Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 270456 AAA AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 1156 PM 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 AM TUESDAY MORNING/... UPDATE...TOP DOWN SATURATION IS SLOWLY TRYING TO GET MORE WIDESPREAD SNWFL INTO THE FORECAST AREA AT THIS HOUR. 00Z GYX SOUNDING SHOWS PRONOUNCED DRY LAYER AT H8...WHICH SHOULD BE ERASED IN THE NEXT COUPLE OF HOURS FOR COASTAL ME. ADJUSTED POP TO REFLECT A SLIGHT DELAY...BUT QUICKLY NWD EXPANDING PCPN SHIELD. ALSO THINKING AHEAD TO THE LARGER PART OF THE FORECAST TO COME IN THE NEXT SEVERAL HOURS. 00Z RAOB OBJECTIVE ANALYSIS SHOWS 27.00Z CMC- REGIONAL AND GFS VERIFYING BETTER THAN 26.12Z ECMWF FOR H5 HEIGHTS INVOF DEVELOPING UPPER LOW PRES. THIS IS IMPORTANT BECAUSE 00Z MODELS HAVE SHIFTED E WITH HEAVIEST QPF. A DEEPER H5 SCENARIO LIKE THE ECMWF WOULD ACT TO CAPTURE AND PULL SURFACE LOW PRES FARTHER W...INCLUDING THE QPF. SO 00Z ECMWF SHOULD BE IMPORTANT IN DETERMINING WHERE TO INTRODUCE SHARPER WRN CUT OFF TO SNWFL TOTALS. ORIGINAL DISCUSSION... SNOW SHOWERS HAVE ALREADY BEGUN DUE TO OCEAN EFFECT AND INCREASED MOISTURE. WARM AIR ADVECTION WILL INCREASE IN EARNEST TONIGHT AND WE SHOULD HAVE SNOW SPREADING ACROSS SOUTHERN NH AND COASTAL MAINE OVERNIGHT. IN FACT SEVERAL INCHES WILL BE POSSIBLE BY DAYBREAK IN THESE LOCATIONS. TEMPERATURES TUMBLE IN THE NORTH TONIGHT AS COLD AIR IS PULLED TOWARDS THE APPROACHING STORM. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... NEW NAM AND GFS ARE MORE PROGRESSIVE TODAY... HOWEVER THE EUROPEAN... WHICH GENERALLY HANDLES WINTER STORMS VERY WELL... IS IN GOOD AGREEMENT WITH THE CANADIAN WHICH INCREASES THE QPF AND WIND FIELDS ACROSS THE OUR REGION. THE EUROPEAN GETS CAUGHT IN THE UPPER LEVEL FLOW AS THE UPPER TROUGH TILTS NEGATIVELY AND NOT ONLY STALLS BUT RETROGRADES SLIGHTLY TUESDAY AFTERNOON... MEANDERING AROUND THE BENCHMARK... AND DEEPENING SLIGHTLY MORE THAN THE OTHER MODELS AS IT DOES SO. NEEDLESS TO SAY THE WIND FIELDS REMAIN VERY IMPRESSIVE. CURRENTLY THE STORM IS LOCATED OFF THE DELMARVA PENINSULA AND IS AROUND 998 MB. WINDS ARE LOOKING NORTHERLY FOR THE MAJORITY OF THE EVENT NOW AS THE SYSTEM WRAPS UP AND IS PULLED CLOSER TO THE COAST. MESOSCALE MODELS ARE ALSO SHOWING AN EYE FEATURE SIMILAR TO A HURRICANE... WHICH ARE PROMINENT ON STRONG MID LATITUDE CYCLONES. IN ADDITION THE MAIN BANDING FEATURE(S) SHOULD BE ORIENTED SSW TO NNE... FROM NEAR PORTSMOUTH NH TO LEWISTON ME TO HARMONY ME EVENTUALLY AS THEY ROTATES ONSHORE. DUE TO THE ABOVE MODEL CHANGES AND THE BANDING FEATURES MENTIONED... SNOWFALL TOTALS WERE BUMPED UP SLIGHTLY. OTHERWISE NO WHOLESALE CHANGES... AND HEADLINES REMAIN THE SAME EXCEPT FOR UPGRADING THE COASTAL STORM WATCHES TO WARNINGS. K INDICES INCREASE TO NEAR 20 ALONG CAPE COD AND DOWNEAST INDICATING THE POSSIBILITY OF THUNDERSNOW LATE TUESDAY NIGHT. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... LOW PRESSURE WILL SLOWLY MOVE EAST AND OUT TO SEA WEDNESDAY. THE EXIT SPEED WILL BE MODEL DETERMINANT...HOWEVER THE EURO IS THE LEAST PROGRESSIVE AND STALLS OVER NANTUCKET BEFORE SLOWLY MOVE THROUGH THE GULF OF MAINE. HIGH PRESSURE WILL FOLLOW. ON FRIDAY...CYCLOGENESIS OCCURS ONCE AGAIN OVER THE NEW ENGLAND WATERS. THE EURO SOLUTION REMAINS VERY INTERESTING...WITH LOW PRESSURE RAPIDLY DEEPENING IN THE GULF OF MAINE. THIS COULD BE AN INTERESTING EVENT AS WELL IF THE SYSTEM CUTS OFF SOON ENOUGH TO OUR SOUTH. VERY COLD ARCTIC AIR POURS IN FOR THE WEEKEND WITH SOME OF THE COLDEST TEMPERATURES OF THE YEAR. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... SHORT TERM...VFR CONDITIONS WILL DETERIORATE QUICKLY TONIGHT TO MVFR AS CLOUDS LOWER AND THICKEN IN INCREASING LOW LEVEL MOISTURE. SNOW AFFECTING CEILINGS AND VISIBILITIES AS FAR NORTH AS A KLEB TO KAUG LINE ARE LIKELY BY 12Z...CREATING LIFR OR LOWER CONDITIONS. ALL TERMINALS WILL DROP TO THESE LEVELS TUESDAY THROUGH WEDNESDAY MORNING WITH THE LIKELY EXCEPTION OF WHITEFIELD. LONG TERM... CONDITIONS WILL GRADUALLY BE IMPROVING WEDNESDAY. LOCALLY...IFR CONDITIONS RETURNING FRIDAY IN ANOTHER COASTAL LOW. && .MARINE... SHORT TERM...STORM WARNINGS REMAIN IN EFFECT THROUGH TUESDAY WITH VERY STRONG WINDS AND SEAS AS HIGH AS 25`. LONG TERM... WINDS AND WINDS WILL GRADUALLY SUBSIDE WEDNESDAY. GALE FORCE WINDS MAY RETURN LATE FRIDAY NIGHT INTO SATURDAY. && .TIDES/COASTAL FLOODING... LARGE...BATTERING WAVES WILL BE BUILDING LATE TONIGHT RIGHT AROUND HIGH TIDE. THIS IN COMBINATION WITH A TWO FOOT STORM SURGE WILL ALLOW PORTLAND AND HAMPTON TO REACH THEIR FLOOD STAGE. WINDS WILL SWITCH TO THE NORTH TOMORROW AFTERNOON JUST PRIOR TO HIGH TIDE...WHICH MAY REDUCE THE STORM SURGE. THIS IS VERY MODEL DEPENDENT HOWEVER WITH THE EURO DANGEROUSLY BACKING IN THE STORM TO NANTUCKET ISLAND. USED THE NORTH ATLANTIC REGIONAL TEAM WAVE RUNUP MATRICES TO FORECAST AND WARN FOR THE TWO TUESDAY HIGH TIDES. THE OUTPUT SHOWS WAVE ACTION WILL ALLOW FOR LOCALLY SIGNIFICANT EROSION AS WELL AS OVERWASH AT FORTUNES ROCKS...JENNIS...CAMP ELLIS AND FERRY BEACHES IN MAINE AND NEW HAMPSHIRE. NERACOOS SPLASH-OVER NOMOGRAMS ALSO SHOWING SIGNIFICANT ISSUES AT THE TIME OF HIGH TIDE FOR THE BEACHES SOUTH OF PORTLAND. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER STORM WARNING UNTIL 4 AM EST WEDNESDAY FOR MEZ007>009- 012>014. BLIZZARD WARNING UNTIL 4 AM EST WEDNESDAY FOR MEZ018>028. COASTAL FLOOD ADVISORY UNTIL 6 PM EST TUESDAY FOR MEZ025>028. COASTAL FLOOD WARNING UNTIL 6 PM EST TUESDAY FOR MEZ023-024. NH...WINTER STORM WARNING UNTIL 4 AM EST WEDNESDAY FOR NHZ002>009- 011-015. BLIZZARD WARNING UNTIL 4 AM EST WEDNESDAY FOR NHZ010-012>014. WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR NHZ001. COASTAL FLOOD WARNING UNTIL 6 PM EST TUESDAY FOR NHZ014. MARINE...STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR ANZ150>154. && $$ NEAR TERM...LEGRO

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