Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 262324
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
724 PM EDT SUN JUL 26 2015

.SYNOPSIS...
A VERY WEAK BOUNDARY WILL STALL ACROSS THE AREA THROUGH
THURSDAY...WHICH WILL BRING A RISK FOR SHOWERS AND THUNDERSTORMS
EACH AFTERNOON. SOME STORMS MAY PRODUCE HEAVY RAIN...AND A FEW MAY
BECOME STRONG TO SEVERE. HOT AND HUMID TUESDAY THROUGH THURSDAY. A
COLD FRONT MAY BRING SCATTERED THUNDERSTORMS LATE THURSDAY AND
THURSDAY NIGHT. WARM AND DRY WEATHER IS EXPECTED FRIDAY INTO NEXT
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
7PM UPDATE...
WARM FRONT WHICH KICKED OFF SOME WARNABLE CONVECTION ACROSS NE MA
AND SRN NH CONTINUES TO SLIDE N...ALLOWING ANY REMNANT STORMS TO
DISSIPATE AND LIFT INTO NRN NEW ENGLAND. MEANWHILE OUT WEST...A
WEAK SFC TROF HAS SETTLED ACROSS THE REGION...STRETCHING FROM NRN
PA INTO SRN NEW ENGLAND. THIS HAS PROVIDED A FOCUS FOR SOME FAIRLY
ACTIVE CONVECTION WITHIN A REGIME OF 1500-2000J/KG MU CAPE...WITH
STEEP ENOUGH LAPSE RATES TO SUPPORT SEVERE HAIL. THE INSTABILITY
BECOMES MORE ELEVATED IN THE NEXT FEW HOURS AS NIGHT FALLS. THIS
SHOULD BEGIN TO LIMIT THE CONVECTION ALTHOUGH IT MAY NOT BE ZERO
SHOULD THE UPPER LVL INSTABILITY REMAINS TAPPED. LOWERED POPS A
BIT LATER ON TONIGHT...BUT NOT ENOUGH TO GO NIL EVERYWHERE.

PREVIOUS DISCUSSION...

AFTER 00Z...SCATTERED SHOWERS/ISOLATED T-STORMS INTO THE EVENING
HOURS BUT SHOULD DIMINISH TO MAINLY LIGHT SCATTERED SHOWERS
FOR THE OVERNIGHT PERIOD WITH A WEAK MID-LEVEL DISTURBANCE MOVING
INTO OUR AREA...AND WEAK LOW LEVEL CONVERGENCE OCCURRING
AS WELL. LOW LEVEL SOUTHERLY FLOW WILL CONTINUE TO BRING MOISTURE
INTO OUR AREA. THE BEST CHANCE FOR SHOWERS OVERNIGHT IS OVER THE
SOUTHERN HALF OF THE CWA...WHERE WILL GO WITH CHANCE POPS. NAM IS
SHOWING SOME ELEVATED INSTABILITY DURING THE
OVERNIGHT...SO ISOLATED THUNDER CAN NOT BE RULED OUT AT THIS TIME.

PARTLY TO MOSTLY CLOUDY SKIES OVERNIGHT...PATCHY DENSE FOG IS
POSSIBLE. LOWS IN THE 60S.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
MONDAY...

REMNANT BOUNDARY /PREVIOUS COLD FRONT WEAKENING/ DRIFTS INTO OUR
AREA FROM THE WEST ON MONDAY. LOW LEVEL SOUTHERLY FLOW WILL CONTINUE
TO KEEP MOISTURE INTO OUR AREA...WITH SURFACE DEWPOINTS IN THE MID
AND UPPER 60S...AND PWATS AROUND 1.5 INCHES. POTENTIAL FOR SURFACE-
BASED INSTABILITY TO INCREASE TO 1000-2000 J/KG FOR THE AFTERNOON.
THE INSTABILITY ACCOMPANIED BY THE REMNANT BOUNDARY WILL ALLOW
FOR SHOWER/THUNDERSTORM DEVELOPMENT. WILL WARRANT CHANCE POPS.
WITH THE MEAN WIND FLOW AROUND 10 MPH OUT OF THE W...THREATS
CONSIDERED ARE HEAVY RAIN / MARGINAL HAIL / PERHAPS STRONG TO
DAMAGING WINDS FROM PULSE-TYPE CONVECTION /WEAK SHEAR ENVIRONMENT/.

POTENTIAL LOCALIZED URBAN/POOR DRAINAGE FLOODING. WARM AND
HUMID WITH HIGHS MOSTLY IN THE 80S.

MONDAY NIGHT...ANY T-STORMS SHOULD SLOWLY DIMINISH IN THE
EVENING...WITH ONLY A SLIGHT CHANCE SHOWERS LATE EVENING AND ON
WITH THE NE-SW ORIENTED BOUNDARY LINGERING IN OUR AREA.
OTHERWISE...A PARTLY CLOUDY AND MUGGY NIGHT WITH PATCHY FOG.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
HIGHLIGHTS...

* VERY WARM WITH SCATTERED THUNDERSTORMS STILL POSSIBLE TUESDAY.
* HOT WEDNESDAY AND THURSDAY WITH HIGHS IN THE LOWER TO MID 90S.
* SCATTERED STORMS POSSIBLE LATE THURSDAY AND THURSDAY NIGHT.

OVERVIEW AND MODEL PREFERENCES...
AFTER A FINAL SHORTWAVE MOVES THROUGH THE REGION TUE...THE
REMAINDER OF THE MID TERM WILL BE DEFINED BY RIDGE BUILDING AND
WARM ADVECTION THEREIN. THE RIDGE/WARMING WILL LEAD TO A PERIOD OF
ABOVE NORMAL HEAT/HUMIDITY MAINLY WED AND THU. UPSTREAM...A CUTOFF
LOW PRES NEAR BAFFIN ISLAND IS EXPECTED TO PHASE WITH ROBUST
SHORTWAVE ENERGY CURRENTLY RESIDING OVER THE PAC NW. THE FIRST
EXPERIENCE OF THIS FEATURE WILL COME FRI...WITH THE PASSAGE OF A
WEAK COLD FRONT WHICH WILL RELIEVE THE AREA OF MUCH OF THE HEAT.
AS THE CUTOFF SETTLES OVER QUEBEC AND N NEW ENGLAND NEXT
WEEKEND...THE COMBINATION OF CYCLONIC CURVATURE ALOFT AND A
CONDUIT FOR SEVERAL SHORTWAVES SUGGEST A COOLER...AND POTENTIALLY
MORE UNSETTLED PERIOD.

DETAILS...

TUE...
WARMING AT MID/LOW LVLS BEGINS BUT WILL BE LIMITED BY THE PASSAGE
OF A WEAK SHORTWAVE DIVING S DOWNSTREAM OF AN AMPLIFYING TROF. A
NEARLY WASHED OUT FRONTAL BOUNDARY REMAINS DRAPED ACROSS THE ERN
HALF OF THE REGION. THE COMBINATION OF THESE FEATURES WITHIN AN
AIRMASS WHERE H85 INCREASE TO NEARLY +18C...H5 TEMPS DROP BRIEFLY
TO AROUND -10C...AND MODEST K-INDICES/PWATS SUGGEST SLOW MOVING
POP-UP SHOWERS AND THUNDERSHOWERS ARE POSSIBLE DURING THE
AFTERNOON/EVENING HOURS. AM NOTING A CORRIDOR OF 1000-1500J/KG SFC
CAPE ACROSS THE ERN THIRD OF THE REGION WHICH SUPPORTS THIS
THINKING. THEREFORE...WILL BE INCREASING POPS...MAINLY E OF A
IJD- ORH-AFN LINE DURING THE AFTERNOONS. THE CU FIELD GENERATED
WILL ALSO LIMIT WARMING...SO WHILE SOME LOCATIONS MAY MAKE THEIR
FIRST RUN AT 90F...SOME ARE LIKELY TO REMAIN JUST SHORT.

WED AND EARLY THU...
POSSIBLY ONE OF THE HOTTEST AND MORE UNCOMFORTABLE PERIODS AS H85
TEMPS INCREASE FROM AROUND +18C/H92 23C WED...TO H85 +21C/H92 26C
ON THU. THESE TEMPS SHOULD BE EASILY REALIZED AND MORE AS
OVERNIGHT MINS ARE LIKELY TO STALL IN THE MID-UPPER 60S AND EVEN
LOW 70S THANKS TO HIGHER DWPTS /MORE ON THIS LATER/.
THEREFORE...WITH DOWNSLOPING WESTERLY COMPONENT TO THE
WIND...SEVERAL LOCATIONS MAKE THEIR RUNS INTO THE LOW-MID 90S EACH
DAY. AS THETA-E RIDGE BUILDS WITHIN THE MASS-FIELD
RIDGING...GRADUAL INCREASE IN SFC DWPT IS EXPECTED FROM THE MID
60S WED...TO NEAR 70 ON THU. A LOCAL CLIMATE STUDY SUGGESTS THAT
THE LOW 60S ARE NEAR SEASONAL NORMALS FOR DWPTS IN SRN NEW ENGLAND
WHILE THE 70F MARK ABOUT 1 STD DEVIATION HIGHER THAN NORMAL.
CERTAINLY AN UNCOMFORTABLE PERIOD REGARDING HUMIDITY WITH 90+
AMBIENT TEMPERATURES. MAY NEED TO MONITOR FOR LOCALIZED HEAT
ADVISORIES ESPECIALLY THU WITH THE INCREASE IN DWPTS ALTHOUGH THE
RISK IS CERTAINLY NON-ZERO WED.

LATE THU INTO FRI...
COLD FRONTAL PASSAGE EXPECTED ALTHOUGH STILL SOME UNCERTAINTY ON
EXACT TIMING WHICH WILL PLAY A ROLE IN POTENTIAL CONVECTIVE
ACTIVITY. MODIFIED EML POSSIBLE AS MOST GUIDANCE FAVORS NEAR
6.5C/KM MID LVL LAPSE RATES. THE ISSUE IS H7 TEMPS NEAR +10C
SUGGEST CAPPING WHICH MAY LIMIT THE POTENTIAL FOR CONVECTION EVEN
WITH THE LOW LVL SOURCE OF LIFT. WILL CONTINUE WITH SLIGHT TO
CHANCE POPS DURING THE PERIOD OF THE EXPECTED FROPA BUT WITH TS
ONE CATEGORY BELOW THE OVERALL POP VALUE. STILL A PERIOD TO WATCH
AS ABOVE THE INVERSION...THANKS TO THE EML CAPE VALUES ARE PROGGED
TO BE QUITE HIGH.

THE WEEKEND...
WITH CUTOFF LOW PRES SETTLING JUST TO THE N...THE COMBINATION OF
COOLER MID LVL TEMPS AND CYCLONIC CURVATURE ARE LIKELY TO YIELD
BUILDING DIURNAL CU EACH DAY IN SPITE OF LOW LVL HIGH PRES RIDGE.
THE CURVED FLOW WILL ALSO ALLOW FOR WEAK SHORTWAVES TO MOVE
THROUGH WHICH IS DIFFICULT TO TIME AT 7 DAYS. H85 TEMPS DROP BACK
TO AN AVERAGE OF +16 SO ALTHOUGH STILL SUMMER-LIKE CONDITIONS WILL
BE MUCH MORE SEASONABLE THEN THE MID-WEEK PERIOD.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT-TERM /THROUGH MONDAY/...

TONIGHT...MODERATE CONFIDENCE.
ONGOING TSRA IN W MA/CT WILL GRADUALLY DIMINISH THROUGH ABOUT 03Z
AS IT SLOWLY MOVES E. MAIN IMPACTS WILL BE TO BAF/ORH/CEF DURING
THIS TIME WITH SOME IFR VSBYS IN HEAVY RAIN/LIGHTNING. AFTER THESE
DISSIPATE...SUSPECT MOST OF THE NIGHT REMAINS QUIET IN TERMS OF
PRECIP/TS...BUT AN ISOLATES SHOWER OR STORM CAN/T BE RULED OUT.
OTHERWISE...MIX OF VFR WITH SOME MVFR FOG POSSIBLE PARTICULARLY IN
WRN MA/CT TERMINALS.

MONDAY...MODERATE CONFIDENCE.
MAINLY VFR...EXCEPT SCATTERED MVFR/IFR CIGS/VSBYS IN SHRA/TSRA
DEVELOPING MAINLY FOR THE AFTERNOON. A FEW STORMS MAY PRODUCE
GUSTY WINDS AND LOCALLY HEAVY RAINFALL.

KBOS TERMINAL...MODERATE CONFIDENCE IN TAF.
MAINLY VFR...AS BULK OF TSRA/SHRA ACTIVITY STAYS W OF THE TERMINAL
THIS EVENING. LOW CHANCE FOR LATE NIGHT FOG/LOW CIGS WITH SOME
MVFR CONDITIONS.

KBDL TERMINAL...MODERATE CONFIDENCE IN TAF.
BULK OF THE THUNDERSTORM ACTIVITY STAYS TO THE NORTH THIS EVENING
BUT CAN/T RULE OUT A NEAR PASSAGE AND BRIEF TSRA CONDITIONS
THROUGH 03Z. OTHERWISE...VFR UNTIL EARLY MORNING...AT WHICH
POINT...MVFR CONDITIONS POSSIBLE WITH SOME FOG/LOW CIGS.

OUTLOOK /TUESDAY THROUGH FRIDAY/...

TUE AND WED...HIGH CONFIDENCE.
MAINLY VFR. ALTHOUGH THERE IS A THREAT FOR A FEW SHOWERS OR
THUNDERSTORMS MAINLY ACROSS E MA AND RI TUE AFTERNOON.
OTHERWISE...HOT.

THU...MODERATE CONFIDENCE.
EXACT TIMING IS UNCERTAIN...BUT A COLD FRONT COULD BRING ABOUT
SHOWERS AND THUNDERSTORMS LATE IN THE DAY ON THU AND THU EVENING.

FRI...MODERATE CONFIDENCE.
DEPENDING ON COLD FRONTAL TIMING...BUT A PERIOD OF DRY WEATHER IS
EXPECTED TO FOLLOW.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH MONDAY NIGHT/...HIGH CONFIDENCE.

TONIGHT...
EARLY EVENING CHANCES FOR SHOWERS/ISOLATED THUNDER DIMINISHING
THROUGH THE EVENING HOURS. S-WINDS CONTINUING WITH THE POTENTIAL
FOR GUSTS UP AROUND 20 KTS. SEAS BELOW 4-FEET.

MONDAY...
WET-WEATHER MAY HOLD MORE ACROSS THE INTERIOR THAN OVER THE WATERS
AS BREEZY S-WINDS CONTINUE WITH THE POTENTIAL FOR GUSTS UP 15 KTS.
SEAS REMAINING BELOW 4-FEET THE HIGHEST OF WHICH ARE ANTICIPATED
OVER THE E/NE-WATERS.

MON NIGHT...HIGH CONFIDENCE. WINDS AND SEAS BELOW SMALL CRAFT
ADVISORY THRESHOLDS. A SHOWER OR THUNDERSTORM IS POSSIBLE IN THE
EVENING WITH LOCALLY ROUGH CONDITIONS.

OUTLOOK /TUESDAY THROUGH FRIDAY/...

TUE AND WED...HIGH CONFIDENCE.
MAINLY QUIET BOATING WEATHER ALTHOUGH A BRIEF
SHOWER/THUNDERSHOWER MAY PRODUCE LOCALLY ROUGHER CONDITIONS ON
TUE.

THU...MODERATE CONFIDENCE.
A BUILDING SWELL TO THE S WILL MOVE UP THE COASTLINE ALONG WITH
SOME GUSTIER SW WINDS MAINLY AROUND 20 KT. THE SWELL HAS THE
CHANCE TO PEAK AT ABOUT 5 FT ON THE OUTER SRN WATERS ON THU...SO
SMALL CRAFT ADVISORIES MAY BE REQUIRED. OTHERWISE...ANOTHER LOW
RISK FOR THUNDERSTORMS LATE IN THE DAY ON THU.

FRI...MODERATE CONFIDENCE.
LOOKS LIKE AFTER THE SWELL RESIDES BOATING WX SHOULD ONCE AGAIN
BECOME QUIET.

&&

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

&&

$$
SYNOPSIS...DOODY/NMB
NEAR TERM...DOODY/NMB
SHORT TERM...NMB
LONG TERM...DOODY
AVIATION...DOODY/NMB
MARINE...DOODY/NMB



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