Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 281720
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1220 PM EST FRI NOV 28 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 310 AM EST FRI NOV 28 2014

COLD WEATHER WILL CONTINUE TODAY WITH WIDESPREAD LIGHT SNOW AND
ACCUMULATIONS OF 1 TO 3 INCHES THAT COULD RESULT IN SLICK SPOTS
ON AREA ROADS. TEMPERATURES WILL MODERATE THIS WEEKEND WITH SOME
LIGHT RAIN SHOWERS AND DRIZZLE BEFORE A MUCH COLDER AIRMASS MOVES
BACK INTO LOWER MICHIGAN MONDAY.

&&

.UPDATE...
ISSUED AT 1146 AM EST FRI NOV 28 2014

WILL LOWER SNOW ACCUMULATIONS FOR TODAY AS LIGHT SNOW HAS BEEN
SLOW TO DEVELOP DUE TO PRE-EXISTING DRY AIR MASS IN PLACE. LATEST
GUIDANCE HAS DELAYED BEST QPF OF AROUND 0.15 UNTIL TONIGHT...
ORIENTED ALONG/JUST NORTH OF I-96 FROM 00Z-06Z. WARM AIR WILL BE
SURGING IN ALOFT AFTER MIDNIGHT SO SOME OF THIS WILL CHANGE TO
LIGHT FREEZING RAIN/SLEET BEFORE DIMINISHING/LIFTING OUT LATE
TONIGHT AND EARLY SATURDAY.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 310 AM EST FRI NOV 28 2014

LIGHT SNOW WILL DEVELOP ACROSS OUR FORECAST AREA TODAY IN AN AREA
OF ISENTROPIC UPGLIDE WELL TO THE NE OF THE WARM FRONT THAT WILL
LIFT SLOWLY NE INTO ILLINOIS. SNOW ACCUMULATIONS FROM MID TO LATE
MORNING THROUGH THIS EVENING WILL RANGE FROM ONE TO THREE INCHES.
HIGHEST ACCUMULATIONS WITHIN THAT RANGE CONTINUE TO LOOK MOST
PROBABLE NW OF KGRR FROM NEAR KMKG NORTHWARD TO KLDM WITH HELP FROM
SSW FLOW LAKE ENHANCED MOISTURE AND AS SUGGESTED BY 00Z ECMWF
GUIDANCE.

PCPN TYPE MAY CHANGE TO A VERY BRIEF PERIOD OF LIGHT FREEZING
DRIZZLE/LIGHT FREEZING RAIN OR SLEET LATE TONIGHT BEFORE ENOUGH
WARM AIR MOVES IN TO CHANGE PCPN TYPE TO PLAIN LIGHT RAIN SHOWERS
AND DRIZZLE SATURDAY THROUGH SUNDAY. MAX TEMPS SATURDAY WILL REACH
THE UPPER 30S TO LOWER 40S AND WILL BE WELL INTO THE 40S FOR SUNDAY.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 310 AM EST FRI NOV 28 2014

EXTENDED PERIOD WILL START OFF WITH A COLD FRONT MOVING THROUGH
SUNDAY NIGHT...WHICH MAY BE ABLE TO FOCUS SOME LIGHT SNOW OR MIXED
PRECIPITATION. THEN DRIER AND COLDER AIR MOVES IN WITH SOME LIGHT
LAKE EFFECT SNOW SHOWERS POSSIBLE EARLY MONDAY. INVERSION HEIGHTS
CRASH AS AN ARCTIC HIGH BEGINS TO BUILD IN LATER IN THE DAY AND THE
SFC HIGH SHOULD BRING DRY WEATHER THROUGH TUESDAY.

WARM ADVECTION BEGINS TUESDAY NIGHT WITH SOME LIGHT SNOW OR MIXED
PRECIPITATION POSSIBLE BEFORE ANOTHER COLD FRONT MOVES THROUGH
WEDNESDAY AND THINGS DRY OUT AGAIN.

THURSDAY IS A QUESTION MARK AS SEVERAL RUNS OF THE GFS HAVE SHOWN
PRECIPITATION IN AN AREA OF ISENTROPIC UPGLIDE NORTH OF A SFC WARM
FRONT ACROSS THE OHIO VALLEY REACHING THE SOUTHERN FORECAST AREA.
THE ECWMF IS ABOUT 24 HOURS SLOWER WITH THE PROGRESSION OF THIS.
KEPT LOW CHANCE POPS IN THE FORECAST FOR NOW. PRECIP TYPE IS ALSO A
PROBLEM WITH GFS SOUNDINGS SHOWING POTENTIAL FOR MIXED PRECIP ACROSS
THE SOUTHERN HALF OF THE FORECAST AREA...WHILE THE ECWMF WOULD BE
MOSTLY LIQUID...AND NOT ARRIVING UNTIL AFTER THURSDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1220 PM EST FRI NOV 28 2014

SOME LIGHT SNOW FOR THE FIRST SIX HOURS OF THE TAF PERIOD WITH
SOME LIFR VISIBILITIES LIKELY AT KMKG AND ALONG THE LAKE SHORE.
REMAINDER OF THE TAF LOCATIONS SHOULD REMAIN MOSTLY MVFR IN SNOW
AT TIMES THROUGH 03Z. AFTER 03Z WARMER AIR ALOFT MOVES INTO LOWER
MICHIGAN BRINGING THE CHANCE FOR SOME LIGHT FREEZING RAIN TO OCCUR
BRIEFLY AROUND OR SHORTLY AFTER 06Z. HAVE INCLUDED SOME PROB30S
IN THE TAFS FOR THIS AT THIS TIME AS CONFIDENCE IS FAIRLY LOW FOR
FZRA TO OCCUR. LOOKS LIKE ANY FZRA THREAT WILL END AFTER 12Z WITH
MOSTLY VFR CONDITIONS OCCURING THROUGH MUCH OF SATURDAY.

&&

.MARINE...
ISSUED AT 310 AM EST FRI NOV 28 2014

A NEW SMALL CRAFT ADVISORY WILL GO INTO EFFECT FROM MID AFTERNOON
TODAY THROUGH SATURDAY AS INCREASING SOUTHERLY WINDS WILL CAUSE
WAVE HEIGHTS TO RAMP BACK UP AFTER A BRIEF LULL THIS MORNING AND
EARLY AFTERNOON.


&&

.HYDROLOGY...
ISSUED AT 310 AM EST FRI NOV 28 2014

NO HYDRO ISSUES ARE ANTICIPATED THIS WEEKEND INTO NEXT WEEK.
PRECIPITATION TODAY THROUGH THE WEEKEND INTO NEXT WEEK WILL BE
LIGHT AND NOT SIGNIFICANT ENOUGH TO CAUSE ANY HYDRO ISSUES.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EST SATURDAY FOR LMZ844>849.

&&

$$

UPDATE...MEADE
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...OSTUNO
AVIATION...MACZKO
HYDROLOGY...LAURENS
MARINE...LAURENS






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