Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 210715 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 215 AM EST Tue Feb 21 2017 .SYNOPSIS... High pressure centered over New England today moves offshore tonight and Wednesday. This brings us dry weather and a trend toward milder temperatures through the week. A weak cold front dissipates as it crosses New England late tonight. A series of low pressure systems move through the Great Lakes Wednesday through Saturday maintaining unseasonably mild temperatures in New England, with near record warmth possible Thursday. A strong cold front will cross the region Saturday, likely bringing some rain, followed by blustery and more seasonable conditions Sunday and Monday. && .NEAR TERM /THROUGH TODAY/... Chilly start to the day with clear skies and light winds allowing radiational cooling. With inland dewpoints between 10 and 17, expect min temps in that same range. Dewpoints along the coast, especially over Cape Cod and Islands, are mostly in the 20s. Expect min temps 20-25 in those are High pressure over the region today will bring dry weather and light wind. Cirrus moves in from the Great Lakes today may thicken during the afternoon, but still expect sufficient heating to tap temps at 925 mb and bring sfc temps into the 40s. && .SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/... Tonight... High pressure shifts offshore. Airflow is light during the evening, which should allow temps to cool initially. South- southwest flow then increases a little overnight. Sky cover mostly thin in the evening with high clouds, but this thickens through the night. Because of both factors, we expect temperatures to cool in the evening, but then rise slowly after midnight. Dying cold front is being pushed along by a 105 knot upper jet which is also diminishing. Sufficient moisture for clouds overnight. Possible brief period of lift between midnight and dawn. This doesn`t inspire great confidence of pcpn, but enough to maintain low-end chance pops. If there is pcpn, what type will it be. Surface temps will be either side of freezing in the interior, and in the mid 30s closer to the coast. So there is a chance that showers may produce scattered icy spots in the interior. With the scattered distribution of the showers and their possibly drying up as they move east, expect any icy spots to be limited in coverage. But drivers will need to exercise caution. Wednesday... High pressure lingers offshore with a south-southwest flow of air into Srn New England. Lingering clouds during the morning should thin and provide at least partly sunny skies. Temps at 1000 mb and 950 mb support max sfc temps near 50. Temps at 925 mb support max sfc temps in the upper 50s. Expect max sfc temps in the 50s, possibly close to 60 if we get sufficient solar heating. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Highlights... * Record warmth possible Thu * A backdoor front may bring cooler temps Fri but low confidence * Mild with widespread showers likely sometime Sat/Sat night * Blustery and cooler Sun/Mon Overview... Guidance in general agreement on amplifying trof moving into the Rockies and Plains toward the end of the week with building downstream ridge along the east coast. This will result in a period of unseasonably mild temps into the weekend, but will have to watch a northern stream shortwave which could allow a backdoor front to cool things off around Friday. Models agree on mid level low lifting across the Great Lakes Sat with inside runner and strong cold fropa likely bringing a period of rain, although timing and details are uncertain. More seasonable and blustery conditions follow for Sun/Mon as broad trof develops across the NE. Details... Wednesday night into Thursday... On Thursday, continued SW flow will push 925 mb temps to near 12C which supports highs well into the 60s away from the south coast with partly sunny skies. Even GEFS mean 925 mb temps around 10C so above average confidence of temps above 60 Thursday with potential for some upper 60s with sufficient sunshine. Could see near record highs at some of our climate sites. See climate section below. Friday... Low confidence temp forecast as a backdoor front will be nearby and may slip south of the region. GFS and GGEM push front to the south with cooler temps while ECMWF hold the front to the north with temps in the 60s again. Expect more cloud cover Fri along with a risk of a few showers as deeper moisture moves into the region, but forcing for ascent is limited so most of the time should be dry. Saturday... Timing uncertain but widespread showers likely to move into the region sometime Sat into Sat night depending on the timing of the cold front. Pre-frontal southerly low level jet should result in more unseasonably mild temps. Sunday into Monday... A return to more seasonable temps with blustery W/NW winds as the low pres moves into the Maritimes. && .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/... Today...High confidence. VFR with some high clouds. Light wind. Tonight...Moderate confidence. VFR much of the night. Possible MVFR cigs/vsbys in showers especially over Northern CT and Western MA. Depending on surface temperatures, there may be the potential for patchy freezing rain in interior MA. Wednesday... High confidence. VFR with south-southwest wind. Leftover MVFR cigs/vsbys possible in the morning, but this will quickly improve to VFR. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. Outlook /Wednesday Night through Saturday/... Thursday...Moderate confidence. Mainly VFR. Friday...Low confidence. Potential for easterly flow and MVFR cigs if backdoor front slips to the south. However, VFR with SW winds if front remains to the north. Saturday...Moderate confidence. Potential for widespread MVFR/IFR conditions with rain overspreading the region. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/... High confidence. Today... High pressure builds over the waters. This will bring diminishing winds and seas. All lingering Small Craft Advisories will be dropped. Tonight... High pressure moves off to the east, bringing increasing wind from the south-southwest. Winds and seas remain below Small Craft thresholds. A diminishing cold front may bring scattered showers to the waters late at night. Wednesday... Any showers will dissipate. Winds will increase from the southwest, but should remain at 20 knots or less. Seas will be 3 feet or less. Outlook /Wednesday Night through Saturday/... Wednesday night into Thursday...High confidence. Mainly SW flow with gusts to 20 kt. A few gusts to 25 kt possible Thu afternoon. Friday...Low confidence. Winds will depend on location of a backdoor front. Easterly flow if the front moves to the south, but continued SW flow with gusts to 20-25 kt possible if front remains to the north. Saturday...Moderate confidence. Increasing southerly flow with SCA gusts likely. Vsbys reduced in developing rain and fog. && .CLIMATE... Record Highs for Thu Feb 23 BOS...65/1990 BDL...68/1990 PVD...60/1990 ORH...61/1990 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...WTB/KJC NEAR TERM...WTB SHORT TERM...WTB LONG TERM...KJC AVIATION...WTB/KJC MARINE...WTB/KJC CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.