595
FXUS63 KGRR 141706
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1206 PM EST SAT DEC 14 2024
KEY MESSAGES
- LIGHT ICING EVENT TONIGHT/SUNDAY MORNING
- MORE RAIN MONDAY
- COOLER WITH SNOW SHOWERS LATE WEEK
UPDATE
ISSUED AT 1206 AM EST SAT DEC 14 2024
WE WILL BE ISSUING A WINTER WEATHER ADVISORY FOR FREEZING RAIN,
WHICH IS EXPECTED TO MOVE IN THIS EVENING. THIS WILL RESULT IN
TRAVEL IMPACTS THAT WILL PERSIST INTO SUNDAY MORNING ACROSS THE
NORTHERN INTERIOR OF OUR FORECAST AREA, NORTH AND EAST OF GRAND
RAPIDS.
DISCUSSION
ISSUED AT 300 AM EST SAT DEC 14 2024
- LIGHT ICING EVENT TONIGHT/SUNDAY MORNING
SHORT RANGE MODELS CONTINUE TO ADVERTISE A COMPACT SHORT WAVE
PUSHING A SURFACE LOW ACROSS THE MISSOURI VALLEY TOWARD LOWER
MICHIGAN TONIGHT. WE MAY SEE A LITTLE SUN THIS MORNING, BUT CLOUDS
WILL INCREASE THROUGHOUT THE DAY AS THE LOW MOVES CLOSER. BUFKIT
RH PROFILES SHOW LOW LEVEL RH INCREASING SIGNIFICANTLY AROUND 00Z.
STRONG LIFT AS NOTED BY WIND BARBS PERPENDICULAR TO THE ISENTROPIC
PRESSURE SURFACES WILL SATURATE THE BOUNDARY LAYER QUICKLY BY
EARLY EVENING, LEADING TO CONDENSATION PRESSURE DEFICITS FALLING
TO LESS THAN 10 MB ACROSS THE WESTERN CWA BY 03Z. PRECIPITATION
SHOULD DEVELOP SHORTLY AFTER 00Z IN THE SOUTHWEST CWA AND
SPREADING NORTHEASTWARD THROUGHOUT THE EVENING. THE WARM AIR
ADVECTION PUSH WILL SEND SURFACE TEMPERATURES ABOVE FREEZING FROM
SOUTHWEST TO NORTHEAST DURING THE NIGHT. GIVEN CURRENT SURFACE
TEMPERATURES WELL BELOW FREEZING...INCLUDING ROAD
TEMPERATURES...WE'LL LIKELY SEE A 3-6 HOUR PERIOD OF FREEZING RAIN
BEFORE THE TRANSITION TO RAIN. THE EXCEPTION TO THAT COULD BE THE
NORTHEAST CWA WHERE THE COLDER AIR IS MORE ENTRENCHED. IN THAT
AREA, THE FREEZING PRECIPITATION MAY LINGER INTO SUNDAY MORNING.
COLLABORATION WITH SURROUNDING OFFICES SUGGESTED HOLDING OFF ON
HEADLINES AT THIS TIME.
- MORE RAIN MONDAY
THE NEXT SYSTEM WILL SEE A COLD FRONT MOVE ACROSS THE NORTHERN
PLAINS SUNDAY NIGHT AND MONDAY WITH DECENT UPPER SUPPORT. ANOTHER
ROUND OF RAIN IS LIKELY LATE MONDAY AND MONDAY NIGHT. A STRONG
FEED OF WARMER AIR WILL PRECLUDE ANY FREEZING PRECIPITATION WITH
THIS SYSTEM. A THIRD TO TWO THIRDS OF AN INCH OF RAIN IS POSSIBLE
WITH THIS.
- COOLER WITH SNOW SHOWERS LATE WEEK
FAST ON THE HEELS OF THE MONDAY SYSTEM WILL BE A PHASING OF A WAVE
MOVING ACROSS THE CENTRAL ROCKIES AND A DEEP TROUGH MOVING SOUTH
FROM CANADA. THE NORTHERN INFLUENCE OF THIS SYSTEM WILL MEAN
COLDER AIR TO WORK WITH AND WE'LL SEE LIGHT SNOW AND MIXED
RAIN/SNOW WEDNESDAY. H8 TEMPERATURES WILL FALL TO -16C BY THURSDAY
AFTERNOON, ENOUGH TO GENERATE SOME LAKE EFFECT SNOW SHOWERS
BEGINNING THURSDAY NIGHT. HIGHS WILL FALL INTO THE 30S WITH THIS
SYSTEM. HOWEVER, YET ANOTHER LOW IS PROGD TO DRAG A COLD FRONT
THROUGH THE REGION FRIDAY AND THAT WILL SEND HIGHS INTO THE 20S BY
NEXT SATURDAY, ALONG WITH SOME LIGHT SNOW.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1124 AM EST SAT DEC 14 2024
A BRIEF PERIOD (3-6 HOURS) OF FREEZING RAIN IS EXPECTED TO IMPACT
ALL OF OUR TERMINALS FROM MID TO LATE THIS EVENING INTO THE EARLY
MORNING HOURS SUNDAY. VFR CONDITIONS THIS AFTERNOON WILL DETERIORATE
TO MVFR THEN IFR TONIGHT AS LOW CIGS DEVELOP AND THE -FZRA
DEVELOPS. IN ADDITION TO THIS HAZARD LLWS WILL ALSO DEVELOP
OVERNIGHT AS SSE WINDS AT 2 KFT AGL INCREASE TO AROUND 40 KTS.
THE -FZRA WILL TRANSITION TO -RA DURING THE EARLY MORNING HOURS
SUNDAY AS WARMER AIR MOVES IN AT AND NEAR THE SFC. MAINLY IFR
CONDITIONS ARE FORECAST SUNDAY MORNING THRU 18Z SUN DUE TO LOW
CIGS AND LINGERING LIGHT RAIN.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR LMZ844>849.
UPDATE...OSTUNO
DISCUSSION...04
AVIATION...LAURENS/RAH
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