747
FXUS63 KGRR 191828
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
228 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 /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 144 PM EDT MON MAY 19 2025
THE LOWER CLOUDS IN THE MVFR CATEGORY ARE SLOWLY LIFTING AND
DISSIPATING FROM SW TO NE EARLY THIS AFTERNOON. WE WILL SEE THAT
TREND CONTINUE, WITH VFR BECOMING WIDESPREAD BY 20-21Z THIS
AFTERNOON. THE LOWER VFR CLOUDS SHOULD THEN CLEAR OUT THIS
EVENING, LEAVING ONLY HIGH CLOUDS OVERHEAD.
OVERNIGHT, WE WILL SEE A LOW LEVEL JET MOVE OVER THE AREA, WITH
THE HIGHEST WINDS OVER KGRR AND KMKG. IT IS AT THESE TWO TERMINALS
THAT THE LOW LEVEL WIND SHEAR WILL BE STRONG ENOUGH TO MENTION.
THE OTHER TERMINALS ARE JUST ENOUGH LOWER TO LEAVE OUT OF THE
FORECAST FOR NOW.
VFR CLOUDS AND VISIBILITIES WILL CONTINUE AT OUR TERMINALS
THROUGH 18Z TUESDAY. WE WILL SEE LIGHT RAIN DEVELOP FROM SW TO NE
AFTER AROUND 13-14Z. THE FEED OF LOW LEVEL DRIER FLOW WILL DELAY
LOWER CONDITIONS UNTIL AFTER 18Z TUESDAY. THE WINDS FROM THE EAST
WILL BECOME GUSTY MID TUESDAY MORNING, AND COULD GUST TO OVER 30
KNOTS TUESDAY AFTERNOON.
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
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