Area Forecast Discussion
Issued by NWS Caribou, ME

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000
FXUS61 KCAR 222319
AFDCAR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CARIBOU ME
619 PM EST MON DEC 22 2014

.SYNOPSIS...
HIGH PRESSURE WILL MOVE EAST INTO THE MARITIMES TONIGHT. A LARGE
AREA OF LOW PRESSURE WILL APPROACH TUESDAY NIGHT AND TRACK TO OUR
WEST WEDNESDAY INTO THURSDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
620 PM UPDATE...ANOTHER CLOUDY NIGHT IN STORE FOR THE CWA WITH
WELL ABOVE NORMAL TEMPERATURES FOR LATE DECEMBER. TEMPERATURES
TONIGHT WILL REMAIN NEARLY STEADY. A STRONG AND PERSISTENT
SUBSIDENCE INVERSION REMAINS IN PLACE WITH MILD/DRIER AIR JUST
ABOVE THE STRATUS. SOME FLURRIES ARE POSSIBLE TONIGHT WITH SPOTTY
DRIZZLE ALONG THE COAST. A WEAK DISTURBANCE IN THE FLOW ALOFT
COULD TOUCH OFF SOME LIGHT SNOW LATE TONIGHT...ESPECIALLY ACROSS
NORTHERN AND WESTERN SECTIONS OF THE CWA. ANY SNOW ACCUMULATION IS
EXPECTED TO BE LESS THAN AN INCH. ONLY MINOR TWEAKS TO THE ONGOING
FORECAST BASED ON THE LATEST OBSERVATIONS...SATELLITE...RADAR...AND
NEAR TERM MODELS.

PREVIOUS DISCUSSION...
NEAR STEADY TEMPERATURES TONIGHT AND GRADUALLY MILDER FOR
TUESDAY.

CLOUDS WILL HANG ON OVER THE REGION RIGHT INTO TUESDAY W/THE
SUBSIDENCE INVERSION HOLDING STRONG. THIS IS SHOWN QUITE WELL BY
THE NAM GUIDANCE. THIS WILL MEAN TEMPERATURES WILL REMAIN ABOVE
NORMAL LEVELS THROUGHOUT THE NIGHT TONIGHT. A DISTURBANCE IN THE
UPPER LEVELS IS FORECAST TO MOVE ACROSS NORTHERN MAINE OVERNIGHT
INTO EARLY TUESDAY. THIS FEATURE LOOKS LIKE IT COULD HAVE ENOUGH
FORCING TO KICK OFF SOME LIGHT SNOW OR SNOW SHOWERS. DECIDED TO
INCREASE THE PRECIP CHANCES UP TO 30-40% FOR THE WESTERN AND
NORTHERN AREAS. QPF IS FORECAST TO BE LESS THAN 0.05" AND SNOWFALL
VERY LIGHT W/LESS THAN 1/2 OF AN INCH. TEMPERATURES OVERNIGHT WILL
BE IN THE 20S ACROSS THE NORTH AND CENTRAL AREAS W/LOWER 30S
ACROSS THE DOWNEAST REGION.

A LLVL SE FLOW WILL ADVECT ATLANTIC MOISTURE NORTHWESTWARD INTO
THE STATE. THIS IN TURN WILL ALLOW THE COLUMN TO MOISTEN UP
DURING THE DAY ON TUESDAY ACROSS THE CWA. LIGHT OVERRUNNING PRECIP
LOOKS LIKE IT WILL BEGIN TO SET UP LATE TUESDAY AFTERNOON ACROSS
THE SOUTHERN AND SOUTHWESTERN AREAS. MODEL SOUNDINGS AND CRITICAL
THICKNESSES SUPPORT PRECIP TO BE IN THE FORM OF LIGHT SNOW ACROSS
THE W AND SW AREAS W/THE DOWNEAST AND THE CENTRAL AREAS SEEING
SOME LIGHT SNOW/RAIN MIX OR EVEN SOME FREEZING PRECIP BY LATE IN
THE AFTERNOON. ATTM, IT LOOKS LIKE ANY ICING THREAT WILL BE
MINIMAL. HIGH PRES RIDGING DOWN FROM THE NE WILL PROVIDE A COLD
AIR DAMMING SETUP. TEMPERATURES ON TUESDAY WILL BE RUNNING ABOVE
NORMAL W/READINGS EXPECTED TO BE IN THE UPPER 20S TO LOWER 30S
ACROSS THE NORTHERN 1/2 OF THE CWA WHILE CENTRAL AND DOWNEAST WILL
SEE LOW TO MID 30S.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
LOW PRESSURE DEVELOPS WEDNESDAY OVER THE OHIO VALLEY THEN MOVES
RAPIDLY NORTH THROUGH THE GREAT LAKES INTO CANADA. WITH STRONG
SYSTEM PASSING THE WEST EXPECT OVERRUNNING PRECIPITATION TO
DEVELOP TUESDAY EVENING AND CONTINUE THROUGH CHRISTMAS DAY. EXPECT
SNOW NORTH AND MIXED PRECIPITATION CENTRAL AREAS WITH MOSTLY RAIN
ON COAST. SNOW WILL CHANGE TO MIXED PRECIPITATION NORTH EARLY
WEDNESDAY...HOWEVER FREEZING RAIN AND SLEET IS EXPECT TO CONTINUE
WELL INTO THE AFTERNOON FAR NORTH. FURTHER DEVELOPMENT OF WEAK LOW
IN GULF OF MAINE COULD KEEP FROZEN PRECIPITATION FAR NORTH EVEN
LONGER. FOR PRECIPITATION TYPE HAVE USED PRECIPITATION THICKNESS
TOOL AND BLENDED THE NAM AND GFS 50/50. HAVE BLENDED THE GFS AND
ECMWF FOR POPS AND QPF. HAVE MANUALLY ADJUSTED TEMPERATURE AND DEW
POINT GRIDS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
LOW PRESSURE CONTINUES TO INTENSIFY OVER NORTHERN QUEBEC PROVINCE
THURSDAY NIGHT GENERATING A STRONG PRESSURE GRADIENT ACROSS THE
STATE ALONG WITH COLD ADVECTION AND GUSTY WINDS. HIGH PRESSURE
THEN BUILDS SOUTH OF THE AREA LATER FRIDAY. ANOTHER AREA OF LOW
PRESSURE IS THEN EXPECTED TO PASS TO THE NORTH OF THE REGION
SATURDAY WITH A COLD FRONT WILL PASS THROUGH NEW ENGLAND SUNDAY
BEHIND THE LOW. HIGH PRESSURE WILL THEN BUILD IN MONDAY. HAVE USED
THE SUPER BLEND TO POPULATE GRIDS.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: MVFR CIGS ACROSS THE NORTHERN TAF SITES W/CIGS DROPPING
TO IFR BY TUESDAY MORNING. KBGR AND KBHB WILL SEE VFR GRADUALLY
GIVING WAY TO MVFR CIGS TONIGHT W/CONDITIONS GOING TO IFR FOR
TUESDAY AND THE POTENTIAL FOR SOME LIGHT ICING OR EVEN SNOW.

SHORT TERM: EXPECT IFR CONDITIONS ON WEDNESDAY AND THURSDAY. MVFR
CONDITIONS EXPECTED FRIDAY. VFR CONDITIONS EXPECTED SATURDAY.

&&

.MARINE...
NEAR TERM: DECIDED TO GO AHEAD W/A SCA FOR TUESDAY INTO WEDNESDAY.
E WINDS WILL VEER TO THE SE LATER TONIGHT AND INCREASE IN SPEED ON
TUESDAY. WAVE HEIGHTS ATTM WERE RUNNING AROUND 2 FT BUT THEY WILL
START BUILDING ON TUESDAY ESPECIALLY BY THE AFTERNOON REACHING 4
TO 6 FT BY LATE IN THE AFTERNOON. THIS WILL ESPECIALLY BE THE CASE
AWAY FROM THE INTRA COASTAL ZONE.

SHORT TERM: FOR SUSTAINED WINDS WILL USE THE NAM12. FOR WAVES:
SOUTHERLY FETCH DEVELOPS FROM THE GULF OF MAINE SOUTHWARD LATE ON
24TH AND PERSISTS UNTIL BROKEN UP BY A WIND SHIFT THURSDAY
AFTERNOON. WITH WEAK WAVE IN GULF OF MAINE AND LOWER WIND SPEEDS
EXPECT WAVE HEIGHT TO BUILD TO MAXIMUM OF 12 FEET/9-10 SECONDS ON
THE 25TH. HAVE RUN THE NEAR SHORE WAVE MODEL AND USED IT TO
POPULATE WAVE GRIDS THROUGH THURSDAY AFTERNOON THEN TRANSITION TO
THE WAVE WATCH III.

&&

.HYDROLOGY...
THERE IS CONCERN FOR RUNOFF FROM SNOWMELT AND THE PROJECTED 1+
INCHES OF RAINFALL INTO CHRISTMAS DAY. ATTM, IT LOOKS LIKE THE
MAINSTEM RIVERS WILL BE ABLE TO HANDLE THE LOAD W/SIGNIFICANT
RISES. THE HEAVIEST RAINFALL LOOKS LIKE IT WILL FALL ACROSS THE
DOWNEAST AND COASTAL AREAS. THE NORTHERN MAINE RIVERS SUCH AS THE
ST. JOHN AND AROOSTOOK HAVE ICE ON THEM BUT THERE IS PLENTY OF
OPEN WATER. AN ICE JAM STILL EXISTS ON THE AROOSTOOK RIVER IN FORT
FAIRFIELD. WARMER TEMPERATURES THAT ARE FORECAST ALONG W/THE EXPECTED
RUNOFF COULD ALLOW FOR THE ICE JAM TO BREAK UP AND MOVE. ACROSS
THE PISCATAQUIS AND PENOBSCOT BASIN, SOME ICE WAS NOTED BUT THE
MAJORITY OF THESE WATERWAYS WERE OPEN. WASHINGTON COUNTY IS A
CONCERN AS THE ST. CROIX RIVER IS RUNNING HIGH W/THE WATER BEING
RELEASED FROM THE DAMS INTO THE RIVER. IF RAINFALL EXCEEDS THE 2
INCH MARK, THEN THERE COULD BE SOME ISSUES. THIS WILL NEED TO BE
MONITORED AS WE CLOSE IN ON THE EVENT.

&&

.TIDES/COASTAL FLOODING...
PRIMARY CONCERN IS RELATIVELY HIGH ASTRONOMICAL TIDE IN
CONJUNCTION WITH MODERATE WAVE EVENT. COINCIDENCE OF A NEW MOON
ON 22 DECEMBER WITH LUNAR PERIGEE ON 24 DECEMBER WILL PRODUCE
PERIGEAN SPRING TIDE. HIGHEST TIDES OF MONTH ON 23RD AND 24TH BUT
REMAIN RELATIVELY HIGH THROUGH THE 26TH. LATEST GUIDANCE INDICATES
WIND FIELD WEAKER ACROSS THE GULF OF MAINE 24TH THROUGH THE 25TH
WHILE STRONG SOUTHERLY FETCH DEVELOPS FURTHER SOUTH. WITH THIS
SCENARIO EXPECTED TO RESULT IN LARGEST WAVES ARRIVING LATE OF
25... AROUND 12 FEET WITH PERIODS OF 9-10 SECONDS. WAVE HEIGHTS
AND LONG PERIODS STILL SUFFICIENT FOR MINOR OVERTOPPING ISSUES.
WITH WITH WEAKER GRADIENT NOW EXPECTED IN THE GULF OF MAINE THE
THREAT OF TIDAL FLOODING HAS NOW BEEN REDUCED DUE TO LOWER WIND
SPEEDS. WITH DELAYED ARRIVAL OF LARGEST WAVES... BAR HARBOR TIDES
OF GREATEST CONCERN FOR OVERTOPPING ARE: THURSDAY 1250 EST (1750Z)
12.73 FEET MLLW AND FRIDAY 0126 EST (0626Z) 11.80 FEET MLLW.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TUESDAY TO NOON EST WEDNESDAY
     FOR ANZ050>052.

&&

$$

NEAR TERM...CB/HEWITT
SHORT TERM...MIGNONE
LONG TERM...MIGNONE
AVIATION...CB/HEWITT/MIGNONE
MARINE...CB/HEWITT/MIGNONE
HYDROLOGY...HEWITT
TIDES/COASTAL FLOODING...MIGNONE


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