Area Forecast Discussion
Issued by NWS Boston, MA

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332 FXUS61 KBOX 160850 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 450 AM EDT Mon Oct 16 2017 .SYNOPSIS... A strong cold front sweeps across the region early this morning and is accompanied by scattered showers, then moves offshore later this morning into early afternoon. Behind the front, it turns sharply cooler and brisk this afternoon with temperatures then dropping down close to freezing by daybreak Tuesday. Gradual warm up begins Wednesday and continues into the weekend. After this mornings showers, dry weather prevails the remainder of the workweek and likely through the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Cold front continues to slowly but steadily shift SE across the region at 08Z. Winds have shifted to W-NW from KBOS-KIJD S and W as seen on latest observations, with dewpoints falling to the lower-mid 50s behind the front. Temps remain in the mid 60s to around 70s across RI/SE Mass with patchy fog and scattered showers. The front will push off the S coast by around 12Z or so, then continue to shift well offshore. Will see some W-NW winds gusting up to around 25 mph this morning as the colder air works across the region, highest across the higher inland terrain and along the coast. Winds will briefly diminish around midday into the afternoon before starting to pick up again by nightfall as the main surge of colder air works in. Highs for today have already occurred early this morning. The daytime highs will occur by midday, only in the mid 50s across the higher terrain to the mid 60s along the coast. It will feel cooler though with the brisk winds. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Tonight... Leading edge of large high pressure will build east out of NY state tonight. The colder air over the milder waters will keep N winds stirring during the night, but as the pressure gradient relaxes, winds away from the coast will diminish especially after midnight. Some clouds will linger along E coastal areas through the night, also helping keep temps milder there. With mainly clear skies and the light winds, will see ideal radiational cooling away from the coast and urban centers. Temps will quickly tumble overnight and, with dewpoints falling to the upper 20s to lower 30s inland, will see temps drop as well. Expect areas of frost across many inland locations, with a few spots possibly bottoming out around the freezing mark. Have issued a frost advisory from 3 AM to 8 AM for most locations away from the coast and urban centers. Areas not included were N central and NW Mass where the growing season ended on Sunday. Expect lows in the lower-mid 30s in the advisory area, ranging to the 40s along the immediate coast, Cape Cod and the islands. Tuesday... As the high becomes firmly established across the region, winds along coastal areas will gradually diminish from about midday through the afternoon. Lingering clouds across the Cape and islands Tue morning will push offshore during the afternoon. Elsewhere, expect mostly sunny to sunny skies. Expect temps to top off in the 50s to around 60, running up to 5 degrees below seasonal normals. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... 355 AM update... * Highlights... - Warmer than normal this period with highs in the 70s Thu-Sat-Sun - Dry weather through the workweek and likely into the weekend * Synoptic Overview... Several low amplitude northern stream short waves ride the Canadian/US border this period. Given the lack of amplitude each trough is moisture starved. Thus very little if any sensible weather across southern New England this period with each short wave passage just providing a wind shift and a reinforcing surge of dry air. Tuesday night... Not as cool as Mon night as the high moves south of New England with low level WAA commencing as winds become WSW. Seasonably cool with lows 35-40, except in the 40s urban areas, high terrain, Cape & Islands. Dry weather prevails. Wednesday... Real nice day with 1028 mb high south of New England providing low level westerly flow advecting 925 mb temps of +11C across the region. This will support highs 65-70. Mild temps will be accompanied by light WSW winds and model RH cross sections suggesting lots of sunshine. Thursday... Next short wave trough moves across the northern Great Lakes into southern Ontario and Quebec. Good low level WAA ahead of this feature with 925 mb temps warming to +14C here in southern New England. These warm temps aloft combined with modest WSW surface winds and mostly sunny conditions will support highs in the low 70s away from the south coast. No precip expected, just a dry frontal passage given the lack of moisture associated with northern stream short wave. It will turn breezy as pres gradient tightens ahead of trough. Model soundings suggest SW winds gusting up to 25-30 mph. Friday... Not much thermal change in the post frontal airmass with 925 mb temps only cooling off to about +11C to +12C. High pres over the OH valley provides a well mixed blyr across New England with NW surface winds. This combination along with mostly sunny conditions will support highs 65-70. Another real nice day especially by late Oct standards. Next Weekend... Subtropical ridge builds over the southeast states into the Mid Atlantic region providing dry weather along with unseasonably warm temperatures here with highs well into the 70s especially Sunday. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...High confidence. Through 12Z... CIGS have been gradually rising across most of the region with some IFR CIGS lingering across the immediate S coast, Cape Cod and the islands at 05Z, with mainly VFR VSBYS. Will see slowly improving CIGS as cold front passes, though sct -SHRA may bring brief MVFR VSBYS. Winds quickly shift to W-NW and may briefly gust up to around 35 kt. Cold front should push to our just off the S coast by around 12Z. Today... Sct -SHRA across S coastal areas move offshore by midday, though a few may linger into early afternoon along the immediate S coast and the islands. Any leftover patchy MVFR VSBYS will improve by midday. SW winds shift to NW as front passes. Gusts around 20 to 25 kt. Tonight... Patchy SCT-BKN VFR clouds linger across Cape Cod, KACK and KMVY early, then should push offshore. N-NW wind gusts up to 20-25 kt along the immediate coast through around midnight, lingering through the night across Cape/Islands. Tuesday... VFR with mostly clear to clear skies. N wind gusts up to around 20 kt across Cape/Islands Tue morning, then diminish. KBOS Terminal...SW wind gusts up to 25 kt through around 09Z, then will shift to W-NW with brief gust up to 30 kt possible as cold front passes. MVFR CIGS through around 09Z-10Z, then improve to VFR. May see some NW wind gusts up to around 20 kt early tonight. KBDL Terminal...N-NW winds around 10-15 kt, may gust up to 20 kt through 09Z. Sct -SHRA push S of the terminal with MVFR CIGS/VSBYS improving to VFR. Expect N-NW wind 10-15 kt into this evening, then slowly diminishing after 04Z tonight. Outlook /Tuesday Night through Friday/...high confidence. 355 AM update... VFR, dry runways and good vsbys. WSW winds may approach 25 kt Thu. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...High confidence. Today... Cold front pushes across Cape Cod and the southern waters this morning. Expect SW winds to shift to NW and gust up to 25 to 30 kt, but will briefly diminish around midday before picking up again this afternoon as colder air works across the waters. Scattered showers may produce brief visibility restrictions across the southern waters this morning. Small Craft Advisories on the outer waters have been extended into Tuesday. Winds and seas on the near shore waters will diminish during the day. Tonight and Tuesday... N-NW winds will gust to around 25 kt early tonight, then will diminish across the open waters. However, seas will remain at or above 5 ft through Tuesday, so Small Craft headlines will continue across the outer waters. Outlook /Tuesday Night through Friday/...Moderate confidence. 355 AM update... Overall quiet/tranquil boating weather by mid to late October standards. Only potential issue will be Thu when WSW winds may gusts up to 25 kt near shore ahead of an approaching weak/dry cold front. Otherwise good vsby and dry weather through the period. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Frost Advisory from 3 AM to 8 AM EDT Tuesday for CTZ002>004. MA...Frost Advisory from 3 AM to 8 AM EDT Tuesday for MAZ005-006- 009>014-017-018-020-021-026. RI...Frost Advisory from 3 AM to 8 AM EDT Tuesday for RIZ001-003- 006. MARINE...Small Craft Advisory until 11 AM EDT this morning for ANZ231>234. Small Craft Advisory until noon EDT today for ANZ235-237-251. Small Craft Advisory until 2 PM EDT Tuesday for ANZ250. Small Craft Advisory until 5 PM EDT Tuesday for ANZ254-255. Small Craft Advisory until noon EDT Tuesday for ANZ256. && $$ SYNOPSIS...Nocera/EVT NEAR TERM...EVT SHORT TERM...EVT LONG TERM...Nocera AVIATION...Nocera/EVT MARINE...Nocera/EVT

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