FXUS63 KGRR 010506
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1205 AM EST TUE DEC 1 2009
LATEST UPDATE...AVIATION...
.SYNOPSIS...(347 PM EST MON NOV 30 2009)
LOW PRESSURE OVER LAKE SUPERIOR WILL MOVE EAST AND DRAG A WEAK FRONT
THROUGH THE AREA. A SHORT PERIOD OF RAIN AND SNOW CAN BE EXPECTED
THIS EVENING AS THE FRONT MOVES THROUGH. THERE COULD BE SOME
LINGERING PRECIPITATION OVERNIGHT AS THE LAKE ADDS SOME MOISTURE TO
THE SYSTEM.
THE PERIOD FROM TUESDAY THROUGH EARLY WEDNESDAY WILL BE DRY WITH
ABOVE NORMAL TEMPERATURES. THEN INTO WEDNESDAY AFTERNOON A STORM
SYSTEM WILL MOVE NORTH OUT OF THE GULF COAST STATES AND HEAD FOR THE
OHIO VALLY. RAIN WILL BE POSSIBLE BY WEDNESDAY AFTERNOON. THE
TRACK OF THIS STORM BEARS WATCHING AS A SLIGHT SHIFT COULD BRING
MORE SNOW TO THE AREA. AS IT STANDS NOW THE SOUTHEAST PORTION OF
THE STATE STANDS THE BEST CHANCE TO SEE SNOW INTO WEDNESDAY NIGHT.
THEN LAKE EFFECT SNOW IS LIKELY THROUGH THE LATTER PORTION OF THE
WEEK.
&&
.SHORT TERM...(950 PM EST MON NOV 30 2009)
(TONIGHT THROUGH WEDNESDAY)
LIGHT SNOW HAS DEVELOPED ACROSS THE NRN 3/4 OF THE CWA IN
THE WARM AIR ADVECTION PATTERN. VSBYS HAVE FALLEN TO A MILE IN SOME
LOCATIONS. UPDATED THE GRIDS TO REFLECT LIGHT ACCUMS...UNDER AN
INCH...ACROSS KENT/ERN OTTAWA COUNTIES. THIS IS A QUICK HITTING
SYSTEM AND WILL BE MOVING OUT OF THE CWA OVERNIGHT. STILL LOOKING
FOR SOME CLEARING PRIOR TO MORNING.
TOUCH CALL INTO TUESDAY DETERMINING HOW MUCH SUNSHINE WE MAY SEE.
AN INVERSION MAY HOLD THE CLOUDS IN FOR MUCH OF THE DAY. HOWEVER
THE MOISTURE GRADUALLY BECOMES SHALLOW AND SUNSHINE APPEARS POSSIBLE
INTO THE AFTERNOON. HAVE GONE WITH A OPTIMISTIC VIEW BASED ON
SATELLITE TRENDS BEHIND TONIGHT/S WAVE. GIVEN THIS IT WILL BE A
WARM DAY WITH HIGHS HITTING THE MID AND UPPER 40S.
THE NEXT CHANCE OF PCPN WILL HOLD OFF UNTIL WEDNESDAY AFTERNOON AT
THE EARLIEST. THIS IS WHEN THE UPPER LOW...NOW JUST SOUTH OF
ARIZONA...WILL EJECT OUT OF THE GULF COAST STATES AND HEAD FOR THE
OHIO VALLEY. STILL A FAIR AMOUNT OF UNCERTAINTY WITH THE PATH OF
THIS SYSTEM. HOWEVER THE MOISTURE FLUX IS PRETTY STRONG AHEAD OF
THE SYSTEM AND CARRYING CHANCE POPS LOOKS REASONABLE FOR WED
AFTERNOON. INITIALLY WE SHOULD SEE MAINLY A CHANCE RAIN AS TEMPS
SHOULD REACH THE 40S AGAIN ON WED.
&&
.LONG TERM...(347 PM EST MON NOV 30 2009)
(WEDNESDAY NIGHT THROUGH SUNDAY)
THE MAIN FCST CHALLENGE IN THE LONG TERM DEALS WITH POTENTIAL FOR
THE MIDWEEK STORM LIFTING OUT OF THE GULF TO PRODUCE SOME SNOW HERE
IN SOUTHWEST LOWER MI. WE ALSO CONTINUE TO EXPECT LAKE EFFECT SNOW
LATE THURSDAY THROUGH FRIDAY.
12Z ECMWF/GFS/GLOBAL GEM GUIDANCE ALL SUGGEST THE GULF COAST LOW
WILL RACE NE FROM THE GULF COAST REGION AT 12Z WED TO WESTERN NEW
YORK STATE BY 12Z THURSDAY. THE 12Z FIM TAKES THE LOW FURTHER WEST
ACROSS EASTERN OHIO. LATEST SREF GUIDANCE IS A LITTLE FURTHER WEST
AND THE 12Z NAM IS FURTHEST WEST OF ALL... BRINGING IT ACROSS
EASTERN LWR MI.
WE PREFER LATEST FIM GUIDANCE AT THIS TIME SINCE OVERALL MEDIUM
RANGE GUIDANCE TRENDS HAVE BEEN A LITTLE FURTHER WEST WITH THIS
SYSTEM THE PAST 24 HRS AND THE FIM IS FAIRLY CONSERVATIVE AND TOWARD
THE MIDDLE OF THE RANGE OF SOLUTIONS. 12Z NAM GUIDANCE BEING SO FAR
WEST IS AN OUTLIER COMPARED TO THE MAJORITY OF SHORT TO MEDIUM RANGE
GUIDANCE.
THEREFORE... THE MOST PROBABLE OUTCOME AT THIS TIME IS THAT THE
MAJORITY OF SYNOPTIC SNOWFALL WILL STAY JUST ESE OF OUR CWFA.
HOWEVER IT WOULD BE A CLOSE ENOUGH CALL THAT MID LEVEL FGEN AND
EVENTUALLY DEFORMATION ZONE PROCESSES COULD IMPACT OUR CWFA WELL TO
THE NW OF THE SFC LOW TRACK WITH SOME SYNOPTIC SNOW WEDNESDAY NIGHT
INTO THURSDAY.
AS NOTED BY OUR PREVIOUS SHIFT... MEDIUM RANGE GUIDANCE HISTORICALLY
STRUGGLES IN HANDLING UPPER LOWS EJECTING OUT OF THE SOUTHWESTERN
U.S. AND MEXICO. SO IT IS CERTAINLY STILL WELL WITHIN THE RANGE OF
POSSIBILITIES THAT THE LOW COULD TRACK FURTHER WEST ACROSS WESTERN
OHIO... BRINGING HEAVIER SNOW INTO OUR CWFA. SO WE WILL NEED TO
MONITOR THIS STORM AND GUIDANCE TRENDS VERY CLOSELY. REGARDLESS OF
THE FINAL LOW TRACK... HOW QUICKLY THE SYSTEM WILL MOVE NE WILL KEEP
SNOW AMOUNTS MORE LIMITED THAN THEY COULD OTHERWISE BE.
BELOW NORMAL TEMPS ARE ANTICIPATED FROM THURSDAY NIGHT THROUGH THE
REMAINDER OF THE LONG RANGE FCST PERIOD. LAKE EFFECT SNOW POTENTIAL
WILL INCREASE LATE THURSDAY THROUGH THURSDAY NIGHT AND FRIDAY AS 850
MB TEMPS FALL TO -10 TO -12 C.
&&
.AVIATION...(1205 AM EST TUE DEC 1 2009)
BURST OF SNOW HAS NOW FOR THE MOST PART COME TO AN END. A FEW
FLURRIES/SPRINKLES MAY REMAIN THROUGH ABOUT 09Z...BUT NOT EXPECTING
MUCH FROM HERE ON OUT. THERE WILL BE SOME VFR CEILINGS THE REMAINDER
OF THE NIGHT THROUGH DAYBREAK WITH BASES AT OR ABOVE 4000FT. MOST
CEILINGS WILL BE IN THE 7000-10000FT RANGE.
AFTER DAYBREAK THE REMAINDER OF THE TAF PERIOD SHOULD BRING MAINLY
CLEAR SKIES. EXPECT SOME BREEZY CONDITIONS TO PREVAIL THROUGH ABOUT
10Z.
&&
.MARINE...(347 PM EST MON NOV 30 2009)
A GALE WARNING WILL KICK IN AT 8 PM THIS EVENING. WEST SOUTHWEST
WINDS WILL REMAIN BRISK OVERNIGHT AS A FAST MOVING LOW CROSSES THE
NORTHERN GREAT LAKES. HOWEVER...SINCE THIS IS SUCH A FAST MOVING
SYSTEM WINDS WILL ALREADY BEGIN TO DIE DOWN TOWARD DAYBREAK. WINDS
AND WAVES WILL BRIEFLY SUBSIDE TUESDAY AFTERNOON...BUT THEN A
SOUTHWEST WIND WILL UP PICK AGAIN TUESDAY NIGHT CAUSING BUILDING
WAVES.
&&
.HYDROLOGY...(347 PM EST MON NOV 30 2009)
PCPN TONIGHT WILL ONLY AMOUNT TO AROUND A TENTH OF AN INCH...A
LITTLE HEAVIER NORTH AND LIGHTER SOUTH. NO HYDRO ISSUES EXPECTED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY THROUGH 8 PM FROM ST JOSEPH TO MANISTEE.
GALE WARNING ST. JOSEPH TO MANISTEE TONIGHT.
&&
$$
SYNOPSIS: JK
SHORT TERM: JK 93
LONG TERM: LAURENS
AVIATION: DUKE
MARINE: JK
HYDROLOGY: JK
