Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 261508 AAC
AFDGYX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAY ME
1008 AM EST MON JAN 26 2015

.SYNOPSIS...
LOW PRESSURE WILL BEGIN TO DEVELOP OFF THE MID ATLANTIC COAST
TODAY THEN RAPIDLY INTENSIFY AS IT MOVES NORTHEASTWARD TO JUST
SOUTH OF NANTUCKET MASSACHUSETTS ON TUESDAY. THE LOW WILL LINGER
AROUND THROUGH WEDNESDAY BRINGING A SIGNIFICANT SNOWFALL TO OUR
REGION. THERE IS ALSO THE POTENTIAL FOR ANOTHER STORM LATE WEEK OR
EARLY IN THE WEEKEND BUT CONFIDENCE IS LOW AT THIS TIME.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
.UPDATE...MINOR CHANGES TO TEMPERATURES AND DEW POINTS THIS
MORNING. OTHERWISE CLOUDS HAVE BEGUN TO THICKEN UP AS WARM AIR
ADVECTION ALOFT INCREASES. SOME LOW LEVEL CUMULUS STREAMERS
APPARENTLY TRYING TO ORGANIZE OVER THE GULF OF MAINE AND THIS MAY
RESULT IN OCEAN EFFECT SHOWERS ALONG THE MIDCOAST THIS AFTERNOON.
NO OTHER CHANGES TO THE FORECAST AT THIS TIME.

&&

.PREVIOUS DISCUSSION...GENERALLY QUIET WX FOR MOST OF TODAY. IT
WILL BE COLD WITH HIGH PRES OVERHEAD...AND WINDS GRADUALLY
INCREASING FROM THE NE THRU THE DAY. LATE IN THE DAY SOME SN IS
POSSIBLE ACROSS SRN NH AS LOW PRES BEGINS TO GET ORGANIZED S OF
NEW ENGLAND.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
A DANGEROUS AND POTENTIALLY CRIPPLING COASTAL STORM IS SET TO
AFFECT THE REGION BEGINNING LATE TODAY THRU TUE NIGHT.

LOW PRES WILL MOVE THRU THE CAROLINAS TODAY...AND EXIT THE EAST
COAST. HERE IT WILL RAPIDLY DEVELOP OVER THE RELATIVELY WARM
WATERS OF THE ATLANTIC. LOW PRES WILL DROP SOME 20 MB IN 24
HOURS...AND TAKE A POSITION S OF NEW ENGLAND AND STALL OR SLOWLY
DRIFT TOWARDS KACK. HEADLINES REMAIN MOSTLY THE SAME...WITH THE
EXCEPTION BEING ERN HILLSBOROUGH BEING ADDED TO THE BLIZZARD
WARNINGS.

A DEPARTING JET STREAK IN EXCESS OF 150 KTS N OF THE CANADIAN
MARITIMES WILL COMBINE WITH A SLY JET STREAK OFF THE EAST COAST IN
EXCESS OF 130 KTS TO PROVIDE A STAGE FOR RELATIVELY EXPLOSIVE
DEVELOPMENT OF LOW PRES. GFS CROSS SECTIONS THRU FORECAST AREA
FROM ROUGHLY KPWM TO KHIE SHOW INTENSE FRONTOGENESIS WITHIN A
LAYER NEAR H7. THE UPPER LEVEL DYNAMICS ARE SUCH THAT AGEOSTROPHIC
FORCING WILL PROVIDE STRONG LIFT THRU THE DENDRITIC GROWTH ZONE.
SNWFL WILL BE IDEAL AND FAIRLY EFFICIENT GIVEN THE WINDS FORECAST
ALOFT. GFS HAS THIS AXIS ALIGNED NEARLY ON TOP OF THE COASTLINE.
GIVEN THE FEATURES AVAILABLE ONE CAN INFER THAT THE ECMWF IS
SHIFTED SLIGHTLY NW OF THE GFS AXIS. ALTERNATIVELY...FINDING THE
AREA WITHIN THE MODELED FRONTOGENESIS AT H8 ON THE COOL SIDE OF
THE DEFORMATION MAXIMUM SUPPORTS THIS ASSESSMENT OF THE ECMWF
BEING SLIGHTLY FARTHER NW WITH IDEAL SNWFL.

HOWEVER...THERE ARE SOME CONCERNS LEFT REGARDING THIS STORM AND
THE OVERALL POTENTIAL FOR HIGH SNWFL AMOUNTS. MODELED QPF IS
STRUGGLING TO ECLIPSE 2 INCHES FOR MOST AREAS OUTSIDE OF EXTREME
SRN NH. THIS WOULD MAKE IT HARD FOR MANY AREAS TO SEE 2 FEET OF
SNWFL. IN ADDITION...OCCLUSION WILL ACT TO SHUT DOWN WAA PROCESSES
AND CUT OFF THE INTENSE LIFT NECESSARY FOR SNWFL RATES IN EXCESS
OF 2 INCHES PER HOUR. THESE TYPES OF RATES WILL BE NEEDED TO SEE
WIDESPREAD 20 INCH TOTALS. FINALLY...A STRONG COASTAL FNT WILL
DEVELOP. THIS WILL NOT MARK THE BOUNDARY BETWEEN SNWFL AND
RA...BUT NEAR FREEZING AIR AND AIR IN THE TEENS AND SINGLE DIGITS.
INTENSE LOW LEVEL LIFT NEAR THIS BOUNDARY MAY ENHANCE SNWFL
IMMEDIATELY ON THE COLD SIDE...BUT FARTHER NW COULD SEE A BIT OF
SUBSIDENCE AND LOWERED TOTALS. FOR THESE REASON I TENDED TO KEEP
SNWFL TOTALS SIMILAR TO THE PREVIOUS SHIFT...WITHOUT DRAMATIC
INCREASES. THOUGH ISOLATED AMOUNTS IN EXCESS OF 2 FEET ARE
POSSIBLE...ESPECIALLY COASTAL SRN NH AND THE MONADNOCKS...WHERE
STRONG ELY UPSLOPE WILL ENHANCE AMOUNTS.

THE GREATEST PERIOD OF CONCERN IS LOOK TO BE ROUGHLY 12Z TO 21Z
TUE. HERE THE BEST COMBINATION OF SNWFL AND WINDS LOOKS MOST
LIKELY. THE ECMWF HAS A 65+ KT LOW LEVEL JET AT 900 MB LIFTING NWD
ACROSS THE AREA. DEEP COLD AIR IN PLACE WILL ALLOW SOME OF THIS TO
MIX DOWN FAIRLY EASILY. GIVEN THE EXPECTED SNWFL AROUND THAT
TIME...AND POTENTIALLY 45-50 KT GUSTS MIXING DOWN...BLIZZARD
WARNINGS LOOK GOOD. ELSEWHERE COULD SEE BRIEF NEAR-BLIZZARD
CONDITIONS BUT THERE WAS NOT ENOUGH CONFIDENCE TO EXPAND...OUTSIDE
OF ERN HILLSBOROUGH. WHERE THE COMBINATION OF 1 INCH OR MORE PER
HOUR RATES AND 50 KT GUSTS OCCURS...TRAVEL WILL BE IMPOSSIBLE AND
LIFE THREATENING.

THE NEXT 12 HOURS WILL BE CRITICAL AS MODELS BEGIN TO HONE IN ON
THE MESOSCALE DETAILS. SOME SURPRISES ARE STILL LIKELY WITH THIS
STORM...AS THE VERY DYNAMIC EVENTS CAN CAUSE NWP TO STRUGGLE AT
TIMES.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE MODELS ARE IN GENERAL AGREEMENT ON THE LONG WAVE PATTERN
THROUGH EARLY NEXT WEEK. HOWEVER...SIGNIFICANT DIFFERENCES EXIST
WITH TIMING AND STRENGTH OF INDIVIDUAL SHORTWAVES LEADING TO
DECREASED CONFIDENCE IN SENSIBLE WEATHER. THE OVERALL THEME IS
WESTERN RIDGE AND EASTERN TROUGH FOR THE CONUS...WITH AN EXTENDED
PERIOD OF BELOW NORMAL TEMPERATURES AND A CHANCE FOR SYNOPTIC
SNOWS ROUGHLY EVERY TWO DAYS...WITH FRIDAY...SUNDAY...AND NEXT
TUESDAY FOR OUR FORECAST AREA.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
SHORT TERM...HIGH CONFIDENCE IN IFR AND LOWER CONDITIONS BEGINNING
IN SRN NH THIS EVENING...AND ACROSS NRN NH AND WRN ME EARLY TUE.
SNWFL RATES OF 2 INCHES OR MORE PER HOUR ARE POSSIBLE DURING THE
DAY TUE. STRONG NELY WIND GUSTS ARE EXPECTED FOR COASTAL
TERMINALS...REACHING UP TO 50 MPH AT TIMES. CONDITIONS GRADUALLY
IMPROVE LATE TUE NIGHT INTO WED. SNWFL WILL CONTINUE INTO
WED...WITH SCT IFR CONDITIONS POSSIBLE.

LONG TERM...

WED...AREAS OF MVFR IN SNOW SHOWERS. NW WIND GUSTING TO 25 KT.

FRI...AREAS OF MVFR IN SNOW WITH LCL IFR CONDS PSSBL.

&&

.MARINE...
SHORT TERM...WINDS AND SEAS WILL TURN NELY AND GRADUALLY BUILD
TODAY. TONIGHT INTO TUE WINDS AND SEAS INCREASE DRAMATICALLY.
STORM FORCE WIND GUSTS ARE LIKELY ON ALL WATERS...WITH SEAS
BUILDING TO 25-30 FT ON THE OUTER WATERS. CANNOT RULE OUT A FEW
GUSTS IN EXCESS OF HURRICANE FORCE TUE...ESPECIALLY ON THE HIGHER
PLATFORMS OF MISM1 AND IOSN3.

LONG TERM...

WED...GALE FORCE WINDS ARE LIKELY.

FRI...GALE FORCE WINDS ARE POSSIBLE.

&&

.TIDES/COASTAL FLOODING...
TIDES ARE RELATIVELY LOW IN THE ASTRONOMICAL CYCLE HOWEVER
PROLONGED NORTHEASTERLY FLOW WILL BUILD SEAS OF 25 TO 30 FEET
OFFSHORE. THIS MAY BE ENOUGH TO PRODUCE MINOR FLOODING AROUND THE
TIMES OF HIGH TIDE. BEACH EROSION AND SPLASHOVER ARE LIKELY. AT
PORTLAND HIGH TIDE IS 10.0 FT AT 420AM TUESDAY...9.1FT AT 453PM
TUESDAY...AND 9.8FT AT 523AM WEDNESDAY.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...WINTER STORM WARNING FROM 10 PM THIS EVENING TO 4 AM EST
     WEDNESDAY FOR MEZ007>009-012>014.
     BLIZZARD WARNING FROM 10 PM THIS EVENING TO 4 AM EST WEDNESDAY
     FOR MEZ018>028.
     COASTAL FLOOD WATCH FROM LATE TONIGHT THROUGH LATE TUESDAY
     NIGHT FOR MEZ023>028.
NH...WINTER STORM WARNING FROM 10 PM THIS EVENING TO 4 AM EST
     WEDNESDAY FOR NHZ002>009-011-015.
     BLIZZARD WARNING FROM 10 PM THIS EVENING TO 4 AM EST WEDNESDAY
     FOR NHZ010-012>014.
     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 4 AM EST
     WEDNESDAY FOR NHZ001.
     COASTAL FLOOD WATCH FROM LATE TONIGHT THROUGH LATE TUESDAY
     NIGHT FOR NHZ014.
MARINE...STORM WARNING FROM 1 AM TUESDAY TO 7 AM EST WEDNESDAY FOR
     ANZ150>154.

&&

$$

UPDATE...HANES
NEAR TERM...LEGRO
LONG TERM...SCHWIBS



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