206
FXUS61 KGYX 130632
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
232 AM EDT MON JUL 13 2026
WHAT HAS CHANGED
A HEAT ADVISORY HAS BEEN ISSUED FOR MOST OF NEW HAMPSHIRE AND
WESTERN MAINE.
CONFIDENCE CONTINUES TO INCREASE FOR A ROUND OF STRONG TO
SEVERE THUNDERSTORMS IN THE TUESDAY EVENING OR OVERNIGHT
TIMEFRAME.
KEY MESSAGES
1. HEAT BUILDS TODAY, WITH TEMPERATURES AND HUMIDITY COMBINING
ON TUESDAY FOR HEAT INDICES OF 95 TO 100 DEGREES SOUTH OF THE
MOUNTAINS. HUMIDITY ABATES WEDNESDAY, BUT HOT CONDITIONS LINGER
INTO THURSDAY WITH HIGHS IN THE UPPER 80S TO LOW 90S.
2. STRONG TO SEVERE THUNDERSTORMS TRACK SOUTHEAST ACROSS THE
AREA STARTING TUESDAY EVENING INTO TUESDAY NIGHT.
DISCUSSION
KEY MESSAGE 1 DESCRIPTION...
WARMER TODAY AS THE CENTER OF HIGH PRESSURE MOVES EAST AND WAA
ARRIVES ON WEST TO SOUTHWEST WINDS. TEMPERATURES WILL TEND TO
PREEMPT HUMIDITY (A FACTOR FOR TOMORROW), WITH INTERIOR
TEMPERATURES CLIMBING INTO THE MID TO UPPER 80S AND A FEW 90
DEGREE READINGS FOR SOUTHERN NH. THE SW WINDS AT THE SURFACE
ONCE MIXING BEGINS WILL ENABLE A SEABREEZE TO WORK ITS WAY
INLAND ALONG THE ME MIDCOAST AND AREAS FROM CASCO BAY NORTH.
THESE WINDS MAY ACT A LITTLE MORE SUPPRESSIVE FOR A SEABREEZE
SOUTH OF CASCO BAY (IE THE YORK AND NH SEACOAST). AS A RESULT,
MID AFTERNOON TEMPS COULD RETREAT TOWARDS THE UPPER 70S ALONG
THE MIDCOAST.
THE OTHER FEATURE OF NOTE MONDAY WILL BE A WEAK EMBEDDED
SHORTWAVE KICKING OFF SOME SHOWERS AND STORMS ACROSS QUEBEC THAT
PROGRESS EASTWARD TOWARDS THE US/CAN BORDER BY LATE AFTERNOON
AND EARLY EVENING. WHAT INSTABILITY IS AVAILABLE (ESPECIALLY
SURFACE BASED) WILL BE WANING, SO THINK THIS WILL FALL MAINLY AS
SHOWERS VS. THUNDER. A LIGHT WIND AND ANY REMAINING CLOUD COVER
SHOULD KEEP MONDAY NIGHT MORE MILD VS. RECENT NIGHTS, WITH LOW
ONLY FALLING INTO THE 60S AREAWIDE.
MONDAY NIGHT INTO TUESDAY, RECORD MAX CLIMO 500MB HEIGHTS
ACROSS THE UPPER MIDWEST FLATTEN, WITH LOW LEVEL WINDS USHERING
A PLUME OF SIMILARLY RATED 850MB TEMPERATURES TOWARDS THE
EASTERN GREAT LAKES AND NEW ENGLAND TUESDAY AFTERNOON. THIS
PLUME SHOULD BE MOVING QUICKER THAN OUR LAST HEAT EPISODE, BUT
WILL STILL RESULT IN A DAY WHERE A HEAT ADVISORY FOR MOST OF THE
AREA WILL BE NEEDED.
NOT ONLY WILL 850MB TEMPS AROUND 20 TO 22 C PUSH MIX DOWN TEMPS
INTO THE LOW TO MID 90S, BUT A LARGER SURGE OF LOW LEVEL
MOISTURE SHOULD RAISE SURFACE DEW POINT TEMPS INTO THE UPPER 60S
TO AROUND 70 DEGREES. THE RESULT IS WIDESPREAD HEAT INDICES
BETWEEN 95 AND 100 FOR TUESDAY AFTERNOON SOUTH OF THE MOUNTAINS.
STRONGER BACKGROUND SW WINDS WILL MAKE IT MORE DIFFICULT FOR
RELIEF VIA SEABREEZE FOR COASTAL COMMUNITIES, ESPECIALLY FOR THE
CUMBERLAND COAST SOUTH.
JUST AS ABRUPTLY THE PUSH OF HEAT AND HUMIDITY ARRIVED, A COLD
FRONT W/ SOME CONVECTION (NOTED BELOW) SHOULD TAMP DOWN MAX
TEMPS AND HUMIDITY FOR WEDNESDAY. HOWEVER, THERE IS SOME
UNCERTAINTY HOW QUICKLY THIS FRONT PROGRESSES TUES NIGHT AND A
WARM, MILD NIGHT WITH LOWS IN THE 70S SEEMS LIKELY. THIS DOES
CREATE A OPPORTUNITY TO START VERY WARM WEDNESDAY MORNING, AND
DAYTIME HIGHS COULD EASILY CLIMB BACK INTO THE 90S FOR MUCH OF
SOUTHERN NH AND FAR SOUTHERN ME, ALBEIT WITH LESS
MOISTURE/HUMIDITY. GIVEN THIS TREND, STILL SEE TUESDAY AS THE
PRIMARY DAY FOR HEAT RELATED HEADLINES, BUT STILL EXPECT A
FOLLOWUP HOT DAY WEDNESDAY.
OVERNIGHT LOWS WED NIGHT AND THEN THURS NIGHT IMPROVE, FALLING
INTO THE 50S/60S AND THEN UPPER 40S/50S RESPECTIVELY.
KEY MESSAGE 2 DESCRIPTION...
A STRONG SHORTWAVE TROUGH AND SURFACE COLD FRONT WILL APPROACH
FROM THE NORTH ON TUESDAY BEFORE CROSSING TUESDAY EVENING AND
NIGHT. THIS WILL SERVE AS A LIFTING MECHANISM FOR THE
DEVELOPMENT OF STRONG TO SEVERE THUNDERSTORMS TUESDAY EVENING
INTO THE FIRST HALF OF TUESDAY NIGHT. THE STRONGEST FORCING FOR
ASCENT IS NOT LIKELY TO ARRIVE UNTIL AFTER SUNSET BUT DESPITE
THIS, LATEST CAMS AND ENSEMBLE BASED GUIDANCE CONTINUE TO SHOW
THAT THE ENVIRONMENT WILL REMAIN FAVORABLE FOR SEVERE STORMS
EVEN AFTER DAYTIME HEATING WANES.
LATEST GUIDANCE INCLUDING THE RRFS SUGGEST THAT STORMS WILL
FORM ACROSS SOUTHERN QUEBEC ON TUESDAY AFTERNOON ALONG THE COLD
FRONT BEFORE DROPPING SOUTH TOWARDS THE CANADIAN BORDER AS
BROKEN LINE SEGMENTS ON TUESDAY EVENING (ROUGHLY BETWEEN 5-8
PM). THIS ACTIVITY IS THEN LIKELY TO CROSS THE REGION FROM NORTH
TO SOUTH THROUGH THE FIRST HALF OF TUESDAY NIGHT. FORECAST
SOUNDINGS SHOW ROUGHLY BETWEEN 1500-2000 J/KG OF MUCAPE ALONG
WITH BETWEEN 50-60 KTS OF 0-6KM BULK SHEAR. SEVERAL FORECAST
MODELS ALSO SHOW AN ELEVATED MIXED LAYER (EML) WITH STEEP MID-
LVL LAPSE RATES OF UP TO 7.5C/KM. THESE PARAMETERS WILL SUPPORT
BOTH LARGE HAIL AND DAMAGING WINDS ALONG WITH A CONDITIONAL
TORNADO THREAT SHOULD SUPERCELLS EXIST. SPC HAS ADDED AN ENH
RISK (LEVEL 3/5) FOR FAR NORTHERN ZONES NEAR THE INTERNATIONAL
BORDER AND MAINTAINS A SLGT RISK (LEVEL 2/5) ACROSS THE
REMAINDER OF THE NORTHERN HALF OF THE FORECAST AREA, WITH A
MRGL RISK (LEVEL 1/5) ACROSS SOUTHERN NH AND COASTAL WESTERN ME.
AVIATION /01Z MONDAY THROUGH FRIDAY/
THROUGH 06Z TUESDAY...PREVAILING VFR THROUGH THE MORNING. SW
WINDS LIKELY SUPPRESS AFTERNOON SEABREEZE FOR PSM AND PERHAPS
PWM, BUT STILL COULD GET A SOUTHERLY PUSH THROUGH TO RKD. AN
INCOMING DISTURBANCE MAY BRING A PERIOD OF SHOWERS AND SLIGHT
CHANCE TS THIS AFTERNOON FOR POINTS NORTH AND EAST OF SFM TO
LEB. BRIEF MVFR CONDITIONS ARE POSSIBLE IN THESE.
OUTLOOK:
TUESDAY/TUESDAY NIGHT: VFR CONDITIONS THROUGH 18Z TUESDAY WITH
SW WIND GUSTS UP TO 25 KTS. SHRA AND TSRA WILL THEN MOVE FROM
NORTH TO SOUTH TUESDAY EVENING THROUGH THE FIRST HALF OF TUESDAY
NIGHT, BRINGING LOCALIZED LIFR RESTRICTIONS. STORMS MAY CONTAIN
HAIL AND DAMAGING WINDS.
WEDNESDAY/WEDNESDAY NIGHT: VFR CONDITIONS WITH DAYTIME NW WIND
GUSTS UP TO 25 KTS.
THURSDAY-FRIDAY: VFR CONDITIONS WITH WNW FLOW PREVAILING.
MARINE
BELOW SCA CONDITIONS THROUGH THIS MORNING, BUT SOUTHERLY GUSTS
INCREASE THIS AFTERNOON 25 TO 30 KT. AS A RESULT, WIND WAVE
SHOULD INCREASE, TO AROUND 5 FT THIS EVENING.
SCA CONDITIONS LIKELY CONTINUE OUTSIDE OF THE BAYS TUESDAY
AFTERNOON INTO WEDNESDAY MORNING WITH SW WIND GUSTS UP TO 25 KTS
AND SEAS OF 3- 6 FT. OTHERWISE WINDS AND SEAS SHOULD REMAIN
BELOW SCA CRITERIA THROUGH FRIDAY.
GYX WATCHES/WARNINGS/ADVISORIES
ME...HEAT ADVISORY FROM 11 AM TO 8 PM EDT TUESDAY FOR MEZ012>014-
018>021-023-033.
NH...HEAT ADVISORY FROM 11 AM TO 8 PM EDT TUESDAY FOR NHZ002>015.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EDT
WEDNESDAY FOR ANZ150-152.
SMALL CRAFT ADVISORY FROM 6 AM TUESDAY TO 6 AM EDT WEDNESDAY
FOR ANZ151.
DISCUSSION...CORNWELL/TUBBS
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