Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 191657
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1157 AM EST FRI DEC 19 2014

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 330 AM EST FRI DEC 19 2014

AFTER SOME LEFTOVER FREEZING DRIZZLE AND SNOW FLURRIES MOVE OUT FROM
THE SOUTHEAST PORTION OF THE AREA EARLY THIS MORNING...WE WILL MOVE
INTO A FAIRLY QUIET WEATHER PERIOD THEN THROUGH THE FIRST PORTION OF
MONDAY. TEMPERATURES WILL ALSO MODERATE THROUGH THE WEEKEND.

THE WEATHER IS EXPECTED TO BECOME MORE ACTIVE NEXT WEEK WITH A TREND
TOWARD COLDER AND SNOWIER CONDITIONS....POSSIBLY JUST IN TIME FOR
CHRISTMAS. THIS COLDER AIR WILL BE USHERED IN BY A COUPLE OF
STRONGER STORM SYSTEMS.

&&

.UPDATE...
ISSUED AT 1151 AM EST FRI DEC 19 2014

CLOUD TRENDS WILL BE THE MAIN FORECAST ISSUE THE NEXT SEVERAL
FORECAST PERIODS IT SEEMS. THIS AFTERNOON WILL BE NO EXCEPTION.
THE CLOUDS HAVE CLEARED OUT OF THE NORTH...WHILE REMAINING ACROSS
SOUTHERN LOWER. ESSENTIALLY FOR AREAS SOUTH OF INTERSTATE 96 QUITE
A BIT OF CLOUDS HAVE REMAINED IN PLACE...WITH MODELS SHOWING IT
EXPANDING TO THE WEST DOWN I94 WITH TIME.

SO...HAVE A MOSTLY CLOUDY OR BECOMING MOSTLY CLOUDY FORECAST IN
PLACE FOR THE AFTERNOON IN THE SOUTHERN TWO ROWS OF COUNTIES.
ELSEWHERE...EXPECTING CONDITIONS TO REMAIN THE SAME...MOSTLY SUNNY
THROUGH SUNSET.

HIGHS WILL LIKELY TOP OUT IN THE 30 TO 35 DEGREE RANGE AT MOST
LOCATIONS.


&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 330 AM EST FRI DEC 19 2014

THE MAIN CHALLENGES OF THE SHORT TERM PORTION OF THE FCST ARE
DEALING WITH THE ONGOING HEADLINE FOR FREEZING DRIZZLE THIS
MORNING...AND THEN MAINLY DETERMINING CLOUD TRENDS THROUGH SUN.

WE WILL BE HOLDING ONTO THE WINTER WEATHER ADVISORY FOR NOW. WE
CONTINUE TO SEE SOME LIGHT FOG BEING REPORTED AT SITES IN THE
ADVISORY...LIKELY INDICATIVE OF RESIDUAL FREEZING DRIZZLE. THE
IMPACT IS NOT AS GREAT AS EARLIER AS HIGHWAY SPEEDS ARE
HIGHER...LIKELY DUE TO TREATMENT OF THE ROADS. THE TREND IN THE
LIGHT ECHOES ON THE RADAR IS DIMINISHING AS THE SFC TROUGH CONTINUES
TO SINK SOUTH THROUGH THE AREA.

THE AMOUNT OF CLEARING EXPECTED TO TAKE PLACE IS NOT A TOTALLY
CERTAIN THING YET FOR EVERYONE. MODEL CONSENSUS DOES PUSH THE
CLEARING LINE JUST SOUTH OF THE CWFA BY LATER THIS AFTERNOON. THE
HIGHER RESOLUTION AND TYPICALLY MORE PESSIMISTIC NAM DOES HOLD THE
LOW LEVEL CLOUD COVER OVER THE SRN PORTION OF THE CWFA. WE ARE
RUNNING WITH A FCST WHERE AT LEAST SOME PARTIAL CLEARING TAKES PACE
AT ALL LOCATIONS.

THE CLEARING LOOKS TO HOLD IN THROUGH THE FIRST PORTION OF THE DAY
ON SAT BEFORE CLOUDS INCREASE FROM THE SW. WE SEE SOME MID/HIGH
CLOUD COVER MOVE IN WELL NORTH OF THE SYSTEM AFFECTING THE SRN
PORTION OF THE COUNTRY. MODELS ARE LINGERING A BAND OF LOW LEVEL
MOISTURE OVER LAKE MICHIGAN BEFORE PUSHING IT ONSHORE AT SOME POINT
LATE SAT INTO EARLY SUN. PCPN CHCS LOOK QUITE LOW AS THERE IS NOT
REALLY GOOD OVERLAPPING OF THE LOW LEVEL AND MID/HIGH LEVEL
MOISTURE. JUST ABOUT ALL OF THE FORCING IS UP HIGH...ABOVE THE
MOISTURE LAYER.

A BIT DEEPER MOISTURE MOVES IN ON SUN AS THE LONG WAVE TROUGH MOVES
OUT INTO THE PLAINS STATES. LOW LEVEL MOISTURE MOVES NORTH...AND
FORCING IS NOT REALLY EXISTENT SO WE EXPECT ANOTHER MAINLY DRY DAY.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 330 AM EST FRI DEC 19 2014

AN ACTIVE WEATHER PATTERN IS EXPECTED FOR CHRISTMAS WEEK. RAIN IS IN
STORE EARLY IN THE WEEK FOLLOWED BY A TRANSITION TO SNOW SHOWERS AND
WINDY AND COOLER CONDITIONS ON CHRISTMAS EVE INTO CHRISTMAS.

THE EVOLUTION OF AN H5 LONGWAVE TROUGH AND SFC LOW/TROUGH OVER THE
CENTER OF THE NATION EARLY NEXT WEEK INDUCES A SOUTHERLY FLOW OF
WARM MOIST AIR INTO THE GREAT LAKES REGION. THIS WILL LEAD TO RAIN
SHOWERS MONDAY INTO TUESDAY WITH HIGHS AT OR ABOVE 40... ALTHOUGH A
BRIEF THREAT OF LIGHT MIXED WINTRY PRECIPITATION MAY EXIST AT THE
ONSET OF THE PRECIPITATION LATE SUNDAY NIGHT AND EARLY MONDAY BEFORE
SUFFICIENT WARMING TAKES PLACE.

FCST CONFIDENCE REMAINS LOW FOR CHRISTMAS EVE WHEN NEGATIVE TILT
UPPER TROUGH PIVOTS NORTHEAST THROUGH THE GRTLKS REGION. LATEST RUN
OF THE ECMWF HAS A CLOSED UPR LOW WITHIN THIS TROUGH AND A DEEPENING
SFC LOW UNDERNEATH IT TRACKING NORTH THROUGH THE EASTERN GREAT LAKES
REGION. THIS SUGGESTS THE POSSIBILITY OF AN IMPACTFUL EVENT WITH
SOME ACCUMULATING HEAVY/WET SNOW WITHIN THE TROWAL AND STRONG WINDS.

HOWEVER THE ECMWF SOLUTION HAS NOT BEEN CONSISTENT AND THE OTHER
SCENARIO SHOWN BY THE FIM IS FOR THE DEEP LOW TO DEVELOP OVER NEW
ENGLAND RATHER THAN NEARBY. REGARDLESS OF HOW CHRISTMAS EVE PLAYS
OUT... ALL MODEL SOLUTIONS INDICATE COLD AIR ADVECTION AND CYCLONIC
FLOW OVER MICHIGAN FOR CHRISTMAS DAY. THIS SUPPORTS SCATTERED SNOW
SHOWERS... BUT THE AIR IS NOT PARTICULARLY COLD AND THE DEEPER
MOISTURE LIFTS OUT RATHER QUICKLY SO NO SIGNIFICANT LAKE EFFECT IS
EXPECTED AT THIS TIME.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 700 AM EST FRI DEC 19 2014

MVFR CIGS AROUND 2000 FT WERE WIDESPREAD EAST OF A LINE FROM RQB
TO GRR TO AZO AT 12Z. THIS AREA OF STRATUS IS EXPECTED TO GRADUALLY
DIMINISH HOWEVER CONFIDENCE IS LOW IF IT WILL ENTIRELY ERODE. WILL
HAVE MOST OF THE TAFS BECOMING VFR BY 15Z BUT LEFT A BKN MVFR DECK
IN THE JXN TAF ALL DAY.

THE FREEZING DRIZZLE THREAT APPEARS TO BE ENDING AROUND JXN AND
BTL AT 12Z HOWEVER SOME ICING MAY LINGER IN THE CLOUD DECK.

WHILE THE EXTENT OF CLEARING IS IN QUESTION FOR TODAY... MVFR
STRATUS AND/OR LIGHT FOG IS EXPECTED TO RETURN AGAIN LATE TONIGHT
PARTICULARLY AFTER 06Z.


&&

.MARINE...
ISSUED AT 240 PM EST THU DEC 18 2014

NO CONCERNS AT THIS TIME. WINDS AND WAVES WILL CONTINUE TO SUBSIDE
THIS EVENING AND STAY LOW INTO THE WEEKEND WITH HIGH PRESSURE IN
CONTROL.


&&

.HYDROLOGY...
ISSUED AT 240 PM EST THU DEC 18 2014

NO SIGNIFICANT HYDRO IMPACTS EXPECTED FOR THE FORESEEABLE FUTURE.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...DUKE
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...EBW
MARINE...TJT





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