Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 282021
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
421 PM EDT TUE JUL 28 2015

.SYNOPSIS...

ISOLATED TO SCATTERED THUNDERSTORMS WILL COME TO AN END THIS
EVENING. OTHERWISE...HOT AND HUMID CONDITIONS EXPECTED THROUGH
THURSDAY. A COLD FRONT MAY BRING SCATTERED THUNDERSTORMS LATE
THURSDAY AND THURSDAY NIGHT. WARM BUT DRIER AND LESS HUMID WEATHER
IS EXPECTED FRIDAY INTO NEXT WEEKEND.

&&

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

***A FEW STRONG TO SEVERE THUNDERSTORMS THROUGH EARLY EVENING MAINLY
  CENTRAL/SOUTHEAST MA INTO RHODE ISLAND AND PERHAPS FAR EASTERN
  CT***

ISOLATED TO SCATTERED THUNDERSTORMS HAVE DEVELOPED LATE THIS
AFTERNOON.  THIS IN RESPONSE TO DIURNAL HEATING RESULTING IN MLCAPES
OF 1500 TO 2000...SOME SEA BREEZE/OUTFLOW INTERSECTIONS AND A
SHORTWAVE PASSING EAST OF THE REGION.  WHILE ISOLATED THUNDERSTORMS
OCCURRED ACROSS OUR FAR WESTERN ZONES EARLIER...MAIN FOCUS FOR
ACTIVITY SHOULD BE IN CENTRAL AND SOUTHEAST MA...AS WELL AS RHODE
ISLAND AND PERHAPS INTO FAR EASTERN CT.  THIS FROM SEA BREEZE AND
OUTFLOW BOUNDARIES ALONG WITH TERRAIN INFLUENCES.  A FEW OF THESE
STORMS MAY BECOME STRONG TO SEVERE AND PRODUCE ISOLATED STRONG WIND
GUSTS AND HAIL THROUGH EARLY EVENING.  ACTIVITY SHOULD WIND DOWN BY
7 OR 8 PM OR SO THIS EVENING AS SHORTWAVE DEPARTS...HEIGHTS RISE AND
INSTABILITY DIMINISHES.

OTHERWISE...DRY WEATHER PREVAILS FOR THE REST OF TONIGHT.  WILL
LIKELY SEE PATCHY FOG DEVELOP ESPECIALLY IN AREAS THAT RECEIVED RAIN
THIS AFTERNOON AND EARLY EVENING.  LOW TEMPS WILL RANGE FROM THE
LOWER TO MIDDLE 60S IN THE OUTLYING LOCATIONS WITH UPPER 60S TO
LOWER 70S IN THE URBAN HEAT ISLANDS OF DOWNTOWN BOSTON AND
PROVIDENCE.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...

***HOT BUT DRY WEATHER ON WEDNESDAY***

UPPER LEVEL RIDING WILL BUILD ACROSS SOUTHERN NEW ENGLAND.  THIS
SHOULD RESULT IN PARTLY TO MOSTLY SUNNY SKIES...DESPITE SOME
DIURNAL CUMULUS CLOUDS.  850 MB TEMPS AROUND +18C WILL YIELD HIGHS
BETWEEN 90 AND 95 ACROSS MOST OF THE REGION.  WEAK PRESSURE GRADIENT
WILL RESULT IN TEMPS A BIT COOLER ALONG PORTIONS OF THE COAST.
WHILE THERE IS A LOW RISK OF A VERY ISOLATED
SHOWER/THUNDERSTORM...GIVEN UPPER LEVEL RIDGING OPTED FOR A DRY
FORECAST.  EVEN IF ONE WERE TO HAPPEN IT PROBABLY WOULD BE VERY
BRIEF AND COVER SUCH A SMALL AREA OF OUR REGION...NOT WORTH A
MENTION AT THIS POINT.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
350 AM UPDATE...

HIGHLIGHTS...

* VERY WARM AND HUMID THU
* SCATTERED STORMS POSSIBLE LATE THU/THU NIGHT
* DRIER/LESS HUMID FRI THRU MON BUT STILL WARM

WED NIGHT/THU/THU NIGHT...

GOOD MODEL AGREEMENT ON SHORT WAVE RIDGING OVER THE AREA WED NIGHT
INTO THU. THUS DRY WEATHER TO START THIS PERIOD HOWEVER THE RISK OF
SHOWERS/T-STORMS INCREASES LATE THU INTO THU NIGHT AS POTENT
NORTHERN STREAM TROUGH CURRENTLY EXITING THE NORTHERN ROCKIES INTO
THE HIGH PLAINS BEGINS TO APPROACH NEW ENGLAND FROM THE WEST.
APPEARS TIMING OF THE FRONT COMES THROUGH OVERNIGHT...WELL AFTER
PEAKING HEATING. THIS COMBINED WITH MARGINAL SHEAR KEEPS THE RISK
LOW FOR STRONG CONVECTION LATE THU INTO THU NIGHT. HOWEVER GOOD
SYNOPTIC SCALE LIFT WITH THIS TROUGH SUGGEST AT LEAST SHOWERS SHOULD
BE ABLE TO HOLD TOGETHER AND MOVE ACROSS THE AREA LATE THU AND THU
NIGHT. PWATS ABOVE NORMAL AND DEW PTS 65 TO 70 WILL INCREASE THE
RISK FOR HEAVY DOWNPOURS. ALTHOUGH STILL 2 DAYS AWAY WILL NEED TO
MONITOR LATER MODEL TRENDS.

OTHERWISE VERY WARM AND HUMID CONDITIONS THU AHEAD OF APPROACHING
COLD FRONT. A MODEL BLEND OFFERS HIGHS U80S TO L90S.

FRIDAY THROUGH MONDAY...

ANOMALOUS CLOSED LOW/VORTEX SETS UP OVER HUDSON/JAMES BAY THIS TIME
PERIOD. THIS RESULTS IN BELOW NORMAL HEIGHTS AND MEAN TROUGH OVER
THE GREAT LAKES INTO THE NORTHEAST. THIS WILL KEEP TEMPERATURES NEAR
NORMAL /HIGHS MU80S/ AND LOWS IN THE 60S ALONG WITH TOLERABLE
HUMIDITY AS DEW PTS AVERAGE IN THE 50S DURING THE DAYLIGHT HOURS.
HOWEVER WITH THE NORTHERN STREAM JET SUPPRESSED SOUTHWARD INTO THE
GREAT LAKES AND NORTHEAST THERE WILL BE THE RISK OF SCATTERED
DIURNAL SHOWERS/T-STORMS JUST ABOUT EVERY DAY. TOO DIFFICULT AT THIS
TIME RANGE TO TIME INDIVIDUAL SHORT WAVES. NOT A WASHOUT BUT THE
RISK OF CONVECTION FROM TIME TO TIME.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH WEDNESDAY AFTERNOON/...

LATE THIS AFTERNOON...MODERATE TO HIGH CONFIDENCE EXCEPT FOR SOME
LOW CLOUDS AND FOG PATCHES ON THE ISLANDS.  MAINLY VFR CONDITIONS
BUT HIT AND MISS SHOWERS/THUNDERSTORMS EXPECTED THROUGH EARLY
EVENING WILL RESULT IN LOCALIZED LOWER CONDITIONS.  ACTIVITY WILL BE
ISOLATED TO SCATTERED...SO MUCH OF THE REGION WILL REMAIN DRY.  BULK
OF ACTION SHOULD BE ACROSS CENTRAL/SOUTHEAST MA...RHODE ISLAND AND
PERHAPS FAR EASTERN CT.

TONIGHT...MODERATE CONFIDENCE. ANY ISOLATED TO SCATTERED CONVECTION
SHOULD COME TO AN END BY 7 OR 8 PM.  OTHERWISE...VFR FOR MOST SITES
EXCEPT FOR SOME PATCHY FOG IN THE TYPICALLY PRONE LOCATIONS.
ALSO...CANNOT RULE OUT IFR IN STRATUS AND FOG ACROSS FAR SE MASS
INCLUDING THE CAPE AND ISLANDS...BUT CONFIDENCE IN THAT IS LOW.

WEDNESDAY...HIGH CONFIDENCE IN VFR CONDITIONS.

KBOS TERMINAL...HIGH CONFIDENCE IN MAINLY VFR THROUGH TONIGHT.
CONVECTION WILL LIKELY REMAIN WEST OF THE BOSTON TERMINAL...BUT
STILL A LOW RISK THAT SOMETHING COULD DEVELOP THROUGH 8 PM

KBDL TERMINAL...HIGH CONFIDENCE IN MAINLY VFR THROUGH TONIGHT.  VERY
LOW RISK OF AN ISOLATED THROUGH 8 PM.

OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...

350 AM UPDATE...

WED NGT/THU...PATCHY MVFR/IFR IN FOG WED NGT BUT QUICKLY IMPROVING
TO VFR THU MORNING. LOW PROB THAT MVFR/IFR IN STRATUS LINGERS ALONG
THE SOUTH COAST THU. THEN UNCERTAINTY ON HOW QUICK THIS FOG/STRATUS
BURNS OFF SOUTH COAST.

THU NIGHT...VFR-MVFR IN SCATTERED SHOWERS/T-STORMS. SOME UNCERTAINTY
ON HOW WIDESPREAD PRECIP WILL BE.

FRI AND SAT...VFR LIKELY. HIGH FORECAST CONFIDENCE.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /TONIGHT THROUGH WEDNESDAY AFTERNOON/...HIGH CONFIDENCE.

WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS
THROUGH WEDNESDAY AFTERNOON.  MAIN CONCERN WILL BE A FEW STRONG TO
SEVERE  STORMS ACROSS THE ADJACENT SOUTH COASTAL WATERS THROUGH 7 OR
8 PM.  LOCALLY STRONG WIND GUSTS AND PERHAPS ISOLATED HAIL ARE THE
MAIN CONCERNS.  ALSO...SOME PATCHY FOG IS POSSIBLE THIS EVENING NEAR
THE ISLANDS BUT VISIBILITIES SHOULD IMPROVE AFTER MIDNIGHT AS WINDS
TURN WEST.

OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...

350 AM UPDATE...

WED NIGHT AND THU...FAIRLY TRANQUIL WIND AND SEAS. POSSIBLE PATCHY
FOG IN HUMID AIRMASS.

THU NIGHT...MODEST SSW WIND AHEAD OF APPROACHING COLD FRONT.
SCATTERED SHOWERS WITH EMBEDDED THUNDER POSSIBLE.

FRI AND SAT...COLD FRONT SLOWLY MOVES OFFSHORE. ANOTHER WEAK FRONT
MAY ENTER THE WATERS SAT. WSW WINDS EXPECTED.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...AIR QUALITY ALERT FROM 11 AM TO 11 PM EDT WEDNESDAY FOR
     MAZ017>024.
RI...AIR QUALITY ALERT FROM 11 AM TO 11 PM EDT WEDNESDAY FOR
     RIZ005>008.
MARINE...NONE.

&&

$$
SYNOPSIS...FRANK
NEAR TERM...FRANK
SHORT TERM...FRANK
LONG TERM...NOCERA
AVIATION...FRANK/NOCERA
MARINE...FRANK/NOCERA


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