708
FXUS61 KGYX 291032
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
632 AM EDT TUE JUL 29 2025
SYNOPSIS
HOT AND HUMID CONDITIONS WILL PERSIST THROUGH WEDNESDAY, BUT
HEAT PEAKS TODAY. A COLD FRONT WILL DROP SOUTH THROUGH THE AREA
WEDNESDAY EVENING BRINGING CHANCES FOR STRONG THUNDERSTORMS AND
RELIEF FROM THE HEAT AND HUMIDITY THE SECOND HALF OF THE WEEK.
THE FRONT MAY STALL CLOSE ENOUGH ACROSS SOUTHERN NEW ENGLAND TO
KEEP CHANCES FOR SHOWERS IN THE FORECAST THURSDAY WITH CANADIAN
HIGH PRESSURE BRINING MOSTLY DRY CONDITIONS LATE FRIDAY THROUGH
THE WEEKEND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
630AM UPDATE...VALLEY FOG WILL DISSIPATE OVER THE NEXT HOUR OR
TWO, LEAVING AN OTHERWISE SUNNY DAY WITH SOME PASSING CIRRUS.
NO LARGE CHANGES TO THE GOING FORECAST.
PREVIOUS DISCUSSION...
KEY MESSAGES:
* HEAT PEAKS TODAY WITH HIGH TEMPERATURES IN THE LOW TO MID 90S
ACROSS MOST LOCATIONS OUTSIDE OF THE MOUNTAINS. HEAT INDEX
VALUES CLIMB INTO THE MID TO UPPER 90S FOR MUCH OF SOUTHERN
NH AND FAR SOUTHERN COASTAL ME.
* HEAT ADVISORY EXTENDED INTO COASTAL YORK COUNTY FOR TODAY.
WITH NEAR FULL SUN TODAY AND WARM AIRMASS ALREADY IN PLACE, NOT
MUCH SWAY IN HOT TEMPERATURE FORECAST TODAY. CONSOLATION WILL
BE NW BREEZE SOURCING DRIER AIR FROM CONTINENTAL AIRMASS VS. A
SOUTHERLY MOISTURE SOURCE. THIS EQUATES TO TEMPERATURES IN THE
90S FOR NEARLY TWO THIRDS OF THE FORECAST AREA, WITH MID TO
UPPER 90S IN SOUTHERN NH AND UPPER 80S TO LOWER 90S UP THE
SOUTHERN ME COASTAL PLAIN.
WHILE THE NW BREEZE WILL BE DRIER, IT DOES QUASH THE POTENTIAL
FOR A RELIEVING SEA BREEZE ALONG AND JUST INLAND FROM THE COAST.
LOOKING BACK AT MONDAY, OBSERVED DEW POINT TEMPERATURES WERE
GREATEST IN AND AROUND CONVERGENCE OF INLAND WINDS AND ONSHORE
SEABREEZE. WITH A STRONGER NW BACKGROUND TODAY, EXPECT THIS
INTERFACE TO BE AT OR NEAR THE COAST. GIVEN THE HOT AIRMASS,
EXTENDED THE HEAT ADVISORY INTO COASTAL YORK COUNTY TODAY WHERE
A NARROW CORRIDOR OF HEAT INDICES AROUND 95 WILL LINGER. CAN'T
RULE OUT THESE VALUES ALSO MAKING IT INTO THE PORTLAND AREA FOR
A COUPLE HOURS TODAY, BUT COVERAGE FOR REST OF COASTAL
CUMBERLAND ISN'T ENOUGH TO WARRANT A ADV.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/
KEY MESSAGE:
* A COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS TO THE
REGION WEDNESDAY. EXTENT OF STRENGTH AND COVERAGE REMAINS
VARIABLE, BUT STRONG STORMS WILL BE POSSIBLE GIVEN FORCING
AND THE VAST AMOUNT OF WIND SHEAR.
INCOMING COLD FRONT WEDNESDAY REMAINS PRIMARY TRIGGER FOR SHOWER
AND STORM DEVELOPMENT DURING THE DAY. ITS PROGRESSION EASTWARD
HAS SLOWED IN GUIDANCE, AND SO CHANGES FOCUS AREA FOR THE THREAT
OF STRONG TO SEVERE THUNDERSTORMS.
SLOWING OF THE FRONT MEANS MORE TIME FOR THE COAST TO REMAIN
UNDER RETURN FLOW FROM DEPARTING HIGH PRESSURE. THIS TRANSLATES
TO A MARINE LAYER THAT'S MORE RESISTANT TO DESTABILIZATION
THROUGH WED AFTERNOON. THUS FOCUS FOR MORE 'FAVORABLE'
CONDITIONS LIES WEST ACROSS CENTRAL NH AND INTO THE
FOOTHILLS/INTERIOR ME. LATEST HREF GUIDANCE DEPICTS MARGINAL
CONFIDENCE OF ATTAINING SBCAPE GREATER THAN 1000 J/KG, AND ONLY
A FEW INSTANCES OF SIMULATED ECHO TOPS GREATER THAN 30KFT.
VARIABLE WITH GREATER CONFIDENCE IS ABUNDANT 0-3/6KM SHEAR OF 30
TO 50 KTS. WILL CONTINUE TO MONITOR TRENDS IN INSTABILITY AS
MORE ASSURANCE HERE WOULD QUICKLY INCREASE SEVERE THREAT.
WITH GREATER CLOUD COVER ANTICIPATED AHEAD OF THE COLD FRONT AND
AMID SHOWERS/STORMS WEDNESDAY, TEMPERATURES FALL A FEW DEGREES
LOWER THAN TUESDAY. HOWEVER, STILL EXPECT HEAT TO BUILD INTO THE
80S AND LOWER 90S FOR AT LEAST A PORTION OF THE DAY BEFORE
PRECIP COVERAGE INCREASES.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
EVENING UPDATE: THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS
WILL WANE WEDNESDAY EVENING AND NIGHT AS THE COLD FRONT SINKS
THROUGH THE REGION AND WE LOSE DAYTIME INSTABILITY. A FEW
LINGERING SHOWERS WILL REMAIN POSSIBLE THOUGH AS A WEAK WAVE OF
LOW PRESSURE MOVES ALONG THE FRONTAL BOUNDARY. LOW TEMPERATURES
WILL RANGE FROM THE 50S ACROSS THE NORTH WITH 60S ELSEWHERE.
THE MAIN QUESTION MARK OF THE EXTENDED CONTINUES TO BE THE
PLACEMENT OF THE COLD FRONT ON THURSDAY INTO FRIDAY AS AN AREA
OF LOW PRESSURE RIDES ALONG IT. A MORE NORTHWARD PLACEMENT WOULD
PROVIDE AN OPPORTUNITY FOR SOME MUCH NEEDED RAINFALL OVER AT
LEAST SOUTHERN AREAS ON THURSDAY INTO THURSDAY NIGHT WHILE A
TRACK FURTHER SOUTH WOULD LIKELY JUST RESULT IN A FEW SCATTERED
SHOWERS RATHER THAN A STEADY SOAKING RAIN. WILL CONTINUE TO
MONITOR THIS BUT COOLER TEMPERATURES ARE OF HIGH CONFIDENCE WITH
HIGHS ONLY INTO THE 70S AND LOWS INTO THE 40S/50S.
HIGH PRESSURE THEN LOOKS TO RETURN SATURDAY THROUGH EARLY NEXT WEEK
WITH GRADUALLY MODERATING TEMPERATURES BACK TOWARDS SEASONABLE
AVERAGES.
PREVIOUS DISCUSSION:
COLD FRONT MAY STALL OVER SOUTHERN NEW ENGLAND THURSDAY INTO
FRIDAY MORNING KEEPING CHANCES FOR SHOWERS IN THE FORECAST
ACROSS SOUTHERN ZONES. AN EMERGING POSITIVE PNA PATTERN WILL
HELP PUSH A COOL AND DRY CANADIAN AIRMASS INTO THE REGION
FRIDAY. THIS COOL AND DRY AIR MASS WILL MODERATE THROUGH THE
WEEKEND AS HIGH PRESSURE BRINGS MOSTLY SUNNY SKIES.
MODELS START TO DIVERGE IN THE PLACEMENT OF THE STALLING FRONT
THURSDAY INTO FRIDAY. SOME SOLUTIONS KEEP THE FRONT CLOSE TO THE
NH/MA BORDER WITH WAVES OF LOW PRESSURE BRINGING ROUNDS OF SHOWERS
WEDNESDAY NIGHT THROUGH FRIDAY MORNING, MAINLY SOUTH OF THE
MOUNTAINS. OTHER SOLUTIONS SHIFT THE FRONT FAR ENOUGH SOUTH THAT
MUCH OF THE FORECAST AREA WILL REMAIN MOSTLY DRY THURSDAY INTO
FRIDAY. HAVE LARGELY STUCK WITH THE NBM DURING THIS PERIOD WHICH
MAINTAINS POPS OF 30 TO 50 PERCENT ACROSS THE SOUTHERN HALF OF THE
AREA. IT WILL BE MUCH COOLER THE SECOND HALF THE WEEK THAN THE FIRST
HALF WITH HIGHS THURSDAY AND FRIDAY MAINLY IN THE 70S. CANADIAN HIGH
PRESSURE BUILDS IN FRIDAY AND WILL BRING FAIR WEATHER OVER THE
WEEKEND WITH TEMPERATURES MODERATING INTO THE 80S BY SUNDAY.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
SHORT TERM...VFR TODAY THROUGH TONIGHT, EXCEPT HIE AND LEB MAY
AGAIN SEE VALLEY FOG. WEDNESDAY, SHRA AND TS DEVELOP AHEAD OF A
COLD FRONT. TS SHOULD MOSTLY FALL INLAND FROM COASTAL TERMINALS,
BUT COULD APPROACH AS THE FRONT PUSHES NEAR THE COAST LATE.
LONG TERM...A COLD FRONT STALLS NEAR THE NH/MA BORDER WEDNESDAY
NIGHT THROUGH THURSDAY THAT COULD BRING AT LEAST PERIODS OF
MVFR CIGS ACROSS SOUTHERN TAF SITES. DRIER AIR ARRIVES FRIDAY
WITH VFR LIKELY OVER THE WEEKEND.
MARINE
SHORT TERM...CONDITIONS ARE EXPECTED TO REMAIN BELOW SCA
LEVELS. LOW PRESSURE WILL BE NEAR THE CANADIAN MARITIMES TODAY
WITH SURFACE TROUGH DRAPED NEAR OR JUST OFFSHORE OF THE ME
COASTLINE. THE LOW AND TROUGH MOVES EAST LATE TODAY INTO
TONIGHT, ALLOWING HIGH PRESSURE TO BUILD IN AND VEER WINDS TO
MORE NORTHERLY. ANOTHER COLD FRONT WILL APPROACH THE WATERS
WEDNESDAY EVENING, BRINGING SHOWERS AND CHANCE OF A
THUNDERSTORM. THIS FRONT MAY STALL INTO LATE WEEK.
LONG TERM...WINDS AND SEAS GENERALLY STAY BELOW SCA THRESHOLDS
INTO THE WEEKEND. BOUNDARY OVERHEAD WILL PROVIDE A FOCUS FOR
CLOUDS AND SHOWERS AND PERHAPS SOME FOG. HIGH PRESSURE BUILDS IN
FROM THE NW FRIDAY INTO THE WEEKEND.
GYX WATCHES/WARNINGS/ADVISORIES
ME...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING
FOR MEZ023.
NH...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING
FOR NHZ008-010-012>015.
MARINE...NONE.
NEAR TERM...CORNWELL
SHORT TERM...CORNWELL
LONG TERM...SCHROETER/TUBBS
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