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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 220641
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
241 AM EDT WED MAY 22 2013

.SYNOPSIS...
-- Changed Discussion --
A STALLED FRONT WILL MOVE BACK NORTH AS A WARM FRONT TODAY. WARM
AND HUMID CONDITIONS CONTINUE INTO THURSDAY AND FRIDAY WITH
SHOWERS AND SCATTERED STRONG THUNDERSTORMS POSSIBLE. COOLER AND
LESS HUMID CONDITIONS ARE EXPECTED FOR THIS HOLIDAY WEEKEND AS
HIGH PRESSURE BUILDS ACROSS THE NORTHEAST.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --
2 AM UPDATE...

CONTINUING TO MONITOR WAVES OF CONVECTION THIS MORNING. LATEST
RUNS OF THE HRRR APPEAR TO HAVE THE BEST HANDLE ON THESE BANDS OF
CONVECTION...ALTHOUGH ITS TIMING WAS SLOW BY A FEW HOURS. LEANED
HEAVILY ON THE HRRR WITH THE APPROPRIATE TIMING ADJUSTMENT FOR THE
EARLY MORNING FORECAST. SHOWERS AND THUNDERSTORMS ARE REASONABLY
HOLDING TOGETHER IN A HIGH SHEAR/LOW CAPE ENVIRONMENT.

LATER TODAY...EXPECTING THE STALLED BACK-DOOR COLD FRONT TO MOVE
BACK NORTH AS A WARM FRONT. THERE ARE STILL SOME QUESTIONS AS TO
HOW FAST THIS WILL HAPPEN. CURRENTLY THINKING THERE IS NOT ENOUGH
PUSH TO DRIVE IT COMPLETELY THROUGH SOUTHERN NEW ENGLAND. AS
SUCH...MAINTAINED COASTAL SEABREEZE FRONTS ALONG BOTH COASTS.

THIS HAS BIG RAMIFICATIONS FOR TEMPERATURES ALONG THE EAST COAST.
SHOULD THIS FRONT GET ENOUGH PUSH...CURRENT FORECAST TEMPERATURES
ARE LIKELY 5-10 DEGREES TOO LOW ALONG THE IMMEDIATE COASTLINE. AM
MORE CONFIDENT WITH TEMPERATURES FARTHER INLAND. SHOULD THERE BE
MORE SUNSHINE THAT CURRENTLY THINKING...LIKELY TOO LOW FARTHER
INLAND AS WELL.

THINKING THERE WILL BE MORE CLOUDS THAN SUNSHINE TODAY OWING TO
LOTS OF CONVECTIVE DEBRIS FROM THE OVERNIGHT SHOWERS...AS WELL AS
NEW CONVECTIVE CLOUDS AS WE HEAD INTO THIS AFTERNOON.

MORE SHOWERS AND THUNDERSTORMS ARE EXPECTED LATER TODAY. THERE IS
THE POSSIBILITY FOR MORE ISOLATED SEVERE WEATHER. THE GREATEST
RISK SHOULD BE FARTHER WEST OF OUR REGION WHERE THE MORE FAVORABLE
COMBINATION OF INSTABILITY AND SHEAR SHOULD BE. THE BEST ADVICE IS
TO KEEP AN EYE ON THE SKY AND LATER FORECASTS IF YOU WILL BE
OUTDOORS THIS AFTERNOON.
-- End Changed Discussion --

&&

.SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/...
-- Changed Discussion --
TONIGHT...MORE OF THE SAME TONIGHT. WARM FRONT CONTINUES TO PUSH
NORTH AS STRONGER SOUTH TO SOUTHWEST SYNOPTIC FLOW DEVELOPS.
DECENT INSTABILITY PERSISTS THROUGH THE NIGHT. SO THINKING WE WILL
BE SEEING ANOTHER NIGHT OF ISOLATED TO SCATTERED THUNDERSTORMS.
THE GREATEST RISK OF THESE WILL BE ACROSS THE INTERIOR...AWAY FROM
THE STABILIZING INFLUENCE OF THE OCEAN.

THURSDAY...SOUTHERN NEW ENGLAND REMAINS IN THE WARM SECTOR OF A
LOW PRESSURE MOVING FROM THE GREAT LAKES INTO THE SAINT LAWRENCE
RIVER VALLEY. THIS LOW HAS A RATHER AMPLIFIED UPPER SYSTEM...SO
ITS COLD FRONT WILL BE SLOW TO MOVE ACROSS OUR REGION.

EXPECTING MORE ROUNDS OF SHOWERS AND SCATTERED THUNDERSTORMS.
VERY HUMID AIRMASS IN PLACE AS WELL...WITH PRECIPITABLE WATER
VALUES AROUND 1.7 INCHES. WILL LIKELY SEE SOME HEAVY DOWNPOURS
WITH SOME SHOWERS...ALONG WITH SOME HAIL AND GUSTY WINDS. MAY NOT
QUITE REACH SEVERE THRESHOLDS AS CLOUDS WILL BE MORE PREVALENT...
THUS TEMPERATURES SHOULD BE LOWER THAN WEDNESDAY.
-- End Changed Discussion --

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
HIGHLIGHTS...

* SHOWERS AND SCATTERED THUNDERSTORMS THURSDAY INTO FRIDAY
* COOLER AND LESS HUMID FOR THE HOLIDAY WEEKEND INTO EARLY NEXT
  WEEK

OVERVIEW AND MODEL PREFERENCES...

MEDIUM RANGE OPERATIONAL MODEL SUITE SIGNALING AN AMPLIFIED...
SLOWLY PROGRESSIVE PATTERN ACROSS THE LOWER 48. AT THE START...
NOTING LONG WAVE TROUGH ACROSS THE UPPER PLAINS INTO THE WESTERN
LAKES THOUGH SOME DIFFERENCES IN POSITIONING...ALONG WITH H5
CUTOFF LOW MOVING INTO THE WEST COAST. LOWER THAN AVERAGE
CONFIDENCE ON THE PROGRESSION OF THE UPPER LEVEL PATTERN
OPERATIONAL SUITE...THOUGH GENERAL SURFACE SYSTEM POSITIONS AND
TIMING SIGNALS THROUGH THE HOLIDAY WEEKEND SEEM FAIRLY GOOD.
BETTER CONTINUITY AMONGST THE MODEL ENSEMBLES...SO LEANED CLOSER
TO THOSE BUT DID INCORPORATE A LITTLE OF THE 12Z GFS/00Z ECMWF
INTO THE EARLY PORTION OF THE LONG TERM /WED NIGHT TO FRI/.

ANTICIPATE SLOW BUT STEADY CHANGE TO THE UPPER PATTERN LATE THIS
WEEK AS UPPER TROUGH MOVES ACROSS THE EASTERN U.S. FRI-SAT. THIS
WILL BRING AIRMASS CHANGE AS UPPER WINDS SHIFT TO NW...BRINGING
COOLER AND DRIER CONDITIONS FOR A GOOD CHUNK OF THE HOLIDAY
WEEKEND. MODERATE TO HIGH CONFIDENCE CONTINUES FOR THE THU-FRI
TIMEFRAME WITH PERIODIC PRECIP AND SCATTERED CONVECTION...THEN
COLD FRONT SHOULD SWEEP THROUGH FRI NIGHT INTO EARLY SAT. MODERATE
CONFIDENCE BEYOND FRIDAY AS MAY SEE SOME TIMING ISSUES WITH THE
PASSAGE OF THE UPPER TROUGH SOMETIME SAT. FEW SHOWERS ARE
POSSIBLE...BUT TIMING IS DIFFICULT. EXPECT HIGH TEMPS THIS WEEKEND
TO RUN UP TO 5 DEGREES BELOW SEASONAL NORMS. DOES LOOK TO BE DRY
INTO EARLY NEXT WEEK WITH CLOSE TO SEASONABLE TEMPS.

DETAILS...

THURSDAY NIGHT...TIMING OF A COLD FRONT IS STILL IN QUESTION.
THOUGH APPEARS IT SHOULD SLOWLY CROSS THE REGION THU NIGHT...MAY
REACH THE COAST BY 12Z FRI. HAVE CARRIED LIKELY TO CAT POPS AS
COLD FRONT PASSES. LOOKS LIKE BEST INSTABILITY MAY PASS E
OVERNIGHT...BUT COULD STILL SEE SOME ELEVATED CONVECTION SO KEPT
SCT THUNDER IN THE FORECAST. TEMPS DO START DROPPING BACK TO THE
LOWER-MID 50S LATE ACROSS FAR INTERIOR AREAS.

FRIDAY...COLD FRONT SHOULD CLEAR THE E COAST DURING THE MORNING
BUT SOME SHOWERS MAY LINGER INTO MID MORNING ACROSS E MA.
OTHERWISE...EXPECT CONDITIONS TO IMPROVE THOUGH IT WILL BE
NOTICEABLY COOLER AND LESS HUMID.

SATURDAY THROUGH TUESDAY...BLOCKING UPPER PATTERN CONTINUES
ACROSS LABRADOR INTO GREENLAND THROUGH THIS TIMEFRAME...WHICH WILL
KEEP HIGH PRES BUILDING OUT OF CENTRAL CANADA DOWN THE EASTERN
SEABOARD. LONG RANGE MODELS AND ENSEMBLES ARE IN PRETTY GOOD
AGREEMENT WITH THIS PORTION OF THE FORECAST. EXPECT DRY AND COOL
CONDITIONS THROUGH THE HOLIDAY WEEKEND INTO EARLY NEXT WEEK. ON
SATURDAY...EXPECT DAYTIME HIGHS ONLY IN THE 60S...RUNNING 4 TO 8
DEGREES BELOW SEASONAL NORMS...THOUGH WILL MODIFY A BIT THROUGH
THE REMAINDER OF THIS TIMEFRAME.

DUE TO SEVERE WEATHER WATCH THIS AFTERNOON...KEPT PREVIOUS FORECAST
GOING FROM SUNDAY ONWARD...BUT LOOKS IN GOOD SHAPE WITH LATEST MODEL
GUIDANCE.
-- End Changed Discussion --

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS...

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

OVERVIEW...MODERATE CONFIDENCE IN TIMING AND AREAL COVERAGE OF
STRATUS AND FOG THROUGH THIS MORNING.

THROUGH 12Z...EXPECTING BANDS OF STRONG ENOUGH CONVECTION TO
AVOID. THESE BANDS OF CONVECTION SHOULD CONTINUE TO WEAKEN AS IT
MOVES EAST. MIXED CONDITIONS THIS MORNING WITH WIDESPREAD IFR
ACROSS THE MA COASTAL PLAIN AND MUCH OF RI AND NORTHERN
CT...IMPROVING TO POCKETS OF MVFR ACROSS THE INTERIOR. EVEN SOME
LOCALIZED VFR POSSIBLE.

TODAY...EXPECT MVFR-LIFR CONDITIONS TO GRADUALLY IMPROVE TO VFR
14-16Z AS SW WINDS DEVELOP. IFR MAY PERSIST MOST OF THE DAY AT
KACK. ISOLATED TO SCATTERED CONVECTION BECOMING MORE WIDESPREAD
THIS AFTERNOON...ESPECIALLY WEST OF KMHT-KORH-KIJD.

TONIGHT...MODERATE CONFIDENCE IN TRENDS. EXPECT VARIABLE
CONDITIONS DEPENDING UPON SHOWER AND FOG DEVELOPMENT. BETTER SHOT
FOR IFR VSBYS IN FOG ALONG S COAST ON S-SW WINDS AND MILD TEMPS
MAINLY AFTER MIDNIGHT. SCT SHOWERS/TSTMS ACROSS MOST OF THE REGION
THOUGH BEST SHOT ACROSS CENTRAL AND WESTERN AREAS...WITH MVFR-IFR
CIGS/VSBYS. MAY SEE LOCAL HEAVY DOWNPOURS. LOW CONFIDENCE ON
TIMING AND PLACEMENT.

THURSDAY...MODERATE CONFIDENCE IN TRENDS. VERY UNSETTLED PATTERN
AHEAD OF APPROACHING COLD FRONT. VARIABLE CONDITIONS BETWEEN VFR
AND MVFR/IFR IN SHRA/TSRA/PATCHY FOG. COLD FRONT CROSSES THE
REGION THU NIGHT...SO WILL SEE IMPROVING CONDITIONS ACROSS WESTERN
AREAS AFTER MIDNIGHT THU NIGHT...THEN INTO CENTRAL SECTIONS AFTER
06Z-07Z. MAY SEE SW WIND GUSTING UP TO 20-25 KT DURING THE DAY AS
WELL. WINDS SHIFT TO W-NW ACROSS CENTRAL AND WESTERN AREAS AFTER
MIDNIGHT.

KBOS TERMINAL...MODERATE CONFIDENCE IN TRENDS...LOWER CONFIDENCE
IN TIMING OF LOWER CONDITIONS AND CONVECTION THIS AFTERNOON.

KBDL TERMINAL...MODERATE CONFIDENCE IN TAF...MAINLY DUE TO TIMING
OF CONVECTION THIS AFTERNOON. COULD SEE BRIEF IFR IN A BAND OF
TSRA. APPEARS THIS BAND WILL PASS TO THE NORTH OF THE TERMINAL
THROUGH 0830Z.  WILL CONTINUE TO MONITOR.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...

FRIDAY...MODERATE TO HIGH CONFIDENCE. MAY SEE LEFTOVER POCKETS OF
MVFR CIGS/VSBYS POSSIBLE ACROSS E MA THROUGH 14Z-15Z FRI.
OTHERWISE...VFR.

SATURDAY-SUNDAY...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 TONIGHT.

WINDS EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH TODAY. INCREASING SW FLOW WILL RESULT IN SEAS BUILDING
OVER THE SOUTHERN COASTAL WATERS. WILL ISSUE A SMALL CRAFT
ADVISORY FOR ROUGH SEAS LATER TODAY INTO THURSDAY. WINDS SHOULD
CONTINUE TO INCREASE TONIGHT INTO THURSDAY AS A LOW PRESSURE MOVES
INTO THE GREAT LAKES.

EXPECT LOW VSBYS IN HEAVY SHOWERS AND PATCHY FOG AT TIMES.
ISOLATED TO SCATTERED THUNDERSTORMS POSSIBLE AS WELL...ESPECIALLY
NEAR SHORE.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...

FRIDAY...MODERATE TO HIGH CONFIDENCE. COLD FRONT WILL BE SLOW TO
CLEAR THE WATERS...SO EXPECT SW WINDS IN PLACE FOR A PORTION OF
THE DAY BEFORE SHIFTING TO W-NW ACROSS THE EASTERN WATERS.

SATURDAY-SUNDAY...MODERATE CONFIDENCE. SEAS WILL REMAIN ABOVE
SMALL CRAFT FOR MOST OF THE WEEKEND ESPECIALLY ON THE OUTER
WATERS. NW GUSTS MAY APPROACH 25 KT.
-- End Changed Discussion --

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...BELK/EVT
NEAR TERM...BELK
SHORT TERM...BELK
LONG TERM...EVT
AVIATION...BELK/EVT
MARINE...BELK/EVT