Area Forecast Discussion
Issued by NWS Boston, MA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 012301
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
701 PM EDT MON JUN 1 2015

.SYNOPSIS...
STALLED FRONT SOUTH OF THE REGION WILL KEEP UNSEASONABLY COOL AND
DAMP CONDITIONS THROUGH TUESDAY ACROSS SOUTHERN NEW ENGLAND.
EXPECT PERIODS OF RAIN...HEAVY AT TIMES TO MOVE ACROSS THE AREA
TONIGHT AND TUESDAY. HIGH PRESSURE RETURNS WITH DRIER WEATHER
WEDNESDAY AND THURSDAY. SHOWERS ARE POSSIBLE FRIDAY INTO
SATURDAY...AS ANOTHER COLD FRONT MOVES THROUGH THEN HIGH PRESSURE
FOLLOWS FOR SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
7 PM UPDATE...
BAND OF MODERATE RAIN LIFTING N ACROSS CT/RI AND INTO MA.
FRONTOGENESIS ALONG THE LOW LEVEL BOUNDARY CONTRIBUTING TO THE
RAINFALL ALONG WITH MODEST 850 MB SW JET OVERRUNNING COOL MOIST
LOW LEVEL NE INFLOW. MODELS SLOWLY LIFT AREA OF BEST FORCING TO
THE NORTH TONIGHT. HI-RES GUIDANCE SUPPORTS CURRENT TRENDS
FOCUSING HEAVY RAINFALL ALONG AND NW OF I95 CORRIDOR TONIGHT.
CONVECTION ALONG MID ATLC COAST EXPECTED TO WEAKEN AS IT LIFTS N
INTO STABLE AIRMASS. CURRENT FORECAST ON TRACK. UPDATED NEAR TERM
POPS FOR CURRENT RADAR TRENDS.

PREVIOUS DISCUSSION...

*** PERIODS OF HEAVY RAIN LIKELY TONIGHT INTO TUESDAY ***

COOL SEASON PRECIP EVENT UNDERWAY WITH COOL AIR DAMMING SETUP AS
1030+ MB ANTICYCLONE SETTLES OVER SOUTHEAST QUEBEC AND NEW
BRUNSWICK...MAINTAINING SHALLOW COOL AIRMASS INTO SOUTHERN NEW
ENGLAND. THIS HAS RESULTED IN A SHARP BAROCLINIC ZONE AT 925 MB AND
850 MB OVER THE REGION. MEANWHILE DEEP LAYER MID LEVEL TROUGH WEST
OF NEW ENGLAND CONTINUES TO STREAM SUBTROPICAL AIRMASS UP AND OVER
THIS BOUNDARY WITH PWATS UP TO 1.5 INCHES ENTERING CT AND RI EARLY
THIS EVENING. THESE VALUES ARE AROUND +2 STANDARD DEVIATIONS ABOVE
CLIMO. HENCE DEEP LAYER MOISTURE AVAILABLE FOR HEAVY DOWNPOURS.

AS FRONTAL WAVE TRACKS SOUTH OF NEW ENGLAND TONIGHT LOW TO MID LEVEL
FGEN BECOMES ENHANCED ACROSS CT/RI AND MA THIS EVENING AND
OVERNIGHT. THUS PERIODS OF HEAVY RAINFALL. SOME INSTABILITY
ALOFT...PERHAPS NOT SUFFICIENT FOR THUNDER BUT SUFFICE TO ENHANCE
RAINFALL RATES. BEST CHANCE OF EMBEDDED THUNDER WILL BE ACROSS CT/RI
AND SOUTH OF THE MASS PIKE.

AS FOR TIMING...AREAS OF DRIZZLE AND SCATTERED SHOWERS EARLY THIS
EVENING BECOME MORE WIDESPREAD LATER THIS EVENING AND ESPECIALLY
OVERNIGHT.

TEMPS...NOT MUCH CHANGE GIVEN COOL ONSHORE FLOW. GOOD CHANCE WE
BREAK THE RECORD FOR COLDEST HIGH TEMPS. DON`T SEE MUCH IF ANY TEMP
INCREASE BETWEEN NOW AND MIDNIGHT. SEE CLIMATE SECTION BELOW FOR MORE
DETAILS.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
*** HEAVY RAIN AND FLOOD THREAT CONTINUES INTO TUE ***

BAROCLINIC WAVE TRAVERSES SOUTH OF NEW ENGLAND WITH MODEST LOW TO
MID LEVEL FGEN SAGGING SOUTHWARD INTO CT/RI AND SOUTHEAST MA IN THE
MORNING. FORCING FOR ASCENT BECOMES ENHANCED AS ANOMALOUS RRQ OF
UPPER LEVEL JET STREAK DESCENDS SOUTHWARD FROM THE ST. LWRNC RVR
VLY. THIS WILL YIELD PERIODS OF HEAVY RAINFALL ESPECIALLY OVER CT/RI
ALONG AND SOUTH OF THE MASS PIKE.

GOOD AGREEMENT AMONG ALL GUID SOURCES WITH BOTH THE HI RES
ARW...NMM...4KM NAM AND EVEN THE GLOBAL EC AND GFS HAVING THE AXIS
OF HEAVIEST RAINFALL ACROSS CT EXTENDING NORTHEAST INTO RI AND
CENTRAL-EASTERN MA. MODELS ALSO IN GOOD AGREEMENT ON MAGNITUDE OF
QPF RANGING FROM 1.5 TO 2.5 INCHES WITH ISOLATED 3+ AMOUNTS POSSIBLE
IN THE AREA MENTIONED ABOVE. THESE AMOUNTS COMBINED WITH HEAVY RAINS
FROM YESTERDAY/LAST NIGHT WILL INCREASE THE RISK FOR ADDITIONAL
FLOODING TONIGHT INTO TUE. THUS HAVE EXPANDED THE FLOOD WATCH.

MID LEVEL TROUGH IS SOMEWHAT PROGRESSIVE SO EXPECTING BACK EDGE OF
RAIN AND CLOUD SHIELD TO MOVE NW TO SE TOMORROW WITH SOME PARTIAL
CLEARING FOR MOST OF THE AREA LATE IN THE DAY AND ESPECIALLY TOWARD
SUNSET. THE EXCEPTION WILL BE OVER SOUTHEAST MA WHERE ANY CLEARING
WILL LIKELY HOLD OFF UNTIL TUE EVENING.

UNSEASONABLY COOL TEMPS CONTINUE WITH STIFF NE WINDS OFF THE CHILLY
OCEAN WATERS ALONG WITH OVERCAST CONDITIONS AND RAIN.

TUE NIGHT...

IMPROVING/DRYING CONDITIONS FROM NW TO SE. CHILLY CONDITIONS
CONTINUE.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
HIGHLIGHTS...

* MAINLY DRY WITH BELOW NORMAL TEMPS WED AND THU
* A FEW SHOWERS POSSIBLE FRI INTO SAT AS A COLD FRONT APPROACHES
* DRY AND SEASONABLE SUN THEN THREAT OF SHOWERS RETURNS MON

OVERVIEW...
MODELS IN GOOD AGREEMENT ON OVERALL PATTERN INTO THE WEEKEND. CLOSED
LOW WILL MEANDER OVER THE SOUTHERN APPALACHIANS THROUGH THU BEFORE
WEAKENING AND MOVING TO THE MID ATLC COAST. DOWNSTREAM RIDGING TO
THE NE OVER THE WESTERN ATLC WILL PROVIDE A FEW DRY DAYS...THEN THE
RIDGE WILL BREAK DOWN BY FRI INTO THE WEEKEND AS NORTHERN STREAM
ENERGY APPROACHES FROM THE NW WITH POLAR JET SHIFTING S. NORTHERN
STREAM TROF DELIVERS A COLD FRONT FRI NIGHT INTO SAT WITH SOME
SHOWERS POSSIBLE. NEXT TROF AMPLIFIES ACROSS GT LAKES BY EARLY NEXT
WEEK WITH DEEPER MOISTURE MOVING BACK IN FROM THE SW.

WEDNESDAY AND THURSDAY...
HIGH PRESSURE BUILDS S ACROSS SNE BRINGING DRY WEATHER BUT BELOW
NORMAL TEMPS UNDER LOW LEVEL EASTERLY FLOW.  COOLEST TEMPS IN E MA
AND WARMEST IN CT VALLEY. MOSTLY SUNNY SKIES EXPECTED WED...BUT
CLOUDS WILL BE INCREASING THU AS THE HIGH SHIFTS TO THE E AND
MOISTURE TO THE SW TRIES TO MOVE BACK IN. THERE IS A LOW PROB OF A
FEW SHOWERS ACROSS W NEW ENG BUT RIDGING SHOULD KEEP THIS TO THE
WEST.

FRIDAY...
HIGH MOVES OFFSHORE AS COLD FRONT APPROACHES N NEW ENG. MODELS SHOW
CONSIDERABLE LOW LEVEL MOISTURE DEVELOPING IN LOW LEVEL SOUTHERLY
FLOW SO MOCLDY SKIES EXPECTED AND CANT RULE OUT A FEW
SHOWERS...BUT MAIN FOCUS WILL BE TO THE N CLOSER TO THE FRONT.

FRIDAY NIGHT INTO SATURDAY...
COLD FRONT MOVES S ACROSS WHICH MAY BRING A PERIOD OF SHOWERS FRI
NIGHT...POSSIBLY LINGERING INTO SAT DEPENDING ON TIMING OF THE
FRONT. GFS IS QUICKER MOVING FRONT OFFSHORE AND HAS A MAINLY DRY DAY
SAT...WHILE SLOWER ECMWF HAS SHOWERS LINGERING SAT ESPECIALLY
SOUTHERN AREAS.

SUNDAY INTO MONDAY...
MAINLY DRY SUNDAY AS HIGH PRES RETURNS...THEN MODEL CONSENSUS FAVORS
MOISTURE AND THE THREAT OF SHOWERS RETURNING MONDAY. GFS SHOWING
TROPICAL SYSTEM MOVING N ACROSS W ATLC BUT CONFIDENCE IN THIS
SOLUTION IS QUITE LOW.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...

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

TONIGHT...MORE OF THE SAME IFR/LIFR WITH RAIN BECOMING STEADY AND
HEAVY AT TIMES. NE WINDS CONTINUE. LOW RISK OF ISOLATED THUNDER
MAINLY CT/RI AND MUCH OF MA EXPECT NORTHWEST SECTIONS.

TUESDAY...IFR/LIFR IN PERIODS OF HEAVY RAIN WITH LOW RISK OF
EMBEDDED THUNDER CT/RI AND SOUTH OF THE MASS PIKE. IMPROVING
CONDITIONS IN THE AFTERNOON FROM NW TO SE BUT NOT REACHING
SOUTHEAST MA UNTIL SUNSET OR SO.

TUE NIGHT...FURTHER IMPROVEMENT CONTINUES WITH RAIN EXITING CAPE
COD AND ISLANDS EARLY IN THE EVENING. MODEST NNE WIND. IFR
TRENDING TOWARD MVFR AND VFR TOWARD MORNING.

KBOS TERMINAL...HIGH CONFIDENCE IN CIGS AND VSBYS BUT LOWER IN
TIMING OF RAIN. GUSTY NE WINDS. SHOWERS BECOME HEAVY WITH A LOW
PROB OF ISOLATED THUNDER TONIGHT INTO TUE MORNING.

KBDL TERMINAL...HIGH CONFIDENCE IN CIGS AND VSBYS BUT LOWER IN
TIMING OF RAIN. GUSTY NE WINDS. SHOWERS BECOME HEAVY WITH A LOW
PROB OF ISOLATED THUNDER TONIGHT INTO TUE MORNING.

OUTLOOK...WEDNESDAY THROUGH SATURDAY...

WEDNESDAY...HIGH CONFIDENCE. AREAS OF MVFR/IFR STRATUS IN THE
MORNING...OTHERWISE VFR. SEABREEZES LIKELY.

THURSDAY...HIGH CONFIDENCE. VFR CIGS. SEABREEZES LIKELY.

FRIDAY...MODERATE CONFIDENCE. VFR/MVFR CIGS. LOW PROB OF A FEW
SHOWERS.

SATURDAY...LOW CONFIDENCE. CIGS AND WEATHER DEPEND ON TIMING OF A
COLD FRONT WHICH IS UNCERTAIN. AREAS OF MVFR AND SHOWERS MAY LINGER
INTO SAT IF FRONT IS SLOWER. VFR IF FRONT MOVES THROUGH QUICKER.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TUESDAY NIGHT/...MODERATE TO HIGH CONFIDENCE.

TONIGHT AND TUE...NE WINDS CONTINUE 15-20 KT WITH GUSTS UP TO 25 KT
AS WEAK WAVES OF LOW PRES TRACK SOUTH OF NEW ENGLAND. PERIOD OF
RAIN...HEAVY AT TIMES POSSIBLE. LOW RISK OF ISOLATED THUNDER.

TUE NIGHT...DRYING TREND AS HIGH PRES BUILDS INTO NEW ENGLAND. WINDS
DIMINISH AND BECOME MORE NORTHERLY.

OUTLOOK...WEDNESDAY THROUGH SATURDAY...

WEDNESDAY AND THURSDAY...HIGH CONFIDENCE. MAINLY EASTERLY WINDS
UNDER 20 KT.

FRIDAY...HIGH CONFIDENCE. WINDS BECOMING S WITH SPEEDS LESS THAN 15
KT.

SATURDAY...MODERATE CONFIDENCE. WINDS BECOMING NORTHERLY BEHIND A
COLD FRONT WITH SPEEDS BELOW SCA.

&&

.CLIMATE...
HIGH TEMPERATURES TODAY RUNNING ABOUT 20-25 DEGS BELOW NORMAL!
NORMAL HIGH TODAY IS 70-75. BELOW ARE THE RECORDS FOR THE COLDEST
HIGHS ON THIS DATE.

BOS...53...1992
PVD...56...1984
BDL...57...1992
ORH...52...2004

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...FLASH FLOOD WATCH THROUGH TUESDAY EVENING FOR CTZ002>004.
MA...FLASH FLOOD WATCH THROUGH TUESDAY EVENING FOR MAZ003>007-
     010>021-026.
RI...FLASH FLOOD WATCH THROUGH TUESDAY EVENING FOR RIZ001>007.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR ANZ230>235-237-
     250-251-254>256.

&&

$$
SYNOPSIS...KJC/NOCERA
NEAR TERM...KJC/NOCERA
SHORT TERM...NOCERA
LONG TERM...KJC
AVIATION...KJC/NOCERA
MARINE...KJC/NOCERA
CLIMATE...



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