000
FXUS63 KGRR 130826
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
325 AM EST FRI DEC 13 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE

.SYNOPSIS...
ISSUED AT 325 AM EST FRI DEC 13 2013

AFTER SEEING QUIET WEATHER TODAY...A STEADY SNOW IS EXPECTED TO
DEVELOP BY THIS EVENING.  THE SNOW WILL CONTINUE THROUGHOUT THE
NIGHT AND SATURDAY...FINALLY DIMINISHING SATURDAY EVENING.  MOST
AREAS ACROSS SOUTHWEST MICHIGAN WILL SEE 3 TO 5 INCHES OF SNOW...
WITH THE HIGHEST TOTALS EXPECTED ACROSS THE LANSING...JACKSON AND
BATTLE CREEK AREAS.  AN EAST WIND WILL ALSO INCREASE LATE TONIGHT
AND CONTINUE SATURDAY...CAUSING DRIFTING SNOW.  A WINTER WEATHER
ADVISORY WILL GO INTO AFFECT AS THIS SNOW BEGINS THIS EVENING.

ALTHOUGH THE SNOW IS EXPECTED TO DIMINISH OVER MOST AREAS SATURDAY
EVENING...AREAS ALONG THE LAKE WILL CONTINUE TO SEE INTO SUNDAY AS
LAKE EFFECT SNOW WILL INCREASE BEHIND THE SYSTEM SNOW.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 325 AM EST FRI DEC 13 2013

HAVE DECIDED TO RUN WITH A WINTER WEATHER ADVISORY FOR THE ENTIRE
CWA STARTING THIS EVENING AND RUN IT INTO SATURDAY EVENING.
GENERALLY EXPECTING ACCUMULATIONS OF 3 TO 5 INCHES BEING FAIRLY
COMMON ACROSS THE CWA.  THERE WILL ALSO BE SOME DRIFTING SNOW INTO
SATURDAY AS EAST WINDS KICK UP TO AROUND 20 MPH.

LITTLE HAS CHANGED IN THE OVERALL PATTERN FOR THE SYSTEM SNOW COMING
TONIGHT AND SATURDAY.  NORTHERN AND SOUTHERN STREAM ENERGY ONLY
BEGIN TO MERGE AS THE WAVES ARE EAST OF MI SATURDAY NIGHT.  THIS
WILL RESULT IN A WEAKER SYSTEM FOR US.  HOWEVER GOOD AGREEMENT IN
THE MODELS SHOW A SURFACE LOW MOVING NE ACROSS OH SATURDAY EVENING
WITH AN EXTENDED SURFACE TROUGH AND MID LEVEL TROWAL PERSISTING OVER
LOWER MICHIGAN.  THIS SET UP SUGGESTS THE HEAVIEST SNOWS SHOULD BE
TO OUR SE...BUT THE PERSISTENT LIFT FROM THE SURFACE TROUGH AND
TROWAL WILL RESULT IN A PROLONG PERIOD OF LIGHT TO MODERATE SNOW
ACROSS SW MI.  HAVE A GENERAL 3 TO 5 INCH TOTAL FOR MOST AREAS...BUT
A FEW FGEN BANDS COULD SET UP IN THE TROWAL...WHICH COULD RESULT IN
HIGHER POCKETS OF ACCUMS.  AREAS SE OF I-69 SEEM LIKE PRIME AREAS
FOR THIS POSSIBILITY.  ALSO EXPECTING AN INCREASE IN THE ENE WINDS
LATE TONIGHT AND LINGERING MUCH OF SATURDAY WHICH WILL CAUSE
DRIFTING SNOW.  ALL IN ALL...A SET UP MAKING FOR DICEY TRAVEL.

LAKE EFFECT SNOW WILL FOLLOW THE SYSTEM LATE SATURDAY NIGHT INTO
SUNDAY.  INVERSION HEIGHTS DO NOT LOOK TOO GREAT...SO ADDITIONAL
ACCUMS OF 1 TO 3 INCHES SEEMS REASONABLE AT THIS POINT.  THE FLOW
LOOKS TO BE WNW...FAVORING AREAS SW OF GRR.

UNTIL THE SYSTEM ARRIVES TONIGHT...WE WILL SEE A WEAK FRONT DROP
SOUTH OVER THE CWA TODAY.  A FEW PERIODS OF LIGHT SNOW WILL DRIFT
DOWN FROM THE NORTHERN CWA THIS MORNING...INTO THE CENTRAL CWA THIS
AFTERNOON.  ANY ACCUMS WILL BE LESS THAN A HALF INCH.  THIS FRONT
COULD ACT TO ENHANCE THE LIFT INTO EARLY THIS EVENING AS THE DEEP
MOISTURE STREAMS UP FROM THE SOUTH...BUT THE MAIN IMPACTS ARE
EXPECTED FROM MID EVENING ONWARD.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 AM EST FRI DEC 13 2013

NO BIG STORMS IN THE EXTENDED. QUICK MOVING CLIPPERS AND LAKE EFFECT
SNOW SHOWERS WILL BE THE FORECAST CHALLENGE. SFC RIDGING BUILDS IN
LATE SUNDAY NIGHT AND RETURN FLOW FOLLOWS FOR MONDAY IN ADVANCE OF
NEXT CLIPPER. WARM ADVECTION SNOWS BREAK OUT LATE MONDAY FOLLOWED BY
LAKE ENHANCED SNOW SHOWERS FOR TUESDAY.

THERMAL TROUGH AXIS MOVES EAST BY WEDNESDAY WITH SNOW SHOWERS ENDING
AS INVERSION HEIGHTS LOWER AND FLOW GOES ANTICYCLONIC. BY WEDNESDAY
NIGHT WARM ADVECTION PATTERN BEGINS AND CONTINUES INTO THE END OF
THE WEEK. SOME LIGHT SNOW COULD FOCUS NORTH OF A SFC WARM FRONT ON
THURSDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 956 PM EST THU DEC 12 2013

COULD BE AN INCREASED RISK FOR ICING IN THE LOW CLOUDS TONIGHT.
THE COMBINATION OF WEAK LIFT IN THE CLOUDS AND LACK OF ICE
SUPPORTS A POTENTIAL FOR ICING...WHICH COULD CONTINUE THROUGH MUCH
OF FRI.

MVFR CEILINGS TO DOMINATE THE TAF SITES FOR MUCH OF THE TIME. SNOW
WILL MOVE IN FROM THE NORTH ROUGHLY AROUND 00Z...REACHING
KMKG...KGRR AND KLAN. BY 06Z SAT AN INCREASED RISK FOR IFR VSBYS
DUE TO SNOW WILL EXIST.

&&

.MARINE...
ISSUED AT 325 AM EST FRI DEC 13 2013

WILL MAINTAIN THE SMALL CRAFT ADVISORY THROUGH THIS MORNING...THEN
WINDS TURN OFFSHORE THIS AFTERNOON ALLOWING WAVES TO SUBSIDE.  THE
OFFSHORE FLOW CONTINUES UNTIL EARLY SUNDAY MORNING WHEN WE WILL
LIKELY NEED ANOTHER SMALL CRAFT ADVISORY.

&&

.HYDROLOGY...
ISSUED AT 325 AM EST FRI DEC 13 2013

NO ISSUES EXPECTED IN THE SHORT TERM.  RIVERS HAVE ICED OVER FOR THE
MOST PART...AND WITH TEMPS STAYING IN THE 20S FOR THE SHORT
TERM...LITTLE CHANGE IS EXPECTED.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 10 PM EST
     SATURDAY FOR MIZ037>040-043>046-050>052-056>059-064>067-
     071>074.

LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR
LMZ844>849.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...OSTUNO
AVIATION...MJS
HYDROLOGY...JK
MARINE...JK