Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 072058 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 358 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/... 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 /21Z 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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