Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 201835
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
235 PM EDT SUN JUL 20 2014

.SYNOPSIS...
HIGH PRESSURE BECOMES ENTRENCHED OFFSHORE MONDAY THROUGH
WEDNESDAY...ALLOWING WARMER AND MORE HUMID AIR TO MOVE IN FROM THE
SOUTHWEST. A COLD FRONT APPROACHES LATE WEDNESDAY AND MOVES
THROUGH THE REGION THURSDAY...BRINGING A THREAT OF SHOWERS AND
THUNDERSTORMS. HIGH PRESSURE BUILDS IN FROM THE WEST FRIDAY AND
SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
CLEARING WILL CONTINUE THIS EVENING...SETTING THE STAGE FOR A
COOL AND CHILLY NIGHT WITH LIGHT WINDS AND RADIATIONAL COOLING.
TEMPERATURES WILL DROP INTO THE 40S OVER THE MOUNTAINS WITH 50S
ELSEWHERE. THIS WILL ALLOW FOR DENSE FOG TO DEVELOP IN MANY AREAS
BY AROUND MIDNIGHT. LOOK FOR SOME AREAS TO DROP TO A QUARTER MILE
OR LESS...ESPECIALLY ACROSS THE INLAND HOLLOWS.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
SEASONABLE TEMPERATURES ARE EXPECTED ON MONDAY AS HIGH PRESSURE
BEGINS TO SHIFT OFF THE COAST AND A SOUTHWESTERLY FLOW DEVELOPS
WITH TIME. READINGS WILL BE IN THE LOWER 80S INLAND...WITH MID TO
UPPER 70S ALONG THE COAST DUE TO A DEVELOPING SEA BREEZE.

A WEAK WEATHER DISTURBANCE WILL ENTER NORTHERN PORTIONS OF THE
FORECAST AREA...TRIGGERING A COUPLE SCATTERED SHOWERS IN THE
MOUNTAINS DURING THE MIDDAY AND AFTERNOON HOURS. ANY PRECIP
HOWEVER WILL BE LIGHT.

THE FOG TAKES HOLD ONCE AGAIN ON OUR REGION MONDAY NIGHT. EXPECT
PATCHY DENSE FOG BY MIDNIGHT IN SOME AREAS. LOWS WILL MAINLY BE IN
THE 50S.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
AN UPPER LVL RIDGE SLIDES ACROSS THE NE ON TUESDAY AS HIGH PRES AT
THE SFC SLIDES OFF SHORE. THIS SETS UP A SW FLOW AT THE SFC AND A
MORE WESTERLY FLOW ALOFT THAT BRINGS IN WARMER AND MORE HUMID AND
UNSTABLE AIR. 850 MB TEMPS CLIMB ABOVE PLUS 15 C BY 00Z WED
SUPPORTING VERY WARM HIGH TEMPS. THE VERY WARM...MOIST AND
INCREASINGLY UNSTABLE ATMOSPHERE MAY ALLOW ISOLD CONVECTION TO
DEVELOP IN THE LATE AFTERNOON/EARLY EVE HOURS...BUT NOT MUCH ELSE
FOR SUPPORT...SO WILL LEAVE OUT OF THE FCST FOR THE TIME BEING.

AN UPPER LVL TROF DIGS SE FROM CENTRAL CANADA INTO THE GREAT LAKES
REGION TUESDAY NGT THEN TURNS TO THE E. THIS FORCES A SFC COLD FNT
TO PUSH SE TOWARD THE FCST AREA ON WEDNESDAY. AS THE FNT AND UPPER
LVL SYSTEM INTERACT WITH THE VERY WARM...MOIST AND UNSTABLE AIR
EXPECT A BETTER CHC OF SHRA/TSTMS WITH POTENTIAL FOR STRONG TO SVR
TSTMS WEDNESDAY AFTERNOON AND EVENING AS AN INCREASINGLY SHEARED
ENVIRONMENT DEVELOPS ALONG WITH INCREASING CAPE, DECREASING LI`S AND
INCREASING AXIS OF HIGHER 850 MB THETA E VALUES TO SUPPORT VERY
STRONG CONVECTION.

THE COLD FNT MOVES THRU WEDNESDAY NGT...OR PERHAPS THURSDAY AS SOME
MODELS SHOW IT SLOWING DOWN AS IT WAITS FOR THE UPPER LVL TROF TO
MOVE. UNTIL THE FNT MOVES OUT TO SEA THERE WILL REMAIN A CHC OF
SHRA/TSTMS. BEHIND THE FNT COOLER AND MUCH LESS HUMID AIR FOLLOWS
WITH HIGH PRESSURE MOVING IN ALONG WITH 850 MB TEMPS DROPPING TO
AROUND PLUS 10 C. THE IMPROVING WX MAY ARRIVE ON THURSDAY...AT LEAST
N/MT ZONES BUT MAY TAKE UNTIL LATE IN THE DAY TO REACH THE COAST.
THE HIGH MOVES THRU FRIDAY AND SATURDAY WITH PLEASANT SUMMER WX...
FOLLOWED BY APPROACHING LOW PRESSURE UNDER AN UPPER LVL TROF THAT
COULD BRING SHRA/TSTMS BACK INTO THE REGION ON SUNDAY AS TEMPS AND
HUMIDITY LEVELS RISE ONCE AGAIN.

USED A BLEND OF VARIOUS MODELS...HPC GUIDANCE...PREVIOUS FCST FOR
PERSISTENCE AND CLIMATOLOGY FOR THE LONG TERM FCST.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
SHORT TERM...AREAS OF IFR WITH SOME REGIONS LIFR OVERNIGHT AS
DENSE FOG DEVELOPS IN PORTIONS OF MAINE AND NEW HAMPSHIRE. THE FOG
WILL LIFT MONDAY MORNING. FOG WILL REFORM MANY AREAS MONDAY NIGHT
AS WELL...WITH A CONTINUATION OF RELATIVELY CLEAR SKIES...LIGHT
WINDS AND HUMID CONDITIONS.

LONG TERM /TUESDAY THROUGH FRIDAY/...ISOLD SHRA/TSTMS COULD
PRODUCE MVFR CONDITIONS LATE TUESDAY AFTERNOON AND EARLY EVENING.
A BETTER CHC FOR SHRA/TSTMS WITH IFR CONDITIONS WEDNESDAY AND
WEDNESDAY NGT WITH POTENTIAL FOR STRONG/SVR TSTMS WEDNESDAY
AFTERNOON AND EVENING.

&&

.MARINE...
SHORT TERM...LIGHT WINDS AND SEAS EXPECTED. WINDS WILL LOCALLY BE
ONSHORE NEAR THE COAST.

LONG TERM /TUESDAY THROUGH FRIDAY/...S SW FLOW MAY INCREASE TO
MINIMAL SCA LEVELS WEDNESDAY AND WEDNESDAY NGT AHEAD OF AN
APPROACHING COLD FNT. THIS MAY ALSO PUSH SEAS TO SCA LEVELS.
OTHERWISE WINDS/SEAS BELOW SCA LEVELS.

&&

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

&&

$$





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