Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 072220
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
520 PM EST SUN FEB 7 2016

.SYNOPSIS...
A COLD FRONT WILL MOVE OFFSHORE TONIGHT. LOW PRESSURE OFF THE
CAROLINA COAST WILL MOVE NORTHEAST AND PASS TO THE EAST OF CAPE
COD ON MONDAY. ANOTHER LOW WILL FORM OFF THE MID ATLANTIC COAST
AND MOVE TOWARD CAPE COD ON TUESDAY. THE RESULT WILL BE WIDESPREAD
SNOWFALL ACROSS THE REGION. THIS LOW WILL SLOWLY MOVE OUT OF THE
AREA WEDNESDAY AND THURSDAY. MUCH COLDER AIR WILL MOVE SOUTH OUT
OF CANADA AND INTO NEW ENGLAND NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATE...
HAVE UPDATED THE GRIDS BASED ON CURRENT CONDITIONS. VERY DRY AND
COLD AIR POURING SOUTHWARD THROUGHT THE STATE OF MAINE THIS
EVENING ON NORTHERLY WINDS. DEW POINTS ARE NOW 5 TO 10 BELOW ZERO OVER
NORTHERN AND MOUNTAIN AREAS...SO TEMPERATURES WILL LIKELY FALL
RAPIDLY TONIGHT...DOWN TO NEAR ZERO IN THE NORTH. SOUTHERN NH WILL
BE MILDER WITH UPPER TEENS TO AROUND 20 DEGREES FOR OVERNIGHT
LOWS.

MESOSCALE MODELS BRING SNOWFALL TO SE NH AROUND 12Z MONDAY
MORNING. COULD BE SOME SUBLIMATION BELOW THE MID LEVEL CLOUD DECK
THAT INITIALLY CONTRIBUTES TO THE SNOWFALL...WHICH WOULD DELAY THE
PRECIP BY A COUPLE HOURS.

PREV DISC...
COLD FRONT CONTINUES A SLOW MARCH SOUTH ACROSS THE
AREA THIS AFTERNOON AND WILL MOVE SOUTH OF THE AREA TONIGHT.
TEMPERATURES ARE DROPPING BEHIND THE FRONT WITH DEWPOINTS FALLING
SUBZERO ALREADY IN NORTHERN AND CENTRAL MAINE. EXPECT COLD
ADVECTION TO CONTINUE THROUGH THE NIGHT ON AN INCREASING NORTHERLY
WIND. TEMPERATURES SHOULD FALL INTO THE TEENS FOR MOST AREAS BY
MORNING... WITH SINGLE DIGITS IN NORTHERN PARTS OF MAINE.
CONSIDERING HOW STRONG THE COLD ADVECTION IS... THERE MAY BE A
LITTLE MORE ROOM TO GO ON THE LOW END OF THE TEMPERATURE FORECAST
TONIGHT.

LOW PRESSURE MOVING NORTH THROUGH THE WESTERN ATLANTIC TO A
POSITION SOUTH OF CAPE COD BY MORNING WILL ALLOW THE PRESSURE
GRADIENT TO INCREASE ACROSS THE AREA. EXPECT WIND SPEEDS TO
INCREASE ESPECIALLY NEAR THE COAST WITH GUSTS TO 25 OR 30 MPH
POSSIBLE. THESE STRONG NORTH TO NORTHEAST WINDS WILL HELP DRAG IN
THE COLDER AIR FROM THE NORTH.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
WINTER WEATHER ADVISORIES POSTED FOR ALL OF THE FORECAST AREA WITH
THE EXCEPTION OF WINTER STORM WARNING FOR COASTAL ROCKINGHAM
COUNTY.

AS THE OFFSHORE LOW MOVES NORTH... DRIVEN BY A WELL DEVELOPED
SOUTHERN STREAM UPPER LOW... THE NORTHERN STREAM UPPER TROUGH WILL
MOVE TOWARD THE EAST COAST. AS IT DOES SO IT WILL ACT TO TRY TO
PULL THE OFFSHORE LOW WESTWARD... BUT MORE LIKELY WILL JUST PULL
SOME OF THE MID AND UPPER LEVEL MOISTURE ASSOCIATED WITH IT
WESTWARD TOWARD THE APPROACHING UPPER TROUGH.

MODELS IN PRETTY GOOD AGREEMENT THAT AREA OF HEAVY PRECIPITATION
ASSOCIATED WITH THE OFFSHORE LOW WILL STAY PRIMARILY TO OUR SOUTH
AND EAST... THOUGH SOUTHEAST NEW HAMPSHIRE COULD GET SCRAPED BY
THE NORTHWEST EDGE OF THIS PRECIPITATION SHIELD IN THE MORNING.

BY AFTERNOON THE LOW WILL BE MOVING NORTHWARD TO THE EAST OF CAPE
COD AND MID LEVEL MOISTURE WILL BEGIN SPREADING WESTWARD TOWARD
THE UPPER TROUGH. MUCH OF THE PRECIPITATION WILL BE FALLING OUT OF
A 10,000 TO 15,000 FOOT CLOUD DECK AND COLD DRY AIR NEAR THE
SURFACE WILL ALLOW FOR EVAPORATION (SUBLIMATION) INITIALLY. THIS
WILL KEEP TEMPERATURES COLD AND MAKE IT DIFFICULT FOR THE INITIAL
SNOWFALL TO REACH THE SURFACE. IN FACT... TEMPERATURES FORECAST TO
BE IN THE TEENS TOMORROW EAST OF THE MOUNTAINS COULD EVEN BE A
LITTLE TOO WARM CONSIDERING THE STRONG NORTH/NORTHEAST WIND AND
THE VERY DRY LOW LEVEL AIR. EVENTUALLY THE COMBINATION OF
MOISTURE TRANSPORT WESTWARD AND LIFT ASSOCIATED WITH THE
APPROACHING UPPER LEVEL TROUGH WILL ALLOW FOR THE LIGHT SNOW TO
BEGIN TO ACCUMULATE.

SNOW RATIOS WILL BE ON THE ORDER OF 20 TO 1 ACROSS THE AREA
INDICATING A DRY FLUFFY SNOW WHICH WILL EASILY BE BLOWN AROUND BY
THE WIND. BEST LIFT FOR SNOW PRODUCTION GRADUALLY LIFTS NORTHWARD
ACROSS THE AREA THROUGH MONDAY NIGHT. OVERALL SNOWFALL RATES ARE
EXPECTED TO BE LIGHT... GENERALLY 2 INCHES OR LESS PER 6 HOUR
PERIOD. HOWEVER... OVER THE COARSE OF THE 24 HOUR EVENT SNOW
TOTALS WILL LIKELY REACH 3 TO 6 INCHES FOR MOST OF THE FORECAST
AREA. HEAVIER AMOUNTS ARE POSSIBLE NEAR THE COAST WHERE THERE WILL
BE A LITTLE BETTER MOISTURE AVAILABLE. SNOWFALL AMOUNTS OVER 6
INCHES ARE POSSIBLE HERE BUT FOR THE MOST PART THIS WILL BE OVER A
LONG DURATION 24 HOUR PERIOD THUS ONLY AN ADVISORY HAS BEEN ISSUED
FOR THIS AREA. THE WINTER STORM WARNING ISSUED FOR COASTAL
ROCKINGHAM COUNTY IS FOR THE POTENTIAL FOR A LITTLE HEAVIER SNOW
AS THE COASTAL LOW MOVES OFFSHORE MONDAY MORNING.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
TUESDAY WILL BEGIN WITH WIDESPREAD SNOW SHOWERS AND GUSTY NORTH
WINDS. THE SECOND IN A SERIES OF SHORT WAVES AND ATTENDANT
SURFACE LOWS WILL BE MOVING TOWARDS NOVA SCOTIA AND WELL OFF THE
NH AND MAINE SHORELINES. THIS SURFACE CIRCULATION WILL EVENTUALLY
BE ENVELOPED BY MONDAYS COASTAL LOW.

THE UPPER LEVEL PATTERN REMAINS LOCKED IN A COUPLED RIDGE TO
THE WEST AND DEEP TROUGH OVER THE EAST. ADDITIONAL MINOR
DISTURBANCES PUSH THROUGH ON WEDNESDAY KEEPING A CHANCE OF SNOW
SHOWERS OVER THE REGION. THERE WILL BE A CHANCE OF UP TO HALF AN
INCH TO AN INCH OF SNOW EVERY 6 HOURS...RESULTING IN NO
SIGNIFICANT IMPACTS. THE FINAL AREAWIDE CHANCE FOR FLURRIES WILL
DIMINISH THURSDAY... WHILE THE MOUNTAINS MAY KEEP LIGHT SHOWERS
THROUGH EARLY FRIDAY MORNING.

THEREAFTER THE MAIN STORY WILL BE THE EXTREMELY FRIGID AIRMASS
POURING OUT OF CANADA. A DENSE COLD DOME NOW POOLING OVER THE
ARCTIC CIRCLE WILL MAKE ITS WAY SOUTH AND EAST. ALTHOUGH THE
DENSE SURFACE HIGH WILL TAKE ITS TIME DROPPING SOUTH OUT OF CANADA
AND MOVING TOWARDS THE GREAT LAKES AND EVENTUALLY THE NORTHEAST...
WE WILL BEGIN FEELING ITS EFFECTS NEXT WEEKEND.

850MB TEMPERATURES DROP TO -25 TO -33C OVER NH AND MAINE WITH
THE COLDEST AIR DAMMING ALONG THE SPINES OF THE GREENS AND
WHITES. OVER THE WEEKEND DAYTIME TEMPERATURES WILL RANGE FROM THE
SINGLE DIGITS NORTH TO THE TEENS SOUTH. SEVERAL NIGHTS OF WELL
BELOW ZERO OVERNIGHT MINIMUMS ARE LIKELY FOR THE NORTH COUNTRY
BEGINNING THURSDAY NIGHT/FRIDAY MORNING. THE COASTAL PLAIN WILL
FAIR SOMEWHAT BETTER AND WILL GENERALLY BE IN THE SINGLE DIGITS.
NEXT MONDAY MORNING LOOKS FRIGID AS WELL AT THIS TIME BUT THE NEXT
BATCH OF LOW PRESSURE/WARM AIR ADVECTION SHOULD PROVIDE SOME
RELIEF NEXT TUESDAY.

&&

.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
SHORT TERM...VFR CONDITIONS TONIGHT WILL GIVE WAY TO GRADUALLY
LOWERING CEILINGS AND LIGHT SNOW BY MIDDAY MONDAY. OCCASIONAL IFR
CONDITIONS WILL EVENTUALLY BE POSSIBLE LATER MONDAY. WINDS SHIFT
TO THE NORTH THIS EVENING AND INCREASE OVERNIGHT. BY MORNING WINDS
WILL BE GUSTING TO 25 OR 30 KT NEAR THE COAST WITH LOWER SPEEDS
INLAND.

LONG TERM...TUESDAY AND WEDNESDAY SCATTERED SNOW SHOWERS WILL
KEEP MVFR OR LOWER CONDITIONS AROUND ALTHOUGH THERE MAY BE SOME
SPOTS OF VFR. THE WINDS WILL BE SOMEWHAT GUSTY TUESDAY BEFORE
DROPPING OFF. IMPROVEMENT IN CEILINGS AND VISIBILITIES WILL OCCUR
THURSDAY AND FRIDAY AS HIGH PRESSURE PUSHES IN FROM THE WEST.

&&

.MARINE...
SHORT TERM...COLD FRONT DROPS SOUTH ACROSS THE WATERS TONIGHT AND
LOW PRESSURE STRENGTHENS AS IT MOVES NORTHWARD OFF THE ATLANTIC
COAST. EXPECT INCREASING NORTHEAST WINDS EVENTUALLY REACHING GALE
FORCE TONIGHT AND LASTING THROUGH MONDAY EVENING. THERE IS A LOW
POSSIBILITY THAT WINDS COULD REACH STORM FORCE AT TIMES. BY LATE
MONDAY NIGHT WINDS SHOULD DROP BELOW GALE FORCE.

LONG TERM...WAVES WILL REMAIN HIGH THROUGH TUESDAY NIGHT AND IN
FACT DO NOT DECREASE OVER THE OUTER WATERS FROM STONINGTON TO
PORT CLYDE FOR MUCH OF THE WEEK. THIS IS IN RESPONSE TO A SERIES
OF LOW PRESSURE SYSTEMS PASSING BY OFFSHORE. WE WILL NEED AT
LEAST A SCA FOR WAVES FOR A PORTION OF THE SEAS TUESDAY THROUGH
FRIDAY. WINDS DROP BELOW SCA TUESDAY MORNING AND STAY BELOW
CRITERIA UNTIL THURSDAY WHEN A SCA WILL BE NEEDED FOR THE OUTER
WATERS.

&&

.TIDES/COASTAL FLOODING...
A 1 TO 1.5 FOOT STORM SURGE WILL COMBINE WITH HIGH ASTRONOMICAL
TIDES AND MODESTLY BUILDING SEAS OF 5 TO 10 FEET. THIS MAY LEAD TO
MINOR COASTAL FLOODING OR SPLASH-OVER ALONG THE COASTAL YORK AND
ROCKINGHAM COUNTIES NEAR THE TIME OF THE MID MORNIG HIGH TIDE
MONDAY.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...WINTER WEATHER ADVISORY FROM NOON MONDAY TO NOON EST TUESDAY
     FOR MEZ007>009-012>014.
     WINTER WEATHER ADVISORY FROM 6 AM MONDAY TO NOON EST TUESDAY
     FOR MEZ018>028.
     COASTAL FLOOD ADVISORY FROM 10 AM TO NOON EST MONDAY FOR
     MEZ023.
NH...WINTER WEATHER ADVISORY FROM 6 AM MONDAY TO 6 AM EST TUESDAY
     FOR NHZ003>013-015.
     WINTER WEATHER ADVISORY FROM NOON MONDAY TO NOON EST TUESDAY
     FOR NHZ001-002.
     COASTAL FLOOD ADVISORY FROM 10 AM TO NOON EST MONDAY FOR
     NHZ014.
     WINTER STORM WARNING FROM 6 AM MONDAY TO 6 AM EST TUESDAY FOR
     NHZ014.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EST
     MONDAY NIGHT FOR ANZ153.
     GALE WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT EST MONDAY
     NIGHT FOR ANZ150>152-154.

&&

$$
JC


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