Area Forecast Discussion
Issued by NWS Boston, MA
Issued by NWS Boston, MA
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704 FXUS61 KBOX 241307 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 907 AM EDT Tue Sep 24 2024 .SYNOPSIS... Weak high pressure will build over our region today, but continued onshore winds should keep cloudiness in place, especially near the coast. Rain chances return late Wednesday into Thursday as a front moves through the area. Dry and warmer weather looks to follow through the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 9 AM update... Low level moisture below a stout inversion will result in strato-cu developing and increasing across SNE today. While there will be lots of strato-cu, expect clouds to mix with some sunshine. May also see a few brief sprinkles in eastern MA and RI as radar is showing some light returns backing in from the ocean. Highs will top out in the mid-upper 60s, perhaps a few locations in the CT valley near 70. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Upper-level ridge axis begins to move east with deep upper-level SW flow and shortwave energy moving toward the region. Surface high pressure will take longer to move out, keeping the flow onshore at the surface. This will result in mostly cloudy to overcast skies for much of the region tonight through Wednesday. Cloud cover should keep tonight`s lows in the 50s, with upper 40s possible in northwestern MA. High temps Wednesday will again be in the low to mid-60s with continued onshore easterly winds at 10- 15mph. Rain chances don`t creep into the forecast until late Wednesday when better moisture and forcing arrive. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Wednesday night and Thursday Deepening northern stream trough will interact with energy from the cutoff southern stream trough over the south-central US. Strengthening warm air advection will bring showers from west to east from late Wednesday into Thursday. Despite PWATs over 1.5 inches, not expecting heavy rain or large amounts of QPF due to marginal upper-level forcing. There is still quite a bit of spread in the ensembles, with the 25th percentile showing less than a tenth of an inch, while the 75th percentile shows up to 0.75 inches. Most global deterministic guidance shows roughly a half inch with isolated spots of 1+ inches. There could be a rumble or two of thunder overnight Wednesday and Thursday with low amounts of elevated instability. Rain showers could linger into Thursday night as the upper level closed low swings south into SNE. However, a cold front ahead of the upper-level trough will bring in much drier air, with PWATS falling near 0.5 inches. Lows Thursday night drop into the low to mid-50s Friday - Monday Upper-level closed low moves offshore to the east while another blocking ridge settles in for Friday through the weekend. High temperatures begin to rebound to more seasonable levels in the upper 60s to low 70s with dry conditions and sunny skies. With good radiational cooling conditions, overnight lows will drop into the upper 40s to low 50s. Patchy radiation fog is possible with the longer nights and dewpoints in the mid to upper 50s && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tuesday...High Confidence. Moderate confidence in timing of improvement to VFR at ORH this AM. Areas of patchy fog/low stratus this morning at BED/ORH. FG at ORH with periods of LIFR early this morning, gradually improving as it scatters out in the 12-14z timeframe. For the rest of the day, mainly VFR with pockets of MVFR possible. Onshore winds out the east at 7-12 knots, higher over Cape Cod and the Islands at 10-20 knots. Tuesday Night...Moderate Confidence. MVFR with pockets of IFR possible especially closer to the higher terrain. Winds remain east at 5-10 knots. Wednesday... Moderate Confidence MVFR possibly improving to VFR. Winds remain east at 5-10 knots. Rain chances increase across western MA and CT late in the day. BOS TAF...High Confidence in TAF. Mainly VFR with periods of MVFR possible. Winds remain east at 10-15 knots for entire TAF period. BDL TAF... High Confidence in TAF. Mainly VFR today, turning MVFR tonight. Winds remain ENE at 5-10 knots for entire TAF period Outlook /Wednesday Night through Saturday/... Wednesday Night: Mainly VFR, with local IFR possible. Chance SHRA. Thursday: Mainly VFR, with areas IFR possible. Chance SHRA. Thursday Night: VFR. Slight chance SHRA. Friday through Saturday: VFR. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Today through Wednesday...High Confidence. Small Craft Advisories remain in effect for all outer open water zones along with the northern near coastal waters for seas of 5-6 feet. Winds will stay just below small craft criteria gusting up to 20 knots from the east through Wednesday. Rip Current Statement remains in effect for both the southern and eastern coasts. Seas of 5-7 feet with continued east winds at 10-20mph will create dangerous rip currents today. Outlook /Wednesday Night through Saturday/... Wednesday Night: Winds less than 25 kt. Areas of rough seas. Slight chance of rain showers. Thursday: Winds less than 25 kt. Local rough seas. Chance of rain showers, isolated thunderstorms. Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Friday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Saturday: Winds less than 25 kt. Seas up to 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...High Risk for Rip Currents until 8 PM EDT this evening for MAZ007- 019-020-022>024. RI...High Risk for Rip Currents until 8 PM EDT this evening for RIZ006>008. MARINE...Small Craft Advisory until 8 PM EDT Wednesday for ANZ250-251- 254>256. && $$ SYNOPSIS...KP NEAR TERM...KJC/KP SHORT TERM...KP LONG TERM...KP AVIATION...Mensch/KP MARINE...KP