Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 281032 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 632 AM EDT SAT MAR 28 2015 .SYNOPSIS... LOW PRESSURE WILL PASS SOUTHEAST OF CAPE COD TODAY AND SOUTH OF NOVA SCOTIA TONIGHT. A LINGERING TROUGH OF LOW PRESSURE WILL ALLOW FOR SOME LIGHT SNOW TODAY. HIGH PRESSURE WILL BUILD IN FOR SUNDAY. WEAK LOW PRESSURE WILL PASS OVER OR NORTH OF OUR REGION LATER MONDAY AND MONDAY NIGHT. WEAK LOW PRESSURE IS EXPECTED TO PASS SOUTH OF NEW ENGLAND TUESDAY NIGHT INTO WEDNESDAY FOLLOWED BY HIGH PRESSURE INTO THURSDAY. A STORM SYSTEM MAY AFFECT NEW ENGLAND LATE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...MINOR CHANGES TO ADJUST FOR CURRENT OBSERVATIONAL TRENDS. PREVIOUS DISCUSSION...LOW PRESSURE WILL FORM WELL SOUTH OF LONG ISLAND NY TODAY AND MOVE WELL SOUTHEAST OF NOVA SCOTIA BY THIS EVENING. STRONG UPPER LEVEL LOW PRESSURE MOVING OVER NEW ENGLAND TODAY WILL AID IN A WEAK LOW LEVEL TROUGH OF LOW PRESSURE TO LINGER ACROSS THE REGION TODAY. THIS TROUGH WILL INDUCE SOME LIGHT SNOW...PERHAPS MIXED WITH A LITTLE LIGHT RAIN AT TIMES AT LOWER ELEVATIONS TODAY. IT APPEARS AS THOUGH THE MAIN FORCING FOR ASCENT AND BEST MOISTURE ADVECTION WITH THIS FEATURE WILL BE ACROSS SOUTHERN NEW ENGLAND AND THIS IS WHERE WE EXPECT THE HIGHEST QPF TO BE. HOWEVER...SOUTHERN AND CENTRAL NH AS WELL AS PORTIONS OF SOUTHERNMOST MAINE MAY SEE IT SNOW JUST HARD ENOUGH FOR SOME ACCUMULATION. CURRENT THINKING IS THAT THE MONOTONIC REGION OF NEW HAMPSHIRE STANDS THE BEST CHANCE AT PICKING UP 1 TO 3 INCHES OF SNOW DUE TO ELEVATION AND PROXIMITY TO BEST CONVERGENT ZONE. THE SUN ANGLE IS QUITE HIGH THIS TIME OF YEAR SO IT WILL TAKE A DECENT INTENSITY TO ALLOW THE SNOW TO STICK EFFECTIVELY AND ACCUMULATE OUTSIDE OF ANY NARROW HEAVIER BANDS OF SNOW THAT DEVELOP. SINCE THIS IS A MESOSCALE-DRIVEN EVENT...IT WILL HAVE TO BE NOWCASTED THROUGH THE MORNING INTO THE AFTERNOON HOURS AND SNOWFALL AMOUNTS CHANGED ACCORDINGLY. HOWEVER...THE UPSHOT IS THAT IT IS EXPECTED TO BE LIGHT FOR MOST EVERYONE BUT A FEW LOCATIONS MAY SEE A FEW HOURS OF HEAVIER SNOWFALL. ACROSS THE FAR NORTHERN AND EASTERN ZONES...NOT MUCH OF ANYTHING MAY FALL. AS FOR TEMPERATURES...THEY SHOULD BE IN THE LOWER TO MID 30S TODAY...COLDER IN THE MOUNTAINS. WINDS WILL BE GUSTY FROM THE NORTH TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... ANY LIGHT PRECIPITATION IS EXPECTED TO RAPIDLY COME TO AN END THIS EVENING...IF NOT LATE THIS AFTERNOON. COLD HIGH PRESSURE BUILDS IN TONIGHT WITH LOWS WELL BELOW NORMAL. WARM AIR ADVECTION REGIME GETS GOING ON SUNDAY SO WE ARE EXPECTED TEMPERATURES TO REBOUND TO AT LEAST THE LOWER 40S UNDER PLENTY OF SUNSHINE. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODEL GUIDANCE REMAINS CONSISTENT WITH THE THEME THRU THE EXTENDED. BROAD TROF WILL EXIST OVER THE ERN CONUS...MEANING GENERALLY NEAR TO BELOW NORMAL TEMPS FOR THE NORTHEAST. THE SILVER LINING FOR THOSE EAGER FOR SPRING IS THAT THE PATTERN DOESN/T SEEM CONDUCIVE FOR SUSTAINED COLD BUT RATHER TRANSIENT SHOTS OF COLDER AIR. THE FIRST OF WHICH ARRIVES MON FROM THE W. PCPN WILL BE LIGHT...BUT EXPECT PLENTY OF RA OR SN SHWRS WILL BE AROUND DURING THE DAY. WLY FLOW WILL KEEP SHSN GOING IN THE MTNS INTO TUE...BEFORE RIDGING BRINGS AN END TO ANY PRECIP. IT IS QUICKLY FOLLOWED UP BY ANOTHER NRN STREAM WAVE...BUT MODEL GUIDANCE IS MORE FOCUSED ON KEEPING THAT S OF OUR AREA. BEYOND THAT TIME FRAME CONFIDENCE IS LOW...AS THESE FAST MOVING...COMPACT S/WV TROFS ARE DIFFICULT FOR NWP TO HANDLE THIS TIME OF YEAR. THESE TIMING AN EVOLUTION DIFFERENCES LEAD TO SOLUTIONS LIKE THE GFS BEING VERY PROGRESSIVE WITH THE NEXT WAVE BY LATE IN THE WORK WEEK. OR CONVERSELY THE STRONGER WAVE COULD DELAY LIKE THE ECMWF AND ARRIVE OVER THE WEEKEND. AGAIN WITH TEMPS AVERAGING NEAR TO BELOW NORMAL AT LEAST SOME SN WILL REMAIN IN THE FORECAST WITH ANY OF THESE SYSTEMS. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...VARIABLE CONDITIONS IN LIGHT SNOW OR A RAIN/SNOW MIX AT THE COAST ARE EXPECTED TODAY. CONDITIONS WILL BE VFR AT TIMES...BUT LATER THIS MORNING INTO THE EARLY AFTERNOON HOURS...CONDITIONS ARE EXPECTED TO BECOME IFR AT TIMES. VFR CONDITIONS RETURN TONIGHT RIGHT THROUGH SUNDAY. LONG TERM...VFR CONDITIONS WILL GIVE WAY TO WIDESPREAD MVFR AS A COLD FRONT APPROACHES FROM THE W. RA AND SN SHWRS WILL CROSS THE AREA MON...WITH LINGERING UPSLOPE SHSN FOR KHIE THRU MUCH OF THE DAY AND OVERNIGHT. GUSTY WLY FLOW AND IMPROVING CONDITIONS ARE EXPECTED TUE AND WED. THERE IS LOW CONFIDENCE IN PCPN ACROSS SRN NH AS ANOTHER WEAK LOW PRES PASSES S OF THE REGION. && .MARINE... SHORT TERM...SCA FOR THE BAYS TODAY FOR WIND GUSTS AROUND 25 KT. SCA FOR THE OCEAN WATERS THROUGH SUNDAY INITIALLY FOR WINDS TODAY...THEN PROBABLY JUST SEAS AOA 5 FT TONIGHT INTO SUNDAY. LONG TERM...WITH TROF HANGING AROUND THE ERN CONUS...THE WATERS WILL BE SUSCEPTIBLE TO CONTINUED SHOTS OF COLDER AIR. THESE COLD FRONTS WILL BRING WITH THEM LIKELY SCA CONDITIONS. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ151- 153. SMALL CRAFT ADVISORY UNTIL 6 PM EDT SUNDAY FOR ANZ150-152-154. && $$

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