907
FXUS61 KGYX 271922
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
322 PM EDT SAT JUN 27 2026
WHAT HAS CHANGED
CONFIDENCE CONTINUES TO INCREASE, DESPITE A FEW COMPLICATING
FACTORS, FOR MID TO LATE WEEK HEATWAVE POTENTIAL.
KEY MESSAGES
1. SEASONABLE TEMPS AND SCATTERED SHOWERS CONTINUE THROUGH
SUNDAY.
2. A HOT AIRMASS MOVES INTO THE REGION THIS WEEK, THIS TIME
ACCOMPANIED BY HUMID CONDITIONS. THIS COMBINATION WILL BRING THE
POTENTIAL FOR EXTREME HEAT WEDNESDAY AND THURSDAY FOR
INTERIOR/COASTAL MAINE AND THE SOUTHERN HALF OF NEW HAMPSHIRE.
PREPARE COOLING SYSTEMS EARLY THIS WEEK, AND IF PLANS INCLUDE
STRENUOUS OUTDOOR ACTIVITIES, CONSIDER RESCHEDULING FOR THE
MORNING WHEN HEAT ISN'T AS INTENSE.
DISCUSSION
KEY MESSAGE 1 DESCRIPTION...
WITH A TROUGH LINGERING ACROSS NORTHERN NEW ENGLAND THROUGH THE
END OF THE WEEKEND, THE WEATHER PATTERN REMAINS SIMILAR THROUGH
SUNDAY. SCATTERED SHOWERS AND AN ISOLATED THUNDERSTORM THIS
AFTERNOON TAPER OFF THROUGH THE EVENING WITH THE LOSS OF DAYTIME
HEATING.
TONIGHT SEES ANOTHER SEASONABLY COOL NIGHT WITH LOWS GENERALLY
DROPPING INTO THE 50S. SOME PATCHY FOG IS LIKELY AGAIN
OVERNIGHT, AND WILL BE MOST PREVALENT ALONG THE COAST AND
THROUGH THE RIVER VALLEYS.
TOMORROW FEATURES ANOTHER DAY OF MORNING SUNSHINE GIVING WAY TO
POP UP SHOWERS AND A FEW THUNDERSTORMS IN THE AFTERNOON HOURS.
THESE WILL BE MORE WIDESPREAD ACROSS THE HIGHER TERRAIN OF
MAINE, AND STAND A BETTER CHANCE OF REACHING THE COASTLINE THAN
TODAY'S SHOWERS. HIGH TEMPS WARM A LITTLE MORE TOMORROW, WITH
GENERALLY MID TO UPPER 70S EXPECTED ACROSS THE NORTH AND ALONG
THE COAST, AND LOW 80S ELSEWHERE.
SHOWERS DISSIPATE AGAIN SUNDAY EVENING, WITH ANOTHER SEASONABLY
COOL NIGHT EXPECTED AS LOWS BOTTOM OUT IN THE 50S. A LIGHT WEST
IS EXPECTED SUNDAY NIGHT. THIS KEEPS THE FOG COVERAGE LESS
OVERNIGHT, AND IT WILL MOST LIKELY REMAIN CONFINED TO THE RIVER
VALLEYS.
KEY MESSAGE 2 DESCRIPTION...
THE MAIN TAKEAWAY GOING INTO THIS WEEK IS PAIRING HEAT WITH
HUMIDITY TO POTENTIALLY BRING A SUMMER HEATWAVE. THE COMBINATION
FEATURING PERIODS OF 97 TO 99TH PERCENTILE PRECIPITABLE WATER
PLUS AROUND 99TH PERCENTILE 850MB TEMPERATURES INSTILLS GREATER
THAN NORMAL CONFIDENCE AT THIS RANGE. THE OUTCOME WOULD BE DAYS
(AND NIGHTS) WORTH OF CUMULATIVE HEAT, LEADING TO BUILDING HEAT
STRESS.
AFTER A PLEASANT WEEKEND WITH TEMPERATURES IN THE 70S TO LOWER
80S, A WARMING TREND STARTS THE WEEK, WITH HOT CONDITIONS
SETTLING OVER THE AREA BY MID TO LATE WEEK. TUESDAY NIGHT,
ANOMALOUSLY WARM 850MB TEMPERATURES BEGIN TO ADVECT EASTWARD
THROUGH THE GREAT LAKES AND OHIO VALLEY WITH HIGH PRESSURE SET
UP ACROSS THE SOUTH. TEMPERATURES AT THIS LEVEL COULD PUSH INTO
THE LOWER 20S (C) BY MIDDAY WEDNESDAY, WELL POSITIONING DAYTIME
SURFACE TEMPERATURES TO CLIMB INTO THE 90S. AT THE SAME TIME,
GREATER MOISTURE COLLOCATED WITH THE WARM AIRMASS SHOULD LEAD
TO INCREASED DEW POINT TEMPERATURES, AND THUS HIGHER HUMIDITY TO
MEET THE HEAT. WILL CONTINUE TO MONITOR THESE INGREDIENTS,
THEIR MAGNITUDE, COVERAGE, AND TIMELINESS, BUT CURRENT FORECAST
DAYTIME HEAT INDICES WOULD RISE ABOVE 95 AND TOWARDS THE TRIPLE
DIGITS WED AND THURS, POTENTIALLY LASTING INTO FRIDAY.
OVERNIGHT LOWS ARE NOT EXPECTED TO PROVIDE RELIEF WED/THURS
NIGHT, SETTLING IN THE UPPER 60S TO LOWER 70S.
THE SPATIAL COVERAGE OF 20C+ TEMPS AT 850 DOES ALLOW GREATER
CONFIDENCE IN THIS FORECAST, HOWEVER THERE ARE A FEW ITEMS THAT
MUDDY FORECAST TEMPS. THE FIRST WILL BE THE GENERALLY UNSTABLE
AIRMASS ACCOMPANYING THE HEAT AND HUMIDITY. SHOWERS/THUNDERSTORMS
COULD RESULT, LEADING TO INCONSISTENT HEATING FOR THE DAY. IT
WILL BE POSSIBLE TO RECEIVE CONVECTIVE SYSTEMS FROM THE WEST,
ROUNDING THE RIDGE AND ANTICYCLONIC FLOW. EITHER OF THESE WOULD
PROVIDE MORE CLOUD COVER OR PRECIPITATION, LIMITING MAX HEAT
POTENTIAL. SECOND, LOCATIONS NEAR THE COAST, BARRING STRONG
ENOUGH OFFSHORE FLOW, WILL BE SUSCEPTIBLE TO AFTERNOON SEABREEZE
THAT COULD PROVIDE MARINE AIR RELIEF. LASTLY, THERE IS SOME
UNCERTAINTY HOW LONG 20C+ 850 TEMPS LINGER OR POTENTIALLY
CONSOLIDATE TO THE SOUTH QUICKER LATER IN THE WEEK.
ON THE THUNDERSTORM THREAT: GREATER MOISTURE AND LOW LEVEL
WARMING TYPICALLY INCREASES THUNDERSTORM FUEL VIA CAPE IF A EML
OR GREATER MID LEVEL LAPSE RATES ARE IN PLACE. VARIOUS MACHINE
LEARNING CONVECTIVE GUIDANCE IS SUGGESTING WED/THURS AS DAYS TO
WATCH FOR POTENTIAL STRONG TO SEVERE THUNDERSTORMS, BUT IT
REMAINS UNCLEAR IF THESE WILL DEVELOP OVERHEAD OR ARRIVE FROM
THE WEST. THUS PREDICTABILITY AND CONFIDENCE REMAIN LOW, BUT
SHOULD BE MONITORED IN THE COMING DAYS IF THE THREAT INCREASES.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
VFR PREVAILS THIS AFTERNOON, WITH BRIEF SHOWERS POSSIBLE ACROSS
INTERIOR TERMINALS. FOG DEVELOPS AGAIN TONIGHT, WITH COASTAL
TERMINALS LIKELY SEEING IFR TO LIFR CONDITIONS BY LATE THIS
EVENING, AND INTERIOR TERMINALS AFTER MIDNIGHT. THE FOG AND LOW
STRATUS GRADUALLY GIVES WAY TO VFR EARLY TO MID MORNING ON
SUNDAY. SOME SCATTERED SHOWERS ARE POSSIBLE AGAIN SUNDAY
AFTERNOON. VFR PREVAILS AT MOST TERMINALS SUNDAY NIGHT, BUT
VALLEY FOG IS LIKELY AT LEB AND HIE AFTER MIDNIGHT.
OUTLOOK:
MONDAY: LOWER CEILINGS/VIS SHOULD CONSOLIDATE TO THE COASTAL
WATERS, WITH INLAND TERMINALS BECOMING VFR.
MONDAY NIGHT: RETURN OF LOWERED CEILINGS POSSIBLE OVERNIGHT FOR
COASTAL ME. MVFR TO IFR POSSIBLE.
TUESDAY AND TUESDAY NIGHT: IMPROVEMENT TO VFR IN THE MORNING,
BUT SHRA ARRIVE FROM THE WEST IN THE AFTERNOON, THESE MAY
CONTINUE INTO THE OVERNIGHT FOR ALL TERMINALS.
WEDNESDAY AND WEDNESDAY NIGHT: SHRA WITH SOME TS POSSIBLY
DEVELOP INLAND THROUGH THE AFTERNOON. THESE SHOULD REDUCE IN
COVERAGE OVERNIGHT.
MARINE
MARINE FOG LINGERS ACROSS THE SOUTHERN WATERS TODAY, AND LIKELY
DEVELOPS NEAR THE COASTLINE AGAIN TONIGHT. PATCHY DENSE FOG
LINGERS THROUGH THE DAY ON SUNDAY, AND THEN DISSIPATES WITH A
WEST WIND SUNDAY NIGHT. OTHERWISE, FAIR CONDITIONS PREVAIL WITH
BROAD HIGH PRESSURE SLOWLY BUILDING ACROSS THE WATERS.
HIGH PRESSURE CONTINUES TO RESIDE OVERHEAD THROUGH TUESDAY
MORNING. A WEAK WARM FRONT MAY DRAPE OVER THE WATERS THROUGH
MIDWEEK WITH STRONG HIGH PRESSURE REMAINING OVER THE DEEP SOUTH.
GYX WATCHES/WARNINGS/ADVISORIES
ME...NONE.
NH...NONE.
MARINE...NONE.
DISCUSSION...CLAIR/CORNWELL
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