Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 010753
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
353 AM EDT WED OCT 1 2014

.SYNOPSIS...
COOL...DAMP CONDITIONS REMAIN IN PLACE INTO THURSDAY MORNING...WITH
MORE WIDESPREAD RAINFALL EXPECTED TODAY. DRY WEATHER RETURNS LATER
THURSDAY INTO FRIDAY AS HIGH PRESSURE BUILDS BACK ACROSS THE REGION.
A COLD FRONT WILL MOVE ACROSS NEW ENGLAND LATER SATURDAY AFTERNOON
AND EARLY SATURDAY NIGHT...FOLLOWED BY COOLER AND DRIER CONDITIONS
FOR SUNDAY AND MONDAY.

&&

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

AN UPPER LEVEL LOW OVER PENNSYLVANIA MOVES EASTWARD OVER SOUTHERN
NEW ENGLAND TODAY.  COMBINED WITH THE LOW PRESSURE SYSTEM WELL
SOUTHEAST OF NANTUCKET...AN INVERTED TROUGH SHOULD DEVELOP JUST WEST
OF SOUTHERN NEW ENGLAND.  THIS WILL CREATE A DEEP LAYER OF LIFT THAT
WILL ALLOW RAIN TO BECOME WIDESPREAD ACROSS THE REGION TODAY.
PERSISTENT NORTHEASTERLY FLOW BRINGS IN PLENTY OF COOL MOIST AIR IN
OFF THE OCEAN AND PWATS ARE 125 TO 175 PERCENT OF NORMAL FOR EARLY
OCTOBER.  THIS WILL ALLOW FOR A MUCH NEEDED STEADY RAINFALL ACROSS
MOST OF THE AREA WITH ROUGHLY HALF AN INCH TO AN INCH OF RAIN
EXPECTED IN MOST LOCATIONS.  HIGHER AMOUNTS ARE POSSIBLE WHERE BANDS
OF HEAVIER RAIN SET UP.  WHILE WE CAN/T DETERMINE EXACTLY WHERE
THESE BANDS WILL DEVELOP...THE BEST CHANCE FOR HIGHER RAINFALL
AMOUNTS LOOKS TO BE ACROSS SOUTHEAST MASS WHERE RAIN WILL LAST THE
LONGEST BEFORE THE LOW PULLS AWAY TO THE EAST.

USED LOCALLY PRODUCED BIAS CORRECTED MOS FOR TEMPERATURES TODAY
WHICH WILL REMAIN COOL AROUND 60 DEGREES FOR MOST LOCATIONS.

&&

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

TONIGHT...STEADY RAIN WILL COME TO AN END SLOWLY FROM WEST TO EAST
AS LOW PRESSURE PULLS FARTHER AWAY FROM THE REGION.  RAIN IS LIKELY
TO CONTINUE ACROSS EASTERN MA AND RI THROUGH MUCH OF THE NIGHT.
CONTINUED EASTERLY FLOW WILL KEEP LOW LEVEL MOISTURE IN PLACE
ALLOWING FOR LOW CLOUDS...DRIZZLE...AND FOG TO REMAIN ACROSS THE
REGION.  LOW TEMPERATURES SHOULD BE IN THE 50S.

THURSDAY...WILL START TO SEE SOME DRYING...PARTICULARLY IN THE WEST
AS HIGH PRESSURE STARTS TO BUILD IN.  CAPE AND ISLANDS WILL BE LAST
TO LOSE THE MOISTURE BUT CLOUDS SHOULD BEGIN BREAKING UP BY THE END
OF THE DAY. BELOW NORMAL TEMPERATURES REMAIN WITH HIGHS AROUND
60...EXCEPT FOR THE CONNECTICUT VALLEY WHERE THEY MAY CLIMB INTO THE
MID 60S.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...

BIG PICTURE... ALASKA SHORTWAVE DIGS OVER THE WESTERN USA/CANADA AND
KICKS THE ESTABLISHED UPPER TROUGH EAST TO THE GREAT LAKES. THIS
BRINGS A BROAD CYCLONIC FLOW OVER THE EASTERN USA WITH BELOW
NORMAL HEIGHTS WHILE AN UPPER RIDGE BUILDS OVER THE WESTERN USA.

EMBEDDED IN THIS FLOW...A CLOSED LOW OVER NEW ENGLAND MOVES OFF
THROUGH THE MARITIMES THURSDAY AND FRIDAY.

THE DAILIES...

THURSDAY NIGHT-FRIDAY... HIGH PRESSURE BUILDS SOUTH OVER NEW
ENGLAND. CROSS SECTIONS OF RH SHOW DRYING IN MOST LAYERS THURSDAY
NIGHT BUT THEN AN INCREASING LAYER OF MOISTURE BELOW 800 MB BY
FRIDAY AFTERNOON. THIS SUGGESTS CLEARING...BUT FOLLOWED BY
INCREASING LOW CLOUDS AGAIN DURING FRIDAY.  RH CHARTS FROM THE GFS
AND ECMWF SHOW CLOUD MOISTURE BEING PUSHED WEST ACROSS THE GULF OF
MAINE FROM THE DEPARTING COASTAL LOW...AND INTO SOUTHEAST NH/EASTERN
MASS FRIDAY AFTERNOON. BY FRIDAY NIGHT THE SAME MODELS SHOW LIGHT
PCPN OVER THIS AREA...SUGGESTING SPRINKLES OR DRIZZLE.

WE WILL HAVE A DRY FORECAST DURING THURSDAY NIGHT AND FRIDAY...BUT
WITH INCREASING CLOUDS FROM THE EAST FRIDAY NIGHT ALONG WITH
FOG/DRIZZLE AND IN EAST COASTAL AREAS A CHANCE FOR MEASUREABLE PCPN.

LIGHT EAST WINDS WILL LIMIT MIXING...AND TEMPS IN THIS SHALLOW LAYER
WILL SUPPORT MAX TEMPS IN THE 60S...COOLEST NEAR THE EAST MASS COAST
AND WARMEST IN THE CT VALLEY.

SATURDAY... THE UPPER TROUGH MOVING ACROSS THE GREAT LAKES DEEPENS
AS IT MOVES IT.  THE TROUGH USES A 110 KNOT JET TO PUSH A COLD FRONT
EAST TOWARD NEW ENGLAND. TEMPERATURE PROFILES SHOW A STRONG THERMAL
GRADIANT ACROSS THE FRONT. THE DEEPENING OF THE TROUGH ALSO TURNS
THE UPPER FLOW OVER NEW ENGLAND MORE FROM THE SOUTH-SOUTHWEST
DRAWING MOISTURE NORTH...PRECIPITABLE WATER VALUES ARE FORECAST TO
REACH 1.5 TO 1.6 INCHES.  STABILITY PARAMETERS ARE LESS THAN
MARGINAL...MID LEVEL LAPSE RATES ARE 5C/KM OR LESS AND TOTALS ARE
LESS THAN 44.

FORECAST WILL CONTINUE TO FEATURE LIKELY POPS BUT SLIGHTLY SLOWER
THAN PREVIOUSLY. THIS SLOWER TIMING ALIGNS WITH SIMILAR TRENDS IN
THE GFS AND ECMWF WITH WINDSHIFT IN THE CT VALLEY 2 PM TO 8 PM AND
IN THE COASTAL PLAIN 8 PM TO MIDNIGHT.

SUNDAY-MONDAY-TUESDAY...SHORTWAVE MOVES NORTH OF OUR AREA
SUNDAY...BUT THE MAIN TROUGH AXIS REMAINS OVER THE GREAT LAKES.
CONTOUR HEIGHTS AT 500 MB ARE BELOW NORMAL OVER THE WEEKEND BUT THEN
MODERATE TO NEAR NORMAL DURING THE FIRST PART OF NEXT WEEK.  SUNDAY
AND MONDAY LOOK DRY WITH SEASONABLY COOL TEMPS.  THE TROUGH AXIS
EJECTS NORTHEAST BY TUESDAY AND MAY SUPPORT A CHANCE OF SHOWERS AT
THAT TIME.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM...TODAY THROUGH THURSDAY...MODERATE CONFIDENCE.

THROUGH 12Z...IFR CIGS LIKELY IN LOW CLOUDS AND SCT SHOWERS.  VSBYS
ARE MAINLY VFR WITH SOME MVFR/IFR VSBYS IN PATCHY DRIZZLE AND
LOCALIZED FOG.

TODAY...IFR CONDITIONS SHOULD CONTINUE THOUGH MVFR CONDITIONS ARE
POSSIBLE IN WIDESPREAD RAIN. A SLIGHT IMPROVEMENT IS POSSIBLE
BEGINNING IN THE WEST LATE IN THE DAY AS RAIN ENDS.

TONIGHT...IFR CONDITIONS IMPROVE SLOWLY FROM WEST TO EAST WITH THE
MOST IMPROVEMENT TOWARDS DAYBREAK THURSDAY.

THURSDAY...AREAS OF IFR /MAINLY IN THE EAST/ WILL IMPROVE TO VFR.

KBOS...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN TIMING.

KBDL...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN TIMING.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...MODERATE CONFIDENCE.

THURSDAY NIGHT-FRIDAY...VFR. AREAS OF IFR CIGS/VSBYS IN PATCHY FOG
EARLY FRIDAY MORNING.  AREAS OF IFR CIGS MOVE WEST OFF THE OCEAN
INTO EAST COASTAL MASSACHUSETTS INCLUDING THE CAPE AND ISLANDS LATE
FRIDAY AND MORE LIKELY FRIDAY NIGHT.

SATURDAY...IFR CIGS FROM THE WORCESTER HILLS EAST DURING THE
MORNING. VFR FARTHER WEST TO START THE DAY BUT LOWERING TO MVFR AND
SCATTERED IFR AS A COLD FRONT APPROACHES LATE IN THE DAY AND BRINGS
SHOWERS.  WIND SHIFTS FROM SOUTH DURING THE DAY TO WEST BEHIND THE
COLD FRONT LATE IN THE DAY AND EARLY AT NIGHT.

SUNDAY...VFR WITH GUSTY WEST WINDS. HIGH PRESSURE BUILDS OVER THE
REGION WITH FAIR WEATHER.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM...TODAY THROUGH THURSDAY...HIGH CONFIDENCE

PERSISTENT NORTHEASTERLY WINDS INCREASE THROUGH THE DAY GUSTING
TO AROUND 25 KTS BY ABOUT MIDDAY TODAY. SEAS CONTINUE TO
INCREASE...PARTICULARLY ON THE NORTHEASTERN WATERS AND INTO BOSTON
HARBOR AND CAPE COD BAY. ADDED ALL THE WATERS EXCEPT FOR
NARRAGANSETT BAY TO THE SMALL CRAFT ADVISORY FOR BOTH WINDS AND
SEAS AND ALL SMALL CRAFT ADVISORIES HAVE BEEN EXTENDED THROUGH
THURSDAY.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...MODERATE CONFIDENCE.

THURSDAY NIGHT-FRIDAY...NORTHEAST WINDS GUSTING 20 TO 25 KNOTS WILL
MAINTAIN 5 TO 9 FOOT SEAS ON THE OUTER WATERS AND EXPOSED EASTERN
WATERS SUCH AS MASSACHUSETTS BAY. SMALL CRAFT ADVISORY WILL BE
NEEDED. FOG AND LOW CLOUDS MOVING IN FROM THE GULF OF MAINE MAY
CREATE POOR VSBYS FRIDAY NIGHT.

SATURDAY... LINGERING POOR VSBYS SATURDAY MORNING IN FOG AND LOW
CLOUDS. THESE CONDITIONS WILL IMPROVE LATER IN THE DAY AS A COLD
FRONT APPROACHES WITH SHOWERS.  SOUTH WINDS WILL GUST 25 TO 30 KNOTS
DURING THE DAY AND EVENING...SHIFTING TO WEST AFTER THE COLD FRONT
MOVES THROUGH SATURDAY NIGHT.  SEAS WILL CONTINUE AT 5 TO 8 FEET ON
THE OUTER WATERS AND OTHER EXPOSED WATERS.  SMALL CRAFT ADVISORY IS
LIKELY.

SUNDAY...WINDS AND SEAS DIMINISH A LITTLE BUT STILL ROUGH. SEAS WILL
LINGER AT 5 TO 7 FEET ON THE OUTER WATERS. WEST TO SOUTHWEST WINDS
WILL GUST TO 25 KNOTS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT
     THURSDAY FOR ANZ232.
     SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 5 PM EDT
     THURSDAY FOR ANZ233-234.
     SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 8 PM EDT
     THURSDAY FOR ANZ230.
     SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 8 PM EDT
     THURSDAY FOR ANZ231.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THURSDAY FOR ANZ235-237-
     250-251-254>256.

&&

$$
SYNOPSIS...WTB/RLG
NEAR TERM...RLG
SHORT TERM...RLG
LONG TERM...WTB
AVIATION...WTB/RLG
MARINE...WTB/RLG


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