957
FXUS61 KGYX 300625
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
225 AM EDT TUE JUN 30 2026
WHAT HAS CHANGED
NO MAJOR CHANGES WERE NEEDED FOR THIS FORECAST PACKAGE. THE
FOCUS CONTINUES TO BE ON THE UPCOMING HEATWAVE AND THUNDERSTORM
CHANCES.
KEY MESSAGES
1. HEAT AND OPPRESSIVE HUMIDITY ARRIVES WEDNESDAY AND LASTS
THROUGH AT LEAST FRIDAY, POSSIBLY INTO SATURDAY. TO BE
COMPLETED AHEAD OF WEDNESDAY'S HEAT, ALL AC INSTALLATIONS AND
PREPARATIONS SHOULD BE COMPLETED BY TODAY.
2. STARTING LATE TODAY THROUGH THE END OF THE WEEK THE
INGREDIENTS WILL BE THERE FOR THUNDERSTORMS, SOME OF WHICH COULD
BE STRONG TO SEVERE. SPC HAS A MARGINAL RISK FOR SEVERE STORMS
LATE TODAY AND AGAIN WEDNESDAY.
DISCUSSION
KEY MESSAGE 1 DESCRIPTION...
TODAY WILL BE VERY WARM WITH HIGHS IN THE 80S TO LOW 90S. DEW
POINTS WILL MAINLY BE IN THE 50S, EXCEPT NEAR THE COAST WHERE
ONSHORE WINDS AND MARINE INFLUENCE WILL BRING DEW POINTS INTO
THE 60S WHILE COOLING AMBIENT AIR TEMPERATURES. THIS WILL LEAD
TO HEAT INDICES BEING CLOSE TO AMBIENT AIR TEMPERATURES.
THE BUILDING HEAT AND HUMIDITY BENEATH AN ANOMALOUS RIDGE OVER
THE OHIO VALLEY WILL PUSH INTO THE AREA ON WEDNESDAY.
TEMPERATURES AT 850 MB ARE STILL FORECAST TO EXCEED +20C WHICH
WOULD SUPPORT HIGHS IN THE UPPER MID TO UPPER 90S. WINDS NEAR
THE COAST WILL HAVE SOME ONSHORE COMPONENT THAT WILL ALLOW FOR
SOME RELIEF DURING THE AFTERNOON. DEW POINTS ARE STILL FORECAST
TO CLIMB INTO THE LOW TO MID 70S THAT WILL BRING HEAT INDICES TO
105 TO 110 DEGREES FOR AREAS UNDER THE EXTREME HEAT WATCH AND
WELL INTO THE 90S ELSEWHERE. THERE CONTINUES TO BE UNCERTAINTY
WITH THE TIMING AND COVERAGE POTENTIAL ROUNDS CONVECTION THAT
COULD IMPACT THE AREA FROM LATE TUESDAY THROUGH THE END OF THE
WEEK. ANY CONVECTION WOULD ACT TO REDUCE TEMPERATURES LOCALLY
WHILE ALSO ACTING TO INCREASE DEW POINTS. MORE DETAILS ON
CONVECTION IS DISCUSSED IN KEY MESSAGE 2.
THURSDAY CONTINUES TO LOOK TO BE THE PEAK OF THE HEAT AS
TEMPERATURES AT 850 MB CLIMB TO +22C TO +23C. THIS WILL SUPPORT
HIGH TEMPERATURES EITHER SIDE OF 100 DEGREES FOR MUCH OF THE
INTERIOR, AND ESPECIALLY FOR SOUTHERN NEW HAMPSHIRE. THERE
REMAINS SOME QUESTION AS TO WHETHER THE COAST WILL SEE A SEA
BREEZE DEVELOP OF NOT, BUT THIS WILL ALSO BE INFLUENCED BY THE
POSSIBLE CONVECTION. DEW POINTS LOOK TO PUSH INTO THE LOW TO MID
70S AGAIN. THIS PUSHES HEAT INDICES TO NEAR 110 DEGREES
ANYWHERE THE AIR TEMPS REACH THE UPPER 90S TO LOW 100S.
THE HEAT AND HUMIDITY WILL CONTINUE INTO FRIDAY AND POSSIBLY
SATURDAY BUT WILL BE ON A SLIGHT DOWNWARD TREND. BY SUNDAY
MODELS ARE IN AGREEMENT THAT HEIGHTS WILL BE LOWERING AS A
TROUGH MOVES THROUGH ATLANTIC CANADA. THIS WILL HELP KNOCK
TEMPERATURES DOWN WHILE THE LATEST NBM STILL BRINGS HIGHS INTO
THE LOW 90S FOR SOUTHWEST MAINE AND SOUTHERN NH.
NIGHTTIME LOW TEMPERATURE FORECASTS WILL BE TRICKY TONIGHT
THROUGH FRIDAY NIGHT. WITHOUT STORMS, LOWS ONLY MAKING IT DOWN
INTO THE MID TO UPPER 70S IS LIKELY ACROSS SOUTHERN AND CENTRAL
LOCATIONS. HOWEVER, WITH ANY THUNDERSTORMS TEMPERATURES WOULD
QUICKLY DROP INTO THE UPPER 60S TO LOW 70S. SO THE LOW
TEMPERATURE FORECAST TRIES TO SPLIT THE DIFFERENCE BETWEEN THESE
TWO OUTCOMES, BUT ACKNOWLEDGES THAT THERE WILL BE VARIABILITY
ACROSS THE AREA. WITHOUT STORMS, LOWS AROUND 80 DEGREES ARE
LIKELY THROUGH THE MERRIMACK RIVER VALLEY WEDNESDAY AND THURSDAY
NIGHTS.
KEY MESSAGE 2 DESCRIPTION...
THERE IS THE POTENTIAL FOR MULTIPLE ROUNDS OF CONVECTION
STARTING LATE TODAY LASTING THROUGH THE END OF THE WEEK WHILE
CONFIDENCE IS LOW ON TIMING AND COVERAGE, ESPECIALLY BEYOND
WEDNESDAY. AS MENTIONED IN PREVIOUS DISCUSSIONS, CAPE AND SHEAR
WILL BE SUFFICIENT FOR SEVERE STORMS WHILE RIDGING DOMINATING
THE PATTERN WILL NOT BE FAVORABLE FOR SYNOPTIC ASCENT. CAMS HAVE
BEEN SHOWING POTENTIAL FOR A COUPLE OF RIDGE ROLLING MCSS OR
CONVECTIVELY INDUCED SHORT WAVES FROM UPSTREAM CONVECTION WITH
ONE CROSSING THE NORTHEAST LATE TODAY/TONIGHT AND ANOTHER
WEDNESDAY OR WEDNESDAY NIGHT. HOWEVER, PLACEMENT, STRENGTH, AND
COVERAGE IS VARIABLE AMONGST CAM SOLUTIONS WITH SOME KEEPING THE
STRONGEST CONVECTION TO THE WEST OVER NY AND VERMONT. SPC HAS A
MARGINAL RISK FOR SEVERE STORMS TODAY WITH A SLIGHT RISK JUST
TO THE WEST OVER NY/VT. WILL HAVE TO KEEP A CLOSE EYE ON TRENDS
IF THIS MCS CAN MATERIALIZE AND WHERE IT TRACKS THIS EVENING AS
IT WOULD BRING A DAMAGING WIND THREAT. LATEST ROUND OF CAM
GUIDANCE DOES HAVE SOME SOLUTIONS BRINGING IT INTO PORTIONS OF
NH. SPC ALSO HAS A MARGINAL RISK FOR SEVERE STORMS WEDNESDAY AS
ANOTHER MCS OR CONVECTIVELY INDUCED SHORT WAVE IS MODELED TO
APPROACH THE NORTHEAST. OUTSIDE OF THESE ROUNDS OF CONVECTION
THERE REMAINS POTENTIAL FOR ISOLATED STORMS TO FORM OVER THE
HIGHER TERRAIN OR ALONG ANY SEA BREEZE CONVERGENCE WHILE CAMS DO
NOT HAVE MUCH OF A SIGNAL FOR THESE OUTCOMES.
THE PERSISTENT HEAT AND HUMIDITY WILL CONTINUE TO SUPPLY FUEL
FOR ANY STORMS THURSDAY INTO THE WEEKEND. HEIGHT FALLS SATURDAY
INTO SUNDAY WOULD LEAD TO BETTER SYNOPTIC SUPPORT FOR STORMS,
BUT THIS TIME RANGE DETAILS REMAIN UNCLEAR.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
THROUGH WEDNESDAY... MAINLY VFR THROUGH TODAY. SHOWERS AND
STORMS BECOME POSSIBLE LATE TODAY THROUGH TONIGHT. THESE COULD
BRING LOCALIZED RESTRICTIONS. INCREASING LOW LEVEL MOISTURE WILL
ALSO BRING POTENTIAL RESTRICTIONS FROM LOW CIGS AND/OR FOG.
MAINLY VFR WEDNESDAY OUTSIDE OF ISOLATED THUNDERSTORMS.
OUTLOOK:
WEDNESDAY NIGHT: CONDITIONS MAY BEGIN TO DETERIORATE AS MARINE
FOG/STRATUS BECOMES MORE LIKELY. CONFIDENCE IS LOW AT THIS TIME
IN MVFR OR LOWER CONDITIONS. LOCAL MVFR OR LOWER ALSO POSSIBLE
IN SHOWERS/THUNDERSTORMS.
THURSDAY - SATURDAY: LOCAL MVFR OR LOWER POSSIBLE IN
SHOWERS/THUNDERSTORMS. AREAS OF IFR OR LOWER POSSIBLE AT NIGHT
WITH MARINE FOG/STRATUS.
SATURDAY NIGHT - SUNDAY: SOME CLEARING POSSIBLE FROM THE NORTH
AS THE HEAT AND HUMIDITY GETS PUSHED SOUTH.
MARINE
WINDS AND SEAS REMAIN BELOW SCA THRESHOLDS THROUGH THE HOLIDAY
WEEKEND. THE MAIN HAZARDS TO WATCH FOR WILL BE DEVELOPING MARINE
FOG, ESPECIALLY AS WINDS BECOME ONSHORE AHEAD OF ANY LOW
PRESSURE APPROACHING, AND THEN THUNDERSTORMS WHICH WILL BE
POSSIBLE MOST DAYS INTO THE WEEKEND.
CLIMATE
HIGH TEMPERATURE RECORDS AT LONG TERM CLIMATE SITES...
JULY 1ST 2ND 3RD
AUG 92 (1971) 93 (1963) 94 (2002)
PWM 93 (1971) 98 (1941) 95 (2002)
CON 99 (1913) 98 (1966) 102 (1966)
GYX WATCHES/WARNINGS/ADVISORIES
ME...EXTREME HEAT WATCH FROM WEDNESDAY AFTERNOON THROUGH FRIDAY
EVENING FOR MEZ012-013-018>021-023>026-033.
NH...EXTREME HEAT WATCH FROM WEDNESDAY AFTERNOON THROUGH FRIDAY
EVENING FOR NHZ004>015.
MARINE...NONE.
DISCUSSION...HARGROVE/SCHROETER
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