Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 130432
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1232 AM EDT SUN JUL 13 2014

.SYNOPSIS...
A WARM FRONT PUSHES TO THE NORTHEAST OVERNIGHT BRINGING IN MORE
HUMID AND UNSTABLE AIR ON SUNDAY WITH AN INCREASING RISK OF
SHOWERS AND THUNDERSTORMS. THE WARM HUMID AIRMASS WILL LINGER FOR
MONDAY AND TUESDAY IN ADVANCE OF A SLOW-MOVING COLD FRONT. THE
COLD FRONT IS EXPECTED TO EXIT THE COAST BY LATE WEDNESDAY. HIGH
PRESSURE WILL BUILD TO THE SOUTH OF THE AREA THURSDAY AND FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WILL UPDATE TO INPUT THE LATEST OBSERVED DATA RESULTING IN JUST
MINOR ADJUSTMENT TO THE CHC/SLGT CHC OF SHRA AND ISOLD TSTMS IN
THE N/MT ZONES OVERNIGHT PER LATEST RADAR LOOP AND TO INCREASE SKY
COVER ACROSS THE FCST AREA A BIT OVERNIGHT PER LATEST SATELLITE
LOOP. STILL SOME VALLEY F POSSIBLE IN LOW LYING AREAS...MAINLY CT
VALLEY AND MERRIMACK VALLEY...AND ALONG THE MID COAST DUE TO
ONSHORE S SW FLOW OF MOIST ATLANTIC AIR.

HIGH PRESSURE OFF THE COAST WITH A WARM FNT APPROACHING FROM THE
SW IS RESPONSIBLE FOR INCREASING CLOUDS AND S SW FLOW OVERNIGHT. A
WEAK UPPER LVL IMPULSE ALONG WITH THE ADVECTION OF WARM...HUMID
AND UNSTABLE AIR IS PRODUCING THE ISOLD/SCT CONVECTION ACROSS OUR
NRN TIER OF ZONES AT THIS TIME. THIS ACTIVITY WILL MOVE E AND
DISSIPATE THRU THE NGT.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 AM MONDAY/...
THE WAA ON SUNDAY WILL ADVECT HIGHER DEWPTS AND TEMPS ALONG WITH
INCRG INSTBLTY. ENOUGH SHEAR SHOULD HELP ENHANCE INSTBLY AND CAUSE
TSTM ACTIVITY IN THE AFTN AND INTO SUNDAY NIGHT. PW`S WILL BE HIGH
SO HVY DOWNPOURS CAN BE EXPECTED. SOME TSTMS MAY BECOME STG LATER
IN THE DAY BUT SHOULD REMAIN BLO SVR LIMITS. GOING WITH HIGH POPS FOR
SUNDAY INTO SUNDAY NIGHT WHICH IS WHAT THE BLENDED MODEL SOLUTION
SUGGESTS. USED A BLEND OF RFCQPF AND MODEL GUID FOR QPF FCST.
AVERAGE BASIN AVG RAINFALL FOR THIS EVENT IS AROUND .50-.75 INCHES
BUT LOCALLY HIGHER AMTS IN SOME OF THE STRONGER STORMS.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
THE MAIN FOCUS OF THE FORECAST WILL BE ON THE STALLING COLD FRONT
OVER THE REGION EARLY TO MID WEEK...AS IT LINES UP WITH DECENT
S-SW FLOW ALOFT. THIS WILL KEEP A THREAT FOR SHRA/TSRA IN THE
FORECAST MON-WED. THE DETAILS IN THIS PERIOD REMAIN UNCERTAIN...AS
THE MODELS DIFFER ON THE WHERE THE FRONT STALLS...THE TIMING OF
THE WAVES THAT MOVE ALONG THE FRONT /ALL AFFECTED BY DEEPER
CONVECTION UPSTREAM/...AND ULTIMATELY...THE STRENGTH AND
EQUATORWARD EXTENT OF THE 500MB TROUGH THAT WILL KICK THE FRONT
EWD AROUND MID WEEK. HAVE GENERALLY OPTED FOR CHC POPS THROUGH THE
PERIOD...SHADING THE HIGHER POPS TOWARD MON NIGHT THRU TUE
NIGHT...AND CLOSER TO THE COAST...MAINLY BASED ON BLENDING THE
MODEL POPS.

VERY HUMID AIR LOOKS TO HOLD...ESPECIALLY S AND E OF THE MTNS MON
THROUGH TUE...WITH SIGNS OF A LOW LEVEL JET DEVELOPING MON INTO
MON NIGHT...WHICH WOULD INCREASE THE THREAT OF TORRENTIAL DOWNPOURS
IN ANY STORMS THAT FROM...AND HAVE ADDED THE MENTION OF HVY RAIN
TO THE FORECAST FOR MON-MON NIGHT. GIVEN A FAIR AMT OF CLOUDS AND
THE RAIN...MAXES WILL GENERALLY BE IN THE MID 70S TO LOW 80S...BUT
TDS WILL RUN IN THE 65-70 RANGE MON-TUE...WITH OVERNIGHT LOWS
MATCHING THE TDS...AT LEAST MON NIGHT.

THE EURO HAS BEEN CONSISTENT IN LINGERING THE FRONT OVER THE AREA
INTO WED...BUT BOTH THE NAM12 AND THE GFS SUGGEST IT WILL BE MORE
PROGRESSIVE AND COULD BE OUT OF HERE BY TUE NIGHT OR EARLY WED.
COULD SEE SOMEWHAT COOLER AND DRIER AIR IN THE MTNS BY LATE TUE IN
THE MORE PROGRESSIVE SOLNS ARE CORRECT. WED IS THE LOWEST
CONFIDENCE DAY AT THIS POINT AS THE FRONT LOCATION VARIES WIDELY
AMONG THE MODELS...BUT HAVE HIGHER CONFIDENCE FOR IMPROVEMENT BY
THU/FRI AS THE FRONT MOVES OUT AND SOMEWHAT LESS HUMID AIR MOVES
IN WITH PARTLY TO MOSTLY SUNNY SKIES.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
SHORT TERM /THROUGH SUNDAY NIGHT/...VFR TNGT. AREAS OF F POSSIBLE
LATE TNGT WHICH MAY IMPACT TAF SITES LIKE KLEB...KHIE AND KCON. ON
SUNDAY AFTN DEVELOPING SHWRS/TSTMS IN THE MTNS AND NH WILL SLOWLY
SPREAD SEWD. MVFR CONDS WILL BE EXPECTED WITH THE DEVELOPING
CONVECTION AS IT WILL CONTINUE AND BECOME MORE WIDESPREAD SUNDAY
NIGHT.

LONG TERM...VARIABLE CONDS EXPECTED MON IN SCT SHRA/TSRA...WITH
COND DETERIORATING TO IFR OR LOWER IN FOG LOW CLOUDS AND CONTINUED
SHRA MON NIGHT. THIS PATTERN LOOKS TO REPEAT ON TUE AND TUE
NIGHT...ALTHOUGH THERE COULD BE SOME IMPROVEMENT AT INTERIOR NH
TUE NIGHT. THE THREAT OF SHRA AND TSRA CONTINUES WED...WITH A
HIGHER CONFIDENCE OF A RETURN TO VFR EXPECTED THU.

&&

.MARINE...
SHORT TERM /OVERNIGHT THROUGH SUNDAY NIGHT/...WILL UPDATE TO INPUT
LATEST OBSERVED DATA. THIS WILL RESULT IN MINOR CHANGES TO WINDS
AND SEAS OVERNIGHT...BUT STILL KEEP CONDITIONS BELOW SCA LEVELS
THRU THE NGT. WILL CONT THE SCA FOR SUNDAY AFTERNOON THRU MONDAY
MORNING. DEVELOPING S FLOW IS EXPECTED TONIGHT AS THE CENTER OF
SFC HIGH PRES MOVES OFF THE COAST. THE S SW FLOW INCREASES SUNDAY
AS THE WARM FNT MOVES TO THE NE AND THE SFC PRESSURE GRADIENT
INCREASES. WIND GUSTS AND SEAS ARE EXPECTED TO REACH SCA CONDS
SUNDAY AFTERNOON AND THRU SUNDAY NIGHT FIRST OVER THE OPEN WATERS
AND THEN THE BAYS AS WELL.

LONG TERM...SW WINDS SUBSIDE A BIT ON MON...BUT S-SW FLOW REMAINS
PERSISTENT RIGHT INTO TUE NIGHT AT LEAST...AND THIS WILL KEEP SEAS
AROUND 5-6 FT IN THE OPEN WATERS. THE FLOW WILL EVENTUALLY SHIFT
MORE W AND WEAKEN AROUND WED AND THU...WITH SEAS SUBSIDING.

&&

.TIDES/COASTAL FLOODING...
AN ASTRONOMICAL HIGH TIDE OF 11.7 FT WHICH WILL BE ONE OF THE
HIGHEST OF THE YEAR, WILL OCCUR AT 1236 AM SUNDAY NIGHT. AN
INCREASING SOUTHERLY FLOW AND BUILDING SEAS MAY CAUSE SOME
PROBLEMS ALONG THE COAST. SOME MINOR COASTAL FLOODING AND
SPLASHOVER IS POSSIBLE. A COASTAL FLOOD WATCH MAY NEED TO BE
ISSUED FOR MUCH OF THE COASTLINE AT A LATER TIME AS IT WILL NOT
TAKE MUCH TO REACH MINIMAL FLOOD BENCHMARKS.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 AM EDT
     MONDAY FOR ANZ150>154.

&&

$$




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