Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 300924
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
524 AM EDT SAT AUG 30 2014

.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND MOVES OFFSHORE TODAY. WARMER MORE
HUMID AIR WILL THEN MOVE UP FROM THE SOUTH AND SOUTHWEST WITH
SUMMERTIME HUMIDITY STARTING SUNDAY. AN UPPER LEVEL DISTURBANCE
A FRONT WILL SLOWLY PUSH ACROSS NEW ENGLAND THROUGH MONDAY BRINGING
A PERIOD OF SHOWERS AND SCATTERED THUNDERSTORMS. ANOTHER FAST MOVING
FRONT MAY BRING A FEW MORE SHOWERS AND THUNDERSTORMS TUESDAY...
MAINLY ACROSS THE INTERIOR. HIGH PRESSURE TAKES OVER LATE NEXT WEEK
WITH DRY AND WARM CONDITIONS.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THROUGH 8 AM...
A FEW PATCHES OF CLOUDS BUT MOSTLY CLEAR SKIES OVER SOUTHERN NEW
ENGLAND. OTHERWISE CLEAR SKIES AND LIGHT WINDS ARE IN PLACE AND
SHOULD CONTINUE FOR MOST OF THE NIGHT.

THESE CONDITIONS SUPPORT RADIATIONAL COOLING. SURFACE TEMPS AT 1
AM WERE APPROACHING DEW POINT AT SEVERAL SPOTS SUCH AS TAN AND
ORE. WE EXPECT AREAS OF RADIATION FOG TO DEVELOP OVERNIGHT
ESPECIALLY IN THE COLDER VALLEY OF THE INTERIOR AND IN SOME OF THE
LOW SPOTS OF EASTERN MASS. LOCAL VSBYS BELOW 1/2 MILE POSSIBLE.

MIN TEMPS WILL BE GUIDED BY DEW POINT VALUES...IN THE UPPER 40S
AND 50S.

TODAY...
GENERAL SUBSIDENCE UNDER THE HIGH SHOULD PROVIDE A SUNNY DAY. A
MOIST LAYER WITH 75 PERCENT RH WILL LINGER BETWEEN 850 AND 900 MB
WITH MIXING EXPECTED TO REACH TO 900 MB OR A LITTLE ABOVE. THIS
SHOULD AGAIN GENERATE DIURNAL CUMULUS LATER THIS MORNING AND
AFTERNOON. TEMPS AT THE TOP OF THE LAYER WILL SUPPORT MAX SFC TEMPS
OF 73 TO 79F...A FEW SPOTS MAY TOUCH 80F. SOUTH WINDS COMING OFF
THE OCEAN WILL KEEP THE SOUTH COAST A LITTLE COOLER...70 TO 75F.
WINDS IN THE MIXED LAYER WILL BE AROUND 15-18 KNOTS...SO EXPECT
SOME GUSTS TO THIS RANGE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
WITH HIGH PRESSURE OFFSHORE...SOUTH WINDS WILL BRING WARMER MORE
HUMID AIR TOWARD NEW ENGLAND. THIS WILL MEAN INCREASING CLOUDS AS
THE HIGHER HUMIDITY AIR RIDES UP OVER THE COOLER AIRMASS AT THE
SURFACE. THE MOIST LAYER WILL BE CONCENTRATED BELOW 950 MB WITH
AT BEST WEAK LIFT...SO EXPECT CLOUDS AND FOG WITH SOME DRIZZLE
POSSIBLE.

SUNDAY...
SHORTWAVE MOVING THROUGH THE UPPER FLOW WILL START THE DAY OVER
THE GREAT LAKES. AN 85-90 KNOT JET WILL DRIVE THE SYSTEM EAST INTO
NEW ENGLAND BY LATER IN THE DAY. THE DYNAMICALLY FAVORABLE ZONES
FOR LIFT ASSOCIATED WITH THE JET WILL BE WELL TO OUR WEST IN THE
MORNING...BUT THEN SHIFT INTO OUR AREA DURING THE AFTERNOON WITH
THE BEST SUPPORT IN WESTERN MASS/SOUTHERN NH LATE IN THE DAY.

CLOUDS MAY THIN IN THE MORNING BUT SHOULD THICKEN AGAIN THROUGH
THE DAY AS SHORTWAVE AND ITS DEEPER MOISTURE MOVE IN. LAPSE RATE
IN THE 850-500 MB LAYER IS SO-SO AT 5.5C/KM. TOTALS CLIMB TO THE
MID 40S. WINDS AT 850 MB REACH 30 KNOTS WHILE 500 MB WINDS REACH
40-45 KNOTS. PRECIPITABLE WATER VALUES WILL CLIMB THROUGH THE DAY
WITH AFTERNOON VALUES OF 2.0 TO 2.25 INCHES...MOVE THAN 2 STD
DEVIATIONS ABOVE NORMAL AND POTENTIALLY NEAR 3.

THIS FAVORS SHOWERS AND SCATTERED THUNDERSTORMS WITH POTENTIAL FOR
STRONG WIND GUSTS AND HEAVY DOWNPOURS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
OVERVIEW AND MODEL PREFERENCES...
MEDIUM RANGE MODELS AND THEIR ENSEMBLES CONTINUE TO SHOW PRETTY
GOOD CONTINUITY WITH THIS FORECAST PACKAGE...THOUGH SOME TIMING
DIFFERENCES WORK IN BEGINNING AROUND THE TUESDAY TIMEFRAME THROUGH
THE REMAINDER OF NEXT WEEK AS THE FLAT UPPER LEVEL WIND FLOW
ACROSS THE NORTHERN TIER STATES TENDING TO CAUSE OPERATIONAL MODEL
RUNS TO EXACERBATE TIMING ISSUES WITH FAST MOVING SYSTEMS IN THIS
FLOW.

UPPER LEVEL PATTERN FOR THIS PORTION OF THE FORECAST STARTS OFF
WITH RATHER HIGH AMPLITUDE RIDGE FROM THE NORTHEAST INTO QUEBEC IN
THE NORTHERN STREAM WIND FLOW...WHILE A TROUGH DIGS OUT OF THE
NORTHERN PLAINS. OVERALL...THIS NORTHERN STREAM HAS BEEN GENERALLY
FLATTER THAN THE LAST SEVERAL MONTHS /WITH HIGH AMPLITUDE SLOW
MOVING PATTERNS/...WHICH SIGNALS A FASTER FLOW OF SURFACE SYSTEMS
WITHIN THIS FLOW. EARLY IN THIS FORECAST...WILL SEE A SHORT WAVE
RIDE ACROSS IN THE FLATTER PORTION OF THE RIDGE ACROSS THE
REGION... WHICH WILL KEEP UNSETTLED CONDITIONS INTO THE HOLIDAY.
ONCE THIS MOVES E...EXPECT A SOMEWHAT AMPLIFIED BUT PROGRESSIVE
PATTERN THROUGH THE REMAINDER OF NEXT WEEK. ONE THING THAT IS
CONSISTENT IS A CONTINUED MILDER THAN NORMAL TEMPERATURE REGIME
WITH RATHER HIGH HUMIDITY TO START OFF...THEN WILL SLOWLY DROP BUT
REMAIN SOMEWHAT UNCOMFORTABLE...OUR SHOT FOR LATE SUMMER
CONDITIONS.

LEANED TOWARD A BLEND OF AVAILABLE GUIDANCE INTO EARLY TUESDAY AS
A PRETTY GOOD CONSENSUS CONTINUES. FROM LATER TUESDAY THROUGH THE
END OF NEXT WEEK...TRANSITIONED OVER TO THE ENSEMBLE MEANS WHICH
HAVE BEEN MORE STABLE THAN THE OPERATIONAL MODEL RUNS DUE TO
TIMING ISSUES WITH THE FAST FLOW ALOFT. HAVE LOWER CONFIDENCE IN
THE FORECAST BEYOND EARLY TUESDAY.

DETAILS...

SUNDAY NIGHT THROUGH MONDAY NIGHT...
EXPECT SHOWERS AND SOME THUNDERSTORMS TO CONTINUE THROUGH MOST OF
THIS TIMEFRAME AS AN UPPER LEVEL FEATURE AND SURFACE REFLECTION
REMAINS PARALLEL TO THE SW UPPER FLOW. AS THE FLOW FLATTENS OUT
LATE MON INTO MON NIGHT...THE LEFTOVER ENERGY WILL SHIFT OFFSHORE
BUT MAY LINGER ACROSS SOUTHERN AREAS.

MODELS CONTINUE TO SIGNAL HIGH PWATS...ON ORDER OF 2.2 TO 2.3
INCHES...SO SOME RAINFALL MAY BE HEAVY AT TIMES ESPECIALLY IN ANY
THUNDERSTORMS. ANTECEDENT CONDITIONS HAVE BEEN PRETTY DRY OVER THE
LAST SEVERAL WEEKS...EXCEPT FOR A FEW SPOTS THAT DID HAVE SOME
LOCALLY HEAVY RAINFALL AROUND 8/27-28 /CENTRAL MA AND S CENTRAL
CT/. THERE MAY BE A FEW LOCALIZED AREAS THAT ARE PRONE TO POOR
DRAINAGE FLOODING THAT MIGHT HAVE SOME PROBLEMS SUN NIGHT INTO MON
MORNING...BUT ONLY A LOW PROBABILITY FOR THIS. ALSO NOTING H85
WINDS UP TO 35-40 KT...SO SOME COULD MIX DOWN WITH ANY STORMS
EARLY SUN NIGHT ACROSS THE INTERIOR.

SHOULD START TO SEE IMPROVING CONDITIONS ACROSS S NH/N MA EARLY
MON NIGHT...THEN WILL SHIFT SOUTHWARD OVERNIGHT. ONLY QUESTION
WILL BE TIMING THE PRECIP EXIT ALONG THE S COAST...WHICH IT MAY
LINGER A BIT LONGER. SHOULD SEE THIS AREA IMPROVE AROUND OR AFTER
MIDNIGHT.

EXPECT WARM AND HUMID CONDITIONS WITH S-SW WINDS IN PLACE. DEWPTS
WILL BE STEAMY...IN THE 65 TO 70 DEGREE RANGE...THOUGH MAY DROP A
BIT INLAND AS CONDITIONS IMPROVE MON NIGHT.

TUESDAY AND TUESDAY NIGHT...
ANOTHER FRONT WILL QUICKLY PUSH TOWARD THE REGION. WILL SEE
ANOTHER ROUND OF SCT SHOWERS MAINLY ACROSS THE INTERIOR WHERE THE
BEST ENERGY AND DYNAMICS OCCUR. CAN NOT RULE OUT A COUPLE OF
THUNDERSTORMS AS WELL. SHOULD SEE IMPROVING CONDITIONS AFTER
LEFTOVER SHOWERS WILL LIFT NE TUE NIGHT.

WARM AND HUMID CONDITIONS WILL CONTINUE WITH HIGHS IN THE LOWER-
MID 80S. IT WILL REMAIN STICKY TUE NIGHT...THOUGH DEWPTS MAY DROP
A FEW DEGS WELL INLAND.

WEDNESDAY THROUGH FRIDAY...
HIGH PRES WILL MOVE ACROSS THE REGION THROUGH MOST OF THIS
TIMEFRAME. WITH CONTINUED W-SW WINDS IN PLACE...TEMPS WILL REMAIN
SEVERAL DEGS WARMER THAN SEASONAL NORMS FOR EARLY SEPTEMBER. DOES
LOOK LIKE DEWPTS WILL BE A BIT MORE COMFORTABLE ON THURSDAY...
FORECAST IN THE MID 50S TO AROUND 60 /VS. 65 TO 70 EARLY IN THE
WEEK/. HIGHS WILL CONTINUE IN THE LOWER-MID 80S.

MAY SEE ANOTHER FRONT TRY TO APPROACH LATER FRIDAY...THOUGH
TIMING IS IN QUESTION. HAVE KEPT A DRY FORECAST DURING THE DAY FOR
NOW...BUT MIGHT SEE SOME SHOWERS TRY TO MOVE IN FRI NIGHT. LOWER
CONFIDENCE ON THIS PORTION OF THE FORECAST.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT-TERM /THROUGH SUNDAY/...HIGH CONFIDENCE.

TODAY...GENERALLY VFR. MVFR/IFR CIGS/VSBYS IN PATCHY FOG THROUGH
SUNRISE ESPECIALLY IN PARTS OF THE CT VALLEY AND FAVORED SHELTERED
SPOTS. LIGHT WINDS WILL INCREASING A LITTLE OUT OF THE SOUTH.

TONIGHT...VFR EARLY. INCREASING RISK OF MVFR CIGS/VSBY IN
DEVELOPING CLOUD COVER AND FOG/DRIZZLE...MAINLY AFTER MIDNIGHT.

SUNDAY...
MVFR/IFR EARLY IN FOG AND LOW CLOUDS. VSBY SHOULD IMPROVE TO VFR
DURING THE MORNING EXCEPT ALONG THE SOUTH COAST WHERE IFR MAY
LINGER. MVFR AND LOW-END VFR CEILINGS AWAY FROM THE SOUTH COAST DURING
THE AFTERNOON. THUNDERSTORMS EXPECTED TO DEVELOP IN THE
AFTERNOON...MOSTLY IN THE CT VALLEY AND SOUTHERN NH. POTENTIAL FOR
HEAVY DOWNPOURS AND STRONG WIND GUSTS WITH ANY THUNDERSTORMS.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

SUNDAY NIGHT AND MONDAY...LOW CONFIDENCE.

LOW END VFR GENERALLY...THOUGH WILL SEE POCKETS OF MVFR-IFR
CIGS/VSBYS IN AREAS OF SHOWERS. POSSIBLE TSRA AT SOME TERMINALS
ESPECIALLY INLAND EARLY SUN NIGHT. S-SW WINDS CONTINUE. PATCHY
FOG DEVELOPS WITH MVFR-IFR VSBYS LATE SUN NIGHT INTO MON MORNING.

TUESDAY...MODERATE CONFIDENCE.

ANOTHER FRONT PUSHES ACROSS THE REGION TUE NIGHT. MAINLY LOW END
VFR CONDITIONS. SCT SHOWERS ACROSS THE INTERIOR TUE
AFTERNOON/EARLY TUE NIGHT...THEN SHOULD LIFT NE. LOW RISK FOR
TSRA. WINDS VEER TO W LATE TUE NIGHT. MAY SEE PATCHY FOG AFTER
MIDNIGHT IN NORMALLY PRONE VALLEY AREAS.

WEDNESDAY...MODERATE CONFIDENCE.

MAINLY VFR. PATCHY FOG EARLY WED MORNING WITH LOCAL MVFR-IFR
VSBYS WILL IMPROVE BY MID MORNING.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

TODAY...HIGH PRESSURE OVER THE WATERS WILL MEAN FAIR SKIES AND
LIGHT SOUTH WINDS. SOME PATCHY FOG POSSIBLE AROUND SUNRISE.

TONIGHT...
WARM HUMID AIR MOVES UP FROM THE SOUTH AND ACROSS THE WATERS. THIS
WOULD FAVOR PATCHY FOG AND POSSIBLY LIGHT DRIZZLE.

SUNDAY...INCREASING SOUTHWEST WIND WITH GUSTS 20-22 KNOTS.
BUILDING SEAS...BUT HEIGHTS BELOW 5 FEET UNTIL EVENING.
SHOWERS/TSTMS WILL DEVELOP WEST AND NORTHWEST OF MASSACHUSETTS.
THERE IS A LOW END CHANCE THESE COULD REACH THE WATERS LATE SUNDAY
WITH HEAVY DOWNPOURS AND STRONG WIND GUSTS.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

SUNDAY NIGHT AND MONDAY...MODERATE CONFIDENCE.

S-SW WINDS GUSTING UP TO 20 KT. MAY SEE A FEW GUSTS CLOSE TO 25
KT ON THE OUTER WATERS SUN NIGHT. SEAS BUILD TO AROUND 5 FT MAINLY
ON THE SOUTHERN OUTER WATERS. MAY SEE PATCHY FOG DEVELOP LATE SUN
NIGHT INTO MON MORNING.

TUESDAY AND WEDNESDAY...MODERATE CONFIDENCE.

EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. SW WINDS WILL
VEER TO W LATE TUE NIGHT INTO WED.

&&

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

&&

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



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