Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 062048 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 348 PM EST Wed Dec 6 2017 .SYNOPSIS...
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Dry and seasonably chilly weather is forecast for tonight and Thursday, into part of Friday. Low pressure will bring the potential for minor snow accumulations Friday night and Saturday across Rhode Island and Southeast Massachusetts, but an impact further back across the interior can not be ruled out. Temperatures will average a bit below normal into early next week with perhaps a coastal storm bring the potential for some rain and/or snow next Tuesday into Wednesday.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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This evening/tonight... 345 pm update... Cold air advection persisted this afternoon, as temps remained nearly steady or slowly fell. For tonight surface ridging extends into southern New England. Expecting mostly clear skies with light west winds, with some cirrus brushing us from the south this evening. Exception could be over the higher terrain of the east slopes of the Berkshires, where lake effect moisture could bring some stratocumulus. Elsewhere, low level westerly flow expected to provide a downslope component to limit spread of any stratocumulus. Expecting good radiational cooling tonight with overnight lows in the 20s, except some low to mid 30s near the shoreline.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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Thursday... Weather influenced by high pressure centered to the SW of our area, as well as dry air from SW mid level flow. Just enough moisture in the low levels to produce some diurnal stratocumulus, mostly sunny skies expected. Low level winds out of the west continue to provide a downsloping component. Temperatures will remain seasonable with highs in the upper 30s to mid 40s, though some locales in the higher terrain of the east slopes of the Berkshires only reach the mid 30s. Thursday night... Dry and cold weather expected Thu night with weak surface ridging and continued SW mid level flow. Our area is in between low pressure systems, one to the NW over the Great Lakes region, and another well to the S. Mostly clear to partly cloudy skies along with light winds should allow for overnight lows in the upper teens and 20s. Could see somewhat less cold lows in the low to mid 30s along some portions of the shoreline.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Highlights... * A bit of accumulating snow possible Fri night/Sat...Low confidence * Chilly with a few snow showers possible Sunday * Potential coastal storm may bring rain/snow to the region next Tue/Wed with unseasonably cold weather to follow Thursday night... Dry and cold weather expected Thu night. Mostly clear to partly cloudy skies along with light winds should allow for low temps to bottom out in the upper teens to middle 20s in most locations by daybreak Friday. Friday... Partial sunshine in the morning should give way to an increase in clouds from the south during the afternoon. This in response to shortwave energy approaching from the west and some weak waves of low pressure off the Carolina coast. Much of the day should remain dry, but a bit of rain/wet snow may work onto the far southeast New England coast late in the day/early evening. High temps will mainly be in the upper 30s to the lower 40s. Friday night and Saturday... Tremendous uncertainty continues in this portion of the forecast. Several pieces of northern stream energy will dig a trough to our west, as low pressure track northeastward off the coast. The majority of the 00z guidance indicates the potential for some light snow or rain/snow mix grazing portions of the region, mainly RI and SE MA. This would bring the potential for a light accumulating snowfall to portions of this region Friday night and Saturday. It is important to remember that there is a lot of uncertainty on how this evolves given that the threat is 72+ hours out on the model guidance. A lot of this will depend upon how far south this trough digs, which will determine how close to the coast low pressure will track. Looking at the individual GEFS/EPS ensemble members reflects this uncertainty nicely. There are some members depicting complete misses, keeping our weather mainly dry as precipitation remains out over the ocean. Other ensemble members bring a light accumulating snowfall to portions of the region with the focus across southeast MA/RI. Finally, there are even a couple of members that show a moderate snowfall back into the interior while the coastal plain is mild enough for a rain/snow mixture. In a nutshell, odds favor a glancing blow Friday night and Saturday with the potential for a light accumulating snow mainly across Rhode Island and Southeast MA. Nonetheless, other options remain on the table. These include a complete miss or the potential for a light to moderate snowfall further back into the interior with boundary layer issues moving onto the coastal plain. Sunday... Vigorous shortwave energy sweeps through the region with perhaps a few snow showers. It will be rather chilly too with high temps mainly in the 30s. Monday through Wednesday... Dry and chilly weather should dominate Monday with high temps mainly in the 30s to near 40. Unsettled weather may return Tuesday into Wednesday as models indicate the potential for a developing coastal storm, that may bring rain and/or snow to the region depending on the track/timing/intensity. Obviously, considerable uncertainty on that given its nearly a week out. Regardless, unseasonably cold air looks to follow for the second half of next week. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
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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 Thursday Night/... 2045Z Update... Tonight into Tomorrow...High confidence. VFR. West wind 5-15 kts during Thu, highest near the shoreline. Thursday Night...VFR. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF.TIDES/COASTAL FLOODING... Outlook /Friday through Monday/... Thursday Night through Friday: VFR. Breezy. Friday Night: Mainly VFR, with areas IFR possible. Breezy. Chance SN.TIDES/COASTAL FLOODING... Saturday: MVFR/IFR conditions possible. Breezy. Chance SN, chance RA. Saturday Night: MVFR/IFR conditions possible. Breezy. Chance SN, chance SHSN. Sunday: MVFR/IFR conditions possible. Breezy. Slight chance SHSN.
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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 Thursday Night/...High confidence. Tonight and Thu...West winds persist overnight and on Thu. Lingering southerly swell keeps rough seas over the southern and eastern outer coastal waters as well as RI/BI Sounds. Could also have some gusts to 25 kts tonight on the southern outer coastal waters. Small Craft Advisory continues thru tonight and into Thu for those areas. Thursday Night...Lingering swell keeps rough seas (and SCA headlines) over the southern outer coastal waters and the waters east of Cape Cod. It may also bring the need for renewed SCA headlines for seas across the southern outer coastal waters and RI/BI Sounds. Also a chance for wind gusts up to 25 kt. Outlook /Friday through Monday/...Moderate to high Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain. Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Rain likely. Local visibility 1 to 3 nm. Saturday: Winds less than 25 kt. Rain likely. Saturday Night: Winds less than 25 kt. Local rough seas. Chance of rain, chance of rain showers. Local visibility 1 to 3 nm. Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain showers. Local visibility 1 to 3 nm.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 2 PM EST Thursday for ANZ235-237- 250. Small Craft Advisory until 5 AM EST Friday for ANZ254>256.
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&& $$ SYNOPSIS...Frank/NMB NEAR TERM...NMB SHORT TERM...NMB LONG TERM...Frank AVIATION...Frank/NMB MARINE...Frank/NMB

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