Area Forecast Discussion
Issued by NWS Boston, MA

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975 FXUS61 KBOX 260850 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 350 AM EST Sun Feb 26 2017 .SYNOPSIS... High pressure centered south of New England brings dry weather today and Monday. Cold air briefly visits for today, then milder air moves back in on Monday. A couple of weather systems will bring periods of wet weather Tuesday into Thursday. Colder air returns late next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Upper shortwave moves east of our area this morning. Colder drier air moves in on northwest winds. There is sufficient cold advection to support mixing up to 850 mb. Winds in this layer reach 30 knots, so expect gusts of 25-30 knots during the day. The mixing diminishes toward sunset, by which point winds will diminish. Dry air through most of the airmass today. Cross sections do show lingering moisture 850-900 mb, which should be enough to form some diurnal clouds. Expect partly to mostly sunny skies. Temperatures at 850 mb cool to -8C over the Southeast and -10C over northern and western MA. This supports max sfc temps in the upper 30s to mid 40s. With enough sunshine, mixing may extend a little higher than 850 mb and allow sfc temps to reach the upper 40s in some spots. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
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Tonight...High Confidence. Surface ridge remains in place to our south. A shortwave moving across Canada pushes a weak cold front to the Canadian border and tightens the pressure gradient over New England, especially northern New England. The gradient over Southern New England will be lighter, and more conductive to radiational cooling. With dew points in the teens, min temps in the coldest spots will likely nudge into the teens, while the remaining areas will have mins in the 20s. Monday...High Confidence. High pressure remains to our south, with surface winds trending west-southwest. Diurnal heating will again create a mixed layer to around 850 mb. Winds in this layer reach 30 knots, and GFS suggests some potential for 35 knots just above the layer. Expect gusty WSW winds. Temperatures at 850 mb are forecast at -3C to -5C, which would support max sfc temps in the 50s. The WSW wind may keep temps a little cooler at the south coast.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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Highlights... * Above average temperatures for next week * Widespread showers possible Tuesday through late Wednesday * More seasonable conditions return on Friday Pattern Overview... 00z models and ensembles remain in generally good agreement and a consensus approach was used. Overall, frontal boundary is forecast to progress through the East during the Wed-Thur timeframe. Upper level trough will remain over the region into next weekend resulting in seasonable conditions. Guidance continues to struggle with strengthen and timing of each wave so an average solution was preferred given the jumpiness in timing/track over the past several days. Details... Tuesday...High confidence. Bermuda high will build south of the region on Tuesday as upper level trough moves over the Plains, putting the region in southwesterly flow. Upper level warm front will approach from the south during the day resulting in showery weather. Still some issues on surface temps and how far north the warm front will lift, so cannot rule some wet flakes north of the Pike, but confidence is low on this occurring. Guidance continues to show the higher theta-e plume moving to the region during the latter half of the day and with an approaching upper level jet, could see some heavy rain late Tuesday as surface low develops. Still timing issues with this system but something to keep an eye on. Temperatures will be above normal with highs rebounding back into the low to mid 50s. Wednesday into Thursday... Moderate confidence. Main weather producer will occur Wednesday into Thursday. Still some uncertainty on the timing and location of the surface low. Southern New England will remain in the warm sector starting Wednesday as upper level trough approaches from the west. This system will drag a cold front across the region by Thursday. Stout southwesterly LLJ near 60 kts will develop ahead of the system. This will tap into Gulf moisture, pushing PWAT values 2-3 STD above normal for this time of year. Moisture flux will be on the increase as the frontal system approaches so anticipate a period of moderate to perhaps heavy rain on Wednesday into Wednesday night. Lapse rates will also steepen to 7 c/km as well as LI dropping below 0 resulting in the potential for thunder. While the whole period don`t be wet, as dry air intrudes in the mid-levels at times, appears that a good slug of rain can fall. Will need to monitor this system as stout mid- level ridge to the south could either slow the system down or push the better dynamics to the north and west of southern New England. Regardless have high confidence that precipitation will fall and temperatures will be above average on Wednesday into Wednesday night. Cold front will sweep through during the the day on Thursday resulting in temperatures falling throughout the day. Still timing issues on FROPA but appears that gusty winds will follow suite as model sounding indicating good mixing. Friday and beyond... Moderate confidence. As the cold front passes through, northwest winds take a hold of the region. Models continue to indicate the potential for a clipper system on Friday/Saturday. This will bring reinforcing cold air to the region allowing temperatures to fall back towards seasonable. Good mixing and cold air over the ocean may result in ocean effect snow showers over the weekend before another clipper system comes through towards the end of the weekend.
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&& .AVIATION /09Z SUNDAY THROUGH THURSDAY/...
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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/... Today... High Confidence. VFR through the period. Enough moisture at 4000-5000 feet to support scattered to broken cigs at that level. Winds up to this level will reach 30 to 35 knots, supporting surface gusts to those speeds during the day. Expect winds to diminish by late in the day. Tonight... High Confidence. VFR with diminishing wind. Trend to light winds in the interior overnight. Monday... High Confidence. VFR with WSW winds gusting to 30 knots. KBOS TAF...VFR. Gusty NW winds to 30 knots. High confidence in TAF. KBDL TAF...VFR. Gusty NW winds to 25 knots. High confidence in TAF. Outlook /Monday Night through Thursday/... Tuesday into Wednesday...Moderate confidence. Periods of -RA through the period will result in MVFR/IFR conditions. Cannot rule out LIFR in fog during the overnight hours. Thursday...Moderate confidence. Improving conditions from west to east during the latter half of the day. Blustery westerly winds are possible.
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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 Monday/...High confidence. Today...NW winds gusting 30-35 knots, slowly diminishing in the afternoon. Seas linger at 5 to 8 feet on the exposed waters most of the day. A Gale Warning is in effect for most of the waters, and we will maintain this. Small Craft Advisory in effect for Boston Harbor, Narragansett Bay, and Block Island Sound. Tonight... Diminishing winds turning West and possibly SW overnight. Gusts near 20 knots. Diminishing seas overnight with lingering 5 foot heights on the outer waters. Monday... WSW winds with gusts 25 to 30 knots. A Small Craft Advisory will be needed on at least some of the waters. Outlook /Monday Night through Thursday/... Tuesday...Moderate confidence. Improving conditions across the waters as high pressure passes southward. Warm frontal passage late Tuesday could drop vsbys in rain and fog. Wednesday into Thursday...Moderate confidence. Approaching system from the west will push a cold front through on Thursday, increasing both seas and winds during the period. Heavy rain and thunder is possible lowering vsbys. There is the potential for southerly gales across the waters Wed night and northwesterly gales on Thursday behind the cold front.
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&& .HYDROLOGY... Rising water levels, partly from rain overnight but also from snowmelt in Northern New England. A couple of rivers in the CT River Valley rose above alert stage during the night, but crested below warning stage. Others crested below alert stage. There is still plenty of water moving downriver from the snowpack. We will need to monitor water levels across southern New England for a while this week. && .CLIMATE... RECORD HIGH TEMPS FOR YESTERDAY BOS 69 * breaks old record 65/1930 PVD 63 * no record BDL 70 * tied old record 70/1976 ORH 65 * breaks old record 64/1976 RECORD HIGH MIN TEMPS FOR YESTERDAY BOS 49 * breaks old record 46/1891 PVD 47 * breaks old record 45/1930 BDL 41 * no record ORH 40 * breaks old record 37/1996, 1984, 1976 DEW POINTS OF NOTE FOR YESTERDAY BOS Max Dew Point 56 is highest for date. Previous high 52/1985 PVD Max Dew Point 54 is highest for date. Previous high 51/1965 BDL Max Dew Point 58 is highest for date. Previous high 48/1984 ORH Max Dew Point 55 is highest for date. Previous high 47/1985 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Gale Warning until 11 AM EST this morning for ANZ231>235-251. Small Craft Advisory until 7 PM EST this evening for ANZ230- 236. Small Craft Advisory until 10 PM EST this evening for ANZ237. Gale Warning until 2 PM EST this afternoon for ANZ250-254>256. && $$ SYNOPSIS...WTB/Dunten NEAR TERM...WTB SHORT TERM...WTB LONG TERM...Dunten AVIATION...WTB/Dunten MARINE...WTB/Dunten HYDROLOGY...WTB CLIMATE...WTB

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