337
FXUS63 KGRR 150819
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
319 AM EST SUN DEC 15 2024
KEY MESSAGES
- FREEZING RAIN ENDING FROM SOUTH TO NORTH TODAY
- RAIN MONDAY
- TURNING COLDER MID WEEK
DISCUSSION
ISSUED AT 316 AM EST SUN DEC 15 2024
- FREEZING RAIN ENDING FROM SOUTH TO NORTH TODAY
TEMPERATURES HAVE RISEN INTO THE MID 30S OVER A FEW COUNTIES IN
THE SOUTHERN CWA. CALLS TO LOCAL LAW ENFORCEMENT IN THOSE COUNTIES
REVEAL LITTLE IF ANY IMPACTS FROM EARLIER FREEZING RAIN. AS SUCH,
WE HAVE REMOVED ALLEGAN, VAN BUREN, KALAMAZOO, AND CALHOUN
COUNTIES FROM THE WINTER WEATHER ADVISORY. COUNTIES FARTHER EAST
ARE CLOSER TO LOWER DEWPOINTS AND CORRESPONDING LOWER WET BULB
ZERO TEMPERATURES AND WILL LIKELY SEE FREEZING RAIN FOR A LITTLE
LONGER. THE REST OF THE COUNTIES NOW HAVE AN EXPIRATION TIME OF
11 AM. AS TEMPERATURES CONTINUE TO WARM THIS MORNING, WE'LL TRIM
COUNTIES FROM THE HEADLINE AS APPROPRIATE.
AS TEMPERATURES SLOWLY INCREASE, REGIONAL RADAR SHOWS THE THE BULK
OF THE PRECIPITATION MOVING INTO SOUTHERN LOWER FROM NORTHERN IN.
AS THE MORNING PROGRESSES, WE'LL SEE BREAKS DEVELOP IN THE
PRECIPITATION AND POPS WERE ADJUSTED ACCORDINGLY.
SECONDARY ROADS NORTH OF I-96 REMAIN SNOW PACKED AND WILL RETAIN
FREEZING SURFACE TEMPERATURES LONGER AND IS THE MAIN REASON WE
PUSHED THE ADVISORY LATER INTO THE MORNING.
MOSTLY DRY CONDITIONS ARE EXPECTED THIS AFTERNOON AND TEMPERATURES
WILL RISE TO AROUND 40.
- RAIN MONDAY
LOW PRESSURE OVER NORTHERN MINNESOTA WILL PUSH A COLD FRONT ACROSS
LOWER MI MONDAY. AHEAD OF IT, RAIN SHOWERS WILL DEVELOP MONDAY
MORNING AND BE EAST OF THE CWA BY LATE IN THE DAY. BETWEEN A TENTH
AND TWO TENTHS OF AN INCH OF RAIN IS EXPECTED MONDAY. MONDAY WILL
BE THE WARMEST DAY OF THE WEEK. SOUTH WINDS WILL PUSH TEMPERATURES
TO AROUND 50 OVER THE SOUTHERN CWA AND MID 40S IN THE NORTH BEFORE
COOLER AIR ARRIVES LATE IN THE DAY BEHIND THE COLD FRONT.
- TURNING COLDER MID WEEK
H8 TEMPS WILL FALL TO AROUND -14C WEDNESDAY NIGHT BEHIND THE
FRONT AND WE MAY SEE SOME LAKE EFFECT SNOW SHOWERS DEVELOP.
HOWEVER, THE ARCTIC AIR IS FLEETING AND WILL BE LIFTING OUT BY
LATE THURSDAY.
A CLIPPER MOVING ACROSS THE STRAITS FRIDAY WILL BRING IN ANOTHER
SHOT OF COLDER AIR. WE'RE LIKELY TO SEE SOME SYNOPTIC SNOW WITH
THE CLIPPER FRIDAY, FOLLOWED BY LAKE EFFECT SNOW SHOWERS OVER THE
WEEKEND. MODELS CURRENTLY SHOW BOUNDARY LAYER WINDS SATURDAY
NORTHERLY WHICH WOULD KEEP THE SNOW SHOWERS CLOSER TO THE LAKE
SHORE. ANY CHANGE IN THAT WIND DIRECTION COULD SEE SOME SNOW
SPREAD INLAND.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1250 AM EST SUN DEC 15 2024
ONGOING FREEZING RAIN WILL CONTINUE TO SHIFT NORTHEAST OVERNIGHT
WITH SOME SNOW MIXING IN AT TIMES. A TRANSITION TO RAIN IS
EXPECTED FROM SOUTHWEST TO NORTHEAST INTO SUNDAY MORNING. TAF
SITES ARE EXPECTED TO TRANSITION TO RAIN BY 9Z. A LIGHT GLAZE OF
ICE WILL BE POSSIBLE UNTIL THEN.
CEILINGS WILL GRADUALLY LOWER OVERNIGHT INTO SUNDAY MORNING WITH
IFR CONDITIONS DEVELOPING BY MID TO LATE MORNING. THERE WILL ALSO
BE SOME LOW LEVEL WIND SHEAR INITIALLY WITH THE LOW LEVEL JET
OVERHEAD. THIS WILL TAPER OFF EARLY SUNDAY MORNING AS THE LOW
LEVEL JET SHIFTS EAST. RAIN CHANCES (20 TO 30 PERCENT) LINGER
THROUGH THE DAY.
GRR AIRPORT DSS UPDATE:
THE TRANSITION FROM FREEZING RAIN TO RAIN MAY LINGER FOR A FEW
MORE HOURS, OTHERWISE NO OTHER ADJUSTMENTS TO THE FORECAST.
GRR WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY UNTIL 11 AM EST THIS MORNING FOR
MIZ037>040-043>046-050>052-056>059-065>067-074.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR LMZ844>849.
DISCUSSION...04
AVIATION...RAH
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