Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 300404
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1204 AM EDT TUE JUN 30 2015

.SYNOPSIS...
ABUNDANT LOW LEVEL MOISTURE FROM RECENT RAINFALL WILL ALLOW FOR
SOME VALLEY FOG TO FORM OVERNIGHT. WEAK HIGH PRESSURE WILL MOVE
INTO THE REGION FOR TOMORROW BEFORE ANOTHER LOW PRESSURE SYSTEM
APPROACHES FROM THE WEST TOMORROW NIGHT AND WEDNESDAY. THE SYSTEM
WILL BRING SHOWERS AND THUNDERSTORMS TO THE REGION ON WEDNESDAY
BEFORE HIGH PRESSURE MOVES IN ON THURSDAY. HIGH PRESSURE THEN
REMAINS IN PLACE INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...

1201 AM...MINOR ESTF UPDATE TO FIRST PERIOD GRIDS TO REFLECT
CURRENT MESONET AND RADAR TRENDS.

PREV DISC...
JUST A COUPLE SPRINKLES REMAIN IN SOUTHERN NEW HAMPSHIRE AND
SOUTHWEST MAINE. VERY LITTLE CHANGE TO THE CURRENT PACKAGE AS
PATCHY FOG BEGINS TO DEVELOP OVER SHELTERED AREAS WITH PARTIAL
CLEARING.

UPDATE...
HAVE UPDATED THE GRIDS BASED ON CURRENT CONDITIONS ACROSS MAINE
AND NEW HAMPSHIRE. WILL CONTINUE TO KEEP A SLIGHT CHANCE OF
SHOWERS IN THE FORECAST FOR ANOTHER COUPLE HOURS ACROSS WESTERN
MAINE AND NEW HAMPSHIRE AS LIGHT PRECIP CONTINUES TO MOVE
EASTBOUND PER LATEST RADAR IMAGERY. MOST OF THE LATEST SUITE OF
MESOSCALE MODELS SHOW THE PRECIP DISSIPATING THIS EVENING.

STRONG ONSHORE COMPONENT WILL CONTINUE TO WEAKEN THIS EVENING
ALONG THE COAST. THIS KEPT TEMPERATURES MUCH COOLER RIGHT ALONG
THE SHORELINE TODAY.

ADDED MORE CLOUDINESS TO THE FORECAST AND MADE MINOR ADJUSTMENTS
TO WINDS AND DEW POINTS.

PREV DISC...
FAIRLY QUIET NIGHT IN STORE. EXPECT CLOUD COVER TO
QUICKLY DIMINISH AFTER SUNSET. RADIATIONAL COOLING...COUPLED WITH
ABUNDANT LOW LEVEL MOISTURE FROM PREVIOUS RAINFALL...WILL ALLOW
FOR SOME PATCHY FOG TO DEVELOP IN FAVORED LOCATIONS. EXPECT FOG TO
FORM PRIMARILY IN VALLEYS AND ALONG COASTAL LOCATIONS.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
FOG SHOULD BURN OFF QUICKLY TOMORROW WITH SIGNIFICANT SUNSHINE
BEING THE RULE FOR THE DAY. WEAK HIGH PRESSURE WILL NOT HOLD IN
PLACE TOO LONG THOUGH. APPROACHING LOW PRESSURE SYSTEM MOVING
THROUGH THE GREAT LAKES WILL BEGIN TO AFFECT THE WEATHER OVER
NORTHERN NEW ENGLAND LATE TUESDAY NIGHT. AS FRONTAL BOUNDARY MOVES
ACROSS CWA LATE TUESDAY NIGHT EXPECT SHOWERS TO FORM FROM SOUTH TO
NORTH. DYNAMICS LOOK STRONG ENOUGH THAT THERE COULD BE SOME
EMBEDDED THUNDER BY SUNRISE WEDNESDAY MORNING.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
WED LOOKS LIKE THE MOST INTERESTING DAY IN THE EXTENDED AT THIS
TIME...AS STRONG S/WV TROF CROSSES THE NORTHEAST AND TRIGGERS
AFTERNOON TSTMS. 50 KT H5 JET STREAK WILL CROSS THE
AREA...PROVIDING AMPLE SHEAR. AT THIS RANGE SPC SREF INDICATES A
HIGH LIKELIHOOD FOR 0-6 KM SHEAR TO FALL BETWEEN 30 AND 40
KTS...WHICH SHOULD LEAD TO SOME STORM ORGANIZATION. LAPSE RATES
ARE A BIGGER QUESTION MARK...WITH THE ECMWF AND GFS ADVECTING
MARGINAL 6 TO 6.5 C/KM LAPSE RATES OVERHEAD...WHILE THE NAM
PREFERS MORE MEAGER VALUES. IF WE CAN REALIZE GREATER THAN 6 C/KM
LAPSE RATES...SUFFICIENT INSTABILITY SHOULD BE IN PLACE FOR SOME
STRONGER TSTMS. GUSTY WINDS AND HAIL WOULD BE THE MAIN
THREATS...WITH WET BULB ZERO VALUES NEAR IDEAL FOR HAIL IN THE GYX
FORECAST AREA PER LOCAL STUDIES. AS PWAT VALUES CLIMB OVER 1.5
INCHES NEAR THE COAST...CANNOT RULE OUT HEAVY RNFL IN ANY
CONVECTION AS WELL.

MAIN UPPER TROF AXIS SWINGS THRU THU...WHICH WILL ALLOW HIGH PRES
TO BUILD IN FROM THE W FOR LATE IN THE WEEK AND HOLIDAY WEEKEND.
AT THIS TIME...THE FINAL PUSH OF THE TROF LOOKS TO KEEP ANY PCPN
WELL S OF THE REGION...BUT CANNOT REMOVE POP COMPLETELY ESPECIALLY
FOR SRN AND COASTAL ZONES WITH ITS PASSAGE. ECMWF AND GFS NOW
AGREE ON HIGH PRES TO BEGIN THE HOLIDAY WEEKEND...ALBEIT COOL
HIGH PRES. HOWEVER...WITH WRN RIDGING STILL HOLDING STRONG THE
TENDENCY WILL BE FOR LOWER HEIGHTS ACROSS THE ERN CONUS...AND
RATHER FREQUENT S/WV ACTIVITY. THE NEXT APPEARS SET FOR LATE IN
THE WEEKEND...MOST LIKELY SUN. FOR THE FORESEEABLE FUTURE TEMPS
LOOK TO REMAIN NEAR TO BELOW NORMAL...WITH UNSETTLED WX
CONDITIONS.

&&

.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /THROUGH 12Z WED/...VFR CONDITIONS WILL DETERIORATE TO
IFR/LIFR AT TAFS SITES WHERE VALLEY FOG IS FAVORED AT PATCHY FOG
DEVELOPS OVERNIGHT. CONDITIONS WILL RAPIDLY IMPROVE TO VFR AT ALL
LOCATIONS TOMORROW MORNING. APPROACHING FRONTAL BOUNDARY LATE
TUESDAY NIGHT WILL BRING CIGS/VSBYS DOWN TO MVFR/IFR BY SUNRISE
WEDNESDAY MORNING.

LONG TERM...VFR EXPECTED TO GENERALLY PREVAIL THRU THE EXTENDED.
COLD FRONT CROSSES THE AREA WED...WITH AREAS OF MVFR AND ISOLD IFR IN
SHRA/TSRA. HIGH PRES LOOKS TO BUILD INTO THE REGION THRU THE
HOLIDAY WEEKEND. ANOTHER TROF CROSSES THE AREA WITH SHRA POSSIBLE
SUN.

&&

.MARINE...
SHORT TERM /THROUGH WEDNESDAY MORNING/...NO FLAGS EXPECTS.

LONG TERM...WINDS AND SEAS GENERALLY LOOK TO REMAIN BELOW SCA
THRESHOLDS. SWLY FLOW WILL INCREASE AHEAD OF THE NEXT COLD FRONT
AND SEAS WILL BUILD TO NEAR 5 FT ON THE OUTER WATERS...THOUGH
CONFIDENCE IS LOW IN REACHING THAT VALUE AT THIS TIME.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.

&&

$$
ES


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