071 FXUS61 KBOX 222348 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 748 PM EDT Fri May 22 2020 .SYNOPSIS... Low pressure tracks south of the region during tonight and Saturday. This low will bring showers and cooler temperatures. There may be a few rumbles of thunder along the south coast. Mainly dry weather expected Sunday into Monday, but with cool afternoons near the coast. Temperatures moderate Tuesday with summer-like warmth expected away from the south coast Wednesday through Friday. Dry weather dominates the majority of next week until a cold front may bring some showers and a few thunderstorms by next Friday and/or Saturday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Tonight... 750 PM UPDATE... The forecast continues on as previously discussed, though, we've made a few minor adjustments. We've adjusted the POPs across CT, RI, and southeast Mass to reflect the latest guidance. Saturday isn't a washout, but, the highest chances for a chance of rain will occur across CT, RI and the south coast of Mass. Far southeast Mass, Cape Cod, and the Island should expect morning fog, which could become dense when you consider the high dewpoints over relatively cooler ocean water. Additionally, the warmest part of the day will occur around 12Z, with cooling temperatures into the afternoon because of a backdoor cold front. SEE PREVIOUS DISCUSSION BELOW... Mid level ridging yields somewhat to the cutoff low's eastward progression, with the mid level cutoff low and associated surface low centers tracking through PA and NJ. This will bring increasing moisture/cloud cover to southern new England from SW to NE, with an increasing chance for showers. 12Z CAMs indicate showers in our western zones holding off until towards 02Z, eastern MA towards 08Z. Also, with surface high pressure lingering over the Canadian Maritimes, it may be a struggle for north central and northeastern MA to see rain. By daybreak Sat, pops range from slight chance in far NE MA, to likely BDL-IJD. Slight chance for thunder mainly across northern CT into RI. As the surface low center moves toward the Mid Atlantic shoreline, winds over our area will become east/northeast. Surface dew points also creep up overnight, keeping lows on the mild/warm side from the mid 50s to low 60s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Saturday... During Saturday the surface low will slide eastward, with the center remaining south of New England through the day. Meanwhile the Maritime ridge will extend through northern New England. This ridge will likely limit the amount of showers we see in northern MA. Across southern New England as a whole, the highest chances for showers will be during the morning and early afternoon, then diminishing. Will have likely pops over northern CT, RI and southeast MA, tapering to chance across central MA, and slight chance far northeast MA. MU Cape values up to a few hundred J/kg in the likely pop area early in the morning, so will continue with a slight chance for thunder there. There still some uncertainty on how much QPF falls within SNE. Very little QPF is expected across the northern tier of MA, however south of the Mass Pike and into CT/RI, CAMs vary on precip intensity. Going with WPC/RFC QPF, 0.25-0.75 inch south of the Pike, with localized higher amounts possible. QPF amounts diminish to the north. Also across the northern tier of MA, skies should become mostly sunny by late in the day. Northeast winds prevail, and the onshore flow will advect cooler air into region. Continue to anticipate high temperatures to occur during the morning, with temperatures decreasing as the day progresses. Saturday Night... Mid level ridge makes a return while the surface/cutoff low moves further offshore, and Maritime surface high builds into our area. For much of the region, this will mean clearing skies. However, guidance is indicating that low clouds and some light rain or drizzle may linger in the vicinity of the Cape and Islands during this timeframe. East/northeast winds continue, with noticeably cooler overnight lows in the 40s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights... * Mainly dry Sun & Mon, but cool afternoons near the coast * Temps moderate Tue with summer-like warmth Wed-Fri * Dry weather dominates next week until the threat for showers and a few t-storms increases with a cold front next Fri and/or Sat Details... Sunday and Monday... High pressure east of the Maritimes, coupled with weak surface low pressure to our south will generate onshore easterly low level flow. This will keep daytime temperatures cool especially along the coast. The winds blowing off the ocean will hold high temps in the middle to upper 50s along the eastern MA coast Sun and probably Mon too. Moving further inland, the onshore flow will have less of an impact; but still enough to keep highs mainly in the 60s. A few lower 70s are possible near and west of the CT River Valley, furthest removed from the onshore flow. Dry weather anticipated Sunday. Model cross sections do indicate the potential for some lower clouds moving in off the ocean Sun night into Mon. Perhaps even a few brief showers/patchy drizzle across eastern New England. Regardless, expect dry weather to dominate with any precipitation that occurs to be extremely light/spotty. Tuesday through Friday... Upper level ridging builds across the region as a Bermuda high pressure system sets up at the surface. There is some uncertainty on how quickly temps moderate Tue, which will be dependent on if we still have lingering clouds off the ocean. Thinking is that many areas warm well into the 70s to lower 80s away from the south coast. It still looks like summer-like warmth for Wed/Thu/Fri with southwest flow and 850T around +16C. This should yield afternoon high temps well up into the 80s to even near 90 away from the cooling marine influence of the south coast. Given upper level ridging and the lack of forcing expect dry weather to dominate most of next week. The chances for some showers and perhaps a few thunderstorms increases by next Fri and/or Sat, depending on the timing of an approaching cold front. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00Z TAF UPDATE... Tonight and Saturday...Moderate confidence Increasing chances of rain showers as a cutoff low lifts into the Mid Atlantic tonight and passes just south of the region on Saturday. Still some uncertainty on how far north the shower activity reaches, but most confident BDL-PVD-PYM vicinity and south. Ceilings/VSBYs gradually lower to MVFR and IFR in scattered showers and fog, except across northern MA including BOS where VFR CIGs/VSBYs conditions may last through Saturday. Saturday Night...Moderate confidence. VFR for most of the area with clearing skies. Exception may be across the Cape and Islands, where IFR/MVFR CIGs may linger with patchy drizzle/light rain possible. KBOS Terminal...High confidence in the TAF through 06Z, then moderate confidence in TAF. KBDL Terminal...High confidence in the TAF through 02Z, then moderate confidence in TAF. Outlook /Sunday through Wednesday/... Sunday: VFR. Breezy. Sunday Night: Mainly VFR, with areas MVFR possible. Breezy. Slight chance SHRA, patchy BR. Memorial Day: Mainly VFR, with areas MVFR possible. Breezy. Monday Night: Mainly VFR, with local IFR possible. Slight chance SHRA, patchy BR. Tuesday: VFR. Breezy. Tuesday Night: Mainly VFR, with areas MVFR possible. Slight chance SHRA, patchy BR. Wednesday: Mainly VFR, with local MVFR possible. Breezy. Slight chance SHRA. && .MARINE... 00Z UPDATE... The only chance we've made to the marine forecast was issuing Small Crafts for all of our waters starting mid-morning Saturday and we increased wind gust to between 25 and 30 kts. SEE PREVIOUS DISCUSSION BELOW... This evening through Saturday... Updated forecast for SCA until 8 pm this evening for southern coastal nearshore waters, SW wind gusts 25 to 30 kt. Elsewhere SW winds 10 to 15 kt with gusts around 20 kt. Seas 1 to 3 feet. After sunset, wind gusts diminish below SCA thresholds for the night, with seas 1 to 3 feet. During Saturday seas gradually build to 4 to 6 feet. Winds become northeast early in the day, with winds gusting to around 25 kts. Thus renewed SCA headlines may be needed. Rain showers spreading in with reduced visibilities and fog along the south coast tonight into Saturday. Confidence lower in the rain chances across the eastern waters, but moderate to high across the south coast. Could have a few rumbles of thunder across the south coast. Outlook /Sunday through Wednesday/... Sunday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Sunday Night: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers, patchy fog. Local visibility 1 to 3 nm. Memorial Day through Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers, patchy fog. Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers, patchy fog. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers, patchy fog. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 10 AM Saturday to midnight EDT Saturday night for ANZ231>235-237. Small Craft Advisory from 8 AM to 8 PM EDT Saturday for ANZ230. Small Craft Advisory from noon to 8 PM EDT Saturday for ANZ236. Small Craft Advisory from 6 AM Saturday to midnight EDT Saturday night for ANZ250-251. Small Craft Advisory from noon Saturday to 8 AM EDT Sunday for ANZ254>256. && $$ SYNOPSIS...Frank/NMB NEAR TERM...Gaucher/NMB SHORT TERM...NMB LONG TERM...Frank AVIATION...Frank/Gaucher/NMB MARINE...Frank/Gaucher/NMB