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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 171745
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
145 PM EDT MON JUN 17 2013

.SYNOPSIS...
A COLD FRONT FROM THE GREAT LAKES WILL SLIDE ACROSS SOUTHERN NEW
ENGLAND TONIGHT. A SECOND COLD FRONT MAY STALL ACROSS THE REGION
TODAY...THEN SLOWLY MOVE OFFSHORE LATE TUESDAY OR TUESDAY NIGHT.
LARGE HIGH PRESSURE WILL BRING MAINLY DRY AND SEASONABLE CONDITIONS
WEDNESDAY THROUGH FRIDAY...THEN WILL ANCHOR SOUTH OF NEW ENGLAND
SATURDAY. AN APPROACHING WARM FRONT MAY BRING WIDELY SCATTERED
SHOWERS AND THUNDERSTORMS NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
***SCATTERED STRONG TO SEVERE THUNDERSTORMS EXPECTED THIS AFTERNOON
  AND EVENING***

1225 PM UPDATE...

SCATTERED SHOWERS AND THUNDERSTORMS WERE RAPIDLY DEVELOPING ACROSS
UPSTATE NEW YORK EARLY THIS AFTERNOON.  THIS ACTIVITY WILL BE
HEADING EAST INTO A MORE FAVORABLE ENVIRONMENT OVER THE NEXT FEW
HOURS.  0 TO 6 KM SHEAR VALUES ON THE ORDER OF 40 TO 50 KNOTS WILL
COMBINED WITH MLCAPE VALUES ON THE ORDER OF 1000 TO 2000 J/KG IN
OUR REGION. IN ADDITION...A POTENT UPPER JET BETWEEN 90 AND 100
KNOTS WILL BE IN PLACE ACROSS OUR REGION.  THE INGREDIENTS ARE
CERTAINLY IN PLACE FOR STRONG TO SEVERE THUNDERSTORMS.

EXPECT SCATTERED STRONG TO SEVERE THUNDERSTORMS TO MARCH ACROSS
SOUTHERN NEW ENGLAND AFTER 1 PM.  THE ACTIVITY WILL FIRST AFFECT
INTERIOR SOUTHERN NEW ENGLAND AND THEN MAKE ITS WAY TO THE COASTAL
PLAIN BY LATE AFTERNOON/EARLY EVENING.  THE PRIMARY THREAT WILL
LAST UNTIL AROUND 8 PM THIS EVENING...ALTHOUGH CAN/T RULE OUT SOME
OF THE ACTIVITY PERSISTING ANOTHER COUPLE OF HOURS.

THE MAIN THREATS WILL BE LARGE HAIL AND/OR DAMAGING STRAIGHT LINE
WIND GUSTS.  IN FACT...A SUPERCELL THUNDERSTORM OR TWO IS POSSIBLE
WITH HAIL TO THE SIZE OF GOLF BALLS GIVEN GIVEN THE AMOUNT OF SHEAR
AND COLD 500 MB TEMPS.  THE TORNADO THREAT LOOKS LOW GIVEN MAINLY
UNIDIRECTIONAL WIND FIELDS...BUT CAN/T RULE ONE OUT GIVEN MAGNITUDE
OF SHEAR AND IF SOME MESOSCALE INTERACTIONS CAN OCCUR.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
-- Changed Discussion --
TONIGHT...
COLD FRONT SLIDES THROUGH THE AREA THEN STALLS IN VICINITY OF
CT/RI AND SE MA AS IT PARALLELS UPPER LVL FLOW. ANY CONVECTION
THAT DEVELOP WILL LIKELY BECOME ELEVATED AND THEN DIMINISH TO
-SHRA AS THE BL DECOUPLES DUE TO LOSS OF HEATING. A FEW STORMS MAY
LINGER TO THE COAST LINES SO MAY NEED TO WATCH THE WATERS
OVERNIGHT EVEN AS STORMS WEAKEN OVERLAND. OTHERWISE...JUST EXPECT
A FAIR AMOUNT OF CLOUDINESS WITH AT LEAST ISOLATED -SHRA AROUND
GIVEN THE LIFT THE FRONT PROVIDES AND A FAIR AMOUNT OF COLUMN
MOISTURE. DWPTS REMAIN ELEVATED IN VICINITY OF AND S OF THE THE
FRONT...SO EXPECT SOME FOG TO DEVELOP ESPECIALLY IN AREAS THAT
HAVE RAIN RAISING SFC MOISTURE.

TUESDAY...
TRICKY FORECAST REGARDING POTENTIAL FOR ANOTHER STRONG-SEVERE
THUNDERSTORM DAY. SFC COLD FRONT WILL BE STALLED ALONG THE
SOUTHERN HALF OF SOUTHERN NEW ENGLAND DURING THE MORNING HOURS.
WHILE THIS WILL PROVIDE THE FOCUS FOR LIFT...AND DWPTS WILL REMAIN
HIGH WITH THE POTENTIAL FOR CAPE VALUES TO ONCE AGAIN REBOUND TO
1000+ J/KG...THE QUESTION WILL BE AVAILABLE SUNSHINE. THE FRONT
WILL LIKELY KEEP AT LEAST SOME BKN CLOUDS IN THE REGION THROUGH
SUNRISE WHICH WOULD SLOW DESTABILIZATION. HOWEVER...SHOULD THE SUN
BREAK OUT...THERE IS THE POTENTIAL FOR AT LEAST AS MUCH IF NOT
MORE INSTABILITY THAN MONDAY. SHEAR WILL BE MUCH THE SAME AS
WELL...40-50 KT FROM 0-6 KM. SPC STILL FOCUSES A SEE TEXT SO WILL
HAVE TO MONITOR FOR ANOTHER ROUND OF STORMS WHICH AT LEAST HAVE
THE POTENTIAL TO BECOME STRONG-SEVERE.

TEMPS UNDER BKN-OVC SKIES WILL BE A BIT COOLER THAN MON...IN THE
MID TO UPPER 70S ALTHOUGH UNDER SUNSHINE COULD REACH CLOSER TO 80+
ESPECIALLY S OF THE STALLED FRONT. HUMID CONDITIONS ALSO ARE
EXPECTED TO CONTINUE WITH DWPTS IN THE LOW TO MID 60S NEAR THE
FRONT...BUT IN NH THE DWPTS WILL BE LOWER FURTHER BEHIND THE
FRONT.

TUESDAY NIGHT...CHC SHOWERS/TSTMS MAY LINGER INTO THE
EVENING...ESPECIALLY S OF THE MASS PIKE AS THE COLD FRONT MOVES TO
THE COAST. THE FRONT AND ANY SHOWERS WILL PUSH OFFSHORE
OVERNIGHT...BUT CLOUDS WILL LINGER NEAR THE COAST FOR MUCH OF THE
NIGHT.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...

-- Changed Discussion --
BIG PICTURE/PREFERENCES... UPPER TROUGH MOVES ACROSS NEW ENGLAND
WEDNESDAY WITH A SMALL AMOUNT OF COLD ADVECTION ALOFT.  BUILDING
HEIGHTS THURSDAY AS HIGH PRESSRUE OVER THE PLAINS EDGES EAST.  EVEN
WITH THE BUILDING HEIGHTS...A COUPLE OF SHORTWAVES SWEEP AROUND
BAFFIN ISLAND UPPER LOW AND ACROSS QUEBEC/NORTHERN NEW ENGLAND
TOWARD THE WEEKEND.

THE DAILIES...

WEDNESDAY-THURSDAY... COLD FRONT MOVES OFFSHORE EARLY WEDNESDAY.
SOUTHERN NEW ENGLAND REMAINS IN THE RIGHT ENTRANCE REGION OF THE
UPPER JET...AND 70 PERCENT RH LINGERS AT 800-850 MB THROUGH THE
AFTERNOON.  SO POTENTIAL EXISTS FOR DIURNAL CUMULUS DURING MAX
HEATING.  FOR THIS REASON WE HAVE 40-60 PCT SKY COVER DURING THE
AFTERNOON.

OTHERWISE DRY WEATHER AS SURFACE HIGH PRESSURE BUILDS OVER THE
REGION...THEN MOVES OFFSHORE DURING THURSDAY.  THIS WILL BRING LIGHT
NORTHEAST FLOW WEDNESDAY AND A DEVELOPING SOUTHWEST FLOW THURSDAY.
MIXING DEPTHS WILL REACH 800 MB WEDNESDAY AND 800-850 MB THURSDAY.
MIXING THE TEMPS AT THE TOP OF THESE LAYERS WILL SUPPORT MID 70S TO
LOWER 80S...ALTHOUGH THE NORTHEAST WIND WEDNESDAY MAY BUFFER ANY
MIXING IN EASTERN MASS AND HOLD TEMPS THERE A FEW DEGREES COOLER.

FRIDAY THROUGH MONDAY... DUE TO THE ONGOING SEVERE THUNDERSTORM
WATCH...FORECAST GRIDS FOR FRIDAY THROUGH MONDAY REMAIN UNCHANGED.

PREVIOUS DISCUSSION...
FRIDAY... MAINLY DRY AND SEASONABLE CONDITIONS EXPECTED TO
CONTINUE WITH HIGH PRES IN CONTROL. TEMPS MOSTLY IN THE 70S...WITH
COOLING SEABREEZES EXPECTED EACH DAY WITH LIGHT BOUNDARY LAYER
FLOW.

SATURDAY AND SUNDAY...
FORECAST CONFIDENCE DECREASES AS GFS/ECMWF DIFFER ON EWD EXTENT OF
WARM SECTOR AIRMASS. AS MENTIONED ABOVE WE LEANED TOWARD THE ECMWF
WHICH KEEPS THE WARM FRONT TO THE WEST WITH INCREASING CHC OF
SHOWERS/TSTMS FROM POSSIBLE MCS...BUT STILL A LOT OF UNCERTAINTY.
TEMP FORECAST ALSO UNCERTAIN AND WILL DEPEND ON POSITION OF WARM
FRONT.  WE UNDERCUT MEX GUIDANCE BY SEVERAL DEGREES MORE IN LINE
WITH ECMWF.
-- End Changed Discussion --

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS...

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

OVERVIEW...HIGH CONFIDENCE IN OVERALL TRENDS THROUGH TUESDAY.
           LOWER CONFIDENCE IN SHRA/T-STORMS TODAY AND TUESDAY

VFR IS EXPECTED TO BE THE DOMINANT CATEGORY THROUGH THE DAY TODAY.
HOWEVER...SOME SHOWERS AND THUNDERSTORMS COULD POTENTIALLY FORM
AHEAD OF A COLD FRONT THIS AFTERNOON/EVENING PARTICULARLY INLAND
AND AWAY FROM THE COASTLINES WITH LOCALIZED MVFR CONDITIONS AND
WET RUNWAYS.

THE STORMS DISSIPATE OVERNIGHT TONIGHT BUT SOME SHOWERS ARE LIKELY
TO BE AROUND AS A COLD FRONT CROSSES THE REGION. EXPECT SOME
IMPROVEMENT BEHIND THE FRONT WITH WINDS SHIFTING TOWARD THE W
AGAIN. SOME FOG IS POSSIBLE OVER INTERIOR TERMINALS...WITH SOME
STRATUS AND FOG POSSIBLE ON THE CAPE/ISLANDS AND IMMEDIATE S COAST
PRODUCING IFR/MVFR CONDITIONS.

VFR ONCE AGAIN DOMINATES TUE OUTSIDE OF FOG/STRATUS...BUT EXPECT
ANOTHER ROUND OF SHOWERS AND STORMS POSSIBLE...THIS TIME IT MAY
APPROACH THE COASTLINES.

KBOS TERMINAL...HIGH CONFIDENCE IN OVERALL TAF TRENDS...SLIGHTLY
LOWER CONFIDENCE IN POTENTIAL FOR SHOWER/T-STORM LATE TODAY OR
OVERNIGHT.

KBDL TERMINAL...HIGH CONFIDENCE IN OVERALL TAF TRENDS...SLIGHTLY
LOWER CONFIDENCE IN TIMING OF ANY SHOWERS/T-STORMS LATE TODAY AND
OVERNIGHT.

OUTLOOK...WEDNESDAY THROUGH FRIDAY...

TUESDAY NIGHT...MODERATE CONFIDENCE. MVFR POSSIBLE IN SCT
SHOWERS/TSTMS IN THE EVENING. PATCHY MVFR/IFR FOG/STRATUS POSSIBLE
NEAR THE SOUTH COAST.

WEDNESDAY THROUGH FRIDAY...HIGH CONFIDENCE. VFR.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS...

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

HIGH CONFIDENCE THROUGH TUESDAY..

TODAY AND TONIGHT...

WINDS SHIFT TO THE SW TODAY WITH GUSTS GENERALLY 10-15 KT ALTHOUGH
MAY NEED TO MONITOR FOR 20-25 KT AGAIN NEAR THE CAPE AND ISLANDS
THIS AFTERNOON. OTHERWISE...THE SOUTHERLY COMPONENT WILL ALLOW THE
5-6 FT SEAS ON THE OCEAN WATER S OF RI/MA TO PERSIST SO WILL
CONTINUE THE SMALL CRAFT ADVISORY THROUGH 00Z. OTHERWISE...WILL
NEED TO MONITOR FOR SOME T-STORMS WHICH MAY REACH THE COASTLINE
BY THE EVENING AND CONTINUE INTO THE OVERNIGHT HOURS. FOG AND
STRATUS MAY DEVELOP LATE TONIGHT WITH SOME REDUCTION IN VSBYS.

TUESDAY...
A STALLED FRONT COULD ALLOW FOR MORE SHOWERS AND STORMS ACROSS THE
WATERS DURING THE DAY...BUT OUTSIDE OF ANY OF THESE STORMS MAINLY
QUIET BOATING WEATHER IS EXPECTED.

OUTLOOK...WEDNESDAY THROUGH FRIDAY...

HIGH CONFIDENCE.

WEDNESDAY-THURSDAY...LINGERING 5 FOOT SEAS ON THE SOUTHERN OUTER
WATERS WEDNESDAY BUT SUBSIDING DURING THE DAY.  WINDS REMAIN
BELOW 20 KNOTS.

FRIDAY...WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. NE WINDS MAY
GUST TO 20 KT WED.
-- End Changed Discussion --

&&

.HYDROLOGY...
RIVERS CONTINUE TO RECEDE ACROSS THE REGION...WITH MOST FALLING
BELOW FLOOD STAGE YESTERDAY AND OVERNIGHT. ONLY THE CHARLES RIVER
AT DOVER AND THE PAWCATUCK AT WESTERLY REMAIN ABOVE FLOOD STAGE.

THERE IS THE THREAT FOR SHOWERS AND STRONG THUNDERSTORMS TODAY AND
TUESDAY WHICH COULD PROVIDE HEAVY RAIN. THIS MAY LEAD TO SOME
LOCALIZED URBAN AND POOR DRAINAGE FLOOD AND MAY ALTER THE TIMING
OF RIVERS OR EVEN ALLOW THEM TO RISE AGAIN AS WELL. THIS WILL HAVE
TO BE MONITORED.

RIVER FORECAST POINTS WHERE FLOOD WARNINGS ARE STILL IN EFFECT AS
OF 400AM.

IN MA... CHARLES RIVER AT DOVER AT CREST AND REMAINS STEADY

THE AREAL FLOOD WARNING FOR SOUTHWESTERN WASHINGTON COUNTY IN RI
HAS BEEN CANCELLED AS THE LOWER PAWCATUCK RIVER HAS FALLEN BELOW
FLOOD STAGE.

REFER TO THE LATEST FLOOD STATEMENTS FOR SPECIFIC FORECASTS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
     ANZ254>256.

&&

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