Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 212030
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 PM EST FRI NOV 21 2014

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

.SYNOPSIS...
ISSUED AT 330 PM EST FRI NOV 21 2014

CLEAR SKIES WILL QUICKLY GIVE WAY TO CLOUDS AND FREEZING RAIN
AFTER MIDNIGHT TONIGHT. THE FREEZING RAIN WILL TRANSITION TO LIGHT
RAIN...DRIZZLE AND FOG BY SATURDAY AFTERNOON. THAT WILL CONTINUE
INTO SUNDAY MORNING. THAN THE PASSAGE OF A WARM FRONT WILL BRING
MUCH WARMER TEMPERATURES AND PERIODS OF HEAVY RAIN SUNDAY
AFTERNOON INTO EARLY MONDAY. THE PASSAGE OF A COLD FRONT DURING
THE MIDDAY HOURS OF MONDAY WILL BEGING BACK THE COLD AIR AND SNOW
SHOWERS WHICH WILL LAST THROUGH MOST OF NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 330 PM EST FRI NOV 21 2014

I CONTINUED THE FREEZING RAIN ADVISORY TONIGHT INTO EARLY
SATURDAY. ONCE THE WARMER AIR REACHES THIS AREA WE WILL SEE LIGHT
RAIN...LIGHT DRIZZLE AND FOG UNTIL THE PRIMARY WARM FRONT COMES
THROUGH THE AREA DURING THE DAY ON SUNDAY. WE WILL THEN GET
RAIN...HEAVY AT TIMES LATER MONDAY INTO MONDAY NIGHT AS THE MAIN
SYSTEM MOVES THROUGH THE AREA.

WITH SURFACE DEW POINTS IN THE 50S OVER SOUTHERN OKLAHOMA THIS
AFTERNOON AND THE 35 TO 45 KNOT LOW LEVEL JET THAT IS AIMED AT US
OVERNIGHT IN CONJUNCTION WITH THE 1000 TO 850 MB MOISTURE
TRANSPORT VECTORS AIMED AT US... I HAVE TO BELIEVE IT WILL RAIN
LATER TONIGHT INTO SATURDAY MORNING. PROBLEM IS WE HAVE A SHALLOW
COLD LAYER OF AIR SO WE WILL SEE A PERIOD OF FREEZING RAIN...MAYBE
SOME SLEET AS THIS AREA OF PRECIPITATION MOVES OUR WAY.

THE WARM AIR OVER THE SNOW PACK WILL RESULT IN FOG UNTIL THE WARM
FRONT COMES THROUGH DURING THE DAY TIME HOURS OF SUNDAY SO I HAVE
FOG IN THE GRIDS SATURDAY AFTERNOON INTO SUNDAY. THE PRIMARY
SYSTEM COMES THROUGH LATER SUNDAY INTO EARLY MONDAY WITH
RAIN...HEAVY AT TIMES.

THERE IS SOME INSTABILITY SATURDAY AND SUNDAY MORNING SO THE
PRECIPITATION WILL BE OF A CONVECTIVE NATURE. THUS IN INCREASED THE
QPF IN OUR FORECAST GRIDS TO ACCOUNT FOR THIS.



.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 330 PM EST FRI NOV 21 2014

MODELS ARE IN DECENT AGREEMENT IN TRACKING THE  COLD FRONT THROUGH
THE REGION MONDAY.  THIS SUPPORTS A TRANSITION OF THE PRECIPITATION
FROM RAIN SHOWERS TO SNOW SHOWERS DURING THE DAY AND INTO THE
EVENING.  SOUNDINGS SHOW SURFACE TEMPERATURES STILL ABOVE FREEZING
THROUGH MOST OF THE DAY...SO AT THIS POINT IMPACTS FROM SNOW ARE NOT
EXPECTED.  MODELS HAVE BEEN ACCELERATING THIS COLD FRONT WITH THE
MOST RECENT RUNS.

MONDAY NIGHT THE MOISTURE WRAPPING AROUND THE LOW PRESSURE SYSTEM
TRACKING THROUGH THE GREAT LAKES REGION MAY CLIP THE LUDINGTON
REGION.  LAKE EFFECT SNOW IS EXPECTED AND LOCALIZED ACCUMULATIONS
ARE LIKELY CLOSE TO THE LAKESHORE.   OVERALL THIS DOES NOT LOOK LIKE
A HEAVY LAKE EFFECT EVENT.  HIGHER POPS ARE WARRANTED FOR LAKESHORE
REGIONS.

NEXT UP WILL BE THE ARRIVAL OF A MID LEVEL TROUGH WED NIGHT OR
THANKSGIVING DAY.  IT WILL BE COLD ENOUGH FOR SNOW.  GIVEN SOME
DYNAMICS AND MOISTURE A RISK FOR SNOW EXISTS.  OVERALL THIS SYSTEM
LOOKS RELATIVELY WEAK AT THIS TIME.  WILL KEEP POPS ELEVATED FOR
THIS POTENTIAL EVENT.



&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 105 PM EST FRI NOV 21 2014

IMPACTS TO AVIATORS EXPECTED DURING THE PERIOD. SOME MVFR CEILINGS
POSSIBLE THIS AFTERNOON AS CUMULUS CLOUDS DEVELOP AS A RESULT OF
THE HEATING. THESE CLOUDS SHOULD MIX OUT DURING THE AFTERNOON
PROVIDING VFR WEATHER BY 21Z.

FREEZING RAIN MOVES INTO MOST TAF SITES BEGINNING 08Z TO 10Z. ONCE
IT ARRIVES IT SHOULD LAST 4 TO 6 HOURS. THEN THE DEEPER MOISTURE
PULLS AWAY AND SURFACE TEMPERATURES ARE FORECASTED TO CLIMB ABOVE
FREEZING DURING THE MORNING. THIS WILL LEAVE BEHIND DRIZZLE. IFR
SHOULD BECOME WIDESPREAD BY 18Z AS THE WARMER AIR MASS MOVING IN
ENCOUNTERS THE SNOW PACK LEADING TO CONTINUED IMPACTS.

KMKG IS FORECASTED TO SEE THE TEMPERATURES RISE ABOVE FREEZING
LATER TONIGHT. THUS THAT SITE IS EXPECTED TO SEE PLAIN RAIN.


&&

.MARINE...
ISSUED AT 330 PM EST FRI NOV 21 2014

LITTLE QUESTIONS WITH 30 TO 40 KNOT WINDS JUST OFF THE DECK
TONIGHT AND SATURDAY THERE WILL BE STRONG WINDS OVER LAKE
MICHIGAN. WITH THE SYSTEM DEEPENING SUNDAY STRONG WINDS WILL
CONTINUE...MOSTLY FROM THE SOUTH. EVEN SO THE AREA WITH GALES
SEEMS LIMITED TO THE NORTHERN 1/3 OF OUR NEAR SHORE TONIGHT ONLY.
GIVEN THAT I THROUGH IT PRUDENT TO ISSUE A SMALL CRAFT ADVISORY
INTO SUNDAY MORNING BUT THAT WILL HAVE TO BE EXTENDED.

&&

.HYDROLOGY...
ISSUED AT 330 PM EST FRI NOV 21 2014

COMPLICATED FORECAST FROM A HYDROLOGY FORECAST.  AT THIS TIME IT
APPEARS THAT HYDRO LOGIC IMPACTS WILL BE MINIMAL...BUT WE WILL NEED
TO MONITOR TRENDS CLOSELY.

SNOW WATER EQUIVALENT VALUES RANGE FROM LESS THAN A HALF INCH INLAND
AROUND LANSING AND JACKSON TO AN INCH AROUND GRAND RAPIDS TO JUST
UNDER AN INCH FOR MUCH OF THE LAKESHORE.  BASED ON RAIN FORECASTS
AND WARMER TEMPERATURES...WE SHOULD LOSE A CONSIDERABLE AMOUNT OF
THIS SNOW PACK.  AFTER PUTTING IN ROUGHLY AND INCH TO AN INCH AND A
HALF OF RAIN...FACTORING IN MELTING MOST OF THE SNOW PACK...ALL THE
RIVERS SHOW A CONSIDERABLE RISE.  HOWEVER VERY LITTLE IF ANY
FLOODING SHOWED UP IN THE HYDROGRAPHS.  THIS IS SUPPORTED BY THE
RIVER ENSEMBLE FORECASTS.  THE PORTAGE RIVER NEAR VICKSBURG WAS ON
OF THE SITES THAT WAS SHOWN TO APPROACH FLOOD STAGE ON MONDAY.

ANOTHER POTENTIAL FLOODING FACTOR IS THAT SOME OF THE RIVERS HAVE
ICE IN THEM.  THIS INCLUDES THE GRAND AND MUSKEGON RIVERS.  HOWEVER
THE ICE DOES NOT APPEAR TO BE THICK...GENERALLY LESS THAN 4 INCHES.
HOWEVER WE ARE TRYING TO GAIN A BETTER HANDLE ON HOW THICK THE ICE
IS.  IF THE ICE IS THICKER THAN 4 INCHES...THAT COULD POTENTIALLY
LEAD TO PROBLEMS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FREEZING RAIN ADVISORY FROM 4 AM TO 9 AM EST SATURDAY FOR
     MIZ037>040-043>046-050>052-056>059-064>067-071>074.

LM...SMALL CRAFT ADVISORY FROM 7 AM SATURDAY TO 4 AM EST SUNDAY FOR
     LMZ848-849.

     GALE WARNING FROM 7 PM THIS EVENING TO 7 AM EST SATURDAY FOR
     LMZ848-849.

     SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST SUNDAY
     FOR LMZ844>847.

&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...MJS
AVIATION...MJS
HYDROLOGY...MJS
MARINE...WDM





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