090
FXUS63 KGRR 192339
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
639 PM EST THU DEC 19 2024
KEY MESSAGES
- ACCUMULATING SNOW THROUGH THE FRIDAY MORNING COMMUTE
- POTENTIAL FOR LAKE EFFECT SNOW FRIDAY EVE INTO SATURDAY MORNING
- ANOTHER ROUND OF SNOW POSSIBLE MONDAY AFTERNOON/NIGHT
DISCUSSION
ISSUED AT 202 PM EST THU DEC 19 2024
- ACCUMULATING SNOW THROUGH THE FRIDAY MORNING COMMUTE
ON MID LEVEL VORT MAX WAS TRACKING EASTWARD THROUGH EASTERN WI AND
WILL PUSH THROUGH OUR NORTHERN ZONES THIS EVENING. WARM AIR
ADVECTION AHEAD OF THIS FEATURE HAS RESULTED IN A BAND OF SNOW
MAINLY IN WESTERN PARTS OF THE CWA AT THIS TIME. THIS FEATURE WILL
PIVOT UP INTO THE NORTHERN ZONES WHERE THE SNOW WILL PERSIST THE
LONGEST. SURFACE TEMPERATURES REMAIN BELOW FREEZING IN THIS AREA
WHICH IS WHERE THE MOST IMPACTS FOR THE EVENING COMMUTE ARE
EXPECTED. THIS IS BASICALLY NORTH OF A LINE FROM NEAR MUSKEGON,
EAST NORTHEASTWARD TO ALMA. THIS IS THE REGION WHERE WE HAVE THE
WINTER WEATHER ADVISORY OUT FOR AND THUS NO CHANGES ARE PLANNED TO
THE HEADLINE AT THIS TIME.
ANOTHER MID LEVEL VORT MAX WAS DIGGING DOWN THE BACKSIDE OF THE
TROUGH OVER THE UPPER MS VALLEY. AS THIS TROUGH SHIFTS EAST
TONIGHT, IT SHARPENS AS A RESULT. DECENT LIFT IN THE DGZ IS SEEN
IN THE MODELS OVER OUR NORTHERN ZONES IN THE EVENING WHERE FGEN
WAS NOTED. AS THIS TROUGH SHIFTS EAST THROUGH THE CWA LATER
TONIGHT/FRIDAY MORNING, THE BAND OF SNOW WILL SHIFT SOUTH. WE
COULD SEE AN ADDITIONAL INCH OR TWO OF SNOW SOUTH OF THE ADVISORY
AREA WHICH COULD LEAD TO SOME TRAVEL IMPACTS FOR THE MORNING
COMMUTE. WE WILL NEED TO MONITOR TRENDS CLOSELY THROUGH THE
EVENING. BY MID MORNING THE BULK OF THE SNOW SHOULD BE SOUTH OF
THE CWA.
- POTENTIAL FOR LAKE EFFECT SNOW FRIDAY EVE INTO SATURDAY MORNING
ARCTIC AIR POURS IN BEHIND THE DEPARTING WAVE FRIDAY INTO SATURDAY.
MODELS HAVE BEEN INDICATING A NORTHERLY FLOW SETTING UP. COMMONLY
THIS LEADS TO LAKE EFFECT SNOW FOR THE LAKESHORE COUNTIES GIVEN
THE ENHANCED LOW LEVEL CONVERGENCE. WE WILL RAISE POPS FOR THIS
REGION, ESPECIALLY NORTH OF MUSKEGON. BUFKIT FROM THE NAM3KM AT
LUDINGTON SHOWS ALL THE MOISTURE BELOW 5K FT, BUT THE DGZ IS AT
THE TOP OF THIS MOISTURE WHICH SUPPORTS AT LEAST SOME POTENTIAL
FOR SNOW. CLOSE MONITORING FOR POSSIBLE IMPACTS FROM THIS
POTENTIAL BAND WILL BE NEEDED.
- ANOTHER ROUND OF SNOW POSSIBLE MONDAY AFTERNOON/NIGHT
A MID LEVEL WAVE TRACKS IN FROM THE WEST DURING THIS TIME. WARM
AND MOIST AIR ADVECTION AHEAD OF IT WILL DEEPEN UP THE CLOUDS AND
THE DGZ BECOMES SATURATED AT TIMES. THUS IT'S LOOKING LIKELY THAT
WE WILL SEE A BAND OF PRECIPITATION LIFTING THROUGH THE CWA DURING
THIS TIME. FORECAST SOUNDINGS SUGGEST A WARM LAYER COULD LEAD TO
THE SNOW MIXING WITH AND/CHANGING TO RAIN. IT'S ALSO POSSIBLE THAT
A PERIOD OF FREEZING RAIN COULD OCCUR. THE ENSEMBLE 24 HOUR QPF
FROM THE MODELS HAS BEEN TRENDING DOWN WHICH MAKES SENSE AS THE
DGZ IS SHOWN TO NOT MAINTAIN ITS SATURATION.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 634 PM EST THU DEC 19 2024
RADAR SHOWS A LITTLE LULL IN THE SNOW CURRENTLY, BUT SHOULD FILL
BACK IN BY 02Z. LIGHT SNOW WILL CONTINUE OVERNIGHT AND
VISIBILITIES WILL FALL TO AROUND A MILE AT TIMES. SOLID IFR CAN BE
EXPECTED TONIGHT WITH IMPROVING CONDITIONS BY LATE MORNING AND THE
AFTERNOON FROM WEST TO EAST.
GRR WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY UNTIL 10 AM EST FRIDAY FOR MIZ037>040-
043>046-050.
MARINE...NONE.
DISCUSSION...MJS
AVIATION...04
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