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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KGRR 112338
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
638 PM EST WED DEC 11 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 327 PM EST WED DEC 11 2013

HIGH PRESSURE WILL MOVE THROUGH THE GREAT LAKES REGION
TONIGHT...ALTHOUGH LIGHT LAKE EFFECT SNOW WILL CONTINUE. SOME MINOR
ACCUMULATIONS MAY OCCUR TOWARDS THE LAKE MICHIGAN SHORE. ANOTHER
BURST OF LAKE EFFECT SNOW SHOWERS ARE EXPECTED ON
THURSDAY...ESPECIALLY FROM AROUND DAYBREAK THROUGH EARLY AFTERNOON.
ONE TO THREE INCHES OF SNOW APPEARS POSSIBLE FROM GRAND RAPIDS AND
HOLLAND NORTH TO LUDINGTON AND BALDWIN. LOW PRESSURE PASSING OFF TO
THE SOUTH OF MICHIGAN WILL BRING SOME LIGHT ACCUMULATIONS TO THE
REGION FROM FRIDAY NIGHT INTO SATURDAY. WINTER LIKE CONDITIONS ARE
GOING TO HANG AROUND FOR AWHILE WITH TEMPERATURES FORECAST TO REMAIN
BELOW FREEZING THROUGH MONDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 327 PM EST WED DEC 11 2013

LAKE EFFECT SNOW SHOWERS WILL CONTINUE TONIGHT WITH MOISTURE AND
LIFT REMAINING IN THE DGZ. THE DGZ WILL BE SHALLOW THOUGH WITH
MARGINAL MOISTURE HEIGHT (AT OR BELOW 5000FT) KEEPING ACCUMULATIONS
IN CHECK. COULD SEE LOCAL ACCUMULATIONS OF AN INCH OR TWO TONIGHT
TOWARDS THE SHORE. WIND SPEEDS IN THE CLOUD LAYER OF LESS THAN 25
KNOTS SHOULD KEEP THE BULK OF THE SNOW IN THE LAKESHORE COUNTIES.

ANOTHER FLARE IN THE LAKE EFFECT IS EXPECTED ON THURSDAY...MAINLY
BETWEEN 700AM AND 100PM. MOISTURE INCREASES IN DEPTH AS A SHORTWAVE
CURRENTLY WEST OF LAKE WINNIPEG DROPS QUICKLY SOUTH MOVING ACROSS
LAKE MICHIGAN TOMORROW MORNING. THE MOISTURE AND LIFT BOOST FROM THE
SHORTWAVE SHOULD REALLY PERK UP THE SNOW ONCE AGAIN. AT THIS POINT
THINKING A SOLID 1-3 INCHES ARE POSSIBLE IN THE WESTERN TWO TIERS OF
COUNTIES...ESPECIALLY FROM SOUTH HAVEN TO PLAINWELL NORTHWARD. A
NICE CROSSHAIRS SIGNATURE (MOISTURE AND LIFT BULLSEYE IN THE
DENDRITIC GROWTH ZONE FOR SNOW) IS NOTED BETWEEN 12Z-18Z. NOT
THINKING THIS RISES TO THE LEVEL OF AN ADVISORY BASED ON
IMPACT...BUT THE MID SHIFT CAN TAKE ANOTHER LOOK AT THIS EVENT.
DECENT WINDS TOWARDS THE SHORE TOMORROW MORNING WILL ADD A LITTLE
BIT OF BLOWING AND DRIFTING SNOW.

THURSDAY NIGHT SOME LAKE EFFECT WILL CONTINUE. THERE COULD BE SOME
LIGHT ACCUMULATIONS ESPECIALLY IN THE NORTHWEST CWA UP TOWARDS
LUDINGTON WHERE MOISTURE IS DEEPER. FRIDAY A FRONTAL BOUNDARY BEGINS
TO SETUP ACROSS THE AREA AS ENERGY BEGINS TO EJECT OUR DIRECTION OUT
OF PLAINS TROUGHING. AT THIS POINT THINKING THINGS WILL NOT BE
PHASED UP MUCH YET AND ONLY EXPECTING SOME LIGHT SNOW. ONLY HAVE
20/30 PCT CHANCES FOR SNOW AT THIS POINT BUT COULD SEE IT NEEDED TO
BE BUMPED UP A LITTLE WITH TIME.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 327 PM EST WED DEC 11 2013

MAIN ITEM OF INTEREST IN THE LONG TERM IS THE SYSTEM EXPECTED TO
BRING A THREAT OF SNOW TO THE REGION LATER FRI NIGHT AND THROUGH
SAT. MAIN TREND OVER THE PAST 24 HOURS IS FOR A LITTLE LESS IMPACT
TO THE CWFA IN GENERAL. IT DOES STILL APPEAR HOWEVER THAT SRN AREAS
HAVE THE POTENTIAL FOR SOME ACCUMULATING SNOW. THERE WILL BE A
FAIRLY DECENT NRN CUTOFF TO THE SNOW. HIGH PRESSURE SITUATED TO OUR
NORTH WILL DRIVE IN LOWER LEVEL DRY AIR FROM THE NORTH. THE FGEN
FORCING IN THE MID LEVELS ALSO WILL NATURALLY ALLOW FOR A DECENT
CUTOFF TO THE SNOW.

WE WILL SEE ADDITIONAL CHCS OF SNOW SHOWERS FROM SAT NIGHT RIGHT ON
INTO THE DAY ON TUE. LAKE EFFECT POTENTIAL ON SAT NIGHT LOOKS
LIMITED AS RIDGING BUILDS IN BEHIND THE SAT SYSTEM. CLIPPER SYSTEMS
ARE THEN EXPECTED TO MOVE IN ON THE NW FLOW ALOFT FOR SUN NIGHT AND
MON NIGHT. PLENTY OF COLD AIR WILL REMAIN SO THAT LAKE MICHIGAN WILL
HELP TO CONTRIBUTE TO POTENTIAL SNOWFALL.

WE SHOULD SEE A TREND TO LESS SNOWFALL AND MODERATING TEMPERATURES
FOR TUE AND WED OF NEXT WEEK. THE RECENT PERSISTENT NW FLOW ALOFT IS
EXPECTED TO FLATTEN OUT A BIT INTO A MORE ZONAL FLOW AS THE TROUGH
MON NIGHT LIFTS OUT AND AS A TROUGH STARTS DIGGING SOUTH ACROSS THE
WRN U.S. COAST. THE MAIN NRN JET CORE WILL MOVE NORTH OF THE
AREA...AND THE LOW LEVEL FLOW WILL TRANSITION TO MORE OF A SRLY
FLOW.

&&

.AVIATION...
-- Changed Discussion --
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 634 PM EST WED DEC 11 2013

SNOW SHOWERS WILL CONTINUE TO DIMINISH THIS EVENING...WITH
CLEARING SKIES OVER THE INTERIOR PARTS OF LOWER MI. STILL COULD BE
SOME PATCHY IFR IN THE STRONGER SNOW BANDS EARLY IN THE PERIOD.
WINDS SHIFT TO THE WEST SOUTHWEST LATE TONIGHT AND THU AM. THIS
WILL HELP TO STRENGTHEN THE SNOW BANDS ONCE AGAIN AND SHIFT THEM
FURTHER NORTH...IMPACTING MAINLY KMKG AND KGRR. ELSEWHERE DURING THE
DAY...SOME VFR CLOUDS ARE EXPECTED TO DEVELOP.
-- End Changed Discussion --

&&

.MARINE...
ISSUED AT 327 PM EST WED DEC 11 2013

WILL LEAVE THE SMALL CRAFT ADVISORY IN PLACE THROUGH THE DAY ON
THURSDAY. COULD SEE THE NEED TO EXTEND IT THROUGH THURSDAY
NIGHT...BUT WILL LET LATER SHIFTS RUN IT FURTHER OUT IN TIME IF NEED
BE. SCA CONDITIONS AT LEAST FOR THE NEXT 24 HOURS. WAVES OF 5 TO 9
FEET SHOULD BE PRETTY COMMON THE NEXT 24 HOURS.


&&

.HYDROLOGY...
ISSUED AT 327 PM EST WED DEC 11 2013

COLD WEATHER CONTINUES THROUGH THE WEEKEND SO THE THREAT OF ICE JAMS
REMAINS THE ONLY HYDRO ISSUE OF NOTE. IT SOUNDS LIKE CONDITIONS ARE
FAIRLY STABLE THOUGH WITH PORTIONS OF THE GRAND ICED OVER. UNTIL WE
GET A PUSH OF ICE DOWNSTREAM ON AREA RIVERS (VIA A WARM UP)...ICE
JAMMING ISSUES APPEAR TO BE LOW. ALL RIVER LEVELS IN LOOKING THROUGH
THE HYDROGRAPHS THIS AFTERNOON LOOK STABLE AS WELL. ALL QUIET ON THE
ICE JAM FRONT FOR NOW.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THURSDAY FOR LMZ844>849.

&&

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...NJJ
AVIATION...MJS
HYDROLOGY...DUKE
MARINE...DUKE