Area Forecast Discussion
Issued by NWS Boston, MA

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292 FXUS61 KBOX 280544 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 144 AM EDT Tue Mar 28 2017 .SYNOPSIS... Damp weather continues Tue and Tue night as low pressure tracks over or near the region. Although Tue should be milder than Monday. High pressure brings dry but chilly weather Wed and Thu. More unsettled weather is expected late Fri into Sat. High pressure builds in Sunday into early next week. && .NEAR TERM /THROUGH TODAY/... 10PM update... As drier air continues to spill in aloft, noting the widespread development of fog and low clouds across the region suggesting a damp and mild night in spite of the drier air trying to spill in from the N-NW flow behind the exiting frontal wave. Therefore, generally more of the same for the overnight hours. A mix of patchy fog/low clouds and temps in the mid to upper 30s. No major adjustments otherwise. Will hold on any fog headlines at this point as the aforementioned N-NW flow may limit the ability for fog to form as dwpts gradually hold or lower through the overnight hours. && .SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/... Tuesday...Over-running with light rain or drizzle. Temps near 50 for highs. Warm front south of Long Island with plenty of mixture keeps it cloudy and damp. POPs of likely to categorical, but the key here is for light rain which I was able to get into the grids. Not a lot of sunshine anticipated, despite southern New England getting into the warm sector of a low pressure in southeast Canada. Max temperatures should be above normal, in the upper 40s and 50s. Could be warmer if clouds and rainfall are delayed until late in the day. Low risk of a isolated thunderstorm or two toward the south coast due to elevated instability. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... No significant changes at this time. Highlights... * Showers linger Tuesday night as cold front passes through * Cooler but dry weather for Wed and Thurs * Unsettled weather returns Friday into Saturday Pattern Overview... 12z Model consensus continues to show an active weather pattern for the period. Split flow aloft will continue through the period with a few shortwaves moving through the flow. Partial phasing of the two streams will occur across the Great Lakes and Northeast on Tuesday. This will result in the development of a low pressure system east of the region late Tuesday into Wednesday. High pressure and upper level ridge will follow Thursday into early Friday. The next upper level low/trough deamplifies as it moves into the mid/upper ridge axis across the eastern U.S. A coastal low is forecast to develop and quickly move east in the aforementioned region of this phasing. The spread has decreased for this timeframe but the still question in strengthen and location of this system will determine p-types and qpf amounts. Details... Tuesday Night...High confidence. Weak shortwave will move over the region on Tuesday with surface low pressure over Northern New England. Along the cold front, guidance develops a secondary low pressure system just south of southern New England by Tuesday night. This wave of low pressure will bring showery weather Tuesday evening into the overnight hours. Cannot rule out some isolated thunder with this system as TT increase above 50 and LI`s drop below 0. This is strongest in the conservative EC. Precip chance will quickly come to an end from west to east during the overnight hours as CAA takes a hold of the region. Wednesday into Friday...High confidence. Trough overhead as upper level low deepens as it moves towards the Canadian Maritimes. This puts the region in northwest flow through the period resulting in dry but breezy conditions. Clouds may be stubborn on Wed over the Cape and islands given northerly flow across the waters. In fact could have some ocean effect rain/snow showers over the outer Cape! Despite cold advection, the environment should be well mixed, so max temperatures will be close to normal. Northwest flow continues on Thursday with an area of high pressure building in New England. Anticipate increasing sunshine and lighter winds. Dry and seasonable conditions should persist through Friday with high pressure in control. Friday night into the weekend...Low confidence. Split flow remains over the region with the next southern stream wave interacting with the northern stream. Still some model spread in this system leading to a low confidence forecast. The EC has become more progressive with this approaching coastal low developing it over 1-95 while the GFS keeps the system suppressed. The UKMET is more in between the two systems, but the GEFS and EPS continue to show the system south of SNE. Overall a chilly rain with potential for wet snow/sleet at times on the northern portion of the precip shield. All guidance suggest system should be or moving offshore by Sunday, thus drying trend possible second half of the weekend. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/... Through 18Z today...High confidence. Mainly IFR/LIFR with CIGS below 800ft (except for some interior sites which are currently MVFR but will too be dropping this morning). The IFR/MVFR conditions continue with a mix of fog/drizzle and low vsbys into the early afternoon hours. Mainly E flow. Late today into tonight...High confidence. Mix of IFR/LIFR continues but with more of a mix of RA/fog rather than drizzle. Rain tapers off from W to E 03Z-09Z. After rain ends a period of IFR/LIFR in fog lingers afterwords. Wed...High confidence. Improving conditions through sunrise with VFR everywhere by 15Z. NNW winds. Gusts to 20-25 kt at times. KBOS TAF...High Confidence. IFR to LIFR through much of the period. KBDL TAF...High Confidence. MVFR gives way to IFR and LIFR through much of the period. Outlook /Wednesday Night through Saturday/... Wednesday into Thursday...High confidence. Gusty N/W winds Wednesday with VFR conditions into Thursday. Friday...Moderate confidence. VFR and dry to start but likely lowering to MVFR or possibly IFR Fri night in rain/wintry precip. Saturday...Moderate confidence. MVFR or possibly lower in rain/wintry mix. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/...Moderate confidence. Rough seas across the eastern outer coastal waters are more likely than the southern outer waters. Continued the Small Craft Advisories for those waters. A few gusts to 25 kt are also possible this evening. Tonight...A weak frontal boundary sweeps the waters, with light west winds developing. This will allow seas to subside and Small Craft Advisories to conclude. Tuesday...Light south winds with frontal boundary north of the region. Vsby reduced at times in rain and fog. Outlook /Wednesday Night through Saturday/... Tuesday night...Moderate confidence. winds becoming northeast late Tue night as front slips south and wave of low pres tracks along the front south of New England. Vsby reduced at times in rain and fog. Wednesday into Thursday...High confidence. Gusty north winds near Wednesday into early Thu then diminishing as high pressure builds into the area later Thu. Friday...High confidence. Quiet weather with high pressure over the area early Fri. However increasing east-southeast winds Fri night as low pres approaches from the west. Also vsby lowering in rain and fog Fri night. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/Dunten NEAR TERM...Doody SHORT TERM...Belk LONG TERM...Dunten AVIATION...Doody/NMB MARINE...Belk/Dunten is the U.S. government's official web portal to all federal, state and local government web resources and services.