Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Graphics & Text | 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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 010932 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 432 AM EST SUN FEB 1 2015 .SYNOPSIS...
-- Changed Discussion --
A MAJOR WINTER STORM WILL AFFECT THE REGION VERY LATER TONIGHT INTO MONDAY EVENING WITH HEAVY SNOW FOR MANY LOCATIONS. BITTERLY COLD WIND CHILLS FOLLOW LATER MONDAY NIGHT INTO TUESDAY MORNING. MODERATING TEMPS WEDNESDAY WILL BE ACCOMPANIED BY SOME LIGHT SNOW THEN VERY COLD CONDITIONS WILL RETURN TOWARD THE END OF THE WEEK. A COASTAL STORM WILL PASS WELL SOUTH OF NEW ENGLAND LATE IN THE WEEK BUT WILL HAVE TO BE MONITORED.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --
ARCTIC FRONT APPROACHING THE CANADIAN BORDER WILL DROP SOUTH ACROSS NEW ENG TODAY MOVING ACROSS SNE THIS AFTERNOON AND REACHING THE SOUTH COAST TOWARD EVENING. MODELS INDICATE SOME LOW LEVEL MOISTURE TODAY WHICH MAY LEAD TO SOME LOWER CLOUDS...OTHERWISE SUNSHINE FOR MOST AREAS WILL GIVE WAY TO INCREASING MID/HIGH CLOUDS DURING THE DAY. MAX TEMPS WILL REACH 25 TO 30 DEGREES BUT FALL INTO THE TEENS TOWARD EVENING IN FAR N ZONES AS ARCTIC AIR DRAINS SOUTH. GUSTY WINDS ON THE CAPE AND ISLANDS WILL DIMINISH...OTHERWISE GENERALLY LIGHT WINDS EXPECTED TODAY.
-- End Changed Discussion --
&& .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...
-- Changed Discussion --
HIGHLIGHTS... * MAJOR WINTER STORM VERY LATE TONIGHT INTO MON EVENING * HEAVY SNOWFALL EXPECTED FOR MUCH OF THE REGION * BIGGEST UNCERTAINTY IS SNOWFALL AMTS ACROSS RI AND SE MA DUE TO PTYPE ISSUES OVERVIEW... MODELS ARE IN GOOD AGREEMENT ON A PROGRESSIVE BUT RATHER POTENT MID LEVEL TROF WHICH MOVES EAST INTO SNE MON AND BECOMES NEGATIVELY TILTED. THE SFC LOW TRACKS EAST FROM THE OH VALLEY AND APPEARS TO JUMP/REDEVELOP ALONG THE MID ATLC COAST...TRACKING NEAR OR JUST S OF LONG ISLAND TO ACK DURING MONDAY. WITH ARCTIC HIGH IN PLACE TO THE NORTH...PLENTY OF LOW LEVEL COLD AIR IN PLACE BUT WARMING ALOFT WILL MAKE FOR A TRICKY SNOWFALL FORECAST NEAR THE S COAST. GOOD MODEL AGREEMENT ON QPF WITH 0.75-1.00" WITH HIGHER AMOUNTS ACROSS SE NEW ENG...BUT THERE ARE SOME DIFFERENCES WITH THE THERMAL PROFILE. NAM IS THE COLDEST BUT LIKELY A RESULT OF IT BEING FASTER WITH THE SFC LOW. GFS HAS TRENDED A BIT COLDER WHILE ECMWF A BIT WARMER AND ONLY MINOR DIFFERENCES EXIST ALOFT. GIVEN STRONG SW FLOW ALOFT ALL MODELS SHOW WARMING IN THE 850-700 MB LAYER MOVING NORTH ALONG THE SNE COAST DURING MON. THE UNCERTAINTY FOR THE SNOWFALL FORECAST IS DETERMINING HOW FAR N THE MIX LINE GETS. SYSTEM REMAINS AN OPEN WAVE AT 700 MB AS IT CROSSES CENTRAL NEW ENG LATE MON SO NOT LOOKING AT TYPICAL BANDING SIGNAL ASSOCD WITH STRONG MID LEVEL FRONTOGENESIS. THIS WILL BE A CLASSIC STRONG OVERRUNNING EVENT AS MILDER AIR AND MOISTURE OVERRUNS VERY STRONG LOW LEVEL BAROCLINIC ZONE ACROSS SNE WITH ARCTIC TO THE NORTH. 1) TIMING AND PTYPE SNOW DEVELOPS IN THE CT VALLEY BY MIDNIGHT THEN QUICKLY OVERSPREADS THE REST OF SNE THROUGH DAYBREAK. THE SNOW WILL QUICKLY BECOME HEAVY LATE TONIGHT INTO MONDAY MORNING AND WILL HAVE A SIGNIFICANT IMPACT ON THE MORNING COMMUTE. GOOD SNOW GROWTH AROUND 12Z AND STRONG MID LEVEL OMEGA WILL RESULT IN A GOOD FRONT END THUMP WITH SNOWFALL RATES OF 1-2 INCHES PER HOUR ACROSS THE REGION FOR SEVERAL HOURS IN THE MORNING. THE UNCERTAINTY INCREASES CLOSER TO THE S COAST MID/LATE MORNING INTO THE AFTERNOON AS WARMER AIR ALOFT SURGES NORTHWARD. WE BLENDED THE MODELS WHICH SUGGEST A MIX OR CHANGE TO SLEET BRIEFLY GETTING TO MA/N RI BORDER BY MIDDAY BEFORE COLLAPSING SE DURING THE AFTERNOON. FURTHER S...DEEPER WARM LAYER WILL LIKELY RESULT IN A PERIOD OF FREEZING RAIN ALONG THE SOUTH COAST AND POSSIBLY SOME RAIN AS THE BOUNDARY LAYER WARMS. A CHANGE TO PLAIN RAIN IS MOST LIKELY OVER THE ISLANDS. ANY RAIN OR MIXED PRECIP WILL CHANGE BACK TO SNOW MID/LATE AFTERNOON BUT NOT UNTIL EVENING FOR THE OUTER/CAPE ISLANDS. THIS IS STILL A VERY TRICKY PTYPE FORECAST DUE TO THE STRONG LOW/MID LEVEL TEMP GRADIENT SO PTYPE WILL BE VERY SENSITIVE TO JUST A MINOR SHIFT IN THE SFC AND 850 MB LOW TRACK. SNOWFALL IN THE AFTERNOON WILL NOT BE AS HEAVY AS THE MORNING AS BEST ISENTROPIC LIFT WEAKENS AND SNOW GROWTH NOT QUITE AS FAVORABLE...BUT STILL SOME DECENT SNOWFALL ESPECIALLY IN THE NORTH. 2) SNOWFALL ACCUMULATIONS AND HEADLINES WE HAVE HIGH CONFIDENCE IN HEAVY SNOWFALL FOR MUCH OF THE REGION WITH THE HEAVIEST SNOW LIKELY ALONG AND NORTH OF THE MASS PIKE WHERE DEFINITELY NO MIXING ISSUES. EXPECT SNOW ACCUM AROUND A FOOT FOR THIS REGION...WITH LESSER AMOUNTS AROUND 6 TO 10 INCHES FURTHER S ACROSS RI AND SE MA DUE TO MIXING ISSUES. WE HAVE ENOUGH CONFIDENCE FOR UP TO 6 INCHES NEAR THE S COAST TO UPGRADE TO A WARNING. IN ADDITION THE POTENTIAL EXISTS FOR UP TO A TENTH OF AN INCH OF ICE ACCRETION NEAR THE COAST. AMOUNTS MAY FALL SHORT OF 6 INCHES ON CAPE COD...BUT WE INCLUDED THEM IN THE WARNING DUE TO COMBINATION OF SNOW AND SOME ICE. FOR THE ISLANDS...WE WILL GO WITH A WINTER WEATHER ADVISORY FOR ACCUM 2 TO 5 INCHES...LEAST ON NANTUCKET. 3) STRONG WINDS AND BLOWING AND DRIFTING SNOW NORTHEAST WIND GUSTS OF 30 TO 40 MPH EXPECTED ALONG THE EASTERN MASS COAST MONDAY AS STORM INTENSIFIES AND PRESSURE GRADIENT INCREASES. THIS WILL RESULT IN POOR VISIBILITY ALONG WITH BLOWING AND DRIFTING SNOW. ITS POSSIBLE THAT A FEW LOCATIONS ALONG THE COAST COULD SEE NEAR BLIZZARD CONDITIONS FOR A VERY SHORT TIME...BUT STORM DOESN/T SEEM TO WARRANT THOSE TYPE OF HEADLINES. 4) TEMPS A VERY STRONG COASTAL FRONT WILL SET UP DURING MONDAY WITH TEMPS IN THE TEENS NORTH OF I-84 TO I-90 CORRIDOR AND WEST OF I-495 WITH EVEN SOME SINGLE NUMBERS FAR N/NW MA...WHILE TEMPS WILL REACH THE LOWER TO MID 30S SE MA. A FLASH FREEZE IS LIKELY ACROSS SE COASTAL MA AND CAPE/ISLANDS IN THE EVENING AS THE COASTAL FRONT MOVES THROUGH AND TEMPS PLUMMET.
-- End Changed Discussion --
&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... HIGHLIGHTS... * COLD PATTERN CONTINUES THRU NEXT WEEKEND * CLIPPER LOW APPEARING MORE LIKELY THAN COASTAL LOW WED/THU GOOD AGREEMENT AMONG 12Z DETERMINISTIC...12Z GEFS AND 00Z ECENS ENSEMBLES THAT THE POLAR JET WILL DOMINATE THE NORTHERN TIER STATES INCLUDING NEW ENGLAND THIS PERIOD. THIS COMBINED WITH STREAMS EXPECTED TO REMAIN UNPHASED WILL SUPPORT MAINLY DRY WEATHER THIS PERIOD. ONE CAVEAT WILL BE CLIPPER LOW ENTERING THE NORTHEAST WED/WED NIGHT. EARLIER MODEL RUNS SUGGESTED SECONDARY DEVELOPMENT ALONG THE TRAILING COLD FRONT SOUTHWEST OF NEW ENGLAND...WITH POSSIBLE COASTAL-OCEAN STORM IMPACTING OUR REGION AROUND THU. HOWEVER LATEST GUID INCLUDING ENSEMBLES SUGGEST MID LEVEL TROUGH WILL LACK SUFFICIENT AMPLITUDE TO BACK THE FLOW FOR A SECONDARY LOW TO IMPACT THE REGION. THEREFORE LEANING TOWARD A MORE OFFSHORE TRACK AND JUST A PERIOD OF LIGHT SNOW POSSIBLE WED/WED NIGHT. HOWEVER AT THIS TIME RANGE CAN/T BE TOO DETERMINISTIC. THUS WON`T TOTALLY DISCOUNT CLOSER SECONDARY DEVELOPMENT. AS FOR TEMPS...BITTERLY COLD TUE BEHIND DEPARTING MON NGT COASTAL LOW. THEN COLD EASES WED AHEAD OF APPROACHING CLIPPER LOW FOLLOWED BUT YET ANOTHER ARCTIC BLAST LATE IN THE WEEK BEHIND THE CLIPPER. AS FOR INTO NEXT WEEKEND ENSEMBLE TRENDS SUGGEST TEMPS COLDER THAN NORMAL. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM.../THROUGH MONDAY/... TODAY...HIGH CONFIDENCE. MAINLY VFR...BUT LOW PROB FOR AREAS OF MVFR CIGS DEVELOPING BY AFTERNOON. TONIGHT INTO MONDAY...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN TIMING. VFR THIS EVENING DETERIORATES TO IFR-LIFR CIGS/VSBYS IN MODERATE TO HEAVY SNOW AFTER MIDNIGHT TO DAYBREAK FROM WEST TO EAST. IFR/LIFR IN MOD/HEAVY SNOW CONTINUES THROUGH THE DAY MON. PTYPE MAY TRANSITION TO A PERIOD OF SLEET/FREEZING RAIN AROUND MIDDAY FROM PVD-TAN-PYM SOUTH AND CHANGING TO RAIN OVER THE OUTER CAPE/ISLANDS. NE WIND GUSTS TO 30-35 KT DEVELOPING ACROSS E COASTAL MA MONDAY...WITH 25 KT ACROSS RI AND REMAINDER OF E MA. KBOS TAF...HIGH CONFIDENCE. LOWER CONFIDENCE IN EXACT TIMING OF IFR CONDITIONS IN SNOW. KBDL TAF...HIGH CONFIDENCE. LOWER CONFIDENCE IN EXACT TIMING OF IFR CONDITIONS IN SNOW. OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/... TUESDAY INTO WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR ON TUESDAY. COULD SEE SOME MVFR CIGS IN SCT SNOW SHOWERS ON WEDNESDAY. THURSDAY...MODERATE CONFIDENCE. MAINLY VFR. LOW RISK OF MVFR ALONG SOUTHEAST MASS DEPENDING ON TRACK OF CLIPPER LOW. && .MARINE...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE. TODAY...WINDS AND SEAS GRADUALLY DIMINISH THROUGH THE DAY BUT EXPECT SCA WAVES TO REMAIN THROUGH THE PERIOD. LIGHT FREEZING SPRAY WILL PERSIST. TONIGHT INTO MONDAY...MODERATE TO HIGH CONFIDENCE. WINDS/SEAS QUICKLY RAMP UP DURING MONDAY AS LOW PRESSURE INTENSIFIES NEAR THE SOUTH COAST. GALE WATCHES CONTINUE. THE MAIN FOCUS FOR GUSTS TO 40 KT MONDAY WILL BE ACROSS EASTERN MA COASTAL WATERS...ESPECIALLY NORTH OF CAPE COD...WITH LIGHTER WINDS OVER THE SOUTH COASTAL WATER. SEAS BUILD TO 15+ FEET ACROSS OUR EASTERN WATERS BY LATE MON AFTERNOON/EVENING. OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...MODERATE TO HIGH FORECAST CONFIDENCE. MONDAY NIGHT...BITTERLY COLD AIR MOVING OVER THE WATERS MONDAY NIGHT WILL RESULT IN THE POTENTIAL FOR HEAVY FREEZING SPRAY. HAVE ALSO ISSUED A FREEZING SPRAY WATCH. TUESDAY...NW GALES LIKELY ALONG WITH FREEZING SPRAY...POSSIBLY MODERATE TO HEAVY. MAINLY DRY WITH GOOD VSBY EXCEPT FAR OFFSHORE WHERE SNOW SHOWERS WILL BE COMMON. WED...WINDS EASE AND BECOME SOUTHWEST AS CLIPPER LOW ENTERS THE GREAT LAKES AND NY STATE. NOT AS COLD SO FREEZING SPRAY UNLIKELY. VSBY MAY BRIEFLY LOWER IN A PERIOD OF LIGHT SNOW. THU...ARCTIC FRONT WITH NW GALES BEHIND FRONTAL PASSAGE. MODERATE TO HEAVY FREEZING SPRAY POSSIBLE.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
*** LOW RISK FOR MINOR COASTAL FLOODING MON NIGHT EASTERN MA COASTLINE *** THE FIRST TIDE CYCLE MONDAY MORNING SHOULD NOT POSE ANY RISKS AS WINDS WILL NOT BE STRONG ENOUGH FOR A LONG ENOUGH PERIOD OF TIME TO PRODUCE THE WAVE ACTION OR SURGE NECESSARY FOR COASTAL FLOODING. A SURGE OF 1 FOOT IS POSSIBLE BUT SEAS WILL BE WELL UNDER 10 FT. AS FOR THE MONDAY EVENING HIGH TIDE CYCLE...ASTRO TIDES ARE ABOUT 1 FT LOWER BUT WAVES WILL BE BUILDING TO 15 TO 20 FT. WE EXPECT ABOUT A 1.5 TO 2.5 FT STORM SURGE BUT THIS MAY NOT OVERLAP THE EVENING HIGH TIDE AND MAY OCCUR CLOSER TO LOW TIDE WITH SURGE VALUES DECREASING TOWARD THE TIME OF HIGH TIDE AS WINDS TURN N. IF THIS TIMING PLAYS OUT...THE PROBABILITY FOR ANY COASTAL FLOODING WILL BE LOW. HOWEVER...WE ARE TALKING ABOUT ONLY 6 HOURS AND IF THE MAX SURGE IS DELAYED AND OVERLAPS THE HIGH TIDE...THERE WILL BE A HIGHER RISK OF MINOR COASTAL FLOODING WITH A LOW RISK OF ISOLD MODERATE FLOODING...MAINLY FROM CAPE COD TO CAPE ANN WITH PERHAPS THE HIGHEST RISK FROM HULL/COHASSET/SCITUATE/ MARSHFIELD/PLYMOUTH TO SANDWICH HARBOR. AGAIN...THIS WILL DEPEND OM THE TIMING OF THE MAX SURGE OCCURING CLOSE TO HIGH TIDE WHICH DOES NOT APPEAR LIKELY AT THIS TIME. WINDS...SEAS AND STORM SURGE WILL BE CONSIDERABLY LESS THAN THE PREVIOUS COASTAL STORM BUT THERE COULD STILL BE SOME IMPACT ESPECIALLY FOR THOSE COMMUNITIES SUCH AS MARSHFIELD MA THAT WERE HIT HARD EARLIER THIS WEEK WHERE COASTAL STRUCTURES SUCH AS SEAWALLS WERE DAMAGED.
-- End Changed Discussion --
&& .CLIMATE... WITH EXTREMELY COLD AIR MOVING IN BEHIND THE DEPARTING LOW MONDAY NIGHT...TEMPERATURES MAY FALL BACK CLOSE TO OR SURPASSING RECORD LEVELS EARLY TUESDAY MORNING. AND THAT IS NOT TAKING INTO ACCOUNT THE STRONG WINDS. HERE ARE THE RECORD LOWS FOR TUESDAY 2/3... BOSTON -5 SET IN 1881 PROVIDENCE -6 SET IN 1961 WORCESTER -7 SET IN 1931, 1955 AND 1971 WINDSOR LOCKS -3 SET IN 1955 BLUE HILL OBS -7 SET IN 1955 && .BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...WINTER STORM WARNING FROM 9 PM THIS EVENING TO 1 AM EST TUESDAY FOR CTZ002>004. MA...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 1 AM EST TUESDAY FOR MAZ023-024. WINTER STORM WARNING FROM 9 PM THIS EVENING TO 1 AM EST TUESDAY FOR MAZ002>022-026. RI...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 1 AM EST TUESDAY FOR RIZ008. WINTER STORM WARNING FROM 9 PM THIS EVENING TO 1 AM EST TUESDAY FOR RIZ001>007. MARINE...GALE WATCH FROM MONDAY MORNING THROUGH TUESDAY MORNING FOR ANZ231>235-237. SMALL CRAFT ADVISORY UNTIL NOON EST TODAY FOR ANZ231-232-251. HEAVY FREEZING SPRAY WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING FOR ANZ231>235-237-250-251-254>256. FREEZING SPRAY ADVISORY UNTIL 8 AM EST THIS MORNING FOR ANZ231- 232-250-251-254-255. SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR ANZ233>235-237. GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR ANZ230-236. GALE WATCH FROM LATE TONIGHT THROUGH TUESDAY MORNING FOR ANZ250-251-254>256. SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ250- 254-255. SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR ANZ256.
-- End Changed Discussion --
&& $$ SYNOPSIS...KJC NEAR TERM...KJC SHORT TERM...KJC LONG TERM...NOCERA AVIATION...KJC/FRANK MARINE...KJC/FRANK/NOCERA TIDES/COASTAL FLOODING... CLIMATE...

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