Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 271008
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
608 AM EDT WED AUG 27 2014

.SYNOPSIS...
A COLD FRONT WILL DROP SOUTH THROUGH THE REGION TODAY AND COULD
SET OFF SOME SHOWERS AND THUNDERSTORMS...BUT NOT BEFORE
TEMPERATURES WARM TO NEAR 90 DEGREES AGAIN IN MANY SPOTS. COOLER
HIGH PRESSURE WILL GRADUALLY BUILD IN FROM THE WEST THURSDAY AND
FRIDAY AND SHIFT OFFSHORE ON SATURDAY. A WARM FRONT CROSSES THE
AREA SATURDAY NIGHT INTO SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
605 AM...FORECAST UPDATE TO COVER SHRA MOVING ACROSS FAR NRN
ZONES BEING FORCED BY WEAK 500MB WAVE AND PRE-FRONTAL TROUGHING. A
FEW SHRA WILL BE POSSIBLE HERE THROUGH ABOUT 12Z. OTHERWISE
TWEAKED T/TD/SKY FOR THE MORNING BASED ON CURRENT OBS...BUT
OVERALL FORECAST THINKING UNCHANGED FOR THE REST OF THE DAY.

PREVIOUSLY FOR TODAY...WILL LKLY SEE A MAINLY DRY DAY AFTER
SUNRISE THROUGH EARLY TO MID AFTERNOON WHEN THE ACTUAL SFC FRONT
BEGINS TO DROP SE ACROSS THE CWA. WHILE A SHRA OR TSRA CANNOT BE
RULE OUT ANYWHERE WITH THE FROPA...GIVEN DECENT INSTABILITY...THE
LACK OF ANY DYNAMICS AND A REAL TRIGGER DOES NOT BODE WELL FOR ANY
WIDESPREAD CONVECTION. NAM12 AND MESOSCALE MODELS CONTINUE TO
FOCUS CONVECTION DEVELOPMENT MID TO LATE AFTERNOON CLOSER TO THE
COAST...PROBABLY ON THE SEA BREEZE BOUNDARY...AND THIS WHERE THE
30ISH CHC POPS ARE...FROM ABOUT 19-23Z. THERE ARE DECENT SHEAR
PROFILES AHEAD OF THE FRONT...AND INSTABILITY GETS IN THE
1000-1500 J-KG RANGE...SO THERE IS AN OUTSIDE CHC THAT AN
ORGANIZED CELL CAN GET A LITTLE ROTATION...ASSUMING A SUSTAINED
UPDRAFT CAN GET GOING.

MAX TEMPS ON THE COASTAL PLAIN AWAY FROM THE IMMEDIATE COAST
SHOULD MAKE A RUN AT 90 AGAIN...GIVEN INCREASED WSW FLOW...WHICH
WILL DOWNSLOPE AND HELP OUT THE HEATING. COASTAL AREAS THAT DO
WELL WITH DOWNSLOPE...KPWM...COULD GET CLOSE TO 90...DEPENDING ON
TIMING OF FROPA AND WHETHER ANY CONVECTION DEVELOPS IN THE AREA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
ANY LINGERING SHRA/TSRA SHOULD WIND DOWN OR MOVE OFFSHORE BY
01-02Z. GIVEN THAT MID-UPPR LVL FLOW WILL NOT SHIFT THAT MUCH
BEHIND THE FRONT IT IS UNLIKELY THAT WINDS WILL MIX DOWN ONCE THE
FRONT MOVES THROUGH COASTAL AREAS. THIS WILL MEAN THAT LOW LVL
MOISTURE WILL LINGER THRU THE NIGHT...AND NOT ONLY WILL KEEP MINS
IN THE LOW TO MID 60S...BUT COULD SEE SOME FOG OR LOW STRATUS
DEVELOPING IN SPOTS ON THE COAST. IN THE MTNS AND FOOTHILLS LOOK
FOR MINS TO DROP OFF INTO THE 50S...WITH SOME PARTIAL CLEARING.

COOLER DRIER WILL MIX DOWN AFTER SUNRISE THU MORNING...AND SHOULD
SEE GOOD CLEARING WITH MOSTLY SUNNY SKIES ON THE COAST...AND
ENOUGH OF A NW WIND FOR DOWNSLOPING TO PUSH TEMPS INTO THE MID TO
UPPER 70S. IN THE MTNS UPSLOPE FLOW WILL PROVIDE A FAIR AMT OF
CLOUDS...AND PERHAPS A FEW SHRA WITH HIGHS ONLY REACHING TO AROUND
70.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GENERAL AGREEMENT ON THE LONG WAVE PATTERN
THROUGH EARLY NEXT WEEK. A RIDGE WILL SLIDE EAST ACROSS THE AREA
FOR THURSDAY ND FRIDAY. THE RIDGE WILL SLIDE OFFSHORE BY SATURDAY
WITH THE RETURN FLOW USHERING WARMER AND MORE HUMID AIR INTO THE
REGION FOR THE HOLIDAY WEEKEND. A SLOW-MOVING COLD FRONT WILL DROP
SOUTHEAST AND PROVIDE AN INCREASING CHANCE OF SHOWERS AND
THUNDERSTORMS AS WE HEAD THROUGH THE HOLIDAY WEEKEND. THE FRONT
WILL STALL ACROSS THE REGION EARLY NEXT WEEK BEFORE RETURNING
NORTH AS A WARM NEXT WEDNESDAY.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
.SHORT TERM...GIVEN AN INCREASING SW FLOW ABV THE BOUNDARY
LYR...MAY NOT SEE TOO MUCH IN THE WAY OF FOG THIS AM...BUT CANNOT
RULE OUT KLEB/KCON/KHIE DROPPING TO IFR FOR A COUPLE HRS AROUND
SUNRISE. OTHERWISE MAINLY VFR TODAY WITH A CHC OF A TSRA MID TO
LATE AFTERNOON AT THE COASTAL TERMINALS. OUTSIDE CHC OF SOME FOG
AND STRATUS AT THE COASTAL TERMINALS LATER TONIGHT.

.LONG TERM...

SAT NIGHT - SUN...AREAS OF MVFR IN SHOWERS AND TSTMS.

&&

.MARINE...
.SHORT TERM...HAVE DROPPED THE SCA FOR TODAY ACROSS ALL BUT THE
WATERS S OF PENOBSCOT BAY...WHERE INCREASING SWELL WILL PUSH SEAS
UP TO 5 FT TODAY AND WITH SW WINDS APPROACHING 15 KTS...COULD BE
QUITE CHOPPY. SWELL FROM CRISTOBAL COULD INCREASE TO CLOSER TO 6
FT LATE TONIGHT INTO THU...AND MAY NEED TO PUSH SCA FURTHER WEST
LATER.

.LONG TERM...

SAT NIGHT - SUN...SMALL CRAFT WINDS AND SEAS ARE POSSIBLE.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ150.

&&

$$
SYNOPSIS...
NEAR TERM...CEMPA
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...


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