Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 271433 AFDBOX Area Forecast Discussion National Weather Service Taunton MA Issued by National Weather Service Upton NY 1033 AM EDT Mon Mar 27 2017 .SYNOPSIS...
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Rain ending and cool across southern New England this afternoon as a weak wave of low pressure tracks across the region. Wet 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 possible late Fri into Sat.
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&& .NEAR TERM /THROUGH TONIGHT/...
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10 AM Update... Rain across central MA and CT moving ENE at 30 KT. Dual Pol Correlation Coefficient (CC) shows mixed phased PCPN in the 5-10 KFT layer - thus reflectivity is showing bright banding. METAR and mesonet data show SFC temps are now at or just above freezing. ZR advisory will expire at 15Z on schedule. Diffuse warm front shows up in the SFC analysis over SE MA with weak low pressure over the NY City area. This weak wave of low pressure rapidly track to east of Boston by mid-afternoon. Rain thus ends from west to east and expecting a cloudy, but dry evening commute.
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&& .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... Tonight... Abundant clouds linger. Lots of low level moisture in the lowest 3,000 feet above the ground in the wake of a low pressure moving offshore. As previously mentioned, cannot completely rule out some patchy drizzle. Still not expecting temperatures to fall much, even with a weak cold front moving through. Tuesday... 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 THROUGH SUNDAY/...
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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... 00z 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.
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&& .AVIATION /14Z MONDAY THROUGH FRIDAY/...
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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 Tuesday Night/...High confidence. Today...-RA/RA with MVFR- LIFR cigs with light E winds initially turning SE and increasing. Tonight...RA diminishing, however IFR-LIFR cigs remain. Could see areas of -DZ. Light winds. Tuesday...MVFR conditions likely in areas of rain and fog, with a trend lowering to IFR as frontal boundary and surface low approach. Low risk for thunder toward the south coast. KBOS TAF...LIFR lowering to IFR in rain. KBDL TAF...IFR lowering to IFR. Outlook /Wednesday through Friday/... Tuesday night...High confidence. MVFR conditions within any passing rain showers with improving cigs to VFR by the morning hours. Low risk for thunder across the south coast. 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.
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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 Tuesday Night/...Moderate confidence. Today...Warm front will lift across the waters, resulting in an increasing southeast flow. 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 across Cape Cod Bay and Nantucket Sound. Have less confidence across those waters, so did not expand an Advisory there. That will need to be monitored as the day progresses. 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 through Friday/... 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.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...None.
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&& $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...

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