FXUS61 KCAR 240024
AFDCAR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CARIBOU ME
724 PM EST WED DEC 23 2009
.SYNOPSIS...
A SURFACE TROUGH WILL MOVE SOUTH ACROSS THE REGION TONIGHT. HIGH
PRESSURE WILL GRADUALLY BUILD OVER THE REGION FROM THE NORTHWEST
THURSDAY AND FRIDAY AND THEN MOVE EAST ON SATURDAY. A LOW PRESSURE
SYSTEM FROM THE MIDWEST WILL APPROACH SATURDAY NIGHT AND MOVE
ACROSS THE REGION ON SUNDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
UPDATE: SNOW BANDS HAVE STARTED TO DECREASE SO HAVE LET WSW
EXPIRE. ANY ACCUMULATIONS THE REMAINDER OF THIS EVENING WILL BE AN
INCH OR LESS.
A BEGINNING OF PERIOD TROF EXTENDS FROM LOW PRESSURE IN NORTH
ATLANTIC WESTWARD ACROSS NORTHERN MAINE. AT SAME TIME STRONG 500
MB LOW CENTER OVER SOUTHERN NEW ENGLAND IS MOVING EASTWARD INTO
GULF OF MAINE. COLDEST AIR AT SURFACE CENTERED UNDER THE UPPER
LOW. THIS CONFIGURATION HAS SET UP AN UNUSUAL THERMAL GRADIENT
WITH THE WARMEST TEMPERATURE TO THE NORTH AND EAST. A SURFACE WARM
FRONT IS ORIENT NORTHWEST TO SOUTHEAST ACROSS NORTHERN MAINE. LOW
LEVEL MOIST AIR IS BEING TRANSPORT FROM ATLANTIC ACROSS THIS
FRONTAL BOUNDARY RESULTING IN BANDED PRECIPITATION ACROSS THE
NORTHERN AND CENTRAL PORTION OF THE FORECAST AREA. BOTH THE RUC13
AND CARWRF HAVE BEEN DOING REASONABLE JOB IN DEPICTING THE
FRONTAL BAND. BOTH MODELS ALSO MOVE THE FRONT TO THE SOUTH. DURING
THE EVENING AS THE UPPER LEVEL SYSTEM MOVES TO THE EAST THE
THERMAL GRADIENT AND HENCE THE SURFACE FRONT WILL WEAKEN.
PRECIPITATION INTENSITY IS EXPECTED TO DECREASE AS THE FRONT
WEAKENS. HAVE USED NAM QPF AS A GUIDE AND HAND MODIFIED BASED ON
EXPECTED FRONTAL BANDING.
IN THE NORTHEASTERN PORTION OF ZONE 2 MIXED PRECIPITATION HAS
OCCURRED IN THE WARMER AIR. THIS IS EXPECTED TO CHANGE BACK TO
SNOW BY EVENING AS SURFACE TEMPERATURES COOL. HAVE USED OPERATIONAL
NAM TEMPERATURES AND DEW POINTS. POPS AND QPF INITIALIZE WITH NAM
BUT HAVE MADE EXTENSIVE MANUAL MODIFICATIONS.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
MODELS SEEM TO HAVE A PRETTY GOOD HANDLE ON THE SHORT TERM. HIGH
PRESSURE WILL RIDGE IN FROM THE NORTHWEST. LLVL CAA BEHIND AN
UPPER LOW MOVING SOUTHWEST OF THE STATE SHOULD PUT AN ABRUPT END
TO THE CURRENT STORM THROUGH THE MORNING HOURS THURSDAY. WILL KEEP
CHANCE AND SLIGHT CHANCE POPS ACROSS THE SOUTHEASTERN ZONES AS THE
SURFACE TROUGH MOVES OVER THE SOUTHERN GULF OF MAINE LATE TONIGHT.
MODELS SUGGEST SOME LLVL MOISTURE REMAINS ACROSS THE CROWN OF
MAINE...SO WILL MAINTAIN PARTLY CLOUDY SKIES THROUGH THURSDAY
NIGHT. TEMPERATURES LOOK TO BE SEASONABLE TO SLIGHTLY ABOVE NORMAL
AS WARM AIR WILL BE SLOW TO MOVE OUT WITH THE CAA. HIGH PRESSURE
WILL CROSS THE REGION FRIDAY THROUGH FRIDAY NIGHT...THEN MOVE TO
THE EAST SATURDAY. AN OCCLUDED FRONT WILL BEGIN TO APPROACH WESTERN
NEW ENGLAND LATER SATURDAY. SKIES WILL BE PARTLY CLOUDY/MOSTLY
CLEAR ACROSS THE REGION FRIDAY THROUGH EARLY SATURDAY...WITH
INCREASING CLOUDINESS LATER SATURDAY IN ADVANCE OF THE OCCLUSION.
TEMPERATURES WILL BE AT ABOVE NORMAL LEVELS FRIDAY/SATURDAY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A FRONTAL SYSTEM WILL APPROACH SUNDAY INTO SUNDAY NIGHT. THIS
FRONT WILL FEATURE STRONG SE WINDS...PARTICULARLY IN COASTAL
REGIONS WITH GFS ADVERTISING H925 LOW LVL JET AT 50 TO 55KTS
DURING SUNDAY. THIS FLOW WILL HELP ENSURE WARM, MOIST AIR MOVES
QUICKLY INLAND. EXPECT THE POSSIBILITY OF A BRIEF PERIOD OF SNOW
IN LOCATIONS SUCH AS BHB AND BGR BEFORE CHANGING OVER. SNOW WILL
LIKELY PERSIST LONGER IN THE NORTHERN HALF OF THE STATE WITH SOME
ACCUMULATIONS MORE LIKELY. ATTM, THE WARM AIR PUSH WILL GRADUALLY
CREEP UP TOWARDS THE ST JOHN VALLEY DURING THE EVENT...CHANGING
PRECIP TO SLEET AND RAIN. FRZRA APPEARS TO BE A POSSIBILITY FOR A
RELATIVELY SHORT PERIOD IN NORTHERN AND CENTRAL MAINE BEFORE TEMPS
RISE ABV FRZ. TIMING ALSO REMAINS UNCERTAIN BUT THE TREND SEEMS TO
BE SLOWER WITH RECENT MODEL RUNS. AS A RESULT, LEANED TOWARDS
LATEST OPERATIONAL ECMWF FROM 23/12Z AND PUSHED HIGHEST POPS TO
SUNDAY NIGHT. THIS BLEND WASHED OUT WIND MAXIMUMS ALONG THE COAST
IN THE GRIDS. ECMWF WOULD FAVOR THE HIGHER WINDS ALONG THE COAST
LATER SUNDAY. ALL IN ALL, PRECIP AMTS HAVE THE POTENTIAL TO REACH
AN INCH OR MORE ALONG THE COAST AS OFTEN OCCURS WITH THIS TYPE OF
SETUP. MONDAY APPEARS TO RELATIVELY CLOUDY AND SEASONABLY MILD
AHEAD OF NEW SHOT OF ARCTIC AIR ARRIVING MONDAY NIGHT. THE ARCTIC
FRONT COULD BRING IN AN INCH OR TWO OF SNOW IN THE NORTH AND
WESTERN MTS. STRONG NW WINDS WILL ARRIVE WITH THE COLD AIR TUESDAY
INTO WEDNESDAY AND HAS THE POTENTIAL TO BRING SOME ADVISORY-LEVEL WIND
CHILLS.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
CURRENT RADAR SHOWS A SOLID BAND OF MDT SN ACROSS NORTHERN THREE
TAF SITES. THIS WILL PIVOT AROUND AN UPPER LOW CURRENTLY MOVING
SSE OVER NH ATTM. EXPECT NORTHERN SITES TO REMAIN IFR TO LIFR IN SN
UNTIL LATE NIGHT AS BAND PIVOTS SOUTH. THE BAND WILL MOVE OVER BGR
AND JUST SCRAPE BHB LATE TONIGHT AS IT WEAKENS IN COLD ADVECTION
FROM THE N. ALL TAF SITES SHOULD SEE MVFR LIFTING TO VFR BY EARLY
THURSDAY THEN REMAIN VFR THROUGH SATURDAY.
LONG TERM: EXPECT IFR TO LIFR TO SPREAD NORTHWARD ACROSS THE STATE
SUNDAY INTO SUNDAY NIGHT. CONDITIONS WILL IMPROVE TO MVFR MONDAY.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 FOR WINDS. FOR
WAVES HAVE USED WNA/4. GENERALLY AN EVEN MIX OF WIND WAVE AND 1
FOOT LONG PERIOD WAVE.
SHORT TERM: VSBYS COULD BE REDUCED IN AREAS OF LIGHT SNOW EARLY
THURSDAY. AN SCA HAS BEEN ISSUED FOR WINDS AND SEAS FROM THURSDAY
MORNING THROUGH THURSDAY NIGHT AS PRESSURE GRADIENT TIGHTENS
BEHIND A SURFACE TROF PASSING OVER THE WATERS LATE TONIGHT.
WINDS/SEAS WILL BE BELOW SMALL CRAFT ADVISORY LEVELS FRIDAY INTO
SATURDAY.
LONG TERM: DECENT SHOT OF A GALE SUNDAY AND AGAIN TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 7 PM EST THURSDAY FOR
ANZ050>052.
&&
$$
NEAR TERM...MIGNONE/FOSTER
SHORT TERM...DOODY/NORCROSS
LONG TERM...MWALKER
AVIATION...MIGNONE
MARINE...MIGNONE/DOODY/NORCROSS
