Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 141930 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 330 PM EDT Thu Mar 14 2024 .SYNOPSIS...
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Clouds increase this evening with a period of rain showers after midnight into early Friday morning along with much cooler high temperatures Friday.Drying out on Saturday before another round of modest precipitation on Sunday. Cooler, but closer to normal most of next week. Lowering risk for diurnal showers as next week progresses, with the greatest risk Monday and Tuesday.
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&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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330 PM Update Tonight A very modest surface low-pressure system currently centered over The Midwest will progress east along a zonal track toward the Northeast this evening. As the system approaches, light/variable winds associated with weak-surface high pressure building east will shift and increase out of the southeast. This will allow higher amounts of moisture to flow into the region ahead of the approaching surface low. Despite the weak forcing and progressive nature of this system, the relatively higher PWATs will allow for a period of steady precipitation overnight and a modest soaking of rain. Model guidance has trended toward the surface low tracking over VT/NH, which is further north than what was being resolved yesterday. As a result, the upper end of overcast rainfall amounts of shifted further north as well. Areas along and north of I-90 can expect a modest 0.15 to 0.25 inches, while areas along and south of I-90 may observed up to 0.1 inches. Not expecting rain to begin until after midnight across the western areas and then a few hours before sunrise across the eastern areas. Low temperatures overnight will be bounded by dewpoints which are forecast to be in the low 40s.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
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Tomorrow Steady rain tapers off tomorrow morning as surface low pressure continues east over The Gulf of Maine. However, a strong-low level version will trap the low-level moisture in place and support a cloudy/dreary day with intermittent periods of light/drizzle and spotty showers through early afternoon. Warm sector air mass characterized by 925 hPa temps near 10 Celsius should support highs ranging from the low to upper 50s. Temperatures are likely to peak around or just afternoon however. After that time, northwest flow kicks in and induces cold air advection which will gradually bring temperatures down to the mid to upper 40s by tomorrow evening. Northwest flow will be accompanied by drier air which bring dewpoints down to the upper 30s and perhaps result in some skies clearing prior to sunset, particularly across the western/interior zones. Tomorrow Night Quiet/dry weather tomorrow night. Deep northwest flow advects cooler/drier air over southern New England which will result in skies gradually clearing overnight across most of the region. Cape/Islands may see clouds linger into Saturday morning. Overnight lows will be in the mid to upper 30s, which is slightly above normal for mid-March.
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&& .LONG TERM /SATURDAY THROUGH THURSDAY/...
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Highlights * Dry and quiet weather Sat, with a mix of sun and clouds. * A frontal system swings through Sun bringing scattered showers. * Still may be unsettled on Mon and Tue, but with spotty showers. Temperatures near to below normal. * Drier weather returns midweek. Fairly significant pattern change during this portion of the forecast, but not all that unusual for mid March in southern New England. Near zonal mid level flow late this week morphs into a modest mid level trough over the Great Lakes this weekend, which should then move more directly overhead early next week. This trough is then expected to linger nearby through most of next week, but gradually weaken with time. This near zonal flow should keep systems moving across southern New England this weekend, along with above normal temperatures. Saturday still appears to be the drier of the two days, but another approaching front should bring some showers sometime Saturday night into Sunday. Looking to be too warm for snow, so have just rain in the forecast for now. Will keep an eye on the higher elevations with later forecasts, as a subtle change in temperatures of a couple of degrees may open that particular door there. This front should not stick around long. Thinking we`ll already start clearing out Sunday evening, and especially after midnight Monday. While there should not be much at the surface to help focus shower potential, the cold pool associated with the mid level trough should be arriving, leading to the possibility of diurnal showers Monday into Tuesday. These would be more of the hit-and-miss variety. The more noticeable change would be the 10 degree drop in temperatures early next week. That said, this is more of a return to temperatures more typical of mid March, which are expected most of next week. By Wednesday, the atmosphere is projected to dry out just enough where the risk for diurnal showers is lessened. However, the diurnal clouds should linger just fine.
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&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/...
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Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18Z TAF Update Through 00Z...High Confidence VFR. Light onshore winds near the coast and light/variable across the interior. Tonight...High Confidence in trends, moderate confidence in timing. VFR persists through about 03Z at most of the terminals. Conditions then deteriorate overnight as an area of low-pressure approaches from the west. Ceilings falling to MVFR levels across the interior, except BAF/BDL may remain above MVFR with cigs around 060 feet. Terminals near the coast likely to fall to IFR/LIFR as southeast flow advects low/marine stratus over the terminals. Low pressure system will be accompanied by -RA beginning around 06Z at BAF/BDL and eventually reaching BOS by 08-09Z. Modest 5 to 10 knot southeast winds. Tomorrow...Moderate Confidence Surface low-pressure circulation exits to the east with -RA by about 15Z. Low-level clouds continue to linger, but we should see any LIFR ceilings improve to at least IFR by mid-morning. Gradual improvements to MVFR by 18-21Z and eventually back to VFR by 00Z. Not expecting any steady periods of precipitation after 15Z tomorrow, but there may be a few spotty showers or intermittent periods of light drizzle. Winds shift to the northwest after 15Z once the surface low exits east. Speeds will be modest topping out in the 10-15 knot range. Tomorrow Night...High Confidence. VFR. Steady northwest winds 5 to 10 knots. Possibly some MVFR ceilings with cloud bases from 020 to 040 over The Cape/Islands terminals. KBOS TAF...Moderate confidence in TAF. Conditions begin to deteriorate around 06Z. Only moderate confidence in ceilings falling to LIFR levels with higher confidence of at least IFR. Low ceilings likely to persist through the morning push before some improvements after 15Z. Could be back to MVFR levels by early afternoon, but likely closer to 18Z. Improvements to VFR between 21-00Z tomorrow. KBDL TAF...High confidence in TAF. Outlook /Saturday through Tuesday/... Saturday: VFR. Saturday Night: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA. Sunday: Mainly VFR, with local MVFR possible. Windy with gusts up to 30 kt. Chance SHRA. Sunday Night: VFR. Breezy. Chance SHRA. Monday: VFR. Breezy. Slight chance SHRA. Monday Night through Tuesday: VFR. Breezy. Slight chance SHRA, slight chance SHSN.
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&& .MARINE...
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Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight Low-pressure moves over southern New England tonight with steady periods of light rain. Additionally this system will support increasing southeasterly winds over the marine zones with speeds ranging from 10 to 15 knots overnight. Calm seas build to 1 to 3 feet by Friday morning. Tomorrow Southeast winds shift to northwest late tomorrow morning/early tomorrow afternoon as low-pressure progresses east over The Gulf of Maine. Winds will be a bit stronger by the low ranging from 13-18 knots with gusts flirting with SCY criteria close to 25 knots at times. Seas continue to build, but generally below SCY conditions from 2 to 4 feet. Tomorrow Night Conditions look to be more quiet tomorrow night over the coastal waters. Northwest winds diminish to more modest speeds below 10 knots. Seas come down as well but wave heights still remain in the 1 to 3 foot range by Saturday morning. Outlook /Saturday through Tuesday/... Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Saturday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of rain showers. Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Monday: Low risk for Small Craft Advisory winds with gusts up to 20 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Monday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Tuesday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain showers.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Frank/BL NEAR TERM...RM SHORT TERM...RM LONG TERM...Belk AVIATION...Belk/RM MARINE...Belk/RM

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