Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 280816
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
316 AM EST SAT FEB 28 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE REGION TODAY AND WILL SHIFT
OFFSHORE SUNDAY. WEAK LOW PRESSURE CROSSES THE REGION SUNDAY
NIGHT...PRODUCING SOME ACCUMULATING SNOW...BEFORE MOVING INTO THE
CANADIAN MARITIMES ON MONDAY. HIGH PRESSURE CROSSES THE AREA
MONDAY NIGHT AND TUESDAY. LOW PRESSURE WILL MOVE OUT OF THE GREAT
LAKES TUESDAY NIGHT AND WILL TRACK NORTHEAST THROUGH THE ST
LAWRENCE VALLEY ON WEDNESDAY...BRINGING A ROUND OF MIXED
PRECIPITATION TO THE AREA. A COLD FRONT FOLLOWS WEDNESDAY NIGHT.
HIGH PRESSURE BUILDS IN FOR THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE WEST TODAY
PROVIDING SUNNY SKIES AND SLIGHTLY WARMER TEMPS. HIGHS WILL RANGE
FROM THE UPPER TEENS TO LOWER 20S NORTH AND MID TO UPPER 20S
SOUTH.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/...
HIGH PRESSURE WILL CREST OVER THE REGION TONIGHT. GOOD RADIATIONAL
COOLING WILL AGAIN SEND TEMPS WELL BELOW NORMAL BUT NOT QUITE AS COLD
AS FRIDAY NIGHT. COLDER MOUNTAIN VALLEYS WILL BOTTOM OUT BETWEEN
5 AND 15 BELOW. TEMPERATURES IN THE SOUTH WILL BE BETWEEN 5 ABOVE
AND 5 BELOW. EXPECT SOME HIGH CLOUDS TO FILTER IN FROM THE WEST
AFTER MIDNIGHT.

CLOUDS WILL BE ON THE INCREASE SUNDAY AS HIGH PRESSURE SHIFTS EAST
AND A COLD FRONT APPROACHES FROM THE WEST. HAVE GONE WITH LOW
CHANCE POPS FOR SOUTHWEST ZONES FOR LATE IN THE DAY BUT EXPECT ANY
SNOW SHOWERS TO BE LIGHT AND SPOTTY. HIGH TEMPS WILL CONTINUE
BELOW NORMAL WITH READINGS RANGING THROUGH THE 20S TO NEAR 30.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
500 MB PATTERN IN THE EXTENDED LOOKS TO REMAIN MOSTLY UNCHANGED
THROUGH THE EXTENDED ALTHOUGH STARTING TO SEE SOME SEASONAL
SHIFTING OF THE JET BACK TOWARD THE POLE. ALSO...SOME WEAKEN IN
BOTH THE UPSTREAM AND DOWNSTREAM BLOCKS WILL ALLOW FOR SOME MORE
COMPACT AND PROGRESSIVE WAVES TO DEVELOP WHICH SHOULD HELP
TRANSPORT SOME WARMER INTO THE NERN CONUS...AT LEAST FOR SHORT
PERIODS.

FIRST ON THE AGENDA IS THE FAST MOVING WAVE THAT SWINGS SE OUT OF
THE CANSDI9AN PRAIRIE AND THEN SHIFTS INTO NEW ENGLAND BEFORE
SHOWING A BIT OF A NEGATIVE TILT. LOOKS LIKE THE ENERGY GET S INTO
THE BASE OF THIS TROUGH TO LATE TO DEEPEN THE SFC LOW UNTIL IT IS
TO OUR EAST...AND SO WE WILL SOME SNOW LATE SUNDAY AND MAINLY
SUNDAY NIGHT. QPF LOOKS TO COME IN THE AROUND 0.20-0.25" FAIRLY
EVENLY ACROSS THE CWA...AND THIS SHOULD GENERALLY TRANSLATE TO
2-4" OF SNOW GIVEN SNOWFALL RATIOS OF ROUGHLY 10-15 TO 1. HIGHEST
AMTS LOOK TO BE IN THE SRN THIRD OF NH...WITH LOWEST AMTS IN
INTERIOR CENTRAL ME.  SNOW SHOULD WIND DOWN IN MOST PLACES BY
12Z...WITH WEST WINDS PICKING UP BY MIDDAY AND TEMPS RISING INTO
THE LOW-MID 30S NEAR THE COAST AND IN SRN NH...AND IN THE MID-
UPPER 30S IN THE NORTH. COLD AIR FILTERS IN MON NIGHT WITH LOWS
DROPPING BACK DOWN BETWEEN -5 AND +10 F. TUE WILL BE A LITTLE
COLDER AS LIGHT FLOW BECOMES MORE ONSHORE AND CLOUDS ROLL IN FROM
THE NEXT APPROACHING FROM THE SW.

THIS NEXT SYSTEM WILL FEATURE A 500MB CLOSED LOW WELL TO OUR NW
AND A FEW WEAK WAVES ROTATING AROUND IT AND GRADUALLY FLATTENING
OUT THE RIDGE UNTIL THE KICKER WAVE COME THRU ON THU. THIS WILL
KEEP THINGS UNSETTLED FROM TUE NIGHT INTO THE THU...ALTHOUGH THE
HIGHEST CONFIDENCE IN PRECIP OCCURRING FOR NOW TUE NIGHT INTO WED
MORNING. IT WILL START OUT AS SNOW...BUT IT WILL BE ACCOMPANIED BY
DECENT SW FLOW ALOFT...AND MAIN CHUNK OF HIGH SHIFTS OFF TO THE
EAST AND DOES NOT ENTRENCH ITSELF TO THE NE. THIS SHOULD ALLOW
THE WARN AIR TO MOVE IN FAIRLY CLOSE TO THE SFC. THE QUESTION IS
HOW LONG DOES THE COLD AIR DAM AT THE SFC HOLD ON...GIVEN THE DEEP
SNOWPACK. MODELS ARE PROBABLY OVERDOING THE WARM TO SOME DEGREE.
HAVE INCLUDED FZRA IN THE MIX ON WED. STILL SYSTEM IS FAIRLY
PROGRESSIVE AND QPFS GENERALLY LOOK TO BE IN THE HALF INCH
BALLPARK...SO NOT A BIG EVENT FOR NOW.

MODELS DO WANT TO STALL THE FRONT JUST TO OR S WED NIGHT INTO
THU...AND THEN DEVELOP A WAVE ALONG THE FRONT. FOR NOW MODELS
GENERALLY AGREE THAT MOST OF ANY PRECIP STAYS TO OUR S...BUT HAVE
KEPT THE CHC POPS IN THE FORECAST TO COVER THIS POSSIBILITY.
COLDER HIGH PRESSURE THEN BUILDS IN FOR FRI.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR TODAY THROUGH TONIGHT. AREAS OF MVFR CIGS
DEVELOPING LATE SUNDAY.

LONG TERM...WILL LKLY SEE IFR CIGS/VIS IN SN FOR A GOOD CHUNK OF
SUN NIGHT AT ALL TERMINALS...BUT SHOULD SEE RAPID IMPROVEMENT OT
VFR FORM SW TO NE DURING MON MORNING /EXCEPT KHIE WHICH WILL SEE
OCCNL MVFR-IFR IN SHSN THRU MON AFTERNOON. VFR HOLDS MON NIGHT AND
TUE BEFORE ANOTHER SYSTEM MOVES IN TUE AND WILL PRODUCE FLIGHT
RESTRICTIONS LATE TUE NIGHT INTO WED.

&&

.MARINE...
SHORT TERM...FREEZING SPRAY ADVISORY THROUGH LATE MORNING.

LONG TERM...EXPECT TO NEED AN SCA MONDAY AFT INTO MON NIGHT IN W
FLOW. MAY NEED GALES FOR A PERIOD LATE MON AND MON
EVENING...BEFORE WINDS DIMINISH LATE MON NIGHT. SCA MAY BE NEEDED
AGAIN IN SW FLOW LATE TUE NIGH AND WED.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...FREEZING SPRAY ADVISORY UNTIL NOON EST TODAY FOR ANZ150>152.

&&

$$



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