922
FXUS63 KGRR 160543
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1243 AM EST MON DEC 16 2024
KEY MESSAGES
- FOG TONIGHT, RAIN MONDAY
- COLDER WITH SNOW CHANCES WEDNESDAY THROUGH SATURDAY
UPDATE
ISSUED AT 922 PM EST SUN DEC 15 2024
HAVE OPTED TO HOLD OFF ON A DENSE FOG ADVISORY FOR NOW, BUT WE ARE
MONITORING CONDITIONS. THE OBSERVATION SITES THAT ARE CURRENTLY
REPORTING 1/4 MILE VISIBILITIES ARE A BIT SCATTERED IN NATURE,
THEREFORE MAKING THE DENSE FOG PATCHY. A STRONG AREA OF HIGH
PRESSURE IS LOCATED OVER NEW ENGLAND THIS EVENING WITH A LOW IN
THE NORTHERN PLAINS. THE GREAT LAKES ARE SITUATED IN THE MIDDLE
WITH A TIGHTENING PRESSURE GRADIENT. CASE IN POINT, THE WINDS AT A
1,000 FEET OVER GRR ARE FORECAST TO INCREASE FROM 12 KNOTS AT 00Z
TO 36 KNOTS BY 12Z. THIS INCREASE IN WIND SPEED SHOULD TRANSITION
THE 1/4 TO 1 MILE VISIBILITIES TO 2 TO 4 MILE VISIBILITIES BY
DAYBREAK. BOTTOM LINE DESPITE IT BEING A WINTER NIGHT WITH PLENTY
OF LOW LEVEL MOISTURE, WE SHOULD SEE IMPROVEMENT GOING FORWARD.
OUR CONSENSUS OF SHORT TERM MODEL GUIDANCE BEARS THIS OUT.
OTHERWISE, WE SHOULD SEE RAIN CHANCES INCREASE LATE TONIGHT FROM
THE SOUTHWEST AHEAD OF A COLD FRONT WHICH IS ASSOCIATED WITH THE
AFOREMENTIONED NORTHERN PLAINS LOW. 30-60 PCT CHANCES FOR RAIN
LOOK REASONABLE BY DAYBREAK, WITH THE HIGHEST CHANCES IN THE FAR
SOUTHWEST CORNER OF THE STATE.
DISCUSSION
ISSUED AT 323 PM EST SUN DEC 15 2024
- FOG TONIGHT, RAIN MONDAY
PATCHY DENSE FOG WILL CONTINUE THROUGH TONIGHT WITH LIGHT WINDS
AND SATURATED LOW LEVELS. THERE WILL BE SLOW IMPROVEMENT MONDAY
MORNING AS LIGHT RAIN HELPS TO SLOWLY DISPERSE THE FOG. WEST
WINDS PICK UP IN THE AFTERNOON AND EVENING WHICH WILL DISPERSE ANY
REMAINING FOG. LOW LEVEL MOISTURE REMAINS ALTHOUGH RH PROFILES
SHOW A PARTIALLY UNSATURATED DGZ, RESULTING IN ONLY LIGHT SHOWERS
AND DRIZZLE PERHAPS MIXING WITH SNOW FLAKES BEFORE ENDING MONDAY
NIGHT.
- COLDER WITH SNOW CHANCES WEDNESDAY THROUGH SATURDAY
COOLER AIR ADVECTS IN ON TUESDAY AND THIS COULD SET THE STAGE FOR
SOME SNOW LATE TUESDAY NIGHT INTO WEDNESDAY MORNING IN AN AREA OF
MID LEVEL FRONTOGENESIS TO THE NORTH OF A SFC LOW TRACKING EAST
NORTHEAST ACROSS THE OHIO VALLEY. THIS IS FOLLOWED BY A THERMAL
TROUGH AND CYCLONIC FLOW RESULTING IN LIGHT LAKE EFFECT SNOW
SHOWERS INTO WEDNESDAY EVENING.
THERE HAS BEEN A SIGNAL IN THE MODEL GUIDANCE FOR A CLIPPER TO
MOVES ACROSS THE GREAT LAKES WITH SNOW BY LATE IN THE WEEK. THE
UNCERTAINTY IN TIMING AND TRACK IS DECREASING AS TODAY THERE
APPEARS TO BE A CONVERGENCE OF MODEL TIMING ON THURSDAY NIGHT TO
FRIDAY FOR SOME SYNOPTIC SNOW FOLLOWED BY A VERY COLD SHOT OF AIR
AND LAKE EFFECT SNOWS FOR THE WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1242 AM EST MON DEC 16 2024
MAINLY IFR TO LIFR CEILINGS ARE PRESENT AND WILL REMAIN OVER THE
AREA UNTIL THE FRONT MOVES THROUGH MONDAY EVENING WHERE CEILINGS
INCREASE TO MVFR. VISIBILITIES ARE CURRENTLY BOUNCING AROUND, BUT
ARE GENERALLY EXPECTED TO BE IN THE 1-4 SM RANGE AND MAY DROP
BELOW 1 SM AS RAIN MOVES IN THIS MORNING. GUSTS SOUTHERLY GUSTS
AROUND 20 KNOTS ARE EXPECTED MAINLY TOWARD LAN AND JXN DURING THE
DAY TODAY AND INCREASE ACROSS THE AREA MONDAY EVENING BEHIND THE
FRONT WITH WESTERLY GUSTS 20 TO 25 KNOTS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
UPDATE...DUKE
DISCUSSION...OSTUNO
AVIATION...RAH
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