Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 310859
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
459 AM EDT SUN AUG 31 2014

.SYNOPSIS...
WARM HUMID FLOW OVER THE NORTHEAST U.S. A UPPER LEVEL SHORTWAVE
FROM THE GREAT LAKES DIVES EAST THROUGH NEW ENGLAND LATE
AFTERNOON/EVENING BRINGING POTENTIAL THUNDERSTORMS WITH HEAVY
DOWNPOURS AND STRONG WINDS. SHOWERS AND THUNDERSTORMS WILL LINGER
INTO MONDAY EVENING...WITH THE BEST CHANCE ACROSS CT/RI AND SOUTH
OF THE MASS PIKE. ANOTHER COLD FRONT APPROACHES LATER TUESDAY
INTO TUESDAY NIGHT. WARM BUT LESS HUMID WEATHER WILL THEN FOLLOW
FOR WEDNESDAY THROUGH FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THROUGH 8 AM...
WARMER MORE HUMID AIR CONTINUES TO FLOW INTO SOUTHERN NEW ENGLAND.
AS OF 2 AM DEWPOINTS HAD CLIMBED INTO THE LOW TO MID 60S. EXPECT
THESE VALUES TO SLOWLY INCREASE THROUGH MORNING. CLOUDS ARE
FILLING IN OVER THE NORTHEAST...SO WE EXPECT MOSTLY CLOUDY SKIES
THROUGH SUNRISE.

TODAY...
BACK EDGE OF THE CLOUD AREA IS SOUTHWEST OF PHILADELPHIA. THIS IS
ABOUT WHERE DEWPOINTS ARE AROUND 70. THIS MEANS A CLOUDY START TO
THE DAY...BUT POTENTIAL FOR THE SUN TO BREAK THROUGH LATER IN THE
MORNING OR EARLY AFTERNOON. A SOUTHWEST UPPER FLOW AND SURFACE
COLD FRONT IN THE GREAT LAKES SUGGESTS NO FROPA TODAY. THE UPPER
SHORTWAVE PASSES ACROSS NORTHERN NEW ENGLAND...BUT CLOSE ENOUGH TO
AFFECT SOUTHERN NEW ENGLAND. A PRE-FRONTAL TROUGH SUPPORTED BY AN
UPPER SHORTWAVE IS A REASONABLE SCENARIO...WITH BEST CHANCE
CLOSEST TO THE SHORTWAVE IN WESTERN/NORTHERN MASS AND IN SOUTHERN
NH.

AT THE LEAST THIS SHOULD BE A WARM VERY HUMID DAY. THE AIRMASS
WILL CONTAIN DEEP TROPICAL MOISTURE WITH PRECIPITABLE WATER VALUES
FORECAST AT 2.0 TO 2.30 INCHES...ABOVE 2 STD DEVIATIONS AND SO
QUITE SIGNIFICANT. QUESTIONS OF THE DAY ARE POTENTIAL FOR
CONVECTION AND POTENTIAL FOR DAMAGING CONVECTION. STABILITY
PARAMETERS ARE FAVORABLE FOR TSTMS...LI AROUND -2 TO -4/TOTALS
INTO THE MID 40S. UPPER WIND FIELDS SUGGEST SEVERE WIND POTENTIAL
WITH 30 KNOTS AT 850 MB AND 40-50 KNOTS AT 500 MB.
AFTERNOON/EVENING SHEAR VALUES LOOK SUFFICIENT TO PROVIDE
ORGANIZATION TO SOME TSTMS.

PUTTING IT ALL TOGETHER: POTENTIAL FOR AFTERNOON/EVENING STRONG
THUNDERSTORMS WITH WIND AND HEAVY DOWNPOURS...AND A LOWER BUT REAL
POTENTIAL FOR DAMAGING WIND GUSTS. FLASH FLOOD INDICES ARE ABOVE
3.5 INCHES... SO FLOODING PROBLEMS WILL BE ALONG THE LINES OF
URBAN AND POOR DRAINAGE FLOODING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
TONIGHT...
CONVECTION LINGERS INTO AT LEAST THE START OF THE NIGHT. SIGNS IN
THE MODEL DATA THAT THE SURFACE BOUNDARY MAY LINGER OVER SOUTHEAST
MASS/RI/CT LATER AT NIGHT. THIS MAY PROVIDE A FOCUS FOR AT LEAST
SCATTERED CONVECTION CONTINUING OVERNIGHT IN THIS AREA. NO
AIRMASS CHANGE SO IT SHOULD BE A WARM AND HUMID NIGHT WITH
DEWPOINTS AROUND 70...AND SO MIN TEMPS SHOULD BE AROUND 70 OR IN
THE LOWER 70S.

MONDAY...
WARM HUMID AIRMASS LINGERS OVER THE REGION. PRECIP WATER VALUES
CONTINUE ABOVE 2 INCHES SOUTH OF THE MASS PIKE AND 1.5 TO 2.0
INCHES NORTH. DYNAMICS WILL BE DIMINISHING...BUT SOUTHERN NEW
ENGLAND WILL CONTINUE UNDER THE RIGHT ENTRANCE REGION OF THE
DEPARTING UPPER JET FOR AT LEAST PART OF THE DAY. WE WILL
CONTINUE WITH CHANCE POPS FOR SHOWERS/TSTMS...AND WITH LOCALLY
HEAVY DOWNPOURS.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
OVERVIEW AND MODEL PREFERENCES...
BROAD RIDGING IS THE DOMINATE FEATURE ACROSS THE EASTERN U.S.
THROUGH MOST OF THIS FORECAST PERIOD...MORE TYPICAL FOR THE
MIDDLE OF SUMMER RATHER THAN EARLY SEPTEMBER. HOWEVER...EARLY IN
THIS PERIOD...THERE WILL BE A COUPLE OF FAST MOVING SYSTEMS IN THE
BROAD NORTHERN STREAM FLOW THAT WILL AFFECT THE REGION. THE RIDGE
FINALLY BECOMES ESTABLISHED AROUND MID WEEK...WITH WARM BUT DRY
CONDITIONS THROUGH THE END OF THE WEEK. SOME QUESTIONS AS TO WHEN
THE RIDGING MAY BREAK DOWN...AS MODEL SOLUTIONS LATE IN THE RUN
TRY TO BREAK DOWN THE RIDGE WHILE BRINGING DOWN A H5 CUTOFF LOW
ACROSS NORTH CENTRAL CANADA INTO NORTHERN QUEBEC. A LOT OF
SOLUTION DIVERGENCE DURING THAT PORTION OF THE FORECAST...HOWEVER.

OVERALL...HAVE FAIRLY GOOD CONFIDENCE WITH MOST OF THE FORECAST...
THOUGH SOME QUESTION AS TO TIMING THE FRONT OFF THE COAST EARLY
MONDAY NIGHT AS THE H5 PATTERN MAY BRIEFLY HANG UP...THEN MORE
QUESTIONS WITH THE POSSIBLE CHANGES IN THE STEERING PATTERN OVER
THE NORTHERN TIER LATE IN THE CYCLE.

HAVE LEANED TOWARD A BLEND OF AVAILABLE GUIDANCE INTO FRIDAY...THEN
PUSHED TOWARD A BLEND OF THE ECENS AND GEFS MEANS WHICH SHOWED A
SLOWER BREAKDOWN OF THE RIDGING ACROSS THE REGION...WITH LOWER
CONFIDENCE IN THE FRIDAY-SATURDAY TIMEFRAME.

DAILIES...

MONDAY NIGHT...
H5 SHORT WAVE HANGS UP A BIT ALONG THE S COAST EARLY MON NIGHT
WHICH WILL KEEP CHANCE FOR SCT SHOWERS/TSTMS THROUGH ABOUT
MIDNIGHT. FAIR AMOUNTS OF INSTABILITY MOVE ALONG WITH THIS
FRONT...WITH K INDICES IN THE LOWER-MID 30S AND TOTAL TOTALS
APPROACHING 50. WILL REMAIN RATHER HUMID AND...WITH ANY LOW LEVEL
MOISTURE FROM RAINFALL...WILL SEE SOME PATCHY FOG REDEVELOP AFTER
MIDNIGHT. WILL REMAIN STICKY OVERNIGHT WITH LOWS IN THE 65 TO 70
DEGREE RANGE.

TUESDAY...
ANOTHER FRONTAL SYSTEM STEADILY WORKS ITS WAY ACROSS OUT OF NY
STATE DURING TUESDAY...THOUGH SOME TIMING ISSUES IN PLACE AMONGST
THE OPERATIONAL MODEL SUITE. FOR NOW...DID INTRODUCE CHANCE POPS
ACROSS SW NH/W MA AROUND MIDDAY /THOUGH THIS MAY BE A BIT TOO
FAST/...THEN PUSHES ACROSS THE REMAINDER OF THE INTERIOR DURING
THE AFTERNOON. MAY HOLD OFF UNTIL EVENING /IF THEN/ FOR COASTAL
AREAS. LOOKS LIKE MOST ENERGY WILL REMAIN ACROSS THE INTERIOR AS
THE H5 HEIGHTS LIFT BACK INTO NORTHERN NEW ENGLAND AND SOUTHERN
QUEBEC TUE NIGHT. EXPECT THE FRONT TO CLEAR THE COAST LATE TUE
NIGHT WITH ANY LEFTOVER PRECIP ENDING.

WEDNESDAY...
EXPECT DRIER AIR TO SLOWLY WORK ACROSS THE REGION DURING THE DAY
ON LIGHT W WINDS. HIGH PRES RIDGE WILL BUILD OUT OF THE
APPALACHIANS. TEMPS WILL REMAIN WARM WITH A GENERAL W WIND FLOW
THROUGHOUT THE LAYER. HIGHS WILL BE IN THE LOWER-MID 80S.

THURSDAY AND FRIDAY...
EXPECT DRY AND MILD CONDITIONS CONTINUING WITH DEWPTS DOWN TO THE
50S...THOUGH AROUND 60 ALONG THE IMMEDIATE COAST. HIGHS WILL BE IN
THE UPPER 70S TO MID 80S BOTH DAYS. A DRY FRONT MAY PUSH THROUGH
EARLY FRI WITH LITTLE MORE THAN A WIND SHIFT.

SATURDAY...
LOTS OF QUESTIONS DURING THIS TIMEFRAME AS A COLD FRONT TRIES TO
WORK ACROSS THE NORTHERN TIER...MAINLY DUE TO UPPER LEVEL PATTERN
THAT MAY TRY TO CHANGE ACROSS NORTH CENTRAL CANADA. TIMING IS VERY
MUCH IN QUESTION...THOUGH FOR NOW HAVE MENTIONED CHANCE POPS AS
THE FRONT MAY TRY TO WORK IN. LOW CONFIDENCE WITH THIS FEATURE.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THRU SUNDAY NIGHT/...HIGH CONFIDENCE IN TRENDS BUT
LOWER CONFIDENCE IN PRECISE DETAILS AND TIMING.

TODAY...VFR SKY COVER WITH AREAS OF MVFR CIGS AROUND 2000 FEET.
THE LOWER CIGS SHOULD IMPROVE TO VFR LATE MORNING AND AFTERNOON.
DEVELOPING TSTMS AFTER NOON WITH BEST CHANCE AFTER 3 PM. BEST
CHANCE WILL BE WESTERN/NORTHERN MASS AND SOUTHERN NH. MVFR/IFR
CONDITIONS IN ANY STORMS WITH POTENTIAL FOR HEAVY DOWNPOURS AND
STRONG WIND GUSTS...POSSIBLY A FEW DAMAGING WIND GUSTS.

TONIGHT...CONVECTION CONTINUES INTO THE EARLY NIGHT BUT SHOULD
DIMINISH AFTER SUNSET. MVFR/IFR CIGS AND VSBYS IN ANY
THUNDERSTORMS. MVFR/IFR CIGS AND VSBYS IN FOG OVERNIGHT.

MONDAY...MVFR CIGS/VSBYS IN SHOWERS AND SCATTERED TSTMS. IFR
CIGS/VSBYS IN MORNING FOG. LOCALLY HEAVY DOWNPOURS STILL POSSIBLE.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF REGARDING TRENDS BUT LOWER
CONFIDENCE ON PRECISE DETAILS AND TIMING.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF REGARDING TRENDS BUT LOWER
CONFIDENCE ON PRECISE DETAILS AND TIMING.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...

MONDAY NIGHT...MODERATE CONFIDENCE.
MVFR-IFR CIGS/VSBYS IN AREAS OF SHOWERS. POSSIBLE TSRA ESPECIALLY
INLAND THROUGH MIDNIGHT. WILL SEE SOME IMPROVING CONDITIONS AS
PRECIP MOVES OFFSHORE OVERNIGHT...BUT MAY CAUSE MVFR-IFR VSBYS IN
AREAS OF FOG AFTER MIDNIGHT.

TUESDAY...MODERATE CONFIDENCE.
MVFR-IFR VSBYS THROUGH AROUND 14Z IN PATCHY FOG...THEN BRIEF
PERIOD OF VFR. MAY SEE PERIODS OF MVFR IN SCT SHOWERS/TSTMS
ESPECIALLY INLAND DURING THE AFTERNOON/EVENING. PRECIP SHOULD
TAPER OFF AFTER MIDNIGHT. PATCHY FOG RETURNS AFTER 05Z-06Z WITH
MVFR-IFR VSBYS IN NORMALLY PRONE INLAND LOCATIONS.

WEDNESDAY AND THURSDAY...MODERATE CONFIDENCE.
EXPECT MAINLY VFR CONDITIONS AS HIGH PRESSURE BUILDS IN. LOCAL
MVFR- IFR VSBYS IN PATCHY FOG THROUGH 14Z WED. MAY AGAIN SEE LOCAL
MVFR- IFR VSBYS IN PATCHY FOG AROUND DAYBREAK THU OVER THE FAR
INTERIOR /SW NH AND N CENTRAL-W MA/.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

MODERATE CONFIDENCE TODAY THROUGH MONDAY.

TODAY...
DRY WEATHER FOR MUCH OF THE DAY. POTENTIAL FOR SHOWERS/TSTMS AFTER
4 PM...EXCEPT AFTER 2 PM NORTH OF CAPE ANN. ANY STORMS WILL HAVE
STRONG WIND GUSTS AS WELL AS POOR VISIBILITY IN HEAVY DOWNPOURS.
SOUTHWEST WIND WILL GUST TO 20-22 KNOTS WHICH IS CLOSE TO SMALL
CRAFT LEVELS. THE PERSISTENCE OF THE WIND WILL BUILD SEAS A TAD
WITH 5 FOOT HEIGHTS MOVING INTO THE OUTER WATERS LATE IN THE DAY.
A SMALL CRAFT ADVISORY HAS BEEN PUT IN EFFECT ON THE OUTER WATERS
STARTING THIS EVENING. IT IS MAINLY FOR THE 5 FOOT SEAS...BUT
WINDS WILL BE CLOSE TO THRESHOLD AND SO WE WILL KEEP THE HEADLINE
NON-SPECIFIC.

TONIGHT...
THE POTENTIAL FOR 5 FOOT SEAS WILL EXTEND INTO RI SOUND ON THE
SOUTHWEST WIND. GAVE SOME THOUGHT ABOUT SIMILAR POTENTIALS FOR
BLOCK ISLAND SOUND AND BUZZARDS BAY...BUT PREFERRED THE BETTER
FETCH INTO RI SOUND WHERE A SMALL CRAFT ADVISORY WILL BE IN
EFFECT.

SHOWERS AND THUNDERSTORMS MAY MOVE ACROSS THE WATERS. BEST CHANCE
ON TIMING OF THE STORMS WOULD BE THE FIRST PART OF TONIGHT...BUT
CONDITIONS WILL REMAIN FAVORABLE THROUGH THE NIGHT. ANY STORMS
WOULD HAVE STRONG WIND GUSTS EARLY TONIGHT AND POOR VISIBILITY IN
HEAVY DOWNPOURS AT ANY TIME.

MONDAY...
WINDS AND SEAS DIMINISH BELOW SMALL CRAFT LEVELS. SMALL CRAFTS
WILL LINGER OVER THE OUTER WATERS DURING THE MORNING.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...

MONDAY NIGHT...MODERATE CONFIDENCE.
SW WINDS DIMINISH DURING THE NIGHT. LEFTOVER 5 FT SEAS MAY LINGER
ACROSS THE FAR OUTER WATERS S AND E OF NANTUCKET EARLY MON
NIGHT...THEN SHOULD SUBSIDE.

TUESDAY THROUGH THURSDAY...MODERATE CONFIDENCE.
EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. MAY SEE SOME SW
WIND GUSTS UP TO 20 KT TUE NIGHT BEFORE SHIFTING TO W-NW AND
DIMINISHING BY WED MORNING.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 5 AM EDT MONDAY
     FOR ANZ250.
     SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 11 AM EDT
     MONDAY FOR ANZ254>256.
     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EDT
     MONDAY FOR ANZ235.

&&

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


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