Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 230224 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 924 PM EST Thu Feb 22 2018 .SYNOPSIS...
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High pressure builds south into New England tonight. A frontal system approaching from the west will bring another round of rain and mixed precipitation Friday afternoon and evening. Active weather pattern continues this weekend with more rain and interior mixed precipitation Saturday night and Sunday. A near- seasonable, quiet pattern for early next week.
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920 PM update... Areas of low clouds persist across portions of SNE this evening and radar indicating a few flurries drifting south across east coastal MA in moist N/NE flow. High pres moves to Maine overnight with ridging extending south into New Eng which will lead to partial clearing moving in from the north and east. Any clearing could lead to patchy fog development given lingering low level moisture. Low temps will settle into the 20s to near 30 so icy spots possible overnight.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Friday... Dry and seasonably cool in the morning as 1042 mb high crest over Maine. Could have some leftover icy spots early that may impact the morning commute. Otherwise fast/progressive upper air pattern results in any breaks of morning sunshine quickly giving way to increasing clouds as next WAA pattern develops. Precip overspreads the region during mid to late afternoon from west east. Cold air is not as deep tomorrow, more shallow and will support a period of sleet and freezing rain across western-central MA. Remainder of the region will see a chilly rain. Friday Night... Weak wave crosses the area with evening rain but risk of freezing rain across western-central MA. Drying trend second half of the night as post frontal airmass overspreads the region. Not as chilly as tonight with lows Fri night in the 30s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Highlights... * Dry and warm as Spring returns on Saturday * Widespread precip on Sunday with wintry mix in the interior * Dry weather trend for early next week * Pattern change for mid to late next week Overview... 12z guidance is in general agreement with the extended forecast. Just some minor differences related to thermals which provide different outcomes in p-type for Saturday night into Sunday. Trough across the western CONUS with southeast ridging deamplifying over the weekend. Last of the Pacific waves will move through Sunday with surface high pressure to follow into Monday. By early next week the pattern will begin to change as NAO turns negative. Mid-level ridge across the southeast into the Great Lakes with cut-off low off the Maritimes. Both the GEFS and EPS show anomolous high pressure building over Greenland which will influence the cut-off low to either retrograde towards SNE or remain across the North Atlantic. Depending on where this all stacks up, appears the trend is there that our pattern could turn more active late next week. Details... Saturday...Moderate confidence. Dry weather day will be on tap as surface high pressure will fill in behind the offshore front. Still seeing westerly to northwest flow as 850mb CAA moves into the region. However, appears that surface temps have the potential to warm into the mid 50s thank to longer daylight hours and mixing to 925mb which are cooler to cool. Some guidance even hints as low 60s. Still some uncertainty as how far south the front will sage will lead to cooler temps or if it slows down then warm temps are possible. Thus a low confidence forecast for temps on Saturday, but high confidence on mainly dry weather. Saturday night into Sunday...Increasing confidence. Potent wave will eject out of the desert southwest producing a surface low pressure system up into the northern Great Lakes. Stalled front to the south will begin to lift northward as a warm front. Along the front, triple point low will develop and strengthen as the system pulls away from the area Sunday night. Before the secondary low develops, another overrunning precip set-up as moisture from the south increase as warm front begins to lift northward. Surface high pressure will be set-up north to northeast of the region allowing for surface temps to fall thanks to cold air damming. Models are always to quick at warming temps above freezing, so trended towards cooler 2m temps and wet-bulb effects. P-type will once again be the issue as models are still struggling with the warm layer. EC trended to be the coolest of the guidance which could suggest more snow than freezing rain, whereas the NAM is the warmest. GFS and the CMC are in the middle of the ground and thus trended towards the ensembles guidance. Therefore, went a bit cooler with this forecast resulting in snow at the onset, as cold air looks to be deep enough north of the Pike and esp Route 2. In fact with good omega in the snow growth region, could see a few inches of snowfall. Once the mid-level warm front pushes into the region, a transition to more sleet/freezing rain will occur leading to slick travel across the interior. South of the Pike and especially across RI and SE MA conditions look to warm for any wintry weather, but still will have to watch as a change in just a few degrees will impact p-type. This system looks to the most roust resulting in more widespread precip, esp as we continue to tap into that Gulf moisture. Thus increases POPs as confidence is high that precip will occur. Lastly, with the surface warm front trying to push northward, may have a large gradient in surface temperatures somewhere across southern New England. While warm fronts tend to struggle to lift northward this time of year something to watch as we could see low 50s across the south coast and mid 30s across the interior. Sunday night into Wednesday...High confidence. Surface cold front will push through the region resulting in a drying trend for Sunday night. Strong high pressure over the Ohio Valley will begin to strengthen Monday into Tuesday as anomolous ridge sets-up over the Mississippi Valley. This high appears to stay in place into middle of next week before a quick moving wave from the southwest gets kick into the flow. Thanks to ridging and surface high, dry weather will prevail as temperatures turn slightly above average. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday Night/...Moderate confidence. 00z TAF update ... After 00z... MVFR in -SN ending by 01z. Trend should be dry, but enough low level moisture for MVFR/IFR cigs to hang around during the overnight hours. Friday... VFR but trending MVFR late in rain with PL western- central MA. Friday night... low risk of LLWS with low level WSW jet. MVFR in evening rain improving to VFR and dry overnight. KBOS Terminal...Moderate confidence TAF. Morning push may be impacted with some MVFR/IFR cigs. KBDL Terminal...Moderate confidence TAF. Outlook /Saturday through Tuesday/...Moderate confidence. Saturday: VFR. Saturday Night: Mainly VFR, with local IFR possible. Breezy. RA likely, SN likely, slight chance FZRA across the interior. Sunday: MVFR/IFR conditions possible. Windy with gusts to 35 kt. RA, FZRA. Sunday Night: Mainly VFR, with local MVFR possible. Monday through Tuesday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday Night/...Moderate confidence. Tonight... SCA for southern RI waters and south of MVY/ACK with marginal NE winds up to 25 kt and seas up to 5 ft, then trending downward later tonight. Snow, sleet and rain limit vsby this evening but improving later this evening from west to east. Friday... 1041 mb high over Maine in the morning slides offshore with weak low pres moving across southern New England. Light NE winds become SE. Vsby lowers late in rain. Friday night... Weak low pres and attending cold front move offshore with WNW winds developing along with improving vsby from early rain showers. Outlook /Saturday through Tuesday/... Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Saturday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Chance of rain. Sunday: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Rain. Sunday Night: Winds less than 25 kt. Areas of rough seas. Monday: Winds less than 25 kt. Seas up to 5 ft. Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ255- 256. && $$ SYNOPSIS...Nocera/Dunten NEAR TERM...KJC/Nocera/Dunten SHORT TERM...Nocera LONG TERM...Dunten AVIATION...Nocera/Dunten MARINE...Nocera/Dunten is the U.S. government's official web portal to all federal, state and local government web resources and services.