Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 252021 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 321 PM EST Sat Feb 25 2017 .SYNOPSIS...
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A strong cold front will cross the region tonight, bringing showers and a low chance for thunderstorms as this front passes. Blustery conditions with more seasonable temperatures expected for Sunday and above average on Monday. A couple of weather systems will bring periods of wet weather Tuesday into Thursday. Colder air looks to return late next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Fine line of convection along the cold front moving into eastern NY. Sct to numerous t-storms along this line where MUCAPES 250-500 J/kg but MUCAPES 1000-1500 J/kg further south across SE PA where greater severe wx threat exists. Hi-res guidance indicates this line will move into western MA and northern CT 00-02z. Strong mid level omega holds together into W MA along with 40-50 kt LLJ so expect the line to maintain itself as it moves into W MA early this evening but the line of convection will begin to outrun better instability to the west so some weakening is expected. Still expect brief heavy downpours and gusty winds in western MA and N CT with low risk of an isold damaging wind gust if convection can mix down stronger winds aloft. Will have to monitor radar closely as deep layer shear and 0-1km helicity values are quite robust and damaging wind or even a brief tornado is favorable in this environment if instability is greater than forecast. As the line moves east across central and eastern New Eng 02-06z it will diminish and weaken as mid level omega weakens rapidly and becomes fragmented. So just a few showers expected by the time it gets to eastern MA. The rain may end as a brief period of snow showers in the Berkshires as deeper colder air rushes in behind the front, but moisture will be exiting as the cold air moves in. Low risk of a coating to less than an inch in the Berkshires. Gusty W/NW winds develop behind the cold front which moves through SNE 01-06z from west to east. Gusts to 30-40 mph possible, strongest over higher terrain. Min temps by Sun morning will range from 35 to 40 degrees, except upper 20s to lower 30s over the higher terrain in central and western MA
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&& .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
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Sunday... Mid level shortwave moves east of New Eng. Expect partly to mosunny skies with sct-bkn strato-cu developing in cold advection pattern. Gusty W/NW winds expected with soundings supporting gusts to 35 mph with chance of a few gusts over 40 mph across the higher terrain where low prob a wind advisory may be needed. Much colder airmass Sun as 850 mb temps drop to -8 to -10C. However, temps will likely overachieve a bit as soundings indicate mixing above 850 mb with good downsloping. Expect maxes ranging from the upper 30s higher elevations to the mid 40s in the coastal plain with a few upper 40s possible. Sunday night... Surface high moves off mid Atlc coast with ridge axis moving east of New Eng. Winds will diminish and shift to SW overnight. Column is dry except for some increase in mid/high level moisture. Expect mostly clear to partly cloudy skies with mins ranging through the 20s.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/... Highlights... * Above average temperatures for next week * Widespread showers possible Wednesday/Thursday * More seasonable conditions return on Friday Pattern Overview... The 00z models and their ensembles have been in generally good agreement through the period with the GFS just a bit displaced. Therefor used a blend of the ensembles for the bulk of the forecast. Overall, zonal flow over the region as Bermuda high begins to build in the mid-levels. By mid-week the western trough is forecast to transition into the east as a surface front will move from the Great Lakes towards the Northeast around Wed/Thurs. Still some issues with the timing of the front as a surface wave may develop along it, which could slow it down a bit. This appears to be more inline with the EC/GEFS and ECENS. Otherwise, northwest flow behind the front could result in several clippers for next weekend. Details... Monday... High confidence. Westerly flow across the region as high pressure builds south of the region. Developing LLJ of near 40 kts will develop with high pressure to the south and quick moving wave to the north. This will make conditions a bit gusty at times. As surface high pressure moves farther to the east, winds will begin to back resulting in WAA. Surface temps could reach into the mid 50s on Monday with full mixing. Otherwise dry weather will prevail. Tuesday...High confidence. More of a transition day for Tuesday as high pressure moves eastward as upper level trough approaches. Southwest flow aloft will help saturate the profile. Guidance does show a weak wave developing a coastal low but appears to be just to far east to bring significant rainfall to the region. Depending on when this occurs, we could see a few flakes north of the Pike but confidence is low on this occurring. For now expect a few showers and clouds on Tuesday. Wednesday into Thursday... Moderate confidence. Main weather produce for the long term will occur Wed into Thursday as upper level trough approaches the region. Warm front ahead of the system will bring some showers to the area as temperatures rise well above average. Upper level low will move from the Plains towards northern Maine. This will drag a potent cold front through the region. Good agreement amongst the guidance with this system, just some issue`s with the exact timing of the front. Trended towards the slower side as there is the potential for a secondary low to develop along the front. This is more inline with the ensembles. This is an anomolous system with PWATs 3 STD above normal as Gulf moisture is tapped out ahead of the frontal passage. Heavy precip is a possibility if secondary low does develop bringing the better dynamics over southern New England. Also have noticed that there is a potent southerly LLJ out ahead of this system with 925 mb LLJ increasing to near 50-60 kts. If heavy rain does develop then we could tap into these stronger winds as the system moves through. Lastly appears that there is some elevated instability so have kept with iso thunder in the forecast. Still a lot of details to work out, but a system to watch in the coming days. High confidence in above average temperatures with a non-diurnal trend Wednesday night. Went several degrees above guidance and could still be a bit low. Friday and beyond... Moderate confidence. As the cold front passes through, northeast winds take a hold of the region. Models appear to be inline with a few shortwaves/clipper systems moving through the flow. So some snow showers are certainly possible as temps drop back to seasonable. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/... Through 00z...Mix of VFR/MVFR cigs this afternoon, but IFR stratus and patchy fog expected to develop along the south coast and Cape/Islands toward 00z. Tonight...Moderate confidence. Widespread showers and isold t-storms will move through western New Eng 00-02z then diminish as it moves into eastern New Eng 03-06z. Brief heavy rain and gusty winds possible with any t-storms in western New Eng. Precip may end as brief snow showers in the Berkshires 03-06z. IFR/MVFR cigs with patchy fog will improve to VFR after cold fropa and wind shift to W/NW 02-06z. W/NW gusts to 30 kt developing after the wind shift, with G35 kt possible over higher terrain. Sunday...High confidence. VFR with sct-bkn cigs 4-5k ft. W/NW gusts to 30 kt, higher gusts possible over higher terrain in the morning. Sunday night...High confidence. VFR. Diminishing W wind becoming SW overnight. KBOS TAF...Moderate confidence through this evening, then high confidence in improving conditions overnight. KBDL TAF...Moderate confidence through this evening, then high confidence in improving conditions late this evening. Outlook /Monday through Thursday/... Monday...High confidence. VFR with westerly wind gusts near 20-30 kts. Tuesday...Moderate confidence. Generally VFR with MVFR conditions possible south of the Pike. Wednesday...Moderate confidence. MVFR to possible IFR in -SHRA.
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&& .MARINE...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/...High confidence. Tonight...Moderate confidence. Southerly winds shift to W/NW behind a cold front 03-06z. Increasing post-frontal winds with a few marginal gale force gusts to 35 kt expected. Will continue gales for most of the open waters. Sunday...High confidence. W/NW gusts to 30-35 kt, especially during the morning with a gradual diminishing trend during the afternoon. Sunday night...High confidence. Diminishing W winds in the evening becoming SW overnight. Another surge of 25-30 kt gusts expected toward daybreak. Outlook /Monday through Thursday/... Monday...High confidence. Improving conditions on Monday with gusts near 20 kts and seas beginning to relax as high pressure builds over the southern waters. Tuesday into Wednesday...Low confidence. Wind and seas will be below SCA for Tuesday. Approaching system to the west could see lower vsbys in rain and fog. Seas build late Tuesday night into Wednesday as low pressure system approaches. There is the potential for southerly gales across the waters.
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&& .HYDROLOGY... We will need to monitor rising water levels across southern New England into early next week. Much, if not all, of our snowpack has, or will have, melted. There is still much more snowpack upstream, over northern new England, that will push into the headwaters and head downstream. Some river levels could approach action stage. && .CLIMATE...
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RECORD HIGH TEMPS FOR YESTERDAY BOS 73/2017 - previous record 70/1985 PVD 72/1985 - topped off at 71 degrees (no record) BDL 73/1985 - topped off at 72 degrees (no record) ORH 69/2017 - previous record 67/1985 RECORD HIGH MIN TEMPS FOR YESTERDAY BOS 49/1930 - bottomed out at 46 (no record) PVD 45/2017 - ties previous record of 45/1984 BDL 43/1981 - bottomed out at 42 (no record) ORH 48/2017 - previous record 46/1985 RECORD HIGH TEMPS FOR TODAY BOS 65/1930 * broken 69 degrees PVD 69/1976 BDL 70/1976 * tied 70 degrees ORH 64/1976 * broken 65 degrees RECORD HIGH MIN TEMPS FOR TODAY BOS 46/1891 PVD 45/1930 BDL 45/1930 ORH 37/1996, 1984, 1976 DEW POINTS OF NOTE FOR YESTERDAY BOS Max Dew Point 54 ties highest for date set in 1985 PVD Max Dew Point 53 is highest for date. Previous high 50/1990 BDL Max Dew Point 54 is highest for date. Previous high 49/1990 ORH Max Dew Point 53 is highest for date. Previous high 48/1985
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Gale Warning from 2 AM to 11 AM EST Sunday for ANZ231>235-251. Small Craft Advisory from 11 PM this evening to 7 PM EST Sunday for ANZ230-236. Small Craft Advisory from 11 PM this evening to 10 PM EST Sunday for ANZ237. Gale Warning from 2 AM to 2 PM EST Sunday for ANZ250-254>256.
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&& $$ SYNOPSIS...KJC NEAR TERM...KJC SHORT TERM...KJC LONG TERM...Dunten AVIATION...KJC/Dunten MARINE...KJC/Dunten HYDROLOGY... CLIMATE...

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