Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 132304
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
705 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/...
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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