Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 241443 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 943 AM EST SAT JAN 24 2015 .SYNOPSIS... LOW PRESSURE WILL MOVE UP THE NORTHEAST COAST TODAY AND EXIT INTO THE CANADIAN MARITIMES TONIGHT. AFTER A BRIEF BREAK SUNDAY ANOTHER LOW PRESSURE SYSTEM MOVES OUT OF THE OHIO VALLEY AND QUICKLY DEVELOPS WELL SOUTH OF NEW ENGLAND AND COULD END UP MOVING FAR ENOUGH NORTH TO AFFECT OUR AREA EARLY NEXT WEEK. THEREAFTER...COLD AND DRY WEATHER WILL MOVE ON IN. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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9AM UPDATE... SNOW HAS JUST MOVED INTO GRAY AND FORECAST REMAINS ON TRACK. UPDATED TEMPS AND DEW POINTS, WHICH ARE RUNNING A BIT COLDER. HAVE NOT CHANGED SNOW TOTALS SIGNIFICANTLY. THE SNOW RATIO AND POTENTIAL FOR HEAVIER SNOW BANDS TO DEVELOP THIS AFTERNOON REMAIN THE STICKING POINT FOR THE FORECAST. 7 AM UPDATE...HAVE UPDATED THE FORECAST TO ACCOUNT FOR RELATIVELY MINOR CHANGES IN POP...QPF...AND SNOW FOR THE MORNING HOURS BASED ON LATEST TRENDS IN OBSERVATIONAL DATA. SNOW HAS REACHED SOUTHERN NEW HAMPSHIRE AND WILL CONTINUE PROGRESSING NORTHWARD THIS MORNING. NO CHANGES IN WARNINGS AND ADVISORIES AT THIS TIME. PREVIOUSLY... LOW PRESSURE CONTINUES OFF OF THE DELAWARE COAST AS OF 4 AM. A PRETTY EXPANSIVE SNOW SHIELD IS GRADUALLY WORKING ITS WAY NORTHWARD ACROSS CONNECTICUT. THIS WILL CONTINUE TO PUSH NORTHWARD AND LIKELY ARRIVE ACROSS SOUTHERN ZONES AROUND SUNRISE IF NOT AN HOUR OR TWO AFTERWARD. OVERALL...WE HAVE NOT MADE SIGNIFICANT CHANGES TO THE FORECAST SNOW AMOUNTS. ON AVERAGE...THE 00Z DETERMINISTIC AND ENSEMBLE GUIDANCE HAS SHIFTED THE HEAVIEST SNOWFALL EASTWARD A BIT...AND THE FORECAST REFLECTS THIS SLIGHT CHANGE. ONE THING IS FAIRLY CERTAIN...AND THAT IS THERE WILL BE A VERY TIGHT SNOWFALL GRADIENT ON THE WESTERN EDGE OF THE PRECIP SHIELD. ONE TOWN MAY HAVE 5 OR 6 INCHES OF SNOW AND ANOTHER TOWN 10 MILES TO THE WEST MAY END UP WITH NEXT TO NOTHING. HAVE TRIED TO ACCOUNT FOR THIS IN THE FORECAST GRIDS BY INCORPORATING THE LATEST HRRR POPS FOR THE FIRST 12-15 HOURS OF THE FORECAST. HOWEVER...THIS BACK EDGE WILL LIKELY HAVE TO BE ADJUSTED TODAY BASED ON LATEST TRENDS. TODAY WILL MOST CERTAINLY BE A CASE OF THE HAVES AND HAVE NOTS. RIGHT NOW...IT APPEARS THAT OUR MOUNTAINS ZONES WILL REMAIN DRY OR MOSTLY DRY. THE HEAVIEST SNOWFALL IS EXPECTED TO OCCUR IN SOUTHEASTERN NH AND COASTAL MAINE...WITH THE HEAVIEST SNOW FALLING THIS AFTERNOON.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... THE SNOW WILL QUICKLY WIND DOWN THIS EVENING...AND MUCH OF THE AREA WILL BE SNOW-FREE AFTER 00Z. A COLD FRONT WILL FOLLOW IN THE WAKE OF THE LOW PRESSURE SYSTEM LATE TONIGHT AND SUNDAY MORNING WITH A CHANCE OF SNOW SHOWERS AND A FEW SQUALLS IN THE MOUNTAINS. COLD AND WINDY WEATHER IS EXPECTED DURING THE DAY ON SUNDAY AFTER THE FRONTAL PASSAGE. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
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ANY CURRENT WEAKNESS IN THE 500MB +PNA PATTERN WILL DISAPPEAR AS THE FLOW BECOMES INCREASINGLY MORE AMPLIFIED AND BOTH UPSTREAM AND DOWNSTREAM BLOCKING STRENGTHEN. THIS WILL PRODUCE PERSISTENT AND FAIRLY DEEP TROUGHING OVER ERN NO AMERICA AND ALLOW COLD CORE OF AIR TO DROP EQUATORWARD ACROSS HUDSON BAY DURING THE LATTER PART OF WEEK. SO...COLD TO START THE EXTENDED...MAYBE A LITTLE WARM UP TO AROUND NORMAL LATE WEEK...AND POTENTIALLY EVEN COLDER NEXT WEEKEND. SUNDAY NIGHT WITH BE COLD WITH ENOUGH WIND SUNDAY EVE TO PUSH APPARENT TEMPS TO NEAR -20 IN THE N...AND BLO ZERO EVERYWHERE ELSE...BUT SHOULD SEE WINDS DIMINISH OVERNIGHT. MONDAY WILL COLD AS HIGH PRES PASSES TO THE N...WITH HIGHS MOSTLY IN THE 10-20 F RANGE AND INCREASING CLOUDS LATE AS 500 MB TROUGH BEGINS TO CLOSE OFF OVER THE MID-ATLANTIC OR CAROLINA COAST....DEPENDING ON WHETHER YOU FOLLOW THE EURO OR GFS. THE EURO IS MUCH MORE AGGRESSIVE WITH CLOSING OFF THE 500 MB LOW AND INTENSIFYING THE SFC LOW IN VICINITY OF THE 40/70 BENCHMARK...ENOUGH TO SPREAD SOME ACCUMULATING SNOW INTO THE CWA. THE GFS KEEPS THE SFC FLOW FURTHER E AND INTENSIFIES LATER...WHICH WOULD MEAN LESS SNOW AND THE BETTER CHANCE FOR ACCUMULATIONS WOULD BE IN THE ERN ZONES. GIVEN THE SOLID PERFORMANCE OF THE EURO LEANING IN THAT DIRECTION AND HAVE SPREAD CHC POPS ACROSS ENTIRE CWA ON TUE. STILL IT LOOKS COLD...WITH TEMPS IN THE SINGLE DIGITS TO TEENS...SO ANY SNOW WILL HAVE A HIGH SNOW TO LIQUID WATER RATIO. SHOULD SEE NW WINDS PICK UP BEHIND THIS SYSTEM WITH A REINFORCING SHOT OF COLD AIR AND HIGHS ON WED LIMITED TO THE TEENS TO AROUND 20 AGAIN. AS THAT INTENSE LOW HEADS NE THROUGH THE NEWFOUNDLAND AND LABRADOR THUS...WILL SEE SOME RIDGING DEVELOPING UPSTREAM OVER NH/ME...AND A BIT OF WARM UP IS EXPECTED ON THU INTO FRI...BEFORE ANOTHER DEEPENING TROUGH APPROACHES AND BRINGS THE COLD BACK BY NEXT WEEKEND.
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&& .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...VFR CONDITIONS ACROSS THE FAR INTERIOR TODAY...WITH SOUTHERN NH AND COASTAL MAINE BECOMING IFR OR LOWER IN SNOW BY AFTERNOON. VFR CONDITIONS RETURN TONIGHT AND LAST THROUGH SUNDAY. LONG TERM...VFR EXPECTED SUN NIGHT INTO MON EVE. POSSIBLE FLIGHT RESTRICTIONS IN SNOW LATE MON INTO TUE EVENING...WITH A RETURN TO VFR BY WED...ALTHOUGH GUSTY NW WINDS ARE POSSIBLE. && .MARINE... SHORT TERM...GALES REMAIN UP FOR MOST WATERS AS COASTAL STORM MAKES ITS CLOSEST APPROACH LATE THIS AFTERNOON AND TONIGHT. STRONG SCA LIKELY ON SUNDAY IN THE WAKE OF THE LOW AND ANOTHER COLD FRONTAL PASSAGE. LONG TERM...WINDS DIMINISH SUN NIGHT...ALTHOUGH LIGHT FREEZING SPRAY IS A GOOD BET SUN NIGHT INTO MON NIGHT...AND PERHAPS RIGHT THROUGH TUE NIGHT. SCA POSSIBLE LATE MON NIGHT...WITH A CHANCE OF GALES TUE INTO TUE NIGHT AS COASTAL LOW TRACKS JUST TO THE S AND E. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MEZ018>021. WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MEZ022>028. NH...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR NHZ008-009-011-015. WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR NHZ010- 012>014. MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 2 PM EST SUNDAY FOR ANZ153. GALE WARNING FROM 5 PM THIS AFTERNOON TO 3 AM EST SUNDAY FOR ANZ150>152-154.
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&& $$ SYNOPSIS... NEAR TERM...CURTIS SHORT TERM...EKSTER LONG TERM...CEMPA AVIATION... MARINE...

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