Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 040153 AAB
AFDGYX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAY ME
953 PM EDT SUN MAY 3 2015

.SYNOPSIS...
HIGH PRESSURE OFFSHORE WILL BRING A SOUTHERLY FLOW OVER THE
NORTHEAST AND TRANSPORT WARMER AIR INTO THE AREA. A WEAK COLD
FRONT WILL CROSS THE AREA MONDAY NIGHT AND EARLY TUESDAY WITH
SCATTERED SHOWERS AND THUNDERSTORMS. A MOISTURE STARVED COLD
FRONT WILL CROSS THE AREA WEDNESDAY. A RIDGE OF HIGH PRESSURE
FOLLOWS FOR LATE WEDNESDAY AND THURSDAY. A DEVELOPING ONSHORE
FLOW AND AN APPROACHING WARM FRONT WILL MAKE THE WEATHER
INCREASINGLY UNSETTLED FOR FRIDAY. THE WARM FRONT SHOULD LIFT TO
THE NORTH OF THE AREA BY SATURDAY FOLLOWED BY A TRAILING COLD
FRONT LATE SATURDAY NIGHT AND SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
.UPDATE...
NO MAJOR CHANGES FOR THIS UPDATE. INGESTED CURRENT MESONET DATA
TO ADJUST TEMPERATURE AND DEW POINT TRENDS.

&&

PREVIOUS DISCUSSION...ISSUED A FIRE WEATHER WATCH AFTER TALKING
WITH NH FORESTRY SERVICE AND SURROUNDING OFFICES. THIS BRINGS US
IN LINE WITH THE SURROUNDING OFFICES. WE ARE STILL SHORT OF
CRITERIA BUT DEW POINTS MAY BE LOWER THAN FORECAST.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
MONDAY WILL BE THE WARMEST DAY OF THE YEAR SO FAR WITH MANY AREAS
CRACKING THE 80 DEGREE MARK. A LITTLE COOLER NEAR THE COAST WHERE
A SEA BREEZE WILL BE PRONE TO DEVELOPING BUT EVEN PORTLAND SHOULD
REACH 70 DEGREES.

STRONG MIXING WITH THE DAYTIME HEATING WILL BRING REALLY DRY AIR
TO THE SURFACE AGAIN MONDAY. MODEL DEW POINT FORECASTS CONTINUE
TO BE PRETTY ATROCIOUS THIS TIME OF YEAR WITH THE DIFFICULTY IN
ACCOUNTING FOR THE MIXING. HAVE UNDERCUT AFTERNOON DEW POINTS BY
SEVERAL DEGREES TO ACCOUNT FOR THE MIXING AWAY FROM THE COAST BUT
EVEN THIS MIGHT NOT BE LOW ENOUGH. THIS DRY AIR WILL SPELL FIRE
WEATHER CONCERNS DETAILED IN THE FIRE WEATHER DISCUSSION BELOW.

COLD FRONT BEGINS MOVING ACROSS THE FORECAST AREA OVERNIGHT. MOIST
ADVECTION AHEAD OF THE FRONT WILL LIKELY LEAD TO CLOUDS AND WARMER
OVERNIGHT TEMPERATURES. REMNANT CONVECTION FROM QUEBEC WILL LIKELY
MOVE SOUTHEAST INTO THE BORDER REGIONS BEFORE DISSIPATING AS THE
FRONT MOVES ACROSS THE FORECAST AREA OVERNIGHT. ANY SHOWERS WILL
NOT ARRIVE UNTIL AFTER DARK AND THIS ALONG WITH THE LACK OF
SUBSTANTIAL FORCING AND SIGNIFICANT MOISTURE WILL MAKE THE THREAT
OF THUNDERSTORMS FAIRLY LOW.

BY TUESDAY MORNING THE FRONT WILL BE NEARING THE COASTLINE AND
SAGGING SLOWLY SOUTHWARD THROUGH SOUTHERN NEW HAMPSHIRE. COULD SEE
SHOWERS TRYING TO DEVELOP ALONG THE FRONT IN THE LATE MORNING OR
EARLY AFTERNOON OVER SOUTHERN NEW HAMPSHIRE BEFORE THE FRONT
FINALLY PUSHES FULLY SOUTH INTO MASSACHUSETTS. OTHERWISE IT WILL
BE A DRY AND WARM DAY AGAIN ACROSS THE REGION. OFFSHORE FLOW WILL
PREVENT MUCH OF A SEA BREEZE SO TUESDAY COULD BE THE WARMEST DAY
IN PORTLAND.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE MODELS ARE IN GENERAL AGREEMENT ON THE LONG WAVE PATTERN
FOR THE ENTIRE FORECAST PERIOD. WE BEGIN THE PERIOD WITH WEST-
NORTHWEST FLOW ALOFT IN ADVANCE OF AN UPPER RIDGE CENTERED ACROSS
THE WESTERN GREAT LAKES. AN IMPULSE EMBEDDED IN THAT FLOW WILL
DRIVE A WEAK MOISTURE STARVED COLD FRONT ACROSS THE AREA
WEDNESDAY. HIGH PRESSURE THEN BUILDS BY TO OUR NORTH LATE
WEDNESDAY THROUGH THURSDAY. THE FLOW TURNS ONSHORE BY THURSDAY
NIGHT...AND WITH AN UPPER RIDGE BUILDING TO OUR WEST...A WARM
FRONT DEVELOPS ACROSS THE REGION THURSDAY NIGHT AND FRIDAY.
LIGHT OVERRUNNING PRECIPITATION AND SOME DRIZZLE AND FOG IS
POSSIBLE FRIDAY MAINLY OVER NORTHERN AND EASTERN SECTIONS OF THE
FORECAST AREA AS THE FRONT PRESSES NORTH. DURING THE PAST
DAY...THE MODELS HAVE COME AROUND TO A SOLUTION THAT DRIVES THE
WARM FRONT TO OUR NORTH BY SATURDAY FOLLOWED BY A TRAILING COLD
FRONTAL PASSAGE SATURDAY NIGHT/EARLY SUNDAY. UNFORTUNATELY...THE
FRONT THEN STALLS OUT AND PROVIDES THE PROSPECT OF CLOUDS AND
UNSETTLED WEATHER FOR THE TAIL END OF THE WEEKEND AND EARLY NEXT
WEEK.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SHORT TERM...AFTERNOON SHOWERS DISSIPATE EARLY THIS EVENING.
SHOULD SEE VFR CONDITIONS AND NEARLY CALM WINDS FOR MOST OF THE
AREA. THE MARINE CLOUDS AND FOG ARE LESS LIKELY TO FORM TONIGHT
THAN LAST NIGHT BUT CANNOT RULE IT OUT COMPLETELY. BEST CHANCE
WOULD BE AT ROCKLAND. IF THIS DOES FORM IT WILL DISSIPATE AGAIN IN
THE MORNING MONDAY LEADING TO VFR CONDITIONS AGAIN AREAWIDE.

LONG TERM...

FRIDAY...SCATTERED MVFR POSSIBLE IN SHOWERS.

&&

.MARINE...
SHORT TERM...LIGHT WINDS OVER THE WATERS TODAY BUT BECOMING MORE
SOUTHWESTERLY AND STRENGTHENING MONDAY EVENING. COULD POTENTIALLY
SEE GUSTS TO 25 KT MONDAY NIGHT OVER THE OUTER WATERS BEFORE A
COLD FRONT MOVES THROUGH.

LONG TERM...

WEDNESDAY EVENING - THURSDAY MORNING...SMALL CRAFT WINDS AND SEAS
ARE POSSIBLE.

FRIDAY...SMALL CRAFT WINDS AND SEAS ARE POSSIBLE.

&&

.FIRE WEATHER...
AFTERNOON HEATING ON MONDAY WILL LEAD TO GOOD MIXING AND PULL DOWN
SIGNIFICANTLY DRIER AIR FROM ALOFT. AFTERNOON HUMIDITY LEVELS FALL
BELOW 25 PERCENT FOR MUCH OF THE AREA BUT WIND SPEEDS WILL ONLY
REACH AROUND 10 OR 15 MPH. BOTH OF THESE CRITERIA ARE ONE CATEGORY
BELOW RED FLAG WARNING CONDITIONS BUT THERE IS SOME CONCERN THAT
DRY AIR COULD BE MORE INTENSE THAN FORECAST. THEREFORE A WATCH HAS
BEEN ISSUED AND WE WILL CONTINUE TO MONITOR CONDITIONS.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY
     EVENING FOR MEZ007>009-012>014-018>021.
NH...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY
     EVENING FOR NHZ001>013-015.
MARINE...NONE.

&&

$$

UPDATE...HANES


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