-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 182320
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
720 PM EDT SAT MAY 18 2013

.SYNOPSIS...
HIGH PRESSURE ACROSS NORTHERN NEW ENGLAND WILL MOVE OFF THE COAST
SUNDAY. A WARM FRONT WILL MOVE THROUGH THE REGION SUN
NIGHT...PROBABLY BRINGING A FEW SHOWERS. THE FRONT WILL LIFT
NORTH OF THE REGION EARLY NEXT WEEK AND THEN STALL OVER NEW YORK
AND CENTRAL NEW ENGLAND. WEAK WAVES OF LOW PRESSURE WILL MOVE
ALONG THE FRONT MIDDLE OF NEXT WEEK BRINGING WARMER...MORE HUMID
CONDITIONS ALONG WITH SCATTERED SHOWERS AS WELL AS POSSIBLE
THUNDERSTORMS...MOST LIKELY DURING THE AFTERNOON AND EVENING
HOURS.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
-- Changed Discussion --
7 PM UPDATE...

INVERTED HIGH PRES RIDGE NOSING INTO THE BOX CWA THIS
EVENING...WHICH HAS ALLOWED MID AND HIGH LVL CLOUDS TO SINK CLOSER
TO THE S COAST OF RI/CT. THEREFORE...WITH LOSS OF DIURNAL HEATING
EXPECT A BIT OF BREAKS IN THE CLOUDS TONIGHT UNTIL A SHORTWAVE
ALLOWS FOR INCREASING CLOUDINESS FROM THE SW DURING THE MORNING
HOURS. MIN TEMPS A BIT WARMER TONIGHT GIVEN THE WARMER
START...INCREASING MID LVL TEMPS UNDER WARM ADVECTION AND
INCREASING MOISTURE IN THE COLUMN DURING THE OVERNIGHT HOURS.
CONTINUED WITH PREVIOUS FORECASTER/S THINKING AND HELD OFF THE
-SHRA ACTIVITY UNTIL WELL AFTER DAYBREAK...SLOWER THAN GUIDANCE
CURRENTLY SUGGESTS.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
SUNDAY...
HIGH PRESSURE MOVES OFF THE NEW ENGLAND COAST AS A WARM FRONT SLOWLY
APPROACHES FROM THE SOUTH.  THIS WILL RESULT IN MID LEVEL WARM
ADVECTION AND AN INCREASE IN CLOUD COVER.  THERE STILL WILL PROBABLY
BE A FEW PEEKS OF SUN AT LEAST IN THE MORNING...BUT THE OVERALL
TREND WILL BE FOR MOSTLY CLOUDY SKIES.  HIGH TEMPS ARE TRICKY AND
WILL DEPEND UPON JUST HOW QUICKLY SKIES BECOME MOSTLY CLOUDY.  WE
BLENDED THE COOLER GFSMOS GUIDANCE WITH THE MUCH MILDER METMOS.
BEST CHANCE OF THE MILDEST READINGS WILL BE ACROSS THE MERRIMACK
VALLEY...AWAY FROM THE COAST AND WHERE SKIES WILL BE SLOWER TO
BECOME MOSTLY CLOUDY. WILL RANGE HIGHS FROM THE MIDDLE 60S TO AROUND
70...BUT LATER SHIFTS MAY HAVE TO MAKE TWEAKS OVERNIGHT.

AS FOR PRECIPITATION CHANCES...BETTER FOCUS/FORCING/MOISTURE WILL
REMAIN TO OUR SOUTH AND WEST.  THEREFORE...EXPECT MOST OF THE DAY
WILL FEATURE DRY WEATHER.  WARM ADVECTION MAY STILL RESULT IN A FEW
SPOT SHOWERS AT TIMES...WITH THE BEST CHANCE IN OUR SOUTHWEST ZONES.
THEREFORE...WILL INCLUDE SOME LOW POPS TO COVER THIS POTENTIAL
ACROSS MOST AREAS.

SUNDAY NIGHT...
THE WARM FRONT GRADUALLY LIFTS NORTH ACROSS SOUTHERN NEW ENGLAND.
MID LEVEL FORCING/DYNAMICS ARE NOT THAT IMPRESSIVE...SO NOT
EXPECTING A LOT OF RAINFALL.  HOWEVER...STILL EXPECT SOME SCATTERED
SHOWERS IN THE WARM AIR ADVECTION PATTERN.  CAN/T RULE OUT SOME
ISOLATED THUNDER SOUTH OF THE MA TURNPIKE...BUT INDICES WERE TOO
MARGINAL TO INSERT AT THIS POINT.

MAY ALSO SEE SOME PATCHY FOG DEVELOP AS HIGHER DEWPOINT AIR
OVERSPREAD THE REGION.  LOW TEMPS SHOULD ONLY FALL INTO THE LOWER TO
MIDDLE 50S GIVEN INCREASING LOW LEVEL MOISTURE AND CLOUD COVER.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
HIGHLIGHTS...

*  WARM AND HUMID WITH SCATTERED SHOWERS THRU AT LEAST THU

OVERVIEW AND MODEL PREFERENCES...
18/12Z LONG RANGE GUIDANCE SUITE IS IN FAIR AGREEMENT THROUGH THE
MID TERM PERIOD...BUT THEN STRUGGLES WITH THE MERGING /OR NON-
MERGING/ OF A SPLIT FLOW REGIME TOWARD THE END OF THE PERIOD.
GIVEN THE AGREEMENT THAT THE CONVERGENT REGION OF THESE TWO
STREAMS WILL DOMINATE THROUGH THE MID TERM...WILL USE A GFS/ECMWF
BLEND TO BASELINE FORECAST. FOR THE TAIL END OF THE LONG
TERM...WILL LIKELY LEAN AWAY FROM THE ECMWF DETERMINISTIC RUN...AS
IT GENERATES A VERY DEEP MEANDERING CUTOFF IN NRN NEW ENGLAND
WHICH WOULD SUGGEST THAT UNSETTLED CONDITIONS CONTINUE WELL INTO
/AND POSSIBLY BEYOND/ THE WEEKEND. IN ANY CASE...WITH CONVERGENT
STREAMS ALOFT THROUGH THE MID TERM...UNSETTLED CONDITIONS ARE
LIKELY...BUT AS WAS NOTED...IT SHOULD NOT BE A WASHOUT.

DETAILS...

MON INTO MON NIGHT...
SFC WARM FRONT SHIFTS INTO NRN NEW ENGLAND WITH TIME...ALLOWING
MUCH OF SRN NEW ENGLAND TO BREAK INTO THE WARM SECTOR THROUGH THE
PERIOD. LOOKS LIKE A FAIR AMOUNT OF MOISTURE WILL COMBINE WITH
DIURNAL HEATING TO YIELD SOME DAYTIME -SHRA...PARTICULARLY OVER
SRN NH AN NRN MA. SOUNDINGS LOOK TO REMAIN FAIRLY STABLE DURING
THE DAY...SO WILL KEEP THUNDER OUT OF THE FORECAST FOR NOW. WITH
HIGH TEMPS IN THE UPPER 60S TO NEAR 70 AND DWPTS IN THE UPPER
50S...CONDITIONS ARE LIKELY TO FEEL MUGGY.

TUE INTO WED...
THE WARM FRONT IN NRN AND CENTRAL NEW ENGLAND IS EXPECTED TO
GRADUALLY SINK S OF THE REGION THROUGH THE PERIOD. ON TUE...THIS
FRONTAL PASSAGE /PARTICULARLY DURING THE AFTERNOON HEAT/ EXPECT
SOME DESTABILIZATION...ESPECIALLY IF THERE ARE SOME EARLY DAY
CLOUD BREAKS AS SOME OF THE GUIDANCE SUGGESTS. COOLING UPPER LVLS
AS HIGH PRES NOSES IN FROM THE N SUGGEST A RISE IN K/TT AND LI/S
DIPPING TO 0 TO NEGATIVE VALUES. SHEAR IS NOT
GREAT...PARTICULARLY THROUGH H85...BUT THERE IS ENOUGH SUPPORT FOR
UPDRAFTS...SO WILL CONTINUE TO SUGGEST THUNDER FOR TUE. ON
WED...WEAK EARLY DAY RIDGING WILL LIKELY YIELD A PARTLY CLOUDY
START TO THE DAY UNTIL RETURN FLOW DEVELOPS AS HIGH PRES SLIDES TO
THE NE. GIVEN THE APPROACHING SHORTWAVE...EARLY CLEARING AND
INCREASING MOISTURE...MAY SEE ANOTHER DAY WITH THE THREAT FOR
TSTMS...ESPECIALLY IN THE W AS A SECONDARY WARM FRONT MOVES
THROUGH THE AREA. A LITTLE BETTER SHEAR ON WED TOO POSSIBLY...SO
WILL CONTINUE WITH A THUNDER THREAT ON WED AS WELL.

THU AND FRI...
TRICKY FORECAST HERE AS IT WILL BE DEPENDENT ON HOW QUICKLY NRN
STREAM JET ENERGY SINKS S FROM QUEBEC AND ONTARIO. THIS WILL
DICTATE HOW QUICKLY A SERIES OF SHORTWAVES AND THEIR SFC LOW PRES
WAVES WILL AFFECT THE REGION. IN ANY CASE...THE WET WX CONTINUES
ALTHOUGH A BIT MORE STABLE THAN TUE AND WED. GIVEN THE DIFFERENCES
BETWEEN MODELS IN HOW THE NRN STREAM WORKS OUT...EXACT TIMING FOR
ANY OF THESE WAVES REMAINS A BIT OF A QUESTION MARK. ONCE
AGAIN...IT WILL LIKELY NOT RAIN EVERYDAY...BUT THERE IS THE THREAT
FOR AT LEAST -SHRA THROUGH THE PERIOD.

THE WEEKEND...
THE SRN STREAM RIDGE BEGINS TO MOVE THE NRN STREAM LONGWAVE TROF
OFFSHORE THROUGH THE PERIOD...SO LOOKS LIKE A TRANSITION TO MORE
DRY WX WILL BE LIKELY SOMETIME DURING THE WEEKEND.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

OVERVIEW...HIGH CONFIDENCE CONTINUES TONIGHT. MODERATE CONFIDENCE
SUNDAY AND SUNDAY NIGHT.


OVERNIGHT...
EXPECTING MOSTLY VFR CONDITIONS DURING THE OVERNIGHT HOURS. LOW
CONFIDENCE IN SOME MVFR CIGS ARRIVING IN THE CT VALLEY TOWARD
DAYBREAK.

SUN...
CONTINUED WITH OPTIMISTIC FORECASTING SUGGESTING THE MVFR CIGS
TAKE UNTIL MID MORNING TO EARLY AFTERNOON TO ARRIVE IN THE
INTERIOR...HOLDING OFF UNTIL EVENING FOR EASTERN TERMINALS.
THEREFORE...MOSTLY VFR TO START...WITH A GRADUAL DOWNWARD TREND
THROUGH THE DAY.

SUN NIGHT...
MAINLY MVFR/IFR IN A MIX OF FOG AND SHOWERS DURING THE OVERNIGHT
HOURS

KBOS TERMINAL...HIGH CONFIDENCE IN TAF OVERNIGHT AND EARLY IN THE
DAY TOMORROW. LOWER CONFIDENCE IN TIMING OF MVFR BY SUN
EVENING...THEN IFR BY OVERNIGHT IN FOG/SHOWERS.

KBDL TERMINAL...MODERATE CONFIDENCE IN TAF OVERNIGHT...MAINLY IN
POTENTIAL FOR MVFR CIGS TO ARRIVE AT TERMINAL BY SUN MORNING. IT
APPEARS BEST CHANCE WILL BE MID DAY ONWARD SUN. THEREFORE...VFR
EXPECTED TO DOMINATE INTO THE MORNING.

OUTLOOK...MONDAY THROUGH THURSDAY...

MODERATE CONFIDENCE THROUGH THE PERIOD.

MAINLY VFR/MVFR DURING THE DAYS...WITH THE BEST CHANCE FOR MVFR IN
ANY DAYTIME SHOWERS OR OCCASIONAL THUNDERSTORMS. EXPECT MAINLY
MVFR/IFR DURING THE OVERNIGHT HOURS IN A MIX OF FOG AND LOW
STRATUS...ESPECIALLY CLOSER TO THE SOUTH COAST.

IN SUM...A PERIOD OF UNSETTELED WX IS EXPECTED THROUGH THE PERIOD.
-- End Changed Discussion --

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

MODERATE TO HIGH CONFIDENCE THROUGH SUNDAY NIGHT.

RELATIVELY WEAK PRESSURE GRADIENT SHOULD KEEP WINDS/SEAS BELOW
SCA THRESHOLDS TONIGHT AND SUNDAY. HOWEVER...HIGH PRESSURE MOVING
OFF THE COAST ON SUNDAY WILL BEGIN TO GENERATE LONG SOUTHWEST
FETCH INTO THE SOUTHERN WATERS. THIS SHOULD ALLOW SEAS TO BUILD TO
SCA THRESHOLDS ACROSS OUR SOUTHERN OUTER-WATERS SUNDAY NIGHT. HAVE
HOISTED SCA HEADLINES FOR HAZARDOUS SEAS IN THIS REGION. SCA
HEADLINES MAY HAVE TO BE EXPANDED INTO SOME OF THE SOUTHERN
SOUNDS...BUT SINCE ITS A 3RD PERIOD EVENT CONFIDENCE WAS NOT HIGH
ENOUGH TO DO AT THIS POINT.

OUTLOOK...MONDAY THROUGH THURSDAY...

MODERATE CONFIDENCE THROUGH THE PERIOD.

WINDS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH
THE PERIOD. ALSO...A COMBINATION OF SHOWERS AND FOG WILL LIKELY
LEAD TO REDUCTIONS IN VISIBILITIES THROUGH THE PERIOD.

MON INTO TUE...LINGERING SWELL ALONG THE SRN WATERS AND ERN OUTER
WATERS GRADUALLY SUBSIDES THROUGH TUE. WILL LIKELY NEED SMALL
CRAFT ADVISORY FOR SEAS INTO THE DAY TUE.

WED AND WED NIGHT...SEAS REMAIN BELOW SMALL CRAFT THRESHOLDS.

THU...AS LOW PRES APPROACHES FROM THE W. EXPECT GRADUALLY BUILDING
SEAS...WHICH MAY REACH 5-7 FT DURING THE DAY THU. SMALL CRAFT
ADVISORIES MAY BE NEEDED AGAIN.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 11 PM SUNDAY TO 8
     AM EDT MONDAY FOR ANZ254-255.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 5 PM SUNDAY TO 8
     AM EDT MONDAY FOR ANZ256.

&&

$$
SYNOPSIS...FRANK/DOODY
NEAR TERM...DOODY
SHORT TERM...FRANK
LONG TERM...DOODY
AVIATION...FRANK/DOODY
MARINE...FRANK/DOODY/THOMPSON