385
FXUS61 KGYX 301020
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
620 AM EDT WED JUL 30 2025
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN HEAT AND HUMIDITY ONE MORE DAY. A SLOW
MOVING COLD FRONT WILL PUSH THROUGH THE REGION LATE THIS
AFTERNOON SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS, SOME
MAY BE STRONG TO SEVERE. THE FRONT WILL STALL OVER SOUTHERN NEW
HAMPSHIRE THURSDAY SUPPORTING MORE WIDESPREAD RAINFALL FOR
AREAS SOUTH OF THE MOUNTAINS. HIGH PRESSURE WILL THEN BUILD FROM
THE NORTH INTO THE WEEKEND, WITH BELOW NORMAL TEMPERATURES,
MUCH DRIER AND PLEASANT CONDITIONS EXPECTED.
NEAR TERM /THROUGH TODAY/
620 AM UPDATE...MAINLY JUST MINOR TWEAKS TO ALIGN WITH
OBSERVATIONS AS THE GOING FORECAST REMAINS IN GOOD SHAPE.
IMPACTS AND KEY MESSAGES:
* ONE MORE HOT AND HUMID DAY WITH HEAT INDICES ABOVE 95 IS
EXPECTED IN SOUTHEASTERN NEW HAMPSHIRE. A HEAT ADVISORY
REMAINS IN EFFECT. HEAT INDICES AROUND 90 ELSEWHERE SOUTH OF
THE MOUNTAINS.
* SOME STORMS TODAY MAY BE STRONG TO SEVERE. THE STRONGER
STORMS MAY BE CAPABLE OF PRODUCING DAMAGING WINDS AND HAIL.
A STATIONARY BOUNDARY NORTH OF THE AREA IS EXPECTED TO BEGIN TO
SINK SLOWLY SOUTHWARD TODAY WITH A BROAD 500MB TROUGH
DEVELOPING AS WELL. WEAK LOW PRESSURE MOVING ALONG THIS BOUNDARY
WILL HELP TO TRIGGER SOME SHOWERS AND THUNDERSTORMS. WITH A HOT
AND HUMID AIR MASS STILL IN PLACE SOUTH OF THE MOUNTAINS, SOME
OF THESE STORMS MAY BE STRONG TO SEVERE. A 60KT JET LOOKS TO
ROUND THE BASE OF THE TROUGH WHICH WILL ACCOUNT FOR AROUND 40KTS
OF BULK SHEAR. THE 00Z RUN OF THE CAMS SUGGEST THIS OVERLAPS
WITH ANYWHERE FROM 500-1500 J/KG. THE HRRR IS NOTABLY ON THE
LOWER END OF THAT RANGE ACROSS THE BOARD. THIS SUGGESTS SOME
POTENTIAL FOR A SUPERCELLULAR STORM MODE WITH FORECAST SOUNDINGS
CONTINUING TO SHOW ELONGATED HODOGRAPHS AND INVERTED V
PROFILES. THIS IS INDICATIVE OF STRONGER STORMS HAVING THE
POTENTIAL TO PRODUCE DAMAGING WINDS AND HAIL. HOWEVER, THE
LIMITING FACTORS WILL BE TIMING AND LAPSE RATES. THE 00Z RUN OF
THE CAMS IS NOT SUGGESTING MUCH COVERAGE OF THUNDERSTORMS
TOMORROW EVENING AS IT LOOKS LIKE THE FRONT WILL CROSS LATE AND
LAPSE RATES WILL ONLY BE AROUND 5 C/KM. BASED ON ALL OF THE
ABOVE INFORMATION I WOULD EXPECT SCATTERED THUNDERSTORMS WITH A
FEW STRONGER CELLS THAT MAY PRODUCE DAMAGING WIND AND HAIL. DUE
TO THE POOR LAPSE RATES AND INCONSISTENT INSTABILITY VALUES IT'S
HARD TO KNOW WHERE THE BEST AREA FOR STORM DEVELOPMENT WILL BE,
SO I HAVE FORGONE ENHANCED WORDING IN THE GRIDS AT THIS TIME AS
THE STRONG TO SEVERE STORMS LOOK TO BE MUCH MORE ISOLATED. SPC
MAINTAINS A MARGINAL RISK FOR THE AREA. HIGH TEMPERATURES SOUTH
OF THE MOUNTAINS WILL BE IN THE UPPER 80S TO AROUND 90, WITH
TEMPERATURES LIKELY TO REACH THE MID 90S IN THE HEAT ADVISORY
AREA. NORTH OF THE MOUNTAINS WILL STAY COOLER, IN THE MID TO
UPPER 70S.
SHORT TERM /TONIGHT THROUGH THURSDAY/
IMPACTS AND KEY MESSAGES:
* HEAVY RAIN SHOWERS ARE POSSIBLE AS EARLY AS THURSDAY
AFTERNOON, MAINLY ACROSS SOUTHERN NEW HAMPSHIRE.
TONIGHT: WEAK LOW PRESSURE CONTINUING TO RIDE ALONG THE FRONTAL
BOUNDARY WILL KEEP ISOLATED SHOWERS IN THE FORECAST OVERNIGHT,
MAINLY IN THE SOUTHERN HALF OF NEW HAMPSHIRE. THIS WILL ALSO
AMOUNT TO INCREASING CLOUDS AS WELL. WITH THE LOWER DEWPOINTS
BEHIND THE FRONT AND A SMALL WINDOW OF MOSTLY CLEAR SKIES, LOW
TEMPERATURES SHOULD BE ABLE TO DROP INTO THE LOW TO MID 60S
SOUTH OF THE MOUNTAINS AND LOW TO MID 50S TO THE NORTH.
THURSDAY: MODELS CONTINUE TO SUGGEST THE FRONT STALLS OVER
SOUTHERN NEW ENGLAND THURSDAY. THIS WOULD STREAM CLOUDS AND
SHOWERS INTO THE AREA DURING THE DAY AS LOW PRESSURE CONTINUES
TO MOVE ALONG THE BOUNDARY. SHOWERS WILL GENERALLY BE LIGHT,
HOWEVER MOISTURE STREAMING INTO THE REGION IS MODELED TO DRIVE
PWATS ACROSS SOUTHERN NEW HAMPSHIRE AND FAR SOUTHWESTERN MAINE
UP TO AROUND 1.50". WHILE THIS CERTAINLY ISN'T THE HIGHEST
VALUES WE HAVE SEEN THIS SUMMER THIS STILL BEARS WATCHING AS IT
SUGGESTS THE POSSIBILITY OF SOME HEAVY SHOWERS. TOWARDS THE
AFTERNOON A MORE STRATIFORM AREA OF RAIN DEVELOPS ACROSS
SOUTHERN AREAS AS LOW PRESSURE MOVES CLOSER. AGAIN THIS MAY HAVE
SOME EMBEDDED HEAVY SHOWERS. FOR MORE DETAILS ON THE HEAVY RAIN
THREAT SEE THE LONG TERM SECTION BELOW AS IT CONTINUES THROUGH
THURSDAY NIGHT AND INTO EARLY FRIDAY. HIGH TEMPERATURES ON
THURSDAY WILL BE MUCH COOLER WITH MID TO UPPER 70S SOUTH OF THE
MOUNTAINS, AND LOW 70S TO THE NORTH.
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
OVERNIGHT UPDATE...THERE CONTINUES TO BE RELATIVELY GOOD
AGREEMENT THAT SHOWERS AND PERHAPS A STEADIER PERIOD OF RAIN
WILL CONTINUE THURSDAY NIGHT ACROSS SOUTHERN NH WITH RAINFALL
AMOUNTS UP TO AN INCH OR SO POSSIBLE. UNFORTUNATELY, FURTHER TO
THE NORTH RAIN CHANCES ARE LOWER AND THEREFORE A BENEFICIAL MORE
WIDESPREAD SOAKING RAINFALL IS LOOKING LESS LIKELY. LOWS WILL
BE INTO THE 40S TO 50S FROM NORTH TO SOUTH. COOL CANADIAN HIGH
PRESSURE THEN BUILDS ON SATURDAY WITH T8 TEMPERATURES ONLY
AROUND +10C. THIS WILL KEEP HIGHS INTO THE LOWER TO MIDDLE 70S
UNDER PARTLY SUNNY SKIES. SATURDAY NIGHT WILL BE ONCE AGAIN COOL
WITH LOWS INTO THE 40S AND 50S.
A MODERATING TREND WILL BEGIN ON SUNDAY WITH T8S CLIMBING BACK
TO AROUND +15C, SENDING HIGHS INTO THE UPPER 70S/LOWER 80S SOUTH
OF THE MOUNTAINS WITH MOSTLY SUNNY SKIES. GRADUALLY MODERATING
TEMPERATURES WILL THEN PERSIST THROUGH EARLY NEXT WEEK WITH
HIGHS INTO THE 80S. DRY CONDITIONS LOOK TO CONTINUE WITH LITTLE
TO NO RELIEF TO THE ONGOING DRY STRETCH.
PREVIOUS DISCUSSION...
KEY MESSAGES
- COMFORTABLE DAYTIME HIGHS AND COOL NIGHTS THIS WEEKEND
- MOSTLY DRY CONDITIONS THROUGH MONDAY
SOME CONCERN EXIST FOR EXCESSIVE RAIN AS DIURNAL INSTABILITY
AND SOME FRONTOGENETIC FORCING FROM A COUPLE OF WAVES GENERATING
MULTIPLE ROUNDS OF RAINFALL ACTIVITY EVEN INTO THE OVERNIGHT,
WITH SOME ENSEMBLE MEMBERS SHOWING 2" OR MORE QPF ACROSS
SOUTHERN NH. PWAT GRADIENT WILL BE TIGHT, UPWARDS OF 1.7" IN THE
SOUTH, AND UNDER 1.0" IN THE NORTH, TRANSLATING TO NOMINAL
RAINFALL FROM THE FOOTHILLS NORTHWARD. AT THIS TIME, MESOSCALE
DETAILS REMAIN TO BE SEEN SO DETERMINING RAINFALL AMOUNTS WOULD
BE TRICKY. EXTENSIVE CLOUD COVER ALONG WITH COLD AIR ADVECTION
WILL FAVOR A COOL DAY, WITH HIGHS IN THE 70S.
THE FINAL PUSH OF THE FRONT WILL COME WITH A ROBUST SHORTWAVE TROUGH
EARLY FRIDAY, FINALLY CLEARLY OUT RAIN IN SOUTHERN AREAS. THIS WILL
USHER IN COOLER AND LESS HUMID AIR FROM CANADIAN HIGH PRESSURE
WITH TEMPS AND DEWPOINTS 10 DEGREES BELOW NORMAL. SURFACE HIGH
PRESSURE WILL DOMINATE THE WEATHER INTO MONDAY, WITH BELOW
AVERAGE TEMPERATURES AND PARTICULARLY COOL NIGHTS. TEMPERATURES
WILL START TO CREEP BACK UP NEXT WEEK, THOUGH HUMIDITY LEVELS
REMAIN COMFORTABLE THROUGH THE END OF THE FORECAST PERIOD.
AVIATION /10Z WEDNESDAY THROUGH SUNDAY/
SHORT TERM...ANY VALLEY FOG THAT DEVELOPED OVERNIGHT WILL
QUICKLY DISSIPATE THIS MORNING. AFTERWARD VFR WILL PREVAIL AT
ALL TERMINALS. SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE
THIS AFTERNOON. CONFIDENCE IN THUNDER NEAR ANY PARTICULAR
TERMINAL IS LOW, SO IT IS NOT INCLUDED IN THE TAFS AT THIS TIME.
CEILINGS LIKELY LOWER TO MVFR AT TIMES, ESPECIALLY AT SOUTHERN
NEW HAMPSHIRE TERMINALS, ON THURSDAY AS MORE WIDESPREAD RAIN
MOVES INTO THE AREA. LOW LEVEL WIND SHEAR IS NOT EXPECTED AT
THIS TIME.
LONG TERM...CEILINGS WILL BE MAINLY VFR FRIDAY THROUGH THE
WEEKEND AS HIGH PRESSURE BUILDS IN.
MARINE
SHORT TERM...WIND GUSTS AND SEAS REMAIN BELOW SCA CRITERIA
THROUGH THURSDAY. ONSHORE WINDS TODAY WILL SHIFT MORE NORTHERLY
OVERNIGHT AS A FRONT CROSSES THE WATERS. WINDS WILL SHIFT BACK
ONSHORE THURSDAY AFTERNOON.
LONG TERM... A SHORTWAVE IS EXPECTED TO CROSS THURSDAY NIGHT
AND FINALLY DRIVE A COLD FRONT FURTHER SOUTH OVERNIGHT,
SUPPORTING STRONGER NE WINDS AROUND 20KT FOR FRIDAY. A SECOND
SURGE COMES SATURDAY, KEEPING WINDS 15-20KT OUT OF THE NE. 1-3
FT SEAS AT THE START OF THE PERIOD WILL BUILD TO 2-3 FT BY LATE
THURSDAY. PROLONGED NORTHEASTERLY FETCH WILL BUILD SEAS FROM
NORTH TO SOUTH FRIDAY NIGHT INTO SATURDAY. HIGHEST WAVES ON
SATURDAY WILL BE AROUND 4FT OFF THE NH COAST. SCA CONDITIONS ARE
BRIEFLY POSSIBLE GIVEN UNCERTAINLY WITH THE FRONT AND
TIMING/STRENGTH OF SHORTWAVES. HIGH PRESSURE THEN BUILDS IN FOR
THE REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK WITH FAIR
BOATING CONDITIONS.
GYX WATCHES/WARNINGS/ADVISORIES
ME...NONE.
NH...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NHZ012-013.
MARINE...NONE.
NEAR/SHORT TERM...BARON
LONG TERM...JAMISON/TUBBS
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