Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 281353 AAA
AFDGYX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAY ME
953 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...ADJUSTMENTS WERE MADE TO POPS AND WEATHER GRIDS BASED ON
CURRENT PRECIPITATION TRENDS. SURFACE LOW PRESSURE MAKING VERY
LITTLE NORTHWARD MOVEMENT AS IT DEVELOPS/DEEPENS ABOUT 285 EAST OF
LONG ISLAND. THIS HAS KEPT PRECIPITATION ECHOES STALLED OVER NEW
ENGLAND THIS MORNING AS TOP DOWN SATURATION OCCURS. AS WELL AS THE
MESOSCALE LIFT... DEEP LONG WAVE TROUGH IS APPROACHING THE EAST
COAST AND WILL BE ANOTHER SOURCE OF LIFT TODAY.

&&

PREVIOUS DISCUSSION...LOW PRESSURE WILL FORM WELL EAST 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 MONADNOCK 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 /14Z 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.

&&

$$

UPDATE...HANES



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