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Area Forecast Discussion
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000
FXUS61 KBOX 251328
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
927 AM EDT FRI JUL 25 2014

.SYNOPSIS...

HIGH PRESSURE CENTERED OVER THE OHIO VALLEY TODAY WILL PASS TO THE
SOUTH OF NEW ENGLAND SATURDAY. A WARM FRONT WILL MOVE ACROSS THE
REGION SUNDAY BRINGING WARM AND HUMID AIR. A COLD FRONT THEN SWINGS
ACROSS THE REGION MONDAY...THEN LINGERS ALONG THE MASSACHUSETTS
COAST TUESDAY AND WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

925 AM UPDATE...

***BEAUTIFUL DAY IN PROGRESS WITH LOW HUMIDITY***

THE STRONG JULY SUNSHINE WAS ALLOWING TEMPS TO QUICKLY RECOVER FROM 
A RELATIVELY COOL START.  PLENTY OF SUNSHINE WILL CONTINUE THROUGH 
THE AFTERNOON AND HIGHS SHOULD RECOVER INTO THE LOWER TO MIDDLE 80S 
IN MOST LOCALES.  IT WILL BE A FEW DEGREES COOLER ACROSS THE HIGHER 
TERRAIN AND IMMEDIATE COAST WITH VERY LOCALIZED SEA BREEZES...BUT 
STILL A BEAUTIFUL DAY.  LOW HUMIDITY AND RELATIVELY LIGHT WINDS WILL 
MAKE FOR A VERY COMFORTABLE AFTERNOON FOR OUTDOOR ACTIVITIES.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...

TONIGHT...AS THE HIGH PASSES TO OUR SOUTH...SKIES WILL BE CLEAR
WITH VERY LIGHT SOUTHWEST WINDS. OVERNIGHT LOWS MAINLY IN THE
UPPER 50S TO LOWER 60S. 

SATURDAY...SOUTHERN NEW ENGLAND WILL BE IN A WARM SOUTHWESTERLY
AIR FLOW BETWEEN HIGH PRESSURE OVER THE OFFSHORE WATERS AND LOW
PRESSURE ADVANCING THROUGH THE GREAT LAKES. SKIES WILL BE SUNNY TO
START BUT WITH ZONAL FLOW ALOFT...SOME HIGH LEVEL CLOUDINESS WILL
MOVE INTO THE REGION IN THE AFTERNOON. DEWPOINTS WILL STILL BE IN
THE COMFORTABLE RANGE...CLOSE TO 60. HIGHS WILL BE IN THE LOWER TO
MID 80S. LATE IN THE AFTERNOON...A WEAK LEE-SIDE TROUGH WILL BE
APPROACHING THE REGION FROM THE SOUTHWEST AND THIS COULD BE ENOUGH
TO TRIGGER A WIDELY SCATTERED SHOWER OR THUNDERSTORM IN WESTERN MA
AND WESTERN CT.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
BIG PICTURE... 

MUCH OF THE UPPER FLOW REMAINS UNCHANGED THROUGH THE FORECAST 
PERIOD. DEEP RIDGES WILL EXTEND ACROSS WESTERN NORTH AMERICA AND THE 
WESTERN ATLANTIC. CLOSED LOW OVER NORTHERN QUEBEC ANCHORS A TROUGH 
OVER EASTERN NORTH AMERICA. SHORTWAVE EJECTING FROM THE PACIFIC 
NORTHWEST WILL PLOW OVER THE TOP OF THE WESTERN RIDGE...THEN MERGE 
WITH THE EASTERN NORTH AMERICA TROUGH OVER THE WEEKEND. THIS WILL 
DEEPEN THE TROUGH AND PULL ITS FEATURES FARTHER SOUTH. THE TROUGH 
BEGINS TO EJECT NORTH THROUGH EASTERN CANADA BY THURSDAY. THE DEPTH 
OF THE TROUGH AND THE EXTENT OF THE RIDGES ON EITHER SIDE WILL MAKE 
STRAIGHT WEST-TO-EAST MOVEMENT DIFFICULT NEXT WEEK.

THE MASS FIELDS AND THERMAL FIELDS OF THE GFS AND ECMWF LOOK SIMILAR 
IN OVERVIEW. SOME DIFFERENCES IN DETAILS EMERGE DURING THE FIRST 
HALF OF NEXT WEEK.  THE SIMILARITY BUILDS CONFIDENCE IN THE OVERALL 
FLOW OF THE FORECAST. THE LONGER RANGE DIFFERENCES IN DETAIL SUPPORT 
USING A BLEND OF THE FORECAST DATA.

THE DAILIES... 

SATURDAY NIGHT-SUNDAY... AS THE SHORTWAVE PHASES WITH THE EASTERN 
UPPER TROUGH...THE SUPPORTING UPPER JET EXTENDS EAST TOWARD NEW 
ENGLAND. MEANWHILE WEST TO SOUTHWEST LOW LEVEL WINDS 30 KNOTS WILL 
BRING INCREASING HUMIDITY...WHICH THEN RIDES OVER THE SURFACE 
AIRMASS. ISENTROPIC FIELD SUGGEST THE BEST LIFT WILL BE OVER 
NORTHERN NEW ENGLAND. BUT LOW LEVEL WIND FIELDS VARY FROM ONE MODEL 
TO ANOTHER. ONE FEEDS THE LOW LEVEL JET TOWARD NORTHERN NEW 
ENGLAND...A SECOND TOWARD MASSACHUSETTS...AND THE THIRD TOWARD LONG 
ISLAND. IN ANY OF THE SCENARIOS...THIS WILL MEAN INCREASING CLOUDS 
AND AN INCREASING CHANCE OF SHOWERS/THUNDER OVERNIGHT INTO SUNDAY AS 
THE RESULTING WARM FRONT APPROACHES. WE WILL FAVOR HIGHER POPS TO 
OUR NORTH BUT MODERATE CONFIDENCE AT BEST. EXPECT DEWPOINTS TO 
INCREASING DURING THIS TIME AND REACH 65-70.  

AS WE MOVE INTO THE WARM SECTOR ON SUNDAY...THE QUESTION WILL BE HOW 
MUCH THE AIRMASS DESTABILIZES. MODEL STABILITY VALUES SUGGEST A FAIR 
AMOUNT OF ENERGY TO FEED UPON. SB CAPES CLIMB ABOVE 1000 J/KG AND 
BETTER THAN 60 PCT CHANCE OF LI VALUES LESS THAN -4. PRECIPITABLE 
WATER VALUES ARE SQUIRRELLY ON THE GFS BUT EITHER SIDE OF 1.5 
INCHES. THIS IS WELL BELOW 2 STD DEV...SO CONFIDENCE IN HEAVY 
DOWNPOURS IS LOW AT THIS TIME. WINDS AT 500 MB ARE FORECAST AROUND 
40 KNOTS. OVERALL...A CONCERN FOR STRONG WIND GUSTS IN ANY 
THUNDERSTORMS WHICH WILL NEED TO BE MONITORED. 

MONDAY-TUESDAY... 

UPPER SHORTWAVE MOVES INTO POSITION ALONG THE TROUGH AXIS OVER THE 
EASTERN GREAT LAKES. STRONG UPPER JET LEADING THE SHORTWAVE SETS UP 
OVER NEW ENGLAND WITH OUR AREA UNDER THE RIGHT ENTRANCE REGION 
/FAVORABLE FOR GENERATING LIFT/. MODELS HINT AT A WAVE DEVELOPING 
ALONG THE APPROACHING COLD FRONT AND PROVIDING AN EXTRA PUSH TO GET 
THE COLD FRONT INTO NEW ENGLAND. INSTABILITY REMAINS WITH TOTALS 
UPPER 40S AND AROUND 50. EXPECT MORE SHOWERS/TSTMS MONDAY...SEVERE 
POTENTIAL WILL NEED TO BE MONITORED.  

THE COLD FRONT AND SUPPORTING UPPER JET DYNAMICS WILL STILL BE IN 
THE VICINITY ON TUESDAY. THE ECMWF HOLDS THE FRONT OVER INTERIOR 
SOUTHERN NEW ENGLAND WHILE THE GFS AIMS TOWARD THE EAST MASS COAST. 
WE WILL SHOW CHANCE POPS FOR MOST AREAS ESPECIALLY IN THE 
AFTERNOON...WITH PCPN PULLING OUT TO THE NORTHEAST IN THE EVENING.

WEDNESDAY-THURSDAY... UPPER TROUGH REMAINS IN PLACE WITH AXIS TO OUR 
WEST. THE AIRMASS DRIES WITH JUST A MOIST LAYER BETWEEN 750 AND 850 
MB...WHICH MAY CONTRIBUTE TO PERIODIC CLOUDS ESPECIALLY DURING THE 
DAY.  SURFACE HIGH PRESSURE BUILDS INTO THE REGION...WHICH SHOULD 
ALSO WORK AGAINST ANY SHOWERS. WILL GO WITH DRY WEATHER IN THE 
FORECAST.

&&

.AVIATION /13Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SATURDAY/...HIGH CONFIDENCE.

TODAY THROUGH SATURDAY...

VFR CONDITIONS RIGHT THROUGH SATURDAY OTHER THAN VERY LOCALIZED
LATE NIGHT/EARLY MORNING FOG. SEA BREEZE ALONG THE COASTLINE THIS
AFTERNOON.

KBOS TAF...HIGH CONFIDENCE. SEA BREEZES ALONG THE IMMEDIATE COAST
BY THIS AFTERNOON. SOUTHWEST WINDS SHOULD BE STRONG ENOUGH ON 
SATURDAY TO PRECLUDE SEA BREEZE DEVELOPMENT.
 
KBDL TAF...HIGH CONFIDENCE.

OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...MODERATE CONFIDENCE. 

VFR BUT WITH AREAS OF MVFR IN SHOWERS/TSTMS.  AREAS OF IFR/LIFR IN 
LATE NIGHT/EARLY MORNING FOG ESPECIALLY ALONG THE SOUTH COAST.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE.

TODAY AND TONIGHT...EXCELLENT BOATING WEATHER THROUGH TONIGHT
WITH WEAK PRESSURE GRADIENT KEEPING WINDS/SEAS WELL BELOW SCA
THRESHOLDS. VISIBILITIES SHOULD BE EXCELLENT MOST OF THE TIME.

SATURDAY...SOUTHWEST WINDS WILL INCREASE TO 15-20 KNOTS AND MAY
GUST TO NEAR 25 KNOTS OVER THE WATERS IN THE AFTERNOON. A SMALL
CRAFT ADVISORY MAY BE NEEDED.

OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...MODERATE CONFIDENCE. 

SATURDAY NIGHT-SUNDAY...A WARM FRONT APPROACHES THE WATERS WITH 
WARMER MORE HUMID AIR AND WITH CLOUDS/SHOWERS/TSTMS. INCREASING 
SOUTHWEST WINDS WITH GUSTS NEAR 25 KNOTS SUNDAY AND SEAS BUILD TO 
5-6 FEET ON THE EXPOSED WATERS. A SMALL CRAFT ADVISORY MAY BE
NEEDED.

MONDAY...WARM HUMID AIR OVER THE WATERS WITH 
CLOUDS/SHOWERS/THUNDERSTORMS. SOUTHWEST WINDS GUSTING 20 KNOTS.
THIS SHOULD KEEP SEAS AT NEAR 5 FEET ON THE EXPOSED WATERS. 
THE POTENTIAL FOR SMALL CRAFT ADVISORY WILL CONTINUE.

TUESDAY...A COLD FRONT MOVES ACROSS THE WATERS...BUT FORECAST MODELS 
DIFFER ON THE TIMING OF FRONTAL PASSAGE.  CONTINUED CHANCE OF 
SHOWERS/THUNDERSTORMS. SOUTHWEST WINDS DIMINISH AND TURN WEST-
NORTHWEST AFTER THE FRONT MOVES THROUGH.  SEAS REMAIN AROUND 5 FEET 
MUCH OF THE DAY.  SMALL CRAFT ADVISORY POTENTIAL CONTINUES.

&&

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

&&

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



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