Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 190457
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1157 PM EST THU DEC 18 2014

LATEST UPDATE...
AVIATION

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

LIGHT SNOW AND FREEZING DRIZZLE ARE EXPECTED TO DIMINISH OVERNIGHT.
QUIET WEATHER IS EXPECTED THROUGH THE WEEKEND WITH SOME SUN ON
FRIDAY. HIGHS WILL BE IN THE 30S OVER THE WEEKEND WITH A WARM UP
INTO THE LOWER 40S EARLY NEXT WEEK.

UNSETTLED WEATHER IS EXPECTED NEXT WEEK...WITH MULTIPLE
OPPORTUNITIES FOR BOTH RAIN AND SNOW.  RAIN OR SNOW WILL BE POSSIBLE
BEGINNING SUNDAY AFTERNOON INTO SUNDAY NIGHT. THEN A PERIOD OF RAIN
IS EXPECTED MONDAY AND TUESDAY. COLDER AIR SHOULD ARRIVE ABOUT
TUESDAY NIGHT WHICH SHOULD CHANGE THE PRECIPITATION TO SNOW WHICH
SHOULD CONTINUE INTO CHRISTMAS DAY.

&&

.UPDATE...
ISSUED AT 940 PM EST THU DEC 18 2014

WINTER WEATHER ADVISORY IS NOW OUT FOR THE COUNTIES MENTIONED IN
THE PREVIOUS UPDATE. REPORTS STARTED TO BECOME NUMEROUS ACROSS THE
ADVISORY COUNTIES THAT ROADS WERE BECOMING QUITE SLICK AND
NUMEROUS ACCIDENTS HAD OCCURRED RECENTLY. WEST OF THE ADVISORY
AREA...PCPN HAS BEEN SOME LIGHT SNOW AND PATCHY FREEZING
DRIZZLE WITHOUT ANY ISSUES.

SFC TROUGH HAS MOVED TO A LINE FROM JUST SOUTH OF HOLLAND...TO
JUST NORTH OF MASON...AND THEN TO DETROIT. DGZ LARGELY REMAINS
UNSATURATED AS THE SFC TROUGH MOVES INTO THE LOW LEVEL MOISTURE IN
PLACE SOUTH OF THE TROUGH. BEHIND THE TROUGH...WINDS BECOME MORE
NRLY AND PCPN PRETTY MUCH ENDS AT THAT POINT. SFC TROUGH SHOULD BE
EXITING THE CWFA AROUND 06Z OR SO WHICH SHOULD END THE THREAT OF
THE GLAZE.

UPDATE ISSUED AT 924 PM EST THU DEC 18 2014

WE WILL BE ISSUING A WINTER WEATHER ADVISORY FOR FREEZING DRIZZLE
FOR THE SE PORTION OF THE CWFA. THE COUNTIES THAT WILL BE IN THE
ADVISORY WILL BE BARRY... EATON...INGHAM...CALHOUN...AND JACKSON
COUNTIES. WE ARE GETTING REPORTS THAT THERE HAVE MANY ACCIDENTS
DUE TO FREEZING DRIZZLE OCCURRING THERE. MORE DETAILS WILL FOLLOW
SOON.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 240 PM EST THU DEC 18 2014

MAIN CONCERN IS DRIZZLE/FREEZING DRIZZLE THIS AFTERNOON LASTING INTO
THE EVENING. SURFACE BOUNDARY HAS STALLED ROUGHLY ALONG A HOLLAND TO
GRAND RAPIDS TO LANSING LINE. TEMPERATURES SOUTH OF THIS BOUNDARY
HAVE BEEN SLOW TO RISE...BUT EXPECT A SLOW CLIMB ABOVE FREEZING THE
REST OF THIS AFTERNOON. SHORT RANGE GUIDANCE INCLUDING THE HRRR
SHOWS THE BOUNDARY DROPPING SOUTH TO I-94 BY 10 PM. THERE IS A
NARROW WINDOW FOR FREEZING DRIZZLE AGAIN THIS EVENING AS
TEMPERATURES BEGIN TO FALL. PRECIPITATION IS MOST LIKELY TO OCCUR
OVER FAR SOUTHWEST LOWER MICHIGAN WHERE SPEED CONVERGENCE OF WINDS
OFF LAKE MICHIGAN WILL SUPPLEMENT BOUNDARY CONVERGENCE. LIGHT SNOW
WILL ALSO CONTINUE TO BE POSSIBLE EARLY TONIGHT IN THE VICINITY OF
THE BOUNDARY.

OTHERWISE NO SIGNIFICANT WEATHER IS EXPECTED THROUGH SATURDAY NIGHT
WITH HIGH PRESSURE IN CONTROL.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 303 PM EST THU DEC 18 2014

STILL A FAIR AMOUNT OF UNCERTAINTY AS TO THE DETAILS OF THE STORM
SYSTEM EXPECTED TO IMPACT THE REGION JUST PRIOR TO CHRISTMAS AND
INTO CHRISTMAS DAY.

THE MODELS HAVE TRENDED FURTHER NORTH WITH THE SURFACE LOW...NOW
TAKING IT ACROSS NORTHERN LOWER TUESDAY NIGHT.  THEY ARE ALSO
HINTING AT AN EAST COAST LOW WHICH MAY TRANSFER ENERGY FROM THE
GREAT LAKES LOW.  BOTTOM LINE...THIS APPEARS TO BE A SLOW MOVING
STORM AND A FEW WOBBLES EITHER WAY WILL BE MAKE A DIFFERENCE ON
TIMING PCPN TYPE.

THE STORM BECOMES NEGATIVELY TILTED BY TUESDAY NIGHT WHICH SHOULD
FAVOR A QUICKER ARRIVAL TO THE COLDER AIR.  BEST BET RIGHT NOW IS
THAT THIS MOVES IN TUESDAY NIGHT.  SO EXPECTING A WET MONDAY AND
TUESDAY...FOLLOWED BY A COOL DOWN AND A SWITCH TO SNOW TUESDAY
NIGHT.  AND EVEN THOUGH SOME OF THE STORM/S ENERGY MAY SHIFT TO THE
EAST COAST...WE SHOULD REMAIN UNDER A MOIST CYCLONIC FLOW LINGERING
INTO CHRISTMAS DAY.  THIS SHOULD RESULT IN LIGHT SNOW CONTINUING
RIGHT INTO THE THURSDAY.  H8 TEMPS SHOULD BE AROUND -8C BY CHRISTMAS
DAY SO EXPECT LAKE MICHIGAN WILL HELP ENHANCE THE SNOW A BIT.  ALL
IN ALL IT APPEARS A WHITE CHRISTMAS IS A GOOD BET FOR MUCH OF SW MI.

UNTIL THEN...I ADDED POPS TO SUNDAY AFTERNOON AND EVENING...MOSTLY
ALONG AND NORTH OF I-96.  MODELS SHOW A SHARPENING WARM FRONT MOVING
NORTH INTO THE AREA WITH DECENT ISENTROPIC LIFT AHEAD OF IT.  WOULD
EXPECT SOME LIGHT SNOW WITH THIS...ALTHOUGH ACCUMS SHOULD REMAIN
UNDER AN INCH.  THEN WARMER AIR ARRIVES LATE SUNDAY NIGHT/MONDAY
WHEN THE PCPN SHOULD SWITCH TO RAIN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1150 PM EST THU DEC 18 2014

THE FREEZING DRIZZLE WILL CONTINUE TO SLOWLY SHIFT SOUTH OF
KJXN...KBTL AND THE KAZO REGION THROUGH 08Z. THUS IMPACTS ARE
STILL EXPECTED.  UNTIL THEN SOME SNOW COULD MIX IN AT TIMES.
GENERALLY MVFR WEATHER WILL PREVAIL TO START THE PERIOD...HOWEVER
SKIES WILL SLOWLY CLEAR FROM THE NORTH LATER TONIGHT INTO FRIDAY.
PATCHY IFR WILL STILL BE POSSIBLE THROUGH 08Z MAINLY FOR KJXN.

ICING WILL REMAIN A POTENTIAL ISSUE RIGHT INTO SATURDAY.

&&

.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...WINTER WEATHER ADVISORY UNTIL 1 AM EST FRIDAY FOR MIZ065>067-073-
     074.

LM...NONE.
&&

$$

UPDATE...NJJ
SYNOPSIS...EBW/JK
SHORT TERM...TJT
LONG TERM...JK
AVIATION...MJS
HYDROLOGY...EBW
MARINE...TJT






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