FXUS63 KGRR 251858
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
155 PM EST FRI DEC 25 2009
LATEST UPDATE...AVIATION...
.SYNOPSIS...(105 PM EST FRI DEC 25 2009)
LIGHT RAIN SHOWERS WILL LINGER THIS AFTERNOON. COLDER AIR MOVES BACK
IN TONIGHT WITH SNOW SHOWERS STARTING THIS EVENING AND LASTING OVER
THE WEEKEND.
&&
.SHORT TERM...(105 PM EST FRI DEC 25 2009)
(THIS AFTERNOON THROUGH SUNDAY)
THE WINTER WX ADVISORY HEADLINE FOR PORTIONS OF OUR CWFA WAS ALLOWED
TO EXPIRE AT 18Z. KGRR RADAR TRENDS INDICATE THE STEADIEST PCPN IS
EXITING OUR EXTREME NE CWFA AND SFC OBS SHOW THAT TEMPS HAVE
MODERATED TO ABOVE FREEZING ACROSS OUR AREA. THEREFORE THE ADVISORY
HEADLINE HAS BEEN ALLOWED TO EXPIRE. LIGHT RAIN SHOWERS WILL LINGER
THIS AFTERNOON BEFORE GRADUALLY CHANGING OVER TO LIGHT SNOW SHOWERS
THIS EVENING. RESIDUAL IMPACTS FROM FREEZING RAIN OVERNIGHT INTO
THIS MORNING INCLUDE THE POTENTIAL FOR SLIPPERY ROADS... SIDEWALKS
AND PARKING LOTS PARTICULARLY ACROSS OUR NORTH/NE CWFA WHERE TEMPS
DID NOT MODERATE AS RAPIDLY.
REMAINDER OF PREVIOUS SHORT TERM FCST DISCUSSION FOLLOWS... COLDER
AIR WILL WRAP IN FROM THE SOUTH SOUTHWEST BY LATE AFTERNOON WITH ANY
RAIN CHANGING TO SNOW BY EVENING...BUT THE DRY SLOT SHOULD MEAN
PRECIP WILL BE LIGHT. TEMPS GO BACK BELOW FREEZING THIS EVENING
BUT SHOULD NOT FALL TOO FAR...SO TREATED ROADS SHOULD ONCE AGAIN
JUST BE WET.
THE SLOW MOVING UPPER LOW PERFORMS A LOOP AROUND THE SFC LOW THEN
FINALLY MOVES EAST AND ARRIVES SATURDAY NIGHT AND INTO SUNDAY WITH
AN INCREASE IN COVERAGE OF LIGHT SNOW. RAISED POPS A BIT FOR
SATURDAY NIGHT.SOME LAKE ENHANCEMENT BECOMES POSSIBLE DURING SUNDAY
AS WINDS BACK TO THE WEST. SOME ACCUMULATIONS POSSIBLE...BUT SHOULD
BE LIMITED TO THE 1 TO 3 INCH RANGE IN MOST PLACES.
&&
.LONG TERM...(318 AM EST FRI DEC 25 2009)
(SUNDAY NIGHT THROUGH THURSDAY)
THE MID RANGE MODELS ARE IN DECENT AGREEMENT IN A SETUP WITH SLOW
MOVING SYSTEMS. SOLUTIONS ARE A BIT QUICKER THAN PREVIOUS VERSIONS
AND START AND END TIMES OF PRECIPITATION EVENTS ARE THE MAIN
CHALLENGES. ONLY SMALL CHANGES NEEDED TO GRIDS.
THE AREA WILL BE EXPERIENCING LAKE EFFECT SNOW SHOWERS AS A LOW
PRESSURE SYSTEM MOVES OUT OF THE REGION SUNDAY NIGHT INTO MONDAY
NIGHT. DELTA T/S WILL BE IN THE 12 TO 16 DEGREE C RANGE WITH 850
TEMPERATURES AROUND -10 C. WINDS WILL BE OUT OF THE NORTHWEST...
WHICH SHOULD RESULT IN THE HEAVIEST SNOWS OVER AREAS SOUTH AND WEST
OF GRAND RAPIDS.
DRY WEATHER WILL MOVE IN SOMETIME MONDAY NIGHT OR EARLY TUESDAY AS
AN AREA OF HIGH PRESSURE MOVES INTO THE REGION AND THE FLOW BECOMES
ANTICYCLONIC. THE NEXT LOW WILL APPROACH THE AREA LATE WEDNESDAY OR
WEDNESDAY NIGHT AND SNOW WILL BE POSSIBLE AS THIS FEATURE SLOWLY
MOVES BY TO THE NORTH THROUGH THURSDAY. AT THIS TIME... THE SNOW
LOOKS TO BE LIGHT.
$$
.AVIATION...(155 PM EST FRI DEC 25 2009)
FOR THE MOST PART...MVFR CEILINGS BETWEEN 1000-2000FT EXIST ACROSS
THE TAF SITES AHEAD OF A COLD FRONT WHICH IS POISED TO THE SOUTH
ACROSS INDIANA. THE FRONT WILL LIFT NORTHEAST THIS AFTERNOON AND
EVENING AND BE ACCOMPANIED BY A BAND OF RAIN SHOWERS THAT WILL
SWITCH OVER TO SNOW SHOWERS FOR A SHORT TIME THIS EVENING.
MVFR CEILINGS WILL PERSIST TONIGHT BEHIND THE COLD FRONT WITH A DEEP
STACKED LOW SPINNING OFF TO THE WEST. ONLY SCATTERED SNOW SHOWERS
ARE EXPECTED...WHICH SHOULD NOT LIMIT VISIBILITY FOR LONG AT MOST
TAF SITES.
THE EXCEPTION WILL BE KMKG WHERE LAKE EFFECT SNOW IS EXPECTED TO
DEVELOP IN SOUTHERLY FLOW. HAVE PREVAILING SNOW SHOWERS OVERNIGHT AT
KMKG. DEPENDING WHERE THE BANDS SET UP...VISIBILITY COULD BE LOWER.
&&
.MARINE...(318 AM EST FRI DEC 25 2009)
GALE WARNING TODAY WITH OFFSHORE WINDS TO 35 KNOTS AND HIGHEST WAVES
BUILDING OUT IN THE OPEN WATERS. WINDS WILL SLOWLY DIMINISH THIS
AFTERNOON AND TONIGHT.
&&
.HYDROLOGY...(318 AM EST FRI DEC 25 2009)
TEMPERATURES IN THE 30S WILL PREVENT MUCH LOSS OF SNOWPACK TODAY SO
RIVER LEVELS SHOULD NOT RISE MUCH OVER THE WEEKEND.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WARNING THROUGH THIS AFTERNOON FOR THE ENTIRE NEAR SHORE.
&&
$$
SYNOPSIS: LAURENS
SHORT TERM: LAURENS
LONG TERM: 69
AVIATION: DUKE
MARINE: OSTUNO
HYDROLOGY: OSTUNO
