Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 300431
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1231 AM EDT SAT MAY 30 2015

.SYNOPSIS...
HIGH PRESSURE WILL RETURN TODAY AND MOVE OFF THE COAST OVER THE
WEEKEND ALLOWING A WARM AND HUMID SOUTHWEST FLOW TO RETURN.
ANOTHER COLD FRONT CROSSES THE REGION SUNDAY MORNING.
COOL...CANADIAN HIGH PRESSURE WILL BUILD BACK OVER THE REGION
EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WILL CONTINUE A DENSE FOG ADVSRY FOR ALL MAINE COASTAL AREAS AND
MOST ADJACENT INLAND AREAS AS WELL. A WIDESPREAD AREA OF DENSE FOG
HAD DEVEPED ALONG THE COAST AND HAD PUSHED INLAND. THIS SHOULD
CONTINUE THE REST OF THE NIGHT AS THE LIGHT ONSHORE FLOW
CONTINUES.

720 PM UPDATE: OCEAN STRATUS/FOG HAS SPREAD FURTHER INLAND TO THE
ADJACENT COASTAL AREAS AT THIS TIME. MINOR ADJUSTMENT FOR
PLACEMENT OF LOW CLOUDS AND FOG FURTHER INLAND. ALSO MINOR TWEAKS
TO TEMPS BASED ON LATEST OBS.

PREVIOUS DISCUSSION:
MAIN FORECAST PROBLEM WILL BE MARINE STRATUS QUICKLY APPROACHING
THE COAST. HI-RES MODEL GUIDANCE ACTUALLY HAS A VERY GOOD HANDLE
ON THE CURRENT DEPICTION BASED ON VISIBLE SATELLITE. LEANING
HEAVILY ON THE NARRE AND HRRR FOR TIMING AND COVERAGE FOR THE
OVERNIGHT PERIOD. COASTAL ME...ESPECIALLY NEAR KPWM WILL SEE
STRATUS SOONEST...WITH ALL COASTAL AREAS LIKELY SEEING LOW CIGS BY
00Z. THRU THE NIGHT THIS WILL CREEP INLAND...AND SHOULD ROUGHLY
MATCH THE CURRENT SEA BREEZE FRONT OUTLINE. WINDS SHIFTING TO SWLY
WILL KEEP STRATUS CONFINED TO MAINLY THE GREAT BAY AREA AND E IN
SERN NH...WHILE ALLOWING IT TO PUSH AS FAR INLAND AS KAUG AND KWVL
IN CENTRAL ME.

WHILE CONFIDENCE IS HIGH IN LOW CLOUDS...CONFIDENCE IS SOMEWHAT
LOWER IN FOG AND DRIZZLE. THERE ARE SOME SIGNS BASED ON FORECAST
SOUNDINGS THAT THIS COULD DEVELOP OVERNIGHT. HRRR IS AGGRESSIVE ON
VSBYS BELOW 1/2 SM...WHILE NARRE IS A LITTLE MORE UP IN THE AIR.
SREF VSBYS PROBABILITIES OF GREATER THAN 80 PERCENT FOR LESS THAN
1 SM VSBY POINT TOWARDS SOME FOG MORE LIKELY THAT NOT. SO WILL
HAVE AREAS OF FOG IN THE GRIDS.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
GUSTY SW FLOW DEVELOPS AHEAD OF A SLOWLY APPROACHING COLD FRONT
SAT. THERE IS SUFFICIENT SHEAR FOR ORGANIZED STORMS ALONG THE
FRONT...BUT IT WILL DELAY IN REACHING THE FORECAST AREA. SREF
CALIBRATED SEVERE TSTM PROBABILITIES PEAK AROUND 21Z ACROSS THE
FAR NRN ZONES. ENVIRONMENT LOOKS FAIR ACROSS THIS AREA...SO WILL
ADD GUSTY WINDS TO THESE ZONES...AND DELAY TSTMS FOR COAST UNTIL
OVERNIGHT. THE OTHER THREAT TO WATCH WILL BE FLASH FLOODING. PWAT
VALUES WILL BE RUNNING HIGHER THAN NORMAL...AND SLOW FRONTAL
MOVEMENT COUPLED WITH TRAINING STORMS COULD YIELD SOME WATER
ISSUES. LOSS OF DAYTIME HEATING SHOULD HELP ANY STORMS TO WEAKEN
AND BECOME MORE SCATTERED...BUT A RENEWAL OF DEVELOPMENT IS
POSSIBLE EARLY SUN AS THE DAY HEATS UP AGAIN.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
POSITIVELY TILTED SHORTWAVE TROUGH PUSHES THE COLD FRONT THE
REMAINDER OF THE WAY OFFSHORE SUNDAY MORNING WITH SHOWERS COMING
TO AN END IN THE EARLY AFTERNOON. DENSE HIGH PRESSURE TO OUR NORTH
MAKES LITTLE HEADWAY SOUTH HOWEVER AS ANOTHER WAVE OF LOW PRESSURE
MOVES ALONG THE OFFSHORE FRONT. LINGERING CLOUDS AND COOLER
CANADIAN AIR MOVING IN WILL KEEP THE MOUNTAINS COOL (MID 50S)
WHILE MUCH OF THE COASTAL PLAIN CLEARS OUT AND WARMS INTO THE
UPPER 60S ON SUNDAY. MONDAY AND TUESDAY WILL GENERALLY WARM INTO
THE 60S.

THE PROXIMITY OF OFFSHORE FRONTAL SYSTEM AS WELL AS A STEADY
STREAM OF SHORT WAVE ENERGY WILL KEEP A CHANCE OF SHOWERS OVER
SOUTHERN AND COASTAL SECTIONS OF NH AND MAINE THROUGH MONDAY.
THERE IS LITTLE INSTABILITY TO BE HAD BUT THERE MAY BE SOME
LIGHTNING OFFSHORE. FOLLOWING THIS A STOUT CUTOFF SHORT WAVE MOVES
TOWARDS THE AREA TUESDAY INTO WEDNESDAY MORNING ON NEARLY ZONAL
FLOW INCREASING RAIN CHANCES ACROSS THE ENTIRE AREA. HIGH PRESSURE
BUILDS IN BEHIND THIS SYSTEM BRINGING DRY AND WARM CONDITIONS
THURSDAY AND FRIDAY.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...WIDESPREAD IFR/LIFR IS EXPECTED TONIGHT FOR COASTAL
TERMINALS AS MARINE STRATUS INVADES THE AREA. BETWEEN 21 AND 00Z
MOST SITES SHOULD BE IFR OR LOWER. KAUG MAY TAKE A COUPLE EXTRA
HOURS FOR LOW CIGS TO WORK INLAND...BUT BY 03Z IFR IS EXPECTED.
LOW CIGS PERSIST INTO SAT MORNING BEFORE LIFTING. GUSTY SW WINDS
AROUND 20 KTS POSSIBLE SAT AFTERNOON. TSTMS ARE POSSIBLE LATE SAT
INTO SUN FOR ALL TERMINALS. HIGHEST CONFIDENCE FOR TSTMS IS FOR
KHIE SAT EVENING.

LONG TERM...IMPROVING CONDITIONS SUNDAY WITH PERIODS OF MVFR IN
SHOWERS ALONG THE COAST CONTINUING THROUGH WEDNESDAY.

&&

.MARINE...
SHORT TERM...SW RETURN FLOW WILL INCREASE SAT. COOL WATERS SHOULD
LIMIT THE AMOUNT OF MIXING OF THE STRONGEST WINDS TO THE
SURFACE...BUT SUSTAINED FLOW SHOULD BUILD SEAS ABOVE 5 FT BY LATE
SAT. OCCASIONAL GUSTS TO 25 KTS ARE NOT OUT OF THE QUESTION
EITHER.

LONG TERM...WAVES DROP BELOW SCA CRITERIA SUNDAY MORNING. HIGH
SEAS RETURN MONDAY EVENING THROUGH TUESDAY NIGHT AS A TIGHT
PRESSURE GRADIENT SETS UP OVER THE WATERS.

&&

.FIRE WEATHER...
INCREASING HUMIDITY AND SOUTHWESTERLY BREEZES
WILL LEAD TO LATE AFTERNOON SHOWERS AND THUNDERSTORMS SATURDAY
AFTERNOON AND NIGHT. WETTING RAINS WILL BE MOST LIKELY IN THE
MOUNTAINS SATURDAY EVENING AND OVERNIGHT. THE AREAS NEAR THE COAST
WILL BE MORE LIKELY TO SEE WETTING RAINS SUNDAY.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...DENSE FOG ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     MEZ019>028.
NH...NONE.
MARINE...NONE.

&&

$$ ..



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