Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 011953 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 353 PM EDT FRI AUG 1 2014 .SYNOPSIS... SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON. LOW PRESSURE MOVING ALONG A STALLED FRONT WILL LIKELY BRING A PERIOD OF STEADY RAIN TO AT LEAST SOUTHEAST NEW ENGLAND ON SATURDAY AND SUNDAY. UNSETTLED WEATHER REMAINS WITH US MUCH OF THE WEEK AS A COUPLE OF COLD FRONTS MOVE THROUGH. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 130 PM UPDATE...SCATTERED SHOWERS AND ISOLATED TSTMS HAVE DEVELOPED ACROSS THE INTERIOR MORE OR LESS ALONG THE PATTERN ADVERTIZED BY THE HRRR. SUFFICIENT INSTABILITY AND WEAK SHORT WAVE TROF SEEN IN WATER VAPOR IMAGERY HELPING TO SET OFF THE SCATTERED CONVECTION. WIND SHEAR IS RELATIVELY LOW AND SO NOT TOO LIKELY TO SEE SEVERE...ALTHOUGH WILL NEED TO BE ON THE LOOKOUT FOR THE RISK OF A HIGHLY LOCALIZED PULSE STORM. AREA OF GREATEST INSTABILITY THIS AFTERNOON ANTICIPATED TO BE BOUNDED BY AREA ALONG AND TO RIGHT OF LWM-BED-IJD-HFD-BAF-ORE-AFN-MHT LINE. BRIEF HEAVY DOWNPOURS POSSIBLE WITH SOME STORMS. WITNESSED DUAL POL RAFL RATE UP TO 1.5 INCHES/HOUR WITH STORM THAT PASSED ACROSS HOLYOKE. TEMPS STILL LOOK ON TRACK FROM MID MORNING UPDATE EXCEPT WHERE LOCAL COOLING IN VICINITY OF CONVECTION. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... ***A PERIOD OF STEADY RAIN APPEARS LIKELY ON SATURDAY FOR AT LEAST THE SOUTHEAST NEW ENGLAND*** TONIGHT... ANY LEFT OVER SHOWERS/ISOLATED THUNDERSTORMS SHOULD DIMINISH EARLY THIS EVENING WITH THE LOSS OF DAYTIME HEATING. OTHERWISE...EXPECT MUCH OF THE NIGHT TO BE DRY WITH MORE PATCHY FOG DEVELOPING LATE IN THE TYPICALLY PRONE LOCATIONS. A WAVE OF LOW PRESSURE WORKING UP ALONG A STALLED BOUNDARY TO OUR EAST MAY ALLOW RAIN TO OVERSPREAD SOUTHERN SECTIONS TOWARDS DAYBREAK SATURDAY. SATURDAY... A WAVE OF LOW PRESSURE AND ITS ASSOCIATED TROPICAL MOISTURE WILL WORK NORTHWARD ALONG A STALLED BOUNDARY TO OUR EAST. GIVEN WEAK BAROCLINICITY THIS TIME OF YEAR...THE MODELS OFTEN STRUGGLE WITH THE PLACEMENT/TIMING OF PRECIPITATION SHIELDS. THIS CASE IS NO EXCEPTION...AS THE MODELS HAVE BEEN ALL OVER THE PLACE IN THE LAST 48 HOURS. WE DO THINK THAT AT LEAST SOUTHEAST SECTIONS WILL SEE A PERIOD OF STEADY RAIN WITH SOME SCATTERED SHOWERS FURTHER BACK INTO THE INTERIOR. PWATS WILL APPROACH 2 INCHES IN OUR SOUTHEAST SECTIONS...SO SOME LOCALLY HEAVY RAINFALL IS POSSIBLE ALONG PORTIONS OF THE SOUTHEAST NEW ENGLAND COAST. INSTABILITY IS VERY LIMITED...SO DID NOT INCLUDE ANY THUNDER IN THE FORECAST. ALL IN ALL...WE HAVE LOW CONFIDENCE IN THE LOCATION/TIMING OF THE RAIN SHIELD ON SATURDAY. HOWEVER...WE DO THINK AT LEAST THE SOUTHEAST NEW ENGLAND COAST WILL SEE A PERIOD OF STEADY RAIN WHICH MAY BE HEAVY FOR A TIME. && .LONG TERM /SUNDAY THROUGH FRIDAY/... BIG PICTURE... UPPER TROUGH OVER THE EAST WITH UPPER RIDGE OVER THE WESTERN USA. ONE SHORTWAVE EJECTS FROM THE EASTERN TROUGH SUNDAY WHILE ANOTHER SHORTWAVE DROPS IN FROM CANADA. THE TROUGH THEN MIGRATES EAST THROUGH NEW ENGLAND WEDNESDAY THROUGH FRIDAY. THIS IS AN UNSETTLED PATTERN...BUT WITH NEAR SEASONABLE TEMPERATURES. THE DAILIES... SUNDAY... COLD FRONT REMAINS STALLED OFF THE SOUTH COAST. MEANWHILE THE UPPER SOUTHWEST JET REMAINS TO OUR WEST WITH SOUTHERN NEW ENGLAND UNDER THE RIGHT ENTRANCE REGION. THIS WILL SUPPORT UPPER VENTING OVER THE LOW LEVEL CONVERGENCE ALONG THE FRONT...RESULTING IN ONE OR MORE WAVES MOVING ALONG THE FRONT AND PRODUCING AREAS OF ISENTROPIC LIFT THAT MOVE UP ACROSS PARTS OF SOUTHERN NEW ENGLAND. THE MOST LIKELY LOCATION FOR LIFT AND RESULTING PRECIP WOULD BE ACROSS RI AND SOUTHEAST MASS. PRECIPITABLE WATER VALUES OF 1.5 TO 1.75 INCHES WITH 2 INCH VALUES JUST SOUTH OF THE COAST...SO POTENTIAL FOR A FEW HEAVY DOWNPOURS. WITH AN ILL-DEFINED SURFACE PATTERN AND THE UPPER JET RIGHT ENTRANCE REGION ALSO OVERHEAD...WITH COOLING TEMPS ALOFT AS THE UPPER SHORTWAVE EJECTS...AND WITH MID LEVEL LAPSE RATES AROUND 6C/KM AND TOTALS AROUND 48 TO OUR NORTHWEST...THERE IS ALSO POTENTIAL FOR AFTERNOON/EVENING TSTMS TO DEVELOP OVER NY AND VT. THESE COULD THEN MOVE INTO OUR WESTERN AND NORTHERN AREAS...BUT THE LESS FAVORABLE ENVIRONMENT HERE SHOULD CAUSE THAT CONVECTION TO DIMINISH. MODEL QPF FIELDS ALSO INDICATE MEASUREABLE PCPN MOSTLY OUTSIDE OF OUR AREA BUT POTENTIALLY CLIPPING OUR NORTHWEST. TEMPS ALOFT AROUND 11C WOULD SUPPORT MAX SURFACE TEMPS AROUND 80F. CLOUDS IN THE EAST SHOULD KEEP TEMPS COOLER...WHILE INTERIOR SECTIONS MAY SEE ENOUGH SUN TO REALIZE THE WARMER MAX TEMPS. MONDAY-TUESDAY... INSTABILITY LINGERS NORTH AND WEST...AND ACROSS OUR NORTHERN/WESTERN ZONES. ON TUESDAY...A COLD FRONT APPROACHES FROM THE NORTHWEST. THIS SHOULD BE ENOUGH TO GENERATE AFTERNOON/EVENING TSTMS EACH DAY. WEDNESDAY THROUGH FRIDAY... THE COLD FRONT MOVES THROUGH NEW ENGLAND ON WEDNESDAY ALONG WITH THE COLDER TEMPS ALOFT. THIS SHOULD BRING A CHANCE OF SHOWERS/TSTMS. LINGERING INSTABILITY THURSDAY WITH THE UPPER TROUGH STILL IN THE NEIGHBORHOOD...BUT A DRIER AIRMASS. WILL INDICATE SLIGHT CHANCE POPS MOST PLACES AND CHANCE POPS MERRIMACK VALLEY. HIGH PRESSURE BUILDS IN PLACE FRIDAY WITH DRIER WEATHER. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THIS AFTERNOON THROUGH SATURDAY... THIS AFTERNOON...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS EXCEPT BRIEFLY LOWER IN VICINITY OF SCATTERED SHOWERS/TSTMS. SEA BREEZES ALONG THE COAST. TONIGHT...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS EXCEPT PATCHY FOG IN THE TYPICALLY PRONE LOCATIONS LATE. SATURDAY...MODERATE CONFIDENCE. EXPECT A PERIOD OF FAIRLY STEADY RAIN ACROSS SOUTHERN AND EASTERN SECTIONS OF THE REGION WITH WIDESPREAD MVFR CIGS AND VSBYS. GENERALLY VFR ACROSS THE NW HALF OF THE AREA. KBOS TAF...HIGH CONFIDENCE IN VFR CONDITIONS THIS AFTERNOON AND TONIGHT. MOST TSTM ACTIVITY SHOULD OCCUR NW OF THE AIRFIELD BUT A LOW PROBABILITY EXISTS OF ONE MOVING ACROSS THE AIR FIELD. EAST SOUTHEAST SEA BREEZE SHOULD PERSIST THROUGH THE AFTERNOON AND THEN SHIFT TO BE FROM SW AFTER ABOUT 00Z. NW EDGE OF RAIN SHIELD MAY BE CLOSE TO BOS LATE SAT MORNING AND AFTERNOON. KBDL TAF...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS THIS AFTERNOON EXCEPT POSSIBLY BRIEFLY LOWER IN VICINITY OF ANY TSTMS. VFR CONDITIONS EXPECTED TONIGHT EXCEPT THERE COULD BE A FEW HOURS OF MVFR VSBYS IN FOG...ESPECIALLY IF THE IMMEDIATE AREA IS AFFECTED BY ANY SHOWERS/TSTMS THIS AFTERNOON. VFR CONDITIONS EXPECTED AT OUTSET SAT BUT RAIN SHIELD MAY COME JUST FAR ENOUGH NORTH FOR MVFR CIGS AND VSBYS. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY...MVFR CIGS/VSBYS SOUTHEAST WITH IFR ALONG THE SOUTH COAST AND ISLANDS. MAINLY VFR NORTHWEST WITH WIDELY SCATTERED MVFR IN AFTERNOON TSTMS. MONDAY-TUESDAY-WEDNESDAY...MAINLY VFR. SCATTERED AFTERNOON/EVENING SHOWERS/TSTMS WITH BRIEF MVFR CIGS/VSBYS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...TODAY THROUGH SATURDAY... HIGH CONFIDENCE. UPPER LEVEL RIDGING EAST OF THE WATERS WILL KEEP WINDS/SEAS BELOW SCA ADVISORY THRESHOLDS THROUGH SATURDAY AFTERNOON. VISIBILITIES WILL GENERALLY BE GOOD...BUT SOME REDUCTIONS ARE POSSIBLE ON SATURDAY ACROSS THE SOUTHERN AND EASTERN WATERS IN RAIN. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY...FRONT REMAINS STALLED EITHER OVER OR JUST SOUTH OF THE COASTAL WATERS. AREAS OF POOR VISIBLITY IN RAIN AND FOG AS DISTURBANCES MOVE ALONG THE FRONT. LIGHT WINDS SHIFTING FROM NORTHEAST TO SOUTHEAST. WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT THRESHOLDS. MONDAY-TUESDAY-WEDNESDAY...LIGHT WINDS MONDAY BECOMING SOUTHWEST TUESDAY. AREAS OF POOR VISIBILITY IN FOG EACH MORNING. SCATTERED THUNDERSTORMS EACH DAY WITH HIGHEST CHANCE ALONG THE NORTH SHORE. WINDS AND SEAS REMAIN BELOW SMALL CRAFT THRESHOLDS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/FRANK NEAR TERM...FRANK/RLG/THOMPSON SHORT TERM...FRANK LONG TERM...WTB AVIATION...WTB/FRANK/THOMPSON MARINE...WTB/FRANK

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