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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 041820 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 220 PM EDT SAT JUL 4 2015 .SYNOPSIS...
-- Changed Discussion --
LOW PRESSURE RACES SOUTH OF NEW ENGLAND THIS AFTERNOON AND EVENING BRINGING SCATTERED POCKETS OF LIGHT RAIN. HIGH PRESSURE RETURNS SUNDAY AND LINGERS THROUGH MONDAY. A TRANSITION PERIOD IS LIKELY MID NEXT WEEK...WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
THROUGH 8 PM...MAIN AREA OF CONCERN IS OVER WESTERN MASS/CONNECTICUT. RADAR SHOWS PATCHY YELLOWS AND ORANGES WHILE OBSERVATIONS SHOW VSBYS AROUND 10 MILES...EXCEPT 4-5 MILES IN THE BERKSHIRES. WITH CLOUD BASES 9-10 THOUSAND FEET...EXPECT MUCH OF THE RAIN ON RADAR IS EVAPORATING ON THE WAY DOWN. WE WILL CONTINUE WITH LIGHT SHOWERS THROUGH THE AFTERNOON IN OUR WESTERN AND CENTRAL AREAS...SCATTERED SPRINKLES IN THE EAST. EARLY AFTERNOON OBSERVED TEMPERATURES SHOW A RANGE OF 65 TO 75. UPPER 60S AND 70S SHOULD COVER THE AFTERNOON MAX TEMPS. TONIGHT... COASTAL LOW PRESSURE MOVES OUT TO SEA. UPPER SHORTWAVE SWINGS OVER NEW ENGLAND. RIGHT ENTRANCE REGION OF THE SUPPORTING UPPER JET WILL BE RIGHT OVER US AT 00Z/8 PM CREATING UPPER VENTING. IF SUFFICIENT MOISTURE LINGERS THEN WE MAY CONTINUE TO SEE WIDELY SCATTERED LIGHT SHOWERS/SPRINKLES FOR A COUPLE OF HOURS. BUT THE AMOUNT OF EVAPORATION IN PROGRESS SUGGESTS A FACTOR COUNTERACTING ANY LINGERING SHOWERS. WE WILL MAKE OUR FINAL CALL ON EVENING POPS BASED ON THE RADAR DISPLAY BETWEEN 3 AND 4 PM. BUT THE TREND ON THE FORECAST IS FOR DIMINISHING CHANCE OF SHOWERS. THE UNCERTAINTY IS WHETHER IT WILL BE STARTING AT 70 PERCENT OR 20 PERCENT OR 5 PERCENT. THE UPPER SHORTWAVE AXIS SWEEPS EAST OF OUR AREA BY MORNING...SO EXPECT A TREND TO CLEARING SKIES AFTER MIDNIGHT. DEW POINTS UPSTREAM ARE IN THE 50S...THIS SHOULD ALLOW MIN SFC TEMPS IN THE 50S AND LOWER 60S.
-- End Changed Discussion --
&& .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
HIGH PRESSURE FROM THE PLAINS BUILDS EAST OVER NEW ENGLAND SUNDAY. CROSS SECTIONS OF RH SHOW DRY AIR ABOVE 800 MB...AND A MOIST LAYER AT 800-850 MB. MIXING SHOULD REACH ABOVE 850 MB. THIS SUGGESTS SOME DIURNAL CUMULUS DEVELOPING SUNDAY AND DISSIPATING SUNDAY EVENING. TEMPERTURES AT THE TOP OF THE MIXED LAYER WOULD SUPPORT MAX SURFACE TEMPS OF 80-85. FAIR SKIES SUNDAY NIGHT WITH LIGHT WINDS AND RADIATIONAL COOLING. DEW POINTS RISE A LITTLE TO AROUND 60. EXPECT MIN SURFACE TEMPS IN THE UPPER 50S AND LOWER 60S. THIS MAY SUPPORT PATCHES OF FOG DEVELOPING LATE AT NIGHT...ESPECIALLY IN WESTERN MASS.
-- End Changed Discussion --
&& .LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
HIGHLIGHTS... * HIGH PRESSURE AND WARMING CONDITIONS INTO EARLY NEXT WEEK. * UNSETTLED CONDITIONS RETURN MID-LATE NEXT WEEK. OVERVIEW AND MODEL PREFERENCES...WITH 04.00Z MODEL GUIDANCE COMING IN...THERE IS BETTER AGREEMENT WITH THE MID AND LONG TERM THAN PREVIOUS RUNS...ALTHOUGH TYPICAL UNCERTAINTY REMAINS IN THE LONG TERM. STRONG RIDGING EARLY IN THE WEEK WILL GIVE WAY TO MAINLY ZONAL FLOW ON THE SW QUADRANT OF A STRONG NRN STREAM VORTEX DEVELOPING ACROSS N CENTRAL CANADA. THE FLATTENING WAVE WILL ARRIVE MID WEEK...WITH HIGH PWATS AND INSTABILITY IN TOW WHICH MAY NEED TO BE WATCHED. THERE ARE TIMING ISSUES...ESPECIALLY REGARDING THE INFLUENCE OF THE RIDGE OF HIGH PRES FOR TUE...BUT WITH BETTER AGREEMENT IN THIS ROUND OF GUIDANCE A BLEND OF OPERATIONAL MODELS WILL WORK WELL AS A BASELINE. DETAILS... MON INTO MON NIGHT...WARM RIDGING BUILDS ACROSS SRN NEW ENGLAND WITH HIGH PRES AT THE SFC. MAINLY DRY WX PREVAILS WITH MODERATING HIGHS/LOWS AS H85 TEMPS INCREASE TO BETWEEN +12C AND +14C BY LATE MON. THIS SUGGESTS HIGHS MAINLY IN 80S ACROSS THE REGION. TUE...UPPER LVL WAVE WILL BE APPROACHING FROM THE W. MODELS INDICATE INCREASING MOISTURE AS PWATS APPROACH 2 STD DEVIATIONS ABOVE NORMAL WITH K-VALUES OVER 30. A WARM FRONT WILL BE THE INITIAL SFC REFLECTION OF THIS WAVE. HOWEVER...SOUNDINGS SUPPORT THE POSSIBILITY OF HIGH PRES REMAINING IN CONTROL THROUGH MUCH OF TUE. THEREFORE...CHANCE FOR AFTERNOON SHRA/T-STORM WITH THE WARM FRONTAL APPROACH MAY BE QUITE LOW TO NEAR ZERO THE FURTHER E ONE GOES. IN FACT...THE BEST AXIS OF SFC CAPE/THETA-E RIDGE IS MAINLY W OF THE MA/NY BORDER. THEREFORE...CHANCE POPS W WILL BE LOWERED TO SLIGHT CHANCE TO NIL POPS FURTHER E. WILL INCLUDE THUNDER WITH THIS FORECAST GIVEN THE FAVORABLE PARAMETERS. WED...AS PREVIOUS FORECASTER NOTED...THIS IS WHERE THE MODEL SOLUTION DIVERGENCE BEGINS TO SHOW MORE SIGNIFICANTLY. MAINLY WITH THE TIMING OF A COLD FRONTAL PASSAGE. GFS REMAINS PROGRESSIVE WHILE ECMWF/CMC CONTINUES TO LINGER AS THE FRONT BEGINS TO PARALLEL THE ZONAL FLOW DEVELOPING ALOFT. WILL CONTINUE WITH THE CHANCE AND SLIGHT CHANCE POPS FROM THE THE PREVIOUS FORECAST SINCE THE CONVERGENT BOUNDARY REMAINS IN PLACE. SOUNDINGS DO SUPPORT SOME SFC BASED CAPE EXCEEDING 1000J/KG AND HIGH K-VALUES...SO WILL CONTINUE TO INCLUDE TS...BUT GIVEN THE LACKING SHEAR...REMAIN SOMEWHAT DUBIOUS OF SEVERE CHANCES AT THIS TIME. THU...THE UNCERTAINTY REMAINS AS THE COLD FRONT CONTINUES TO PUSH FURTHER SOUTHEAST...ALBEIT SLOWLY. WILL GRADUALLY REDUCE POPS FROM N-S DURING THE DAY...BUT WILL HAVE TO WAIT BEFORE WE CAN NAIL DOWN TIMING FOR THE LATE WEEK. FRI AND SAT...UNCERTAINTY REMAINS BUT WITH ZONAL FLOW...A SERIES OF RIDGE/TROUGH COUPLETS IS LIKELY TO YIELD PERIODS OF DRY/POTENTIALLY WET PERIODS ARE LIKELY. INTERESTINGLY...WITH SRN NEW ENGLAND ON THE RIDGE PERIPHERY MAY NEED TO MONITOR FOR MCS STEERING FLOW AS WELL. STILL WAY TOO MANY VARIABLES TO NAIL ANYTHING DOWN...BUT SEASONABLE TEMPS AND LOW TO NIL POPS SHOULD COVER THE SPREAD.
-- End Changed Discussion --
&& .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /THROUGH FRIDAY NIGHT/... THROUGH 8 PM...MODERATE TO HIGH CONFIDENCE. LARGE AREA OF RAIN ON RADAR BUT ONLY LIGHT AMOUNTS REACHING THE GROUND. EXPECT CONDITIONS TO REMAIN VFR THROUGH EVENING. THERE IS SOME POTENTIAL FOR MVFR CIGS/VSBYS BUT MAINLY IN NORTHWEST MASSACHUSETTS WHERE 1000-1500 FOOT CIGS AND 4-5 MILE VSBYS ARE POSSIBLE IN ANY HEAVIER SHOWERS. TONIGHT...HIGH CONFIDENCE. ANY LINGERING RAIN TAPERS OFF EARLY IN THE NIGHT. PATCHES OF MVFR CIGS/VSBYS ARE POSSIBLE...BUT WE THINK DRY AIR BELOW 5000 FEET WILL OVERCOME MOST OF THE POTENTIAL FOR MVFR. DRIER AIR MOVING IN AFTER MIDNIGHT WILL BRING CLEARING SKIES BY MORNING. LIGHT WINDS TREND TO WEST/NORTHWEST TOWARD MORNING. SUNDAY...HIGH CONFIDENCE. VFR SUNDAY NIGHT...HIGH CONFIDENCE. VFR. PATCHES OF IFR IN LATE NIGHT FOG POSSIBLE IN THE CT VALLEY OF MASSACHUSETTS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK /MONDAY THROUGH WEDNESDAY/... MON...HIGH CONFIDENCE. VFR WITH HIGH PRES. SEA BREEZES LIKELY. TUE AND WED...MODERATE CONFIDENCE. FIRST A WARM FRONT TUE...THEN A COLD FRONT WED MAY PROVIDE A FOCUS FOR OCCASIONAL SHOWERS AND THUNDERSTORMS EACH DAY WITH PERIODIC MVFR OR LOWER CONDITIONS. OTHERWISE VFR. SOME FOG POSSIBLE DURING THE OVERNIGHTS.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TONIGHT...HIGH CONFIDENCE. LOW PRESSURE PASSES SOUTH OF THE WATERS AND MOVES OFF SOUTH OF NOVA SCOTIA TONIGHT. WINDS SHIFT FROM EAST TO NORTH AFTER THE PASSAGE OF THE LOW...BUT WILL REMAIN BELOW 25 KNOTS. EXPECT SEAS TO BUILD A LITTLE WITH HEIGHTS AROUND 5 FEET ON THE SOUTHERN OUTER WATERS. TIMING ON THE ADVISORY HAS BEEN ADJUSTED TO A LATER START TIME BUT OTHERWISE THE HEADLINE REMAINS THE SAME. SUNDAY AND SUNDAY NIGHT...HIGH CONFIDENCE. HIGH PRESSURE BUILDS OVER THE WATERS WITH LIGHT WIND AND DIMINISHING SWELL. THE SMALL CRAFT ADVISORY WILL END AROUND MIDDAY. OUTLOOK /MONDAY THROUGH WEDNESDAY/... MON...HIGH CONFIDENCE. ANY LINGERING SWELL RECEDES BELOW 5 FT SUN NIGHT. HIGH PRES THEN BRINGS QUIET BOATING WEATHER TO THE WATERS THROUGH MON. TUE AND WED...MODERATE CONFIDENCE. A WARM FRONT ON TUE...THEN A COLD FRONT ON WED WILL BE APPROACHING FROM THE W. WHILE WINDS SHOULD GENERALLY REMAIN OUT OF THE S-SE...WIND SPEEDS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS. SEAS IS ALSO LIKELY TO REMAIN BELOW SMALL CRAFT THRESHOLDS. SOME SHOWERS/THUNDERSTORMS AND/OR FOG ARE POSSIBLE OVER THE WATERS.
-- End Changed Discussion --
&& .BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 AM TO 4 PM EDT SUNDAY FOR ANZ255-256.
-- End Changed Discussion --
&& $$ SYNOPSIS...WTB/DOODY NEAR TERM...WTB/DOODY SHORT TERM...WTB LONG TERM...DOODY AVIATION...WTB/DOODY MARINE...WTB/DOODY

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