FXUS63 KGRR 260646
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
145 AM EST SAT DEC 26 2009
LATEST UPDATE...SHORT TERM...
.SYNOPSIS...(415 PM EST FRI DEC 25 2009)
LINGERING LIGHT RAIN SHOWERS LATE THIS AFTERNOON WILL GRADUALLY
CHANGE OVER TO SNOW SHOWERS FROM SOUTHWEST TO NORTHEAST THIS EVENING
AS COLDER AIR MOVES IN. INTERMITTENT SNOW SHOWERS ARE ANTICIPATED
THIS WEEKEND INTO MONDAY. DRY WEATHER WILL RETURN TUESDAY AS HIGH
PRESSURE BUILDS IN.
&&
.SHORT TERM...(145 AM EST SAT DEC 26 2009)
(TONIGHT THROUGH SATURDAY NIGHT)
A 1 TO 2 HR PERIOD OF FREEZING RAIN/FREEZING DRIZZLE COMBINED WITH
FALLING TEMPERATURES HAS CREATED ICY CONDITIONS IN THE AREA. ANY
ADDITIONAL ICE COATINGS WILL REMAIN UNDER A TENTH OF AN INCH THROUGH
THE REMAINDER OF THE NIGHT. A TRANSITION TO SNOW EXPECTED BY 10Z.
UNTREATED SURFACES WILL REMAIN SLICK THROUGH SAT AM...LOCALLY UP TO
AN INCH OF SNOW COULD ACCUMULATE. ISSUED A WINTER WEATHER ADVISORY
THROUGH 11 AM SAT.
THE OCCLUDED LOW PRESSURE SYSTEM WILL CONTINUE TO DRIFT ENE INTO OUR
AREA LATE TOMORROW AND TOMORROW NIGHT BRINGING LIGHT SNOW. WE
ANTICIPATE LIGHT ACCUMULATIONS OF ONLY AROUND AN INCH TO INCH AND A
HALF ACROSS THE MAJORITY OF OUR CWFA FROM SATURDAY THROUGH SATURDAY
NIGHT.
HOWEVER... SOUTHERLY FLOW LES AND LAKE ENHANCED SYNOPTIC SNOW MAY
CLIP PORTIONS OF OUR WESTERN LAKESHORE COUNTIES. THE BEST CHANCE FOR
THAT WOULD BE FROM NEAR WHITEHALL NORTH TO LUDINGTON... AND
ESPECIALLY AT BIG AND LITTLE SABLE POINTS. IN FACT I BELIEVE A SOLID
2 TO 4 INCH TYPE SNOWFALL (AT MINIMUM) IS CERTAINLY PLAUSIBLE AT THE
POINTS AND PERHAPS LDM AND PENTWATER FROM SATURDAY MORNING THROUGH
SATURDAY NIGHT... WITH LOCALLY HIGHER AMOUNTS CERTAINLY POSSIBLE.
THIS NOTION IS ALSO SUPPORTED BY 12Z GFS BUFKIT SNOWFALL PROGS FOR
LDM. THE BEST CHC FOR SNOW MAY COME TOWARD DAYBREAK SUNDAY AS LOW
LEVEL FLOW VEERS TO THE SSW RATHER THAN SSE TO SOUTH. WE ALSO
NOTICED THAT FCST SOUNDINGS SHOW INVERSION HEIGHTS UP TO AROUND 7 TO
10 KFT AGL IN LDM SATURDAY THROUGH SATURDAY NIGHT WITH DEEP MOISTURE
THROUGH THE DGZ.
&&
.LONG TERM...(415 PM EST FRI DEC 25 2009)
(SUNDAY THROUGH FRIDAY)
LONG TERM PERIOD BEGINS...WITH THE UPPER LOW THAT IS PRESENTLY
PIVOTING WESTWARD ACROSS IOWA...MOVING EAST ACROSS LAKE MICHIGAN ON
SUNDAY. THERE WILL BE SOME SYSTEM RELATED SNOW MOVING THROUGH THE
FORECAST AREA SUNDAY...BUT THERE WILL ALSO LIKELY BE SOME LAKE
ENHANCED SNOW IN WESTERLY FLOW. POTENTIALLY SOME DECENT SNOW BANDS
BETWEEN MUSKEGON...GRAND RAPIDS AND SOUTH HAVEN. SOME LIGHT LAKE
EFFECT SNOWS WILL CONTINUE IN NORTHWEST FLOW SUNDAY NIGHT AND MONDAY.
FAIRLY QUIET WEATHER IS EXPECTED MONDAY NIGHT THROUGH TUESDAY NIGHT
AS A RIDGE OF HIGH PRESSURE MOVES THROUGH THE GREAT LAKES REGION.
NEXT WEATHER MAKER SLIDES THROUGH THE AREA WEDNESDAY AND WEDNESDAY
NIGHT IN ZONAL FLOW. HAVE SNOW IN THE FORECAST BOTH PERIODS.
AN UPPER TROUGH SETTLES INTO THE AREA TOWARD THE END OF THE WEEK
WITH 850MB TEMPS COOLING DOWN. HAVE CHANCE POPS FOR LAKE EFFECT SNOW
SHOWERS THURSDAY AND FRIDAY.
$$
.AVIATION...(1215 AM EST SAT DEC 26 2009)
THE COLD AIR HAS BEEN POURING IN FROM THE SOUTH TONIGHT AND
PRECIPITATION HAS CHANGED OVER TO A MIXTURE OF FREEZING RAIN...
SLEET AND SNOW. THIS MIX WILL GO TO ALL SNOW VERY SOON WITH
CONTINUED COLD AIR ADVECTION... SO WILL NOT CARRY ANY FRZG RAIN IN
THE 06Z TAFS. GENERALLY MVFR CONDITIONS WILL PREVAIL THROUGH 12Z....
ALTHOUGH A FEW HOURS OF DRY SLOTTING APPROACHING FROM THE SOUTHWEST
INBETWEEN VORT LOBES MAY BRING A BRIEF PERIOD OF VFR CONDITIONS.
DEEPER MOISTURE AND THE NEXT MID LEVEL SHORTWAVE PIVOTING AROUND THE
UPPER LOW IS EXPECTED TO ARRIVE FROM THE SOUTHWEST TOWARD/AFTER 12Z.
SNOW SHOWER COVERAGE/INTENSITIES OUGHT TO INCREASE AS THIS OCCURS...
PARTICULARLY OVER THE WRN PORTION OF THE AREA AND ESPECIALLY IN THE
AFTERNOON. WILL GO WITH IFR SNOW SHOWERS (1-3SM) DEVELOPING AT
MKG/GRR/AZO/BTL... AND MVFR (4-5SM) AT LAN/JXN.
&&
.MARINE...(837 PM EST FRI DEC 25 2009)
SMALL CRAFT ADVISORY IN EFFECT THROUGH LATE SATURDAY NIGHT AS THE
WINDS HAVE FALLEN BELOW GALE FORCE. WAVES AND WINDS HAZARDOUS TO
SMALL CRAFT WILL CONTINUE INTO SATURDAY NIGHT AS A LOW PRESSURE
SYSTEM REMAINS IN THE REGION.
&&
.HYDROLOGY...(415 PM EST FRI DEC 25 2009)
NOT ENOUGH QPF FROM THIS SYSTEM TO CAUSE HYDRO ISSUES. IN
ADDITION... COLDER TEMPERATURES MAINLY IN THE 20S TONIGHT THROUGH
THE WEEKEND WILL RESULT IN FAIRLY MINOR FLUCTUATIONS IN AREA RIVER
LEVELS. LIGHT PCPN THROUGH THE WEEKEND AND MONDAY FOR MOST OF OUR
HSA WILL NOT RESULT IN ANY HYDRO ISSUES.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY THROUGH 6Z SATURDAY NIGHT FOR THE ENTIRE
NEAR SHORE.
&&
$$
SYNOPSIS: LAURENS
SHORT TERM: LAURENS MJS
LONG TERM: DUKE
AVIATION: MEADE
MARINE: 63
HYDROLOGY: LAURENS
