857
FXUS61 KGYX 082314
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
714 PM EDT WED JUL 8 2026
WHAT HAS CHANGED
CONFIDENCE HAS INCREASED THAT SOUTHEASTERN NEW HAMPSHIRE IS
GOING TO SEE HEAT INDEX VALUES GREATER THEN 95F THURSDAY
AFTERNOON. A HEAT ADVISORY HAS BEEN ISSUED ACCORDINGLY.
KEY MESSAGES
1. HEAT AND HUMIDITY BUILD THURSDAY, LASTING THROUGH FRIDAY
BEFORE A SLOW MOVING FRONT BRINGS COOLER AND DRIER AIR BY LATE
FRIDAY NIGHT.
2. A COUPLE OF WEAK COLD FRONTS BRING A CHANCE OF THUNDERSTORMS
ON BOTH THURSDAY AND FRIDAY AFTERNOONS AND EVENINGS. SOME OF
THESE COULD BE STRONG TO SEVERE.
3. MOSTLY DRY WITH SEASONABLE TEMPERATURES THIS WEEKEND WITH A
WARMING TREND POSSIBLE DURING THE EARLY TO MIDDLE PART OF NEXT
WEEK.
DISCUSSION
KEY MESSAGE 1 DESCRIPTION...
LATEST MODEL GUIDANCE IS ALL IN GOOD AGREEMENT ON WARM AND
STICKY WEATHER BEGINNING THURSDAY AS 850 MB TEMPERATURES CLIMB
TO +16-18C UNDER A LOW AMPLITUDE RIDGE THAT WILL BE QUICKLY
SWINGING THROUGH THE REGION. THIS SUPPORTS SURFACE TEMPERATURES
IN THE UPPER 80S TO 90F, WITH SOUTHWESTERLY FLOW PROVIDING AN
EXTRA BOOST TO VALLEY LOCATIONS THAT MAY PUSH THEM MORE TOWARD
91-92F VIA DOWNSLOPING. THE SOUTHWESTERLY WINDS ARE ALSO GOING
TO BRING ELEVATED DEWPOINTS (MIDDLE TO UPPER 60S) THAT WILL PUSH
HEAT INDICES UP ABOVE 90 IN MANY LOCATIONS. THE SOUTHERN NEW
HAMPSHIRE PORTION OF THE MERRIMACK VALLEY MAY EVEN SEE HEAT
INDEX VALUES IN 95+ RANGE, SO HAVE GONE AHEAD WITH A HEAT
ADVISORY FOR EASTERN HILLSBOROUGH AND INTERIOR ROCKINGHAM. THE
SEA BREEZE LIKELY GETS KEPT AT BAY, SO THESE AFOREMENTIONED WARM
TEMPERATURES SHOULD BE REALIZED RIGHT DOWN TO THE COAST. FOR
AREAS NORTH OF THE MOUNTAINS, THE FRONT LOOKS TO BEGIN TO SAG
SOUTH OF THE INTERNATIONAL BORDER BRINGING INCREASED CLOUD COVER
AND SHOWERS/STORMS (DETAILED IN KEY MESSAGE 2). THIS STUNTS
WARMING POTENTIAL, LIMITING THESE LOCATIONS TO THE LOW TO MID
80S.
AS THE FRONT CONTINUES TO SINK SOUTHWARD FRIDAY COOLER AND
DRIER AIR WILL BE MOVING IN BEHIND IT. AS OF NOW AREAS NORTH OF
THE MOUNTAINS STAND THE BEST CHANCE OF SEEING A MORE PLEASANT
DAY WITH HIGHS IN THE MID TO UPPER 70S AND DEWPOINTS DOWN INTO
THE UPPER 50S AND LOW 60S. SOUTH OF THE MOUNTAINS, 850 MB
TEMPERATURES AROUND +17C LINGER IN SOUTHERN ZONES SO THOSE
LOCATIONS ARE LIKELY TO SEE ANOTHER DAY WITH TEMPERATURES
CLIMBING INTO THE UPPER 80S TO 90F. ELEVATED DEWPOINTS LINGER
TOO, BUT WITH TEMPERATURES A LITTLE BIT LOWER ON FRIDAY, HEAT
INDICES SHOULD BE AS WELL. GUIDANCE IS STILL STRUGGLING SLIGHTLY
WITH THE TIMING OF THE FRONT, BUT IT LOOKS LIKE BY LATE FRIDAY
NIGHT MOST LOCATIONS SHOULD BE SEEING THE RELIEF WITH LOW
TEMPERATURES DROPPING INTO THE 50S AND 60S.
KEY MESSAGE 2 DESCRIPTION...
IN ADDITION TO THE HEAT AND HUMIDITY, A COUPLE OF WEAK COLD
FRONTS WILL ALSO BRING CHANCES FOR SHOWERS AND THUNDERSTORMS
DURING THE AFTERNOON TO EARLY EVENING HOURS EACH DAY FOR
THURSDAY AND FRIDAY.
FOR THURSDAY, THE HIGHER OVERALL CHANCES FOR STORMS WILL BE
ACROSS THE NORTH IN CLOSER TO PROXIMITY TO THE COLD FRONT
ITSELF, AND SOME OF THESE COULD BE STRONG TO SEVERE WITH 30-35
KT OF EFFECTIVE SHEAR AND AROUND 500 J/KG OF MUCAPE PER THE HREF
ENSEMBLE MEAN (SOME DETERMINISTIC GUIDANCE HAS MORE
INSTABILITY). FARTHER SOUTH, INSTABILITY IS FORECAST TO BE MORE
IN THE 1000-1500 J/KG RANGE, BUT COVERAGE MAY BE MORE LIMITED
BECAUSE OF LESSER FORCING, LESSER SHEAR, AND SOME DRY AIR ALOFT.
HOWEVER, IF STORMS DO DEVELOP IN SOUTHERN AREAS, THEY MAY CARRY
MORE OF A WIND THREAT WITH THE DRY AIR ALOFT BRINGING MORE IN
THE WAY OF DCAPE. PWATS CLIMBING OVER 1.50" AND DEEPENING WARM
CLOUD DEPTHS WILL ALSO SUPPORT EFFICIENT RAIN RATES, AND WITH
FLOW ROUGHLY PARALLEL THE BOUNDARY, WE'LL HAVE TO MONITOR FOR A
LOCALIZED FLASH FLOOD RISK IF ANY TRAINING CAN SET UP. THIS
LINES UP WELL WITH A MARGINAL RISK FOR EXCESSIVE RAINFALL FROM
WPC IN AND AROUND THE MOUNTAINS.
MOST GUIDANCE HAS THIS FRONT PUSHING OFFSHORE FRIDAY MORNING
WITH A SECONDARY FRONT APPROACHING LATER IN THE DAY, AND LIFT
FROM THIS FRONT SHOULD AGAIN ALLOW SHOWERS AND STORMS TO DEVELOP
IN THE AFTERNOON. TODAY'S 12Z GUIDANCE DOESN'T LOOK TO BRING
QUITE AS MUCH INSTABILITY, BUT THERE STILL MAY BE ENOUGH FOR A
COUPLE OF STRONG TO SEVERE STORMS AS SHEAR PARAMETERS LOOK
FAIRLY SIMILAR TO THURSDAY (THE HIGHER POTENTIAL LOOKS TO BE
SOUTH OF THE MOUNTAINS THIS TIME).
KEY MESSAGE 3 DESCRIPTION...
SURFACE HIGH PRESSURE BUILDS TOWARD NEW ENGLAND OVER THE
WEEKEND, BUT A 500MB SHORTWAVE MAY PROVIDE ENOUGH LIFT FOR A FEW
SHOWERS ON SATURDAY. OTHERWISE, DRY CONDITIONS ARE FORECAST
WITH FAIRLY SEASONABLE TEMPERATURES IN THE 80S.
FOR THE EARLY TO MIDDLE PART OF NEXT WEEK, THERE IS HIGH
CONFIDENCE IN A STRONG RIDGE OF HIGH PRESSURE TO BECOME CENTERED
OVER THE CENTRAL AND NORTHERN PLAINS AND INTO THE GREAT LAKES.
SOME EXPANSION OF THE RIDGE IS POSSIBLE TOWARD THE NORTHEAST TO
BRING A WARMING TREND, BUT WE ALSO MAY REMAIN MORE ON THE
EASTERN PERIPHERY TO BRING OCCASIONAL CHANCES OF SHOWERS/STORMS
("RIDGE ROLLERS") AND MORE CLOUD COVER.
AVIATION /00Z THURSDAY THROUGH MONDAY/
THROUGH THURSDAY....VFR CONDITIONS CONTINUE THROUGH THURSDAY
AFTERNOON WITH LEB AND HIE POSSIBLE SEEING LOCALIZED IFR
CONDITIONS AFTER MIDNIGHT AS VALLEY FOG DEVELOPS AGAIN TONIGHT.
THIS IS MORE OR LESS A PERSISTENCE BASED FORECAST WITH A SLIGHT
DELAY IN TIMING DUE TO DRIER CONDITIONS. ANY VALLEY FOG THAT
FORMS SHOULD CLEAR OUT QUICKLY AFTER SUNRISE WITH THE
PREVAILING CONDITION TURNING BACK TO VFR. SOME TEMPO MVFR IS
POSSIBLE IN SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON BUT
CONFIDENCE IS TOO LOW TO ADD TO TAFS AT THIS TIME.
OUTLOOK...
THURSDAY NIGHT: MOSTLY VFR WITH MVFR REMAINING POSSIBLE
AS SHOWERS AND STORMS LINGER. IFR FOG IS ALSO POSSIBLE AGAIN,
ESPECIALLY IN LOCATIONS THAT SEE RAIN AND VALLEYS, BUT
UNCERTAINTY IS HIGH REGARDING THAT.
FRIDAY: LINGERING IFR POSSIBLE AT LEB THROUGH AROUND 13Z DUE TO
VALLEY FOG. VFR OTHERWISE, BUT AFTERNOON THUNDERSTORMS COULD BRING
TEMPO IFR TO MVFR RESTRICTIONS.
SATURDAY-SUNDAY: MAINLY VFR. HOWEVER, NIGHTTIME/EARLY MORNING VALLEY
FOG MAY BRING IFR TO LIFR RESTRICTIONS, MAINLY AT HIE AND LEB.
MONDAY: TEMPO IFR TO MVFR POSSIBLE DUE TO AFTERNOON/EVENING
SHRA/TSRA. OTHERWISE, VFR.
MARINE
WINDS SHIFT SOUTHWESTERLY TONIGHT WITH THAT BEING THE
PREVAILING WIND THROUGH THURSDAY. HIGH PRESSURE BUILDS BACK OVER
THE ATLANTIC KEEPING WIND GUSTS AND WAVES GENERALLY BELOW SCA
THRESHOLDS. THE EXCEPTION MAY COME THURSDAY NIGHT AS HIGH
PRESSURE MOVES OFF TO THE EAST AND SOME 5FT SEAS CREEP INTO THE
OUTER COASTAL WATERS, BUT AT THIS TIME THE EXTENT DOES NOT
WARRANT AN SCA.
FRIDAY-WEDNESDAY...SCA CONDITIONS ARE NOT EXPECTED THROUGH AT LEAST
THE WEEKEND. A WEAK COLD FRONT CROSSES FRIDAY WITH A BRIEF WIND
SHIFT TO THE NORTH LATER IN THE DAY INTO FRIDAY NIGHT. HIGH PRESSURE
THEN BUILDS ACROSS THE NORTHEASTERN US OVER THE WEEKEND BEFORE
SHIFTING TO THE EAST EARLY NEXT WEEK. AS THE HIGH SHIFTS EAST, SOUTH
TO SOUTHWEST FLOW MAY APPROACH SCA LEVELS DURING THE EARLY TO
MIDDLE PARTS OF NEXT WEEK.
GYX WATCHES/WARNINGS/ADVISORIES
ME...NONE.
NH...HEAT ADVISORY FROM 11 AM TO 8 PM EDT THURSDAY FOR NHZ012-013.
MARINE...NONE.
DISCUSSION...BARON/COMBS
AVIATION...LEGRO
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