Area Forecast Discussion
Issued by NWS Boston, MA

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839 FXUS61 KBOX 192337 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 637 PM EST Sun Nov 19 2017 .SYNOPSIS... Blustery and cold conditions will prevail tonight into Monday. Winds shift to southwest with milder temperatures on Tuesday, followed by a cold front sweeping across the region that will bring showers late Tuesday night and Wednesday morning. Dry and colder conditions expected late Wednesday through the end of the week. Well below average temperatures will spill into the region this weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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700 PM Update... Wind advisory has been expired as gusts across southern New England have been below criteria over the past hour or two. Many spots are still gusting around 30-33 kts but conditions should begin to subside over the next few hours. Breezy westerly winds will remain during the overnight hours which will limit temps from radiating out. Aside from the wind, cloud cover is advancing eastward ahead of the secondary trough. Went ahead and increased cloud cover for the overnight period. Otherwise the bulk of the forecast remains on track for tonight. Previous Discussion... Secondary mid level trough and shortwave moves into New Eng tonight with cooling temps aloft. 500 mb temps down to -35C by 12z Mon. This combined with some moistening of the column in the low and mid levels may result in a few flurries or snow showers, mainly western MA and northern CT where some lake effect moisture may spill into the region. Hi-res guidance just showing some spotty light QPF so continued slight chc pops in the west. While peak of the wind will be diminishing tonight, it will remain blustery with gusts 25-30 mph at times as cold advection continues. Lows mid 20s to lower 30s but the wind will make it feel considerably colder.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Monday... Mid level trough exits the region with high pres building south of New Eng. It will be a dry day, but area of low and mid level moisture moving through will result in sct-bkn cu developing. 850 mb temps starting out -10 to -12C with some moderation in the afternoon. Chilly day with highs ranging from mid 30s interior high terrain to lower 40s coastal plain. Strong pressure gradient remains in place so it will be another windy day. Soundings are well mixed in the lower levels and suggest potential for gusts 30-40 mph at times, especially through 18z. Strongest gusts expected over interior northern MA. Monday night... High pres moves off mid Atlc coast with area of mid level moisture lifting to the north so expect mostly clear skies. Winds will be diminishing and backing to the SW and there will still be enough gradient so not as cold as it otherwise would be if winds were calm. Generally followed a blend of MOS guidance for min temps. Temps will likely slowly rise overnight along the south coast and Cape/Islands. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Warm but windy for Tuesday * Cold frontal passage on Wednesday will drop temps through the day with showers. * Dry but chilly for Thanksgiving day Pattern Overview/Confidence... Building high pressure over Baja California will push the ridge into the Western CONUS for next week. This in combination of the blocking high over northeastern Canada and Greenland will favor East Coast troughing through the period. 12z Models and their ensembles are in good agreement on the large scale pattern. However, some differences will remain on timing and amplitude of each wave. Overall trend in the forecast for southern New England will be wet weather for Wednesday with drying trend into the end of the week. Will have to continue to watch the weekend as with offshore low to the east and approaching system from the West and how those two systems will impact each other. Otherwise temperatures will trend below average for the week. Details... Tuesday into Wednesday...High confidence. Mid-level ridge will build over the region on Tuesday as winds switch to the SW and WAA returns. Temperatures will warm within this southwesterly wind as 50`s return back to the region. A few sites may be near 60F depending on how much mixing occurs. Approaching cold front from the west will result in a developing LLJ with 925mb winds reaching 40-45 kts. Once again another windy day on Tuesday. Cold front from the Great Lakes will pass through the region on Wednesday. A coastal low off the coast of the Carolinas appears to ride along or out ahead of the front. Latest guidance continues to trend this low closer to the region, thus allowing for more moisture in the mid-levels. The GFS appears to be on the slow end of the developing low, thus not capturing enough moisture when the front moves through. Therefore trended with the EC/UKMET/NAM for this portion of the forecast. Precip will begin to overspread the region overnight and result in widespread rainfall Wed morning. Highest confidence is south and east of I-95, closer to the mid-level moisture. Regardless appears that most of the region will see some rainfall, which highest amounts closer to SE MA. One thing we will have to watch on Wednesday is the available moisture and timing of the CAA. Some guidance indicates that a few flakes can fly on the backside of the front. Uncertain on if there will be moisture. Regardless, trend is only trace to less than if it does accumulate on the roads. Thanksgiving into Friday...High confidence. Behind the front on Wednesday, CAA will move back into the region for Thursday. High pressure will move south of the region resulting in a chilly but dry day for Thanksgiving. Passing shortwave to the north Friday morning may bring in some clouds, but another dry but more seasonable day. The weekend...Low confidence. High pressure and mid-level ridge Friday night will lead to a warming trend on Saturday. Winds will back to the southwest as another front from the west approaches. Behind this system anomolous cold air will spill into the region putting temps well below average. While a few waves will move through this period, overall precip looks light. && .AVIATION /00Z 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 Monday Night/...High confidence. Tonight...VFR with sct-bkn cigs 040-050 developing. A few lake effect snow showers may spill into western MA and northern CT tonight. W/NW winds diminishing but remaining gusty with 25-30 kt gusts. Monday...VFR. Sct-bkn cigs 050-060. West gusts 25-35 kt. Monday night...VFR. Diminishing wind. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Tuesday through Friday/... Tuesday: VFR. Windy with gusts to 30 kt. Tuesday Night: Mainly VFR, with areas MVFR possible. Windy with gusts to 35 kt. Chance SHRA. Wednesday: Mainly VFR, with areas MVFR possible. Breezy. SHRA likely. Wednesday Night: VFR. Breezy. Thanksgiving Day through Friday: VFR.
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&& .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/... Near gale force gusts will continue tonight. Winds may diminish below gale for a time tonight but another surge of stronger winds expected by Mon morning. As a result we extended the gales into Monday for most of the waters. Winds gradually diminish Mon night to near 25 kt. Outlook /Tuesday through Friday/... Tuesday: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Tuesday Night: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Rain showers likely. Wednesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Rain showers likely. Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Thanksgiving Day: Winds less than 25 kt. Areas of rough seas. Thursday Night through Friday: Winds less than 25 kt. Seas up to 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Gale Warning until 2 PM EST Monday for ANZ232>235-255-256. Gale Warning until 10 PM EST this evening for ANZ230-236-237. Gale Warning until 6 PM EST Monday for ANZ231-250-251-254.
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&& $$ SYNOPSIS...KJC/Dunten NEAR TERM...KJC/Dunten SHORT TERM...KJC LONG TERM...Dunten AVIATION...KJC/Dunten MARINE...KJC/Dunten

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