414
FXUS61 KGYX 011443
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1043 AM EDT TUE JUL 1 2025
SYNOPSIS
A COLD FRONT WILL APPROACH THE REGION THIS AFTERNOON...CROSSING
THE AREA TONIGHT WITH A FEW SHOWERS AND THUNDERSTORMS. DRIER
AIR MOVES BACK IN FOR WEDNESDAY BEFORE A SECONDARY...STRONGER
COLD FRONT BRINGS A RENEWED CHANCE FOR SHOWERS AND THUNDERSTORMS
FOR THURSDAY AFTERNOON. DRIER AND COOLER CANADIAN AIR ARRIVES
FOR INDEPENDENCE DAY AND SATURDAY BEFORE TEMPERATURES MOVE ABOVE
NORMAL TO END THE HOLIDAY WEEKEND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
1030 AM UPDATE: REFRESHED THE NEAR TERM FORECAST TO DECREASE SKY
COVER SOMEWHAT AS SKIES SLOWLY CLEAR ACROSS THE AREA FROM SW TO
NE. LATEST CAMS CONTINUE TO PAINT AN ISOLATED THREAT FOR SEVERE
WEATHER THIS AFTERNOON AND EVENING. KINEMATIC/THERMODYNAMIC
VARIABLES APPEAR SUPPORTIVE FOR THE MARGINAL THREAT...THOUGH
THE BEST FORCING/SHEAR WILL REMAIN SOMEWHAT NORTH OF THE BEST
LLEVEL INSTABILITY. HAVE NOT INCLUDED ENHANCED WORDING AT THIS
TIME GIVEN WHAT CURRENT APPEARS TO BE AN ISOLATED THREAT. WARM
AND HUMID CONDITIONS WILL PERSIST...WITH THE ASH-MHT CORRIDOR
SEEING HEAT INDICES PEAK IN THE LOWER 90S.
9 AM UPDATE: WITH IMPROVING VISIBILITIES ACROSS THE AREA OF THE
ADVISORY...WILL CANCEL THE REMAINDER OF THE DENSE FOG ADVISORY.
NO OTHER CHANGES AT THIS TIME.
8 AM UPDATE...DENSE FOG ADVISORY FOR THE ME COAST, CLEARING
FROM W TO E AFTER SUNRISE. MIDCOAST FOG COULD LINGER THROUGH
LATE MORNING AS REINFORCING SURGE OF MOISTURE OFF THE COOL GULF
DELAYS BURN OFF. SHOWERS ADVANCING FROM THE WEST ALONG WITH
THICKENING CLOUDS IN THE NORTH, BUT GENERALLY LIGHT TO MODERATE
RAINFALL AND NO THUNDER AT THIS TIME. CAN'T RULE OUT A FEW
RUMBLES OF THUNDER THROUGH LATE MORNING AS THIS TROUGH FEATURE
SWINGS BY. THE MAIN FOCUS REMAINS ON HOW MUCH DAYTIME HEATING IS
INHIBITED BY THESE MORNING CLOUDS, AND THUS THE POTENTIAL FOR
SEVERE WEATHER AHEAD OF THE COLD FRONT LATER THIS AFTERNOON AND
EVENING. FORECAST APPEARS ON TRACK FOR AN ISOLATED STRONG STORM
WITH DAMAGING WINDS AND HEAVY RAINFALL.
AS FOR PRECIP THIS MORNING...GUIDANCE IS FOCUSING MAINLY ON THE
NORTHERN ZONES. CONVECTION TO THE SOUTH AROUND NYC IS FORECAST
TO DISSIPATE AS IT MOVES NORTHEAST AND LARGELY STAY SOUTH OF THE
FORECAST AREA. WARM ADVECTION SHOWERS TO THE NORTH ARE FORECAST
TO CONTINUE IN THE MTNS. WHILE THE SOUTHERN END OF THOSE SHOWERS
MAY INCREASE A BIT IN INTENSITY...THE COOLING EFFECT OF PRECIP
AND CLOUDS IN THIS AREA SHOULD LIMIT THE AFTERNOON SEVERE
WEATHER THREAT ACROSS THE NORTH.
TO THE SOUTH OVER MUCH OF THE REST OF THE FORECAST AREA THE
STORM PREDICTION CENTER STILL HAS A MARGINAL RISK FOR SEVERE
WEATHER. THIS IS DRIVEN PRIMARILY BY THE THREAT FOR WIND GUST.
BASED ON FORECAST SOUNDINGS I DO NOT DISAGREE WITH THAT
ASSESSMENT. SKINNY CAPE PROFILES WITH AN AREA OF DRYING IN THE
700 TO 500 MB LAYER WOULD SUPPORT PRECIP LOADING AND DOWNBURST
POTENTIAL. WE ALSO SHOULD HAVE MORE THAN ENOUGH SHEAR TO
ORGANIZE THE UPDRAFTS. THE LIMITING FACTOR WILL BE COVERAGE OF
CONVECTION. CURRENT CAMS ARE FAIRLY SCATTERED THRU THE DAY AND
BY THE TIME THE FRONT REALLY ARRIVES IN THE FORECAST AREA IT IS
AFTER DARK AND WE ARE RAPIDLY LOSING INSTABILITY. I DID REMOVE
THE SEVERE WORDING FROM THE GRIDS GIVEN THE OVERALL UNCERTAINTY.
IT IS POSSIBLE THAT ONCE WE SEE HOW MORNING PRECIP EVOLVES THAT
MORE TARGETED AREAS COULD BE ADDED BACK TO THE FORECAST. I DID
ALSO ADD HEAVY RAIN WORDING TO THUNDERSTORMS FOR THE AFTERNOON.
PWATS WILL BE NEAR 2 INCHES...AND HREF MAX QPF IN 6 HOURS LATE
THIS AFTERNOON IS PUSHING 3 INCHES.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/
AS THE FRONT NEARS THE COAST THIS EVENING SHOWERS AND STORMS
WILL BE RIDING NORTHEAST ALONG THE BOUNDARY. GIVEN THAT THE
THREAT FOR SEVERE WEATHER IS EXPECTED TO BE TIED MOSTLY TO
ELEVATED CORES...AS WE INCREASE CIN THE THREAT SHOULD DECREASE
PRETTY QUICKLY. HOWEVER SOME TORRENTIAL RAIN WILL REMAIN
POSSIBLE AS THE NEAR 2 INCH PWATS WILL NOT BE PUSHED SOUTH OF
THE LOCAL AREA UNTIL WELL AFTER MIDNIGHT.
SOME MARINE FOG WILL ALSO BE POSSIBLE...BUT MY CURRENT THINKING
IS THAT SOUTHWESTERLY WIND DIRECTION AND RAIN OUTFLOW WILL HELP
TO KEEP THAT IN THE GULF OF ME VS ONSHORE.
WED WILL FEATURE A SIMILARLY WARM DAY BUT SLIGHTLY LESS HUMIDITY
AND WEAKER OVERALL FORCING. BUT DIURNAL HEATING ALONE MAY BE
ENOUGH TO POP OFF SOME ISOLATED SHOWERS OR THUNDERSTORMS. THESE
WOULD MAINLY BE TIED TO HEATING OF THE HIGHER TERRAIN AND WILL
TEND TO DISSIPATE AS THEY LEAVE THAT HEAT SOURCE AND DRIFT
EAST/SOUTHEAST.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
KEY MESSAGE: ANOTHER FRONT WILL CROSS THE AREA THU WITH THE
THREAT OF SHOWERS AND STORMS. THIS WILL BE FOLLOWED BY HIGH
PRESSURE AND GENERALLY DRY AND PLEASANT WEATHER THRU THE
WEEKEND.
IMPACTS: VARIOUS CONVECTION ALLOWING MODELS (CAMS) AND ENSEMBLES
ARE HINTING AT A THREAT FOR STRONG TO SEVERE STORMS THU. THIS
WILL BE HIGHLY DEPENDENT ON TIMING OF THE FRONT...AS IT MAY
ALREADY BE NEAR THE COAST AT PEAK HEATING HOWEVER.
FORECAST DETAILS: A REINFORCING COLD FRONT IS FORECAST TO DROP
OUT OF QUEBEC AND CROSS NEW ENGLAND THU. CSU MACHINE LEARNING
SEVERE PROBABILITIES INDICATE THAT A MARGINAL TO LOW END SLIGHT
RISK SEVERE THREAT IS POSSIBLE GIVEN THE SET UP. FORECAST
SOUNDINGS SHOW BOTH SUFFICIENT CAPE AND SHEAR TO SUPPORT THAT
THINKING. IN ADDITION ECMWF EFI ALSO HAS AN ELEVATED CAPE/SHEAR
OVERLAP...ESPECIALLY FOR SOUTHEAST HALF OF THE FORECAST AREA.
THAT ALSO MEANS THAT WE HAVE A NARROW SPATIAL WINDOW FOR THIS
THREAT GIVEN THE CURRENT FORECASTS OF FRONTAL TIMING. IF THE
BOUNDARY SPEEDS UP IT WILL ALREADY BE IN THE GULF OF ME BY THE
TIME PEAK HEATING OCCURS.
AFTER THE FRONT HIGH PRESSURE BUILDS IN FROM THE WEST. THE RIDGE
AXIS IS NOT FORECAST TO CROSS THE FORECAST AREA UNTIL SOMETIME
SAT. THIS WILL MEAN LARGELY WEST TO NORTHWEST FLOW FRI AND
LITTLE IN THE WAY OF MOISTURE ADVECTION. THAT WILL MEAN A WARM
4TH WITH REFRESHING DEWPOINTS.
SAT INTO SUN HUMIDITY WILL START TO CREEP BACK UP AGAIN WITH THE
NEXT FRONTAL PASSAGE POSSIBLE MON OR TUE.
AVIATION /15Z TUESDAY THROUGH SATURDAY/
SHORT TERM...DENSE FOG LIFR PREVALENT ACROSS THE MIDCOAST WITH
IMPROVING CONDITIONS FROM WEST TO EAST. THIS IS IMPACTING
AUG/RKD PRIMARILY. ELSEWHERE FOCUS WILL BE ON CONVECTIVE
DEVELOPMENT. SHOWERS IN THE NORTH WILL EXPAND IN COVERAGE, WITH
THE POTENTIAL FOR THUNDERSTORMS THIS AFTERNOON. FOG CONDITIONS
LIKELY AGAIN OVERNIGHT.
LONG TERM...LARGELY VFR CONDITIONS EXPECTED THRU THE EXTENDED.
THE EXCEPTION WILL BE WITH ANOTHER FRONTAL PASSAGE AROUND THE
THU TIMEFRAME. SOME REDEVELOPING COASTAL FOG WILL BE POSSIBLE
AND THREATEN IFR CONDITIONS FOR COASTAL TERMINALS. THE FRONTAL
PASSAGE WILL BRING INCREASING CHANCES FOR SHRA/TSRA WITH LOCAL
MVFR OR LOWER CONDITIONS POSSIBLE.
MARINE
SHORT TERM...AREAS OF FOG ARE DEVELOPING AS MOISTURE CONTINUES
TO INCREASE ACROSS THE COASTAL WATERS. SOME OF THIS FOG MAY BE
LOCALLY DENSE THRU DAYBREAK. A THE FRONTAL BOUNDARY NEARS THE
WATERS TONIGHT THE SOUTHWEST WINDS WILL INCREASE...AND A FEW
GUSTS NEAR 25 KT ARE POSSIBLE. IN ADDITION ANY CONVECTION THAT
SURVIVES OVER THE TRIP INTO THE GULF OF ME MAY ALSO CONTAIN
GUSTY WINDS AND TORRENTIAL RAIN.
LONG TERM...WINDS AND SEAS GENERALLY EXPECTED TO REMAIN BELOW
SCA THRESHOLDS THRU THE WEEKEND. ANOTHER FRONTAL BOUNDARY WILL
CROSS THE WATERS AROUND THU. WILL HAVE TO WATCH FOR THE
REDEVELOPMENT OF COASTAL FOG ALONG WITH THE THREAT OF CONVECTION
BRINGING GUSTY WINDS TO THE WATERS.
GYX WATCHES/WARNINGS/ADVISORIES
ME...NONE.
NH...NONE.
MARINE...NONE.
NEAR TERM UPDATE...ARNOTT
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page