Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 140206 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1006 PM EDT SAT SEP 13 2014 .SYNOPSIS... A COLD FRONT WILL MOVE THROUGH NORTHERN NEW ENGLAND TONIGHT...SETTING OFF SOME RAIN SHOWERS THROUGH THIS EVENING. HIGH PRESSURE WILL BUILD OVERHEAD SUNDAY AND MONDAY. ANOTHER COLD FRONT WILL MOVE THROUGH THE REGION TUESDAY. REINFORCING SHOT OF COLD AIR COMES THROUGH WEDNESDAY...WITH HIGH PRESSURE IN CONTROL THROUGH FRIDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 10 PM UPDATE...LITTLE CHANGE TO THE GOING FORECAST. SCT SHOWERS AND SOME DRIZZLE REMAINS BUT THE STEADIER RAIN ACTIVITY HAS MOVED OFF TO THE EAST. COLD FRONT TRAVERSING VERMONT WILL MOVE ACROSS THE CWA AFTER MIDNIGHT AND THIS SHOULD SWEEP OUT MOST OF THE FOG AND THE STRATUS. 7 PM UPDATE...HAVE UPDATED THE FORECAST MAINLY FOR POP TIMING BASED ON LATEST RADAR AND MESOSCALE MODEL DATA. THE MAIN BATCH OF RAIN SHOULD MOVE OFF THE COAST OVER THE NEXT TWO HOURS...WITH LINGERING SHOWERS...ESPECIALLY IN THE MOUNTAINS...LASTING A FEW HOURS LONGER. PREVIOUSLY... FORECAST REMAINS ON TRACK FOR THE FROPA TONIGHT AS BAND OF SHRA MOVING EWD OUT OF NY AND INTO NEW ENGLAND ATTM. THIS BAND WILL TRACK ACROSS THE CWA THROUGH THE LATE AFTERNOON AND EVENING HOURS...AND SHOULD EXIT THE CWA AROUND OR JUST AFTER MIDNIGHT. BEST FORCING WITH THIS SYSTEM LOOKS TO BE HAPPENING NOW...AND THIS WILL LKLY WEAKEN AS THE BAND MOVES EAST...AS IS SUPPORTED BY NAM12 AND RECENT MESO MODELS....SO QPFS WILL GENERALLY BE AROUND OR LESS THAN A TENTH OF AN INCH...WITH SOME SLIGHTLY HIGHER AMTS IN SW NH AND ALONG THE INTL BORDER. WILL SEE TEMPS DROP OFF SEVERALDEGREES WHEN THE SHRA ARRIVE DUE TO WET BULBING...WITH SOME ADDITIONAL COOLING BEHIND THE FRONT. STILL MAY HAVE TO WAIT FOR MORNING FOR WINDS TO MIX DOWN...AND PATCHY FOG IS POSSIBLE ACROSS THE AREA. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... BEHIND THE FRONT WILL SEE NW WINDS PICK UP A BIT...GENERALLY 10-15 MPH WITH SOME GUSTS OF 20-25 MPH...ESPECIALLY DURING THE MORNING AND EARLY AFTERNOON. THE UPSLOPE/DOWNSLOPE MACHINE WILL BE WORKING AS WELL...WITH MORE CLOUDS IN THE MTNS...AND MOSTLY SUNNY SKIES ON THE COASTAL PLAIN. HIGHS SHOULD GENERALLY BE IN THE UPPER 50S TO MID 60S. AS SFC HIGH BUILDS IN WILL SEE A GOOD RAD COOLING NIGHT...AS SKIES CLEAR AND MAY LOCATIONS DECOUPLE. THE SHELTERED VALLEYS IN THE N WILL LKLY SEE TEMPS DROPPING INTO THE MID TO UPPER 30S...WITH A FEW READINGS IN THE LOW 30S POSSIBLE. THE BIG QUESTION IS WHETHER THESE AREAS FROST OR FOG EARLY MON MORNING. I HAVE ADDED FROST TO THE FORECAST ACROSS THE NRN ZONES...AND ALSO ALONG THE CT VLY. OUTSIDE OF THESE COLDER SPOTS...LOOK FOR LOWS OF 40-45. && .LONG TERM /MONDAY THROUGH SATURDAY/... AT THE START OF THE EXTENDED WEAK HIGH PRES CRESTS OVER THE REGION MON. A S/WV TROF MOVING THRU THE GREAT LAKES WILL PUSH A WEAK COLD FNT THRU THE AREA TUE. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON TIMING OF THE FROPA...WITH PASSAGE NEAR OR SHORTLY AFTER 18Z TUE. AS TEMPS ALOFT COOL BEHIND THE FNT...LINGERING PCPN MAY TRY AND MIX WITH FLAKES AT THE HIGHEST ELEVATIONS. TIS THE SEASON. ALL GUIDANCE ALSO CONTINUES TO ADVERTISE A NRN STREAM S/WV DRIVING A STRONG COLD FNT THRU THE REGION LATE WED INTO THU. THIS WOULD USHER IN THE COLDEST AIR OF THE SEASON SO FAR. NWP DOES LIKE TO RUSH THE COLD DURING THIS TRANSITION SEASON...SO I WILL BACK OFF THE RAW GUIDANCE SOMEWHAT. HOWEVER...THIS FORECAST DOES REPRESENT A COOLER SECOND HALF OF THE EXTENDED...ESPECIALLY THU NIGHT AND FRI. THE 13/00Z ECMWF AND 13/12Z GFS BOTH INSISTED ON -4 C TEMP AT H8 OVER NRN ZONES BY 12Z FRI...WHICH WOULD EQUATE TO A HARD FREEZE FOR MANY LOCATIONS THERE AS HIGH PRES CENTERS OVERHEAD. HOWEVER...13/12Z ECMWF HAS BACKED OFF A COUPLE DEGREES...AND THIS MATCHES GFS ENSEMBLES NICELY. OTHERWISE EXPECT A SEASONABLY COOL EXTENDED FOR TEMPS WITH LITTLE IN THE WAY OF PCPN. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... SHORT TERM...CIGS CONTINUE TO DROP THIS AFT AND MVFR CIGS SHOULD HOLD THROUGH SUNSET OR SHORTLY AFTER AS SHRA MOVE THROUGH THIS EVE. SHOWERS WILL WIND DOWN BY MIDNIGHT...AND DEPENDING ON HOW MUCH NW FLOW MIXES DOWN BEHIND THE FRONT...COULD IMPROVE CONDS BACK TO MVFR OR VFR QUICKLY...OR WE COULD SEE IFR OR LOWER IN LIGHT FLOW AT THE USUAL TERMINALS...KHIE/KLEB/KCON AND MAYBE KAUG. SHOULD SEE IMPROVEMENT TO VFR EVERYWHERE SUN MORNING...AND WITH THE EXCEPTION OF VLY FOG...SHOULD STAY VFR THRU SUN NIGHT. LONG TERM...EXPECT SCT MVFR CIGS AND POSSIBLY VSBYS IN A WEAK FROPA MON NIGHT INTO TUE. OTHERWISE HIGH PRES WILL DOMINATE THE FORECAST WITH VFR CONDITIONS EXPECTED TO PREVAIL. WILL HAVE TO WATCH FOR VALLEY FOG AS HIGH PRES CENTERS OVER THE REGION LATE IN THE WEEK. && .MARINE... SHORT TERM...NW WINDS BEHIND A COLD FRONT WILL FLARE UP LATE TONIGHT INTO EARLY SUNDAY. COULD SEE A FEW GUSTS TO 25 KT AROUND THIS TIME...BUT HAVE HELD OFF ON THE SCA FOR NOW. OTHERWISE WINDS SHOULD DIMINISH QUICKLY SUNDAY AFTERNOON AND REMAIN LIGHT SUN NIGHT AS HIGH PRES BUILDS IN. LONG TERM...WINDS AND SEAS LOOK LIKELY TO REACH SCA THRESHOLDS IN CAA OVER THE WARM WATERS ON THU. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ NEAR TERM UPDATE...MLE NEAR TERM...CEMPA SHORT TERM...CEMPA LONG TERM...LEGRO AVIATION...CEMPA/LEGRO MARINE...CEMPA/LEGRO

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