Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KBOX 310604
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
204 AM EDT FRI JUL 31 2015

.SYNOPSIS...
PATCHY FOG AND LOW CLOUDS EARLY THIS MORNING GIVES WAY TO DRIER
AND LESS HUMID WEATHER THIS AFTERNOON...BUT IT WILL REMAIN VERY
WARM. WARM AND HUMID CONDITIONS WILL RETURN THIS WEEKEND...THEN
WILL BECOME LESS HUMID WITH TEMPERATURES CLOSER TO NORMAL NEXT
WEEK. THERE IS A LOW RISK FOR SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THIS WEEKEND INTO EARLY NEXT WEEK...HOWEVER MUCH OF
THE TIME DRY WEATHER WILL PREVAIL.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...

2 AM UPDATE...

COLD FRONT SLOWLY MOVING ACROSS THE REGION WITH DEW PTS INTO THE
60S ACROSS NORTHWEST MA. THIS SHOWERS WITH EMBEDDED THUNDER ACROSS
CAPE AND ISLANDS...ESPECIALLY OVER THE WATERS SOUTH OF NEW
ENGLAND. THIS CONVECTION WILL CONTINUE TO MOVE STEADILY EASTWARD
AND EVENTUALLY WELL OFFSHORE AS UPSTREAM SHORT WAVE OVER THE
EASTERN GREAT LAKES MOVES EASTWARD.

SURFACE FRONTAL BOUNDARY WILL ACCELERATE EASTWARD SHORTLY AFTER
SUNRISE AS BLYR DEEPENS AND DRIER AIR WITH WNW WINDS ALOFT MIX TO
THE SURFACE...HELPING FRONT SURGE EASTWARD. UNTIL THIS HAPPENS
PREFRONTAL AIRMASS WITH DEW PTS IN THE 70S WILL YIELD PATCHY FOG
AND LOW CLOUDS OVER CT/RI AND SOUTHEAST MA.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
FRONT WILL BE OFFSHORE FRIDAY MORNING WITH DRIER AND MORE COMFORTABLE
AIRMASS IN ITS WAKE. KEEPING FRIDAY NIGHT DRY ALTHOUGH WE SHOULD
SEE INCREASING CLOUDS AS NEXT SHORT WAVE APPROACHES.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...

* EXPECT MORE SEASONABLE TEMPS AND LOWER HUMIDITY THROUGH MOST OF
  THIS PERIOD

* CHANCE FOR A FEW SHOWERS/ISOLATED THUNDER EACH DAY BUT MUCH OF THE
  TIME REMAINING DRY

SYNOPTIC OVERVIEW AND MODEL PREFERENCES...

MEDIUM RANGE FORECAST CONTINUES TO FEATURE ANOMALOUS H5 CUTOFF
VORTEX ACROSS JAMES AND HUDSON BAYS WHICH WILL ELONGATE ACROSS
QUEBEC DURING THE LONG TERM PERIOD. WILL STILL SEE LONG WAVE TROUGH
ACROSS THE EASTERN GREAT LAKES AND DOWN THE APPALACHIANS WHICH WILL
TEND TO FLATTEN...THOUGH SHORT WAVES WILL ROTATE AROUND THE BASE OF
THE CUTOFF LOW INTO THE MEAN TROUGH. THIS WILL BRING PERIODS OF
SHOWERS/THUNDERSTORMS ACROSS THE REGION FROM TIME TO TIME. NOT
EXPECTED A TOTAL WASHOUT AT ANY TIME...THOUGH MODELS LOOK LIKE THEY
MAY HAVE SOME CONTINUITY WILL BE AROUND THE LATE MON/MON NIGHT AND
TUE NIGHT TIMEFRAMES. HOWEVER...OPERATIONAL MODEL SOLUTION SPREAD
DOES WIDENS OVER TIME AS ONE WOULD EXPECT ESPECIALLY THIS TIME OF
THE YEAR...SO CONFIDENCE IN SPECIFIC TIMING OF CONVECTION AND ANY
SHORT WAVE PASSAGE LOWERS.

USED A BLEND OF AVAILABLE GUIDANCE INTO MONDAY...THEN TRANSITIONED
OVER TO THE GFS AND EC ENS MEANS WHICH GAVE A BIT MORE CONTINUITY
WITH PREVIOUS FORECASTS.

DETAILS...

SATURDAY...MODELS CONTINUE TO PAINT A WEAK H5 SHORT WAVE IN THE MEAN
UPPER FLOW FOR LATER SAT INTO SAT NIGHT. LOOKS LIKE BEST INSTABILITY
AND MOISTURE...WHAT THERE IS OF IT...WILL BE ACROSS CENTRAL AND
WESTERN AREAS. ANOTHER QUESTION WILL BE WHETHER THERE WILL BE SOME
NOCTURNAL INSTABILITY SHOWERS/TSTMS ALONG THE S COAST WHERE HIGHEST
HUMIDITIES ARE IN PLACE. HAVE LEFT OUT FOR NOW...BUT IT IS SIGNALED
ON THE GFS MODEL.

HAVE GENERALLY SLIGHT CHANCE POPS GOING...BUT MAY SEE A LINE OF SCT
SHOWERS/TSTMS ACROSS CT VALLEY INTO CENTRAL MA/NE CT POSSIBLE DURING
THE LATE AFTERNOON/EARLY EVENING. EXPECT THE SHORT WAVE TO SHIFT E
AND WEAKEN SO PRECIP SHOULD ALSO WEAKEN OVERNIGHT.

HIGHS WILL GENERALLY BE IN THE 80S. IT WILL BE COOLER WELL INLAND
LATE SAT NIGHT WITH LOWS AROUND 60...RANGING TO AROUND 70 ALONG THE
S COAST...CAPE COD AND THE ISLANDS.

SUNDAY...WEAK SURFACE RIDGE BUILDS ACROSS SO EXPECT A MAINLY DRY
DAY. H85 TEMPS WILL BE FROM +15C TO +16C...WHICH WILL TRANSLATE TO
THE 80S FOR MOST AREAS...A BIT COOLER ALONG THE S COAST WITH THE S-
SW WINDS IN PLACE.

MONDAY...SOUTHWEST WIND FLOW REMAINS IN PLACE. MODELS SIGNALING A
POSSIBLE PRE FRONTAL TROUGH APPROACHING LATE MON OR MON NIGHT
/TIMING IN QUESTION/. MAY SEE WIDELY SCT SHOWERS/ISOLD TSTMS ACROSS
CENTRAL AND WESTERN AREAS...WITH THE BEST CHANCE ACROSS W MA AND W
HARTFORD COUNTY. WITH THE MILDER S-SW FLOW IN PLACE...EXPECT HIGHS
MAINLY IN THE 80S.

TUESDAY...W-SW FLOW ALOFT AS QUEBEC VORTEX BROADENS. ANOTHER SHORT
WAVE AND ASSOCIATED COLD FRONT LOOKS TO APPROACH LATE TUE INTO TUE
EVENING. GFS MOST AGGRESSIVE IN DIGGING H5 TROUGH TO THE W WHICH
WILL KEEP WARM AND HUMID AIR IN PLACE. HAVE CARRIED CHANCE POPS
ACROSS THE REGION...THEN SHOULD PUSH OFFSHORE TUE NIGHT.

WEDNESDAY-THURSDAY...A LOT OF QUESTIONS AS TO WHETHER FRONT WILL
STALL S OF NEW ENGLAND DURING THIS TIMEFRAME AND IF WAVES WILL MOVE
ALONG THIS FRONT. FOR NOW...HAVE CHANCE POPS MOVING ACROSS WED
NIGHT/THU...BUT TIMING IS STILL VERY MUCH IN QUESTION. LOW
CONFIDENCE DURING THIS TIMEFRAME DUE TO TIMING DIFFERENCES.

&&

.AVIATION /06Z 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.

THRU 12Z...MAINLY VFR WITH PATCHY MVFR AND IFR OVER CAPE COD AND
ISLANDS INCLUDING INTERIOR VALLEYS IN AREAS OF FOG.

AFTER 12Z...RAPID IMPROVEMENT WITH ALL TERMINALS VFR. DRY WEATHER
PREVAILS.

TONIGHT...VFR WITH LOW RISK OF A FEW SHOWERS AND MVFR CONDITIONS
ACROSS WESTERN MA TOWARD DAYBREAK.

SATURDAY...VFR BUT SCATTERED SHOWERS AND POSSIBLE ISOLATED T-STORM
IN THE AFTERNOON.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF. NO SEABREEZE TODAY WITH
MODEST WNW WINDS. SOME UNCERTAINTY ON AREAL COVERAGE OF SHOWERS
SATURDAY.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF. SOME UNCERTAINTY ON AREAL
COVERAGE OF SHOWERS SATURDAY.

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

EXPECT GENERALLY VFR MOST OF THE TIME. LOW CHANCE OF SCT SHOWERS/
ISOLD THUNDERSTORMS SAT NIGHT AND AGAIN MON- TUE. BRIEF LOCAL
MVFR IN ANY PRECIP.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

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

SCA REMAINS POSTED FOR 20-30 KT GUSTS THIS AFTERNOON NEAR SHORE
AS GRADIENT TIGHTENS AHEAD OF COLD FRONT. IN ADDITION...LONG
SOUTHWEST FETCH WILL ALLOW FOR SEAS TO BUILD TO BETWEEN 3 TO 5
FEET ACROSS MOST OPEN WATERS. WINDS DIMINISH THIS EVENING...BUT
KEEPING SCA THROUGH TONIGHT FOR THE OUTER WATERS DUE TO LEFTOVER
SWELL.

HIGH PRESSURE WILL BUILD OVER REGION FRI AND FRI NIGHT WITH LIGHT
WINDS AND DIMINISHING SEAS.

OUTLOOK /SATURDAY THROUGH TUESDAY/...

SATURDAY-SUNDAY...SW WINDS MAY GUST UP TO 20 KT SAT/SAT NIGHT THEN
DIMINISH. WITH LONG S-SW FETCH...SEAS FORECAST UP TO 5 FT MAINLY ON
THE SOUTHERN OUTER WATERS.

MONDAY-TUESDAY...CONTINUED SW WINDS IN PLACE...WHICH MAY GUST TO 20
KT AT TIMES. SEAS UP TO 5-7 FT ON THE SOUTHERN OUTER WATERS. MAY SEE
SCT SHOWERS/THUNDERSTORMS MON NIGHT/TUE.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ250-
     254>256.

&&

$$
SYNOPSIS...EVT/JWD
NEAR TERM...NOCERA
SHORT TERM...JWD
LONG TERM...EVT
AVIATION...NOCERA/EVT
MARINE...EVT/JWD


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.