESSURE OVER THE PLAINS.
THAT LOW WILL MOVE EAST TUESDAY AND BEGIN TO PUSH RAIN INTO THE
CWA FROM SOUTHWEST TO NORTHEAST. THE MODEL TRACK OF THE LOW HAS
BEEN CONSISTENT FOR A FEW RUNS AFTER DEVIATING TO THE NORTH A
COUPLE DAYS AGO. GENERALLY, THE TRACK OF THE LOW WILL TAKE IT
ACROSS NORTHERN IL/IN AND SOUTH OF THE CWA, WHICH MEANS WE'LL HAVE
A STEADY EAST WIND DURING THE NEXT COUPLE OF DAYS. COOLER AIR WILL
FEED INTO THE CWA FROM ONTARIO AND WHEN COMBINED WITH THE RAIN
EXPECTED, TEMPERATURES WILL ONLY REACH THE MID TO UPPER 50S
TUESDAY THROUGH FRIDAY.
A LARGE BAND OF CONDENSATION PRESSURE DEFICITS LESS THAN 10 MB
SLOWLY ENCROACHES ON THE CWA BEGINNING LATE MORNING TUESDAY
REACHING THE NORTHERN CWA TUESDAY EVENING. ECMWF ENSEMBLES POINT
TOWARD QPF AROUND A HALF INCH TUESDAY/WEDNESDAY, EXCEPT IN THE
FAR NORTHEAST CWA WHERE ONLY A TENTH OR SO MAY FALL. GIVEN THE
LONG DURATION OF THIS EVENT, WE ARE NOT ANTICIPATING FLOODING.
CURRENTLY WE EXPECT TO BE ON THE NORTH SIDE OF THE LOW TRACK. IF
THAT LOW DRIFTS TO THE NORTH AND WE GET INTO THE WARM SECTOR,
THEN, OBVIOUSLY, TEMPERATURES WOULD BE WARMER, BUT CONVECTION
COULD ALSO BE A PLAYER, VERSUS THE STRATIFORM PRECIPITATION WE'RE
CURRENTLY ANTICIPATING.
- WEEKEND WARMING TREND
WHILE THE SURFACE LOW WILL MOVE EAST OF THE CWA THURSDAY NIGHT,
THE UPPER LOW WILL REMAIN. SEVERAL SHORT WAVES ROTATING AROUND THE
UPPER LOW WILL KEEP A CHANCE OF SHOWERS IN THE FORECAST FRIDAY
TOO, BEFORE THE TROUGH WEAKENS AND LIFTS OUT.
TEMPERATURES WILL BEGIN TO WARM SATURDAY AND CONTINUE THROUGH THE
HOLIDAY WEEKEND WITH LOWER TO MID 60S SATURDAY AND MID TO UPPER
60S BY MONDAY. THAT'S STILL COOLER THAN NORMAL, GIVEN NORMAL HIGHS
AROUND 70.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 727 PM EDT MON MAY 19 2025
LOWER MVFR CLOUDS HAVE BEEN PESKY TO LIFT/DISSIPATE THIS AFTERNOON
AND EVENING. THE LAST VESTIGES OF THIS CLOUD COVER IS PRETTY MUCH
ALONG THE I-96 CORRIDOR AS OF 2330Z. WE STILL THINK THAT ALL OF
THE LOW CLOUD COVER WILL DISSIPATE, AND ALL SITES SHOULD SEE VFR
CONDITIONS ALL NIGHT. THE LOW LEVEL WIND SHEAR MENTIONED EARLIER
LOOKS A TAD WEAKER, AND HAVE ADJUSTED THIS ACCORDINGLY AT KMKG AND
KGRR, WHERE THE OTHER SITES WILL NOT HAVE ENOUGH SHEAR TO JUSTIFY
A MENTION IN THE ACTUAL FORECAST.
WINDS WILL PICK UP AT THE END OF THE NIGHT AND IN THE MORNING
HOURS ON TUESDAY. THEY WILL PEAK AROUND 30-34 KNOTS. LIGHT RAIN
WILL GRADUALLY ADVANCE FROM SW TO NE DURING THE MORNING TO EARLY
AFTERNOON HOURS. THIS WILL BE VFR FOR THE FIRST FEW HOURS.
EVENTUALLY ENOUGH MOISTURE WILL BE PRESENT IN THE LOWER LEVELS
WITH BETTER RAIN RATES. MVFR IS LIKELY TOWARD THE END OF THIS
FORECAST PERIOD.
MARINE
ISSUED AT 228 PM EDT MON MAY 19 2025
APPROACHING LOW PRESSURE WILL CAUSE WINDS TO INCREASE TONIGHT FROM
THE EAST UP TO 30 KNOTS; A SMALL CRAFT ADVISORY IS IN EFFECT
TONIGHT THROUGH TUESDAY EVENING. THE STRONG WINDS WILL CONTINUE
THROUGH TUESDAY EVENING, BEFORE THE LOW CENTER IS CLOSE ENOUGH
THAT THE PRESSURE GRADIENT DIMINISHES. AS THE LOW MOVES EAST
THURSDAY AND NORTH WINDS DEVELOP, WAVES WILL INCREASE SUCH THAT
ANOTHER SMALL CRAFT ADVISORY MAY BE NEEDED.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TUESDAY TO 2 AM EDT WEDNESDAY FOR
LMZ844>849.
DISCUSSION...04
AVIATION...NJJ
MARINE...04
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page