Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 142231 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 531 PM EST Tue Feb 14 2017 .SYNOPSIS...
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Quiet and dry weather continues tonight. Another storm center develops Wednesday into Wednesday night across the Gulf of Maine, bringing a period of rain and/or snow to much of the region. The low will be in the Canadian Maritimes Thursday and Friday, bringing mainly dry but blustery and cold weather to the region. Dry weather continues this weekend, but with a significant moderation in temperatures especially by Sunday when much of the region may see highs exceeding 50.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Other than leftover high clouds passing across the region, noting mostly clear skies across most of the region. Area of mid level clouds working across western NY state will approach western areas late tonight, then push eastward overnight. Some lower clouds will work into inland areas after midnight. Will also start to see some patchy light snow push in as weak low pressure heads SE out of southern Ontario into upstate NY. Noting decent overrunning setting up ahead of warm front. This lift will allow light snow to develop. Not a whole lot of QPF amounts with this system in moisture starved W-SW flow ahead of approaching H5 short wave. Expect less than 0.1 inches melted by daybreak, so should only a dusting across some locations, possibly up to 1/2 inch across the higher inland terrain. However, will see lower rain/snow ratios with generally light S-SW flow in place. With this somewhat milder albeit light S-SW winds, temps will have a tough time falling overnight. Will probably fall prior to midnight, down to the 20s at most locations by 05Z-06Z, then will hold steady or may even slowly rise especially across south coastal areas.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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Wednesday and Wednesday night...Moderate confidence. A lot of questions in play during this timeframe. Models have varying solutions in handling development of secondary low pressure tracking NE out of the Carolinas to the E coast during Wednesday. Noting decent short wave in the southern stream flow moving off the Carolinas, hooking up with a strong northern stream H5 short wave. Models starting to merge the two waves as they move off the New England coast. In the meantime, surface low moves near or just S of the 40N/70W benchmark by around 00Z Thu. With this low moving NE, rounding the developing cutoff H5 low, looks like an inverted trough may try to set up somewhere across the region. Each model in the suite has its own solution, anywhere from across E Mass/SE NH to the SW Maine coast early Wed night. Noting the surface low moves to the Gulf of Maine and deepens rapidly overnight. Big question at this point will be whether the inverted trough tries to wrap around this developing low SW of Nova Scotia back into NE and N Central Mass, bringing some more decent snowfall late Wed and Wed night, or if the low will continue to track into the Maritimes. At this point, will see best chance for precip during the day Wed, but milder air will work in on southerly winds, temps will top off in the upper 30s to lower 40s across the coastal plain allowing any snow will change to rain. Across inland areas, will see snow and/or rain, especially across the higher terrain. With lowering rain/snow ratios, only expecting light snow accumulations. As the low moves offshore, winds shift to W and colder air will cause the precip to change back to snow but again, should be light amounts depending upon the ultimate solution to this weather scenario. Have carried best chance for precip near and N of the Mass Pike Wed night, leaning toward a bit further N solution with the inverted trough set up, for now. Winds will shift to W and increase as strong low level jet passes. Could see gusts up to around 25 kt across the higher inland terrain mainly after midnight, and possibly up to 30- 35 kt across Cape Cod and the islands. Expect temps to fall back through the 20s to around 30.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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Highlights... * A few snow showers possible Thu otherwise dry into Mon * Blustery and cold Thu into Fri * Moderating temps Sat and unseasonably mild by Sun * Above normal temps continue into early next week Details... Thursday... Rapidly intensifying low pressure will be already lifting into the Canadian Maritimes Thursday morning. While the inverted trough axis extending back from the storm will have weakened, left over low level moisture coupled with shortwave energy/cold pool aloft may result in a few snow showers. Highest risk will be in northern and eastern MA, where better low level moisture will exist. Otherwise, the majority of the day will be dry but strong cold advection behind the system will keep highs in the 30s. Northwest wind gusts of 25 to 35 mph are also expected with good mixing in the cold air advection pattern. Thursday night and Friday... Strong low pressure over the Canadian Maritimes will only slowly lift northeast as a weak ridge of high pressure approaches from this midwest. This should result in mainly dry but cold and blustery weather across the region Thu night/Fri. Low temps Thu night mainly in the teens to lower 20s. Highs on Thu generally in the lower to middle 30s. Saturday and Sunday... Upper trough moves northeast of the region allowing for rising height fields and more zonal flow. So while it will remain dry, the result will be much milder air overspreading the region from the west. High temps should recover into the upper 30s to lower 40s on Saturday, but by Sunday expect highs to break 50 across much of the region. Monday and Tuesday... A backdoor cold front will bring a bit cooler temperatures on Monday, but highs still probably well up into the 40s with above normal temps continuing into early next week. A shortwave may bring a few showers to the region Tuesday afternoon/night, but best forcing/dynamics will probably pass to our north and west.
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&& .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Range /through Wednesday night/... Through 00Z...High confidence. VFR. Tonight...High confidence. Mainly VFR through 06Z. Will see MVFR-IFR CIGS develop across central and N Mass as patchy -SN moves in. May see a dusting toward daybreak. Wednesday...Moderate confidence. Mainly MVFR-IFR CIGS/MVFR VSBYS. Will see areas of -RN and/or -SN. Best chance for -SN across central and N Mass, mainly -RA along the coastal plain by 16Z-18z. S-SE winds gusting to 20-25 kt across Cape Cod and the islands during the afternoon. Winds shift to W from W-E after 18Z. Wednesday night...Moderate confidence. Precip changes to -SN before tapering off across N CT/RI/SE Mass with mainly VFR conditions. May see patchy -SN lingering near and N of the Mass Pike extending to the outer Cape through the night with areas of MVFR conditions. W winds gusting to around 30 kt across Cape Cod and the islands around or after midnight. KBOS TAF...High confidence in TAF. Weak sea breeze should kick out, with wind becoming SW at 5-8 kt by 23Z-00Z. KBDL TAF...High confidence in TAF. Outlook /Thursday through Sunday/... Thursday...Moderate confidence. Some MVFR ceiling along with a few snow showers remain possible particularly across northern and eastern MA into Thu afternoon. Otherwise, northwest wind gusts of 20 to 30 knots expected. Friday through Sunday...High confidence in mainly VFR conditions.
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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 Range /through Wednesday night/... Moderate to high confidence. Tonight...Expect W-SW winds around 10 kt, backing to S after midnight. Seas remain at or above 5 ft across the eastern open waters to S of Nantucket where small crafts continue. May see local visibility restrictions toward daybreak in patchy light snow. Wednesday...S-SE winds gusting up to 25 kt by mid-late morning, strongest across the eastern waters. Winds shift to W across the southern waters during the afternoon. Seas build up to 6-10 ft by midday. Visibility restrictions in light rain and/or snow. Wednesday night...Winds shift to W in the evening on the eastern waters. Winds gusting up to 25-35 kt around or after midnight. Have issued Gale Watch on the outer waters as well as Cape Cod Bay, Rhode Island/Block Island and Nantucket sounds. Visibility restrictions in lingering light snow mainly across the eastern waters to Cape Cod. Outlook /Thursday through Sunday/... Thursday and Thursday night...Moderate to high confidence. Cold advection will result in northwest wind gusts of 30 to 35 knots Thu into Thu night so Gale Watches will be issued. The airmass will be cold enough to support some light freezing spray late Thu night. Friday...Moderate to high confidence. While pressure gradient weakens a bit, still expect northwest wind gusts of 20 to 30 knots and small craft headlines will be needed for most waters. Saturday and Sunday...Moderate to high confidence. Weak pressure gradient should keep winds and seas generally below small craft advisory thresholds.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Gale Watch from late Wednesday night through Thursday morning for ANZ231-232. Small Craft Advisory until 6 PM EST Wednesday for ANZ231-250- 251-254>256. Gale Watch from late Wednesday night through Thursday evening for ANZ235-237. Gale Watch from Wednesday evening through Thursday evening for ANZ250-254>256.
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&& $$ SYNOPSIS...Frank/EVT NEAR TERM...EVT SHORT TERM...EVT LONG TERM...Frank AVIATION...Frank/EVT MARINE...Frank/EVT

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