263
FXUS63 KGRR 160223
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
923 PM EST SUN DEC 15 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 /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 800 PM EST SUN DEC 15 2024
LIFR AND LOWER CIGS DUE TO DENSE FOG WILL CONTINUE FOR MOST OF THE
TAF SITES FOR MOST OF THE FORECAST PERIOD. THERE IS SOME DRIER
AIR THROUGH THE SOUTH BUT THAT SHOULD DROP BACK DOWN OVERNIGHT.
RAIN SHOWERS WILL MOVE IN EARLY MONDAY ALLOWING FOR IFR AND LOWER
CIGS AND VSBYS TO CONTINUE THROUGH MOST OF MONDAY. IFR TO LIFR
VSBYS WILL IMPROVE BETWEEN 15Z TO 18Z WITH CIGS FINALLY IMPROVING
TO NEAR MVFR LATE MONDAY AFTERNOON.
WITH THE SYSTEM MOVING IN HAVE PUT A PERIOD OF LLWS BETWEEN 14Z
AND 18Z.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
UPDATE...DUKE
DISCUSSION...OSTUNO
AVIATION...CERU
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