Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 291008
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
608 AM EDT FRI APR 29 2016

.SYNOPSIS...
DRY AIR AND SURFACE HIGH PRESSURE PERSISTS INTO SATURDAY...AS A
SERIES OF WEAK DISTURBANCES PASS TO OUR SOUTH. LOW PRESSURE TRACKING
SOUTH OF THE AREA LATE SUNDAY INTO MONDAY WILL BRING THE NEXT
CHANCE OF PRECIPITATION...WHICH WILL BE MAINLY RAIN. WEAK HIGH
PRESSURE BUILDS IN FOR TUESDAY...WITH ANOTHER LOW PASSING
OFFSHORE MID TO LATE NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

600 AM...MINOR ESTF UPDATE TO REFLECT CURRENT GOES SATELLITE
TRENDS AND TO INGEST THE CURRENT MESONET INTO NEAR TERMS GRIDS.

PREV DISC...
AT 06Z...A NORTHWEST TO SOUTHEAST ORIENTED RIDGE OF HIGH PRESSURE
REMAINED DRAPED ACROSS THE FORECAST AREA. GOES INFRARED IMAGERY
SHOWED HIGH AND PATCHY MID CLOUDS ACROSS THE SOUTHERN HALF OF NEW
HAMPSHIRE AND ADJACENT SOUTHWEST MAINE. FOR TODAY...LITTLE CHANGE
IS EXPECTED WITH THE BRIGHTEST SKIES ACROSS NORTHERN NEW HAMPSHIRE
AND THE MAINE MOUNTAINS AND FOOTHILLS AND FILTERED SUNSHINE THROUGH
HIGH CLOUDS FURTHER SOUTH. HIGHS WILL BE MAINLY IN THE 50S WITH THE
COOLEST READINGS ACROSS THE MOUNTAINS...AND ALONG THE COAST AS THE LIGHT
SYNOPTIC FLOW QUICKLY TURNS ONSHORE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
LITTLE CHANGE TONIGHT AND SATURDAY AS THE RIDGE OF HIGH PRESSURE
AND DRY AIR REMAINS DRAPED ACROSS THE FORECAST AREA. CLOUDS WILL
BRIEFLY THICKEN EARLY TONIGHT OVER THE SOUTHERN HALF OF NEW
HAMPSHIRE INTO ADJACENT SOUTHWEST MAINE AS A SHORTWAVE IMPULSE
RACES ACROSS THE REGION. LOWS TONIGHT WILL RANGE FROM THE 20S
ACROSS NORTHERN AND MOUNTAIN SECTIONS WHERE CLOUD COVER WILL BE
MINIMAL TO THE 30S ELSEWHERE. IT`LL BE SEVERAL DEGREES WARMER ON
SATURDAY AS 850 MILLIBAR TEMPERATURES BEGIN TO MODERATE. SIMILAR
TO TODAY...THE COOLEST TEMPERATURES WILL BE FOUND OVER MOUNTAIN
SECTIONS...AND ALONG THE COAST AS LIGHT SYNOPTIC FLOW TURNS
ONSHORE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HIGH IMPACT WX: NONE.

500 MB PATTERN WILL REMAIN WELL AMPLIFIED AND BLOCKY THROUGH THE
EXTENDED...ALBEIT WITH A BRIEF BREAK DOWN OF THE BLOCKING OVER
THE WEEKEND INTO EARLY NEXT WEEK...BEFORE A WELL AMPLIFIED TROUGH
TRIED TO FORM INTO THE GREAT LAKES AND OH/TN VLYS. THIS WILL LEAD
TO AN UNSETTLED...AND LOW CONFIDENCE...FORECAST PERIOD STARTING
SUNDAY AND EXTENDING INTO LATE NEXT WEEK.

MODELS DO SHOW BETTER LARGE SCALE AGREEMENT FOR SUNDAY AND MONDAY
AS SHALLOW BUT POTENT 500MB WAVE TRACKS THRU THE GREAT LAKES AND
ACROSS NEW ENGLAND. PRECIP SHOULD HOLD OFF THROUGH SAT NIGHT AND
MAY STRUGGLE TO MAKE ITS WAY OUT OF THE CT VLY ON SUNDAY AS DRY
AIR MASS IN PLACE...AND THE FACT THAT MID-LVL WAA MOVES INTO WEAK
RIDGING AT 500 MB. DEVELOPING ONSHORE COULD PRODUCE SOME DRIZZLE
ON THE COASTAL PLAIN LATE IN THE DAY AS WELL. BEST CHANCE OF
PRECIP WILL BE SUNDAY NIGHT AND MONDAY AS THE SFC LOW DEVELOPS
OVER THE MID-ATLANTIC AND TRACKS JUST OUTSIDE THE 40/70 BENCHMARK.
GFS. WHILE BOTH MODELS PRODUCE A SIMILAR TRACK...GFS MORE
AGGRESSIVE WITH DEEPENING THE SFC LOW AND HAS MORE QPF...BUT
NEITHER MODELS PRODUCES A SOAKER...GENERALLY HALF TO AS MUCH A
0.75 INCHES IN THE GFS. LEANED MORE TOWARD THE EURO AND ITS
OVERALL BETTER PERFORMANCE. SINCE THERE IS SOME COLD AIR BEING
PULLED SOUTH AND BEING GENERATED BY PRECIP PROCESS...HAVE TO TALK
ABOUT SNOW...BIT THIS SYSTEM IS WARMER THAN THE PREVIOUS SYSTEM
FORM TUESDAY...AND 850 TEMPS GENERALLY STAY ABOVE -2C /COMPARED TO
-4 OR -5 LAST TUESDAY/...AND THIS WILL BE MAINLY IN THE NRN ZONES.
THE HIGHER TERRAIN IN THE MOUNTAINS COULD SEE SOME ACCUMULATING
SNOW ON MONDAY...BUT EVERYWHERE ELSE SHOULD SEE SOME RAIN. THE SFC
LOW WILL TRACK OUT TO THE NE QUICKLY BY TUE MORNING AND TUE-WED
LOOK MAINLY DRY IN THE EURO...AS HIGH PRESSURE BUILDS TO OUR
SOUTH. BY THURSDAY COULD SEE ANOTHER COASTAL LOW BRING SOME RAIN
TO THE REGION...BUT CONFIDENCE IS LOW.

TEMPS THRU THE PERIOD WILL BE RUNNING A LITTLE BELOW
NORMAL...BUT THE COOLEST DAYS WILL BE SUNDAY AND MONDAY WITH HIGHS
SUNDAY AROUND 50...AND MONDAY WILL BE IN THE 40S TO MAYBE 50.
OVERALL THOUGH...SHOULD SEE A VERY GRADUAL WARMING TREND MID-LATE
WEEK.

&&

.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
SHORT TERM /THROUGH SATURDAY/...LCL MVFR PSBL THIS AM IN
CEILINGS...OTW VFR CONDITIONS EXPECTED THROUGH THE PERIOD.

LONG TERM...MAINLY VFR SAT NIGHT INTO SUNDAY MORNING...WITH SOME
MVFR POSSIBLE SUN AFTERNOON. EXTENDED PERIOD OF FLIGHT
RESTRICTIONS /PROBABLE IFR OR LOWER SUNDAY NIGHT INTO MONDAY/ IN
RA AND DZ AND LOW CIGS. IMPROVEMENT TO MVFR MON NIGHT AND VFR
TUE.

&&

.MARINE...
SHORT TERM /THROUGH SATURDAY/...WINDS AND SEAS WILL REMAIN
RELATIVELY LIGHT THROUGH THE PERIOD...THEREFORE NO SCAS ARE
EXPECTED. WINDS ARE EXPECTED TO BECOME LOCALLY ONSHORE DURING THE
AFTERNOON HOURS.

LONG TERM...MAY NEED SCA FOR BOTH WINDS/SEAS MONDAY AND MON NIGHT.

&&

.FIRE WEATHER...
AN ONSHORE WIND WILL RESULT IN MINIMUM RELATIVE HUMIDITY VALUES
IN THE 30S AND 40S ACROSS SOUTHERN NEW HAMPSHIRE AND THE MAINE
COASTAL PLAIN. ACROSS NORTHERN NEW HAMPSHIRE AND THE WESTERN MAINE
MOUNTAINS AND FOOTHILLS...MINIMUM RELATIVE HUMIDITIES WILL RANGE
FROM 20 TO 30 PERCENT BUT WITH LIGHT WINDS. SIMILAR RELATIVE HUMIDITY
VALUES ALONG WITH LIGHT WINDS ARE EXPECTED SATURDAY. GOOD RELATIVE
HUMIDITY RECOVERY WILL OCCUR TONIGHT. A WIDESPREAD PRECIPITATION
EVENT IS LIKELY FOR LATE SUNDAY AND MONDAY.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.

&&

$$
ES



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