Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 210711
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
311 AM EDT MON APR 21 2014

.SYNOPSIS...
HIGH PRESSURE CONTINUES TO SLOWLY SHIFT EAST TODAY WITH FAIR
WEATHER EXPECTED. LOW PRESSURE APPROACHES FROM THE WEST
TUESDAY...CROSSING THE AREA TUESDAY NIGHT AND WEDNESDAY. HIGH
PRESSURE BUILDING ACROSS THE REGION WILL BRING FAIR WEATHER MID
TO LATE WEEK. ANOTHER AREA OF LOW PRESSURE TRACKING TO OUR NORTH
BRINGS A THREAT OF SHOWERS SATURDAY.

&&

.NEAR TERM /THROUGH TODAY/...
MID LEVEL FRONTAL BOUNDARY ACROSS THE INTERNATIONAL BORDER IS
PROVIDING THE FOCUS FOR SOME CLOUDS AND SPRINKLES THIS MORNING.
HAVE TO LOOK ALL THE WAY BACK TO SRN ONTARIO TO FIND ANYTHING
REACHING THE GROUND OR CIGS BELOW 8 KFT. HAVE KEPT POP BELOW 15
ATTM EXPECTING NO MEASURABLE PCPN...BUT A SPRINKLE OR FLURRY IS
POSSIBLE. PATCHES OF MID LEVEL CLOUDS WILL PLAY WITH TEMPS IN THE
NEAR TERM. CLEARING WILL ALLOW AREAS TO DROP INTO THE 20S...WHILE
CLOUDS WILL BOUNCE READINGS BACK INTO THE 30S.

SHOULD BE A FAIR DAY TODAY...ESPECIALLY AWAY FROM THE COAST.
DEPARTING HIGH WILL ALLOW SLY RETURN FLOW TO DEVELOP. THIS ONSHORE
COMPONENT WILL KEEP COASTAL ME IN THE 50S...WHILE INTERIOR
SECTIONS WARM INTO THE 60S TO NEAR 70. WARMING TEMPS AND DRY AIR
MASS WILL PRODUCE RH VALUES CLOSE TO 25 PERCENT ACROSS MUCH OF NH
TODAY. WINDS SHOULD REMAIN BELOW 20 MPH ON GUSTS...BUT THIS WILL
STILL LEAD TO AN ELEVATED FIRE DANGER. NOT ENOUGH FOR A RED
FLAG...BUT WILL MENTION HERE AND IN THE HWO TO HIGHLIGHT DRY
CONDITIONS.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
CONTINUED SLY/SWLY FLOW SHOULD YIELD A MILD NIGHT...WITH READINGS
IN THE 40S. SOME SHRA MAY SPILL INTO NRN ZONES FROM CANADA AS FNT
PRESSES CLOSER TO THE REGION. LOW PRES WILL CONTINUE TO PUSH FNT
TOWARDS NEW ENGLAND TUE. EXPECT A MAINLY DRY DAY FOR AREAS SE OF
THE MTNS...WITH SHRA BECOMING MORE NUMEROUS ACROSS THE N AS THE
DAY WEARS ON. HIGH TEMPS SHOULD BE SIMILAR TO TODAY...COOLER AT
THE COAST AND FAR N UNDER CLOUD COVER...WARMING NICELY INLAND.
LATE IN THE DAY COASTAL STRATUS MAY BEGIN TO FORM...AS DEEPER SLY
FLOW DEVELOPS OVER THE WATERS. HOWEVER...THIS LOOKS MORE LIKELY TO
HOLD OFF UNTIL TUE NIGHT.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
00Z MODELS IN FAIR AGREEMENT THAT THE NEAR ZONAL FLOW AT
500MB...BREAKS DOWN AND BECOMES QUITE AMPLIFIED AND BLOCKY BY THE
WEEKEND. HOWEVER...THERE DETAILS VARY QUITE A BIT...AND THIS WILL
MEAN LOWERING FORECAST CONFIDENCE AS WE MOVE INTO NEXT WEEKEND
AND BEYOND.

FAIRLY HIGH CONFIDENCE EARLY IN THE PERIOD AS SHRA MOVE THROUGH
THE CWA TUE NIGHT INTO WED MORNING AS WEAK LOW AND COLD FRONT
TRACK ACROSS THE AREA. TUE NIGHTS TEMPS WARM ENOUGH THAT PRECIP WILL
BE RAIN EVERYWHERE BUT THE HIGHEST TERRAIN. UNCERTAINTY ALREADY
BEGINS TO ENTER THE FORECAST LATE WED AND WED NIGHT...AS UPPR LVL
LOW CLOSES OFF TO OUR SE AND COULD SLOW SFC LOW OR HANG SFC TROUGH
BACK TO THE WEST. THIS COULD LINGER SOME SHRA THU AFT INTO THU
NIGHT ALONG THE MID-COAST AND INTO THE KENNEBEC AND PENOBSCOT
VLYS. AS THAT LOW INTENSIFIES OFFSHORE...WILL SEE N-NW WINDS PICK
UP ON THE BACK SIDE...WITH SOME BREEZY CONDS IN STORE WED INTO
THU.

DECENT RIDGING ALOFT BUILDS BEHIND THE LOW THU INTO FRI...SO
EXPECTING A DRY PERIOD...WITH TEMPS NEAR TO SLIGHTLY ABV NORMAL.
ITS AFTER THIS WHEN WE START TO GET INTO MULTIPLE STRONG BLOCKS
AND GYRES AT 500 MB...AND CONFIDENCE IN ANY MODELS ABILITY TO
HANDLE THESE FEATURES IS LOW...BUT FOR NOW LOOK FOR A CHC OF
SHOWERS AT SOME POINT OVER THE WEEKEND.



&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
SHORT TERM...VFR CONDITIONS EXPECTED TO PREVAIL INTO EARLY TUE.
EVENTUALLY APPROACHING TROF WILL SPREAD SHRA AND POSSIBLE MVFR
CONDITIONS INTO NH TERMINALS BY TUE AFTERNOON. WILL HAVE TO WATCH
FOR COASTAL STRATUS DEVELOPING LATE IN THE PERIOD IN ONSHORE FLOW.

LONG TERM...EXPECT A PERIOD OF IFR OR LOWER TUE NIGHT INTO EARLY
WED...WITH CONDS IMPROVING TO VFR DURING THE DAY WED. THEN...VFR
IS EXPECTED TO HOLD THROUGH FRI.

&&

.MARINE...
SHORT TERM...PERSISTENT ONSHORE...SLY FLOW WILL EVENTUALLY BUILD
SEAS TO NEAR 5 FT BY TUE AFTERNOON. A SCA MAY BE REQUIRED.

LONG TERM...N-NW FLOW INCREASES ON WED AS LOW PRES INTENSIFIES E
OF THE WATERS. WILL LKLY SEE SCA CONDS LATE WED INTO THU...AND
COULD SEE GALES IN THE OPENS WATERS.

&&

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

&&

$$

NEAR TERM...LEGRO
SHORT TERM...LEGRO
LONG TERM...CEMPA
AVIATION...CEMPA/LEGRO
MARINE...CEMPA/LEGRO







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