Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 190830
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 AM EST WED NOV 19 2014

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

.SYNOPSIS...
ISSUED AT 330 AM EST WED NOV 19 2014

A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES REGION WILL
BRING MORE SNOW TODAY WITH MORE UNSEASONABLY COLD AIR AND LAKE
EFFECT SNOW TO FOLLOW LATE TODAY THROUGH TONIGHT AND THURSDAY.
SNOW SHOWERS WILL TAPER OFF TO FLURRIES FRIDAY. UNSEASONABLY
COLD WEATHER WILL CONTINUE THROUGH FRIDAY BEFORE TEMPERATURES
FINALLY MODERATE THIS WEEKEND. A POTENTIALLY VERY STRONG LOW
PRESSURE SYSTEM WILL BRING RAIN AND WINDY CONDITIONS SUNDAY INTO
MONDAY.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EST WED NOV 19 2014

LAKE EFFECT SNOW SHOWERS WILL CONTINUE MAINLY NEAR TO WEST OF
US-131 EARLY THIS MORNING. SOUTH TO SW FLOW LAKE ENHANCED SNOW
LATER THIS MORNING WILL LIKELY BECOME HEAVIER AT TIMES FROM NEAR
GRAND HAVEN AND KMKG NORTHWARD TO KLDM WHERE STRONG LOW LEVEL
CONVERGENCE WILL DEVELOP.

LAKE EFFECT SNOW SHOWERS WILL BECOME WEST EAST ORIENTED AGAIN THIS
AFTERNOON THROUGH TONIGHT AS WINDS VEER TO THE WEST AND INCREASE
BEHIND THE BOUNDARY. LIGHT ACCUMULATIONS ARE LIKELY ACROSS MUCH OF
OUR AREA THIS AFTERNOON THROUGH TONIGHT AS H8 TEMPS GRADUALLY FALL
BACK TO AROUND -15 TO -17 C BY 12Z THURSDAY.

HOWEVER SNOWFALL AMOUNTS THIS AFTERNOON THROUGH THURSDAY WILL NOT
BE NEARLY AS SIGNIFICANT AS COMPARED TO THE SNOWFALL MONDAY THROUGH
TUESDAY DUE LARGELY TO SIGNIFICANTLY LOWER INVERSION HEIGHTS AND
LESS OMEGAS.

SNOWFALL AMOUNTS TODAY SHOULD GENERALLY RANGE FROM AROUND 1 TO 2
INCHES ACROSS MOST OF OUR AREA TO AROUND 3 TO 6 INCHES FROM NEAR
GRAND HAVEN AND KMKG NORTH TO LUDINGTON. ADDITIONAL SNOW
ACCUMULATIONS OF AN INCH OR TWO ARE EXPECTED TONIGHT AND AGAIN ON
THURSDAY WITH ISOLATED LOCALLY HIGHER AMOUNTS WHERE LOW LEVEL
CONVERGENCE IS MAXIMIZED AND GIVEN THE NATURE OF LAKE EFFECT
BANDS.

IN TERMS OF HEADLINES... OUR EXISTING WINTER WX ADVISORY HEADLINE
FOR ALL OUR LAKESHORE COUNTIES IN EFFECT THROUGH TONIGHT LOOKED
GOOD AND REMAINED UNCHANGED. MUCH STRONGER LOW LEVEL CONVERGENCE
WILL FOCUS ACROSS THOSE COUNTIES TODAY AS COMPARED TO THE REST OF
OUR AREA. ANY ADDITIONAL SNOW ACCUMULATIONS ACROSS THE REST OF OUR
AREA TODAY WILL BE LIGHT.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM EST WED NOV 19 2014

A LOT GOING ON IN THE LONG TERM PORTION OF THE FORECAST. A PATTERN
SHIFT TO MORE OF A ZONAL FLOW WILL BRING A WARM UP TO THE AREA OVER
THE WEEKEND. WARMER AIR IS SURGING INTO THE AREA FRIDAY NIGHT AND
THIS CONTINUES INTO THE WEEKEND. THE +8C ISOTHERM AT 850MB/S MAKES
IT INTO SOUTHERN LOWER MICHIGAN ON SUNDAY WHICH IS IN STARK CONTRAST
TO THE -20C WE SAW OVER LAKE MICHIGAN THIS PAST EVENING.

THE MAIN CONCERN AS THIS WARMER AIR SURGES IN IS MIXED
PRECIPITATION. THE LOW LEVELS WILL OBVIOUSLY BE STUBBORN HANGING
ONTO THE COLD AIR WITH THE SNOW PACK...BUT THE WARM AIR ADVECTION IS
STRONG ENOUGH TO SUPPORT A TRANSITION AND THEN A CHANGE TO ALL RAIN.

AT THIS POINT EXPECTING CHANCES FOR LIGHT SNOW DEVELOPING FRIDAY
NIGHT MIXING WITH SLEET AND FREEZING RAIN. SATURDAY MORNING A MIX OF
SLEET AND FREEZING RAIN IS EXPECTED BEFORE TRANSITIONING TO ALL RAIN
SATURDAY AFTERNOON.

FROM SATURDAY AFTERNOON IN MONDAY MORNING A SOAKING RAIN IS
EXPECTED...ON TOP OF A SNOW PACK THAT HAS BUILT UP TO AROUND A FOOT
IN THE HARDEST HIT AREAS OF KALAMAZOO...VAN BUREN...ALLEGAN...OTTAWA
AND KENT COUNTIES. WE COULD BE LOOKING AT RAINFALL ON THE ORDER OF
AN INCH IN BROAD...DEEP SOUTHERLY FLOW. PWATS RISE TO AROUND AN INCH
WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR.
WE WILL NEED TO MONITOR SNOW PACK WATER EQUIVALENTS AS WELL AS
ZEROING IN ON HOW MUCH RAIN WE WILL ACTUALLY SEE. SOME MINOR
FLOODING WILL BE POSSIBLE.

A TRANSITION BACK TO COLDER WEATHER SWEEPS IN FOR EARLY NEXT WEEK AS
A DEEP LOW PRESSURE SYSTEM MOVES NORTHEAST THROUGH THE GREAT LAKES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1207 AM EST WED NOV 19 2014

LAKE EFFECT SNOW WILL BRING WIDELY VARYING CONDITIONS THROUGH
WEDNESDAY EVENING. CONDITIONS WILL BE MOSTLY MVFR EXCEPT AREAS
FROM MKG TO GRR WHERE IFR IS EXPECTED TO PREVAIL. VFR AND MVFR
CONDITIONS CAN BE EXPECTED MOST OF THE TIME FROM BTL TO JXN.
SOUTHWEST WINDS WILL GUST TO 20 KNOTS AT TIMES THROUGH WEDNESDAY.

&&

.MARINE...
ISSUED AT 330 AM EST WED NOV 19 2014

SOUTH TO SW WINDS THIS MORNING WILL VEER TO THE WEST AND
STRENGTHEN THIS AFTERNOON TO GALE FORCE BY LATE AFTERNOON THROUGH
TONIGHT RESULTING IN CONTINUED HIGH WAVE HEIGHTS THAT WILL BUILD
THIS AFTERNOON TO 6 TO 10 FEET AND TO 8 TO 12 FEET TONIGHT AND
THURSDAY. THEREFORE UPGRADED TO GALE WARNING FOR LATE THIS
AFTERNOON THROUGH TONIGHT.

&&

.HYDROLOGY...
ISSUED AT 330 AM EST WED NOV 19 2014

NO HYDRO ISSUES THROUGH FRIDAY WITH UNSEASONABLY COLD AIR IN PLACE
AND ALL PCPN IN THE FORM OF SNOW. HYDRO ISSUES ARE POSSIBLE LATE
THIS WEEKEND INTO EARLY NEXT WEEK DUE TO A POTENTIALLY STRONG
SYSTEM THAT WOULD BRING RAIN SUNDAY INTO MONDAY. THIS IN CONJUNCTION
WITH MELTING SNOW WILL POTENTIALLY RESULT IN SOME HYDRO ISSUES BY
SUNDAY AND MONDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR MIZ037-043-
     050-056-064-071.

LM...SMALL CRAFT ADVISORY UNTIL 3 PM EST TODAY FOR LMZ844>849.
     GALE WARNING 3 PM EST TODAY THROUGH TONIGHT FOR LMZ844>849.

&&

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...DUKE
AVIATION...OSTUNO
HYDROLOGY...LAURENS
MARINE...LAURENS






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