Area Forecast Discussion
Issued by NWS Boston, MA

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286 FXUS61 KBOX 201723 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 123 PM EDT WED JUL 20 2016 .SYNOPSIS... High pressure will bring dry and warm conditions through Thursday with comfortable humidity. Heat and humidity return Friday along with the risk for scattered showers and thunderstorms during the afternoon and evening, some of which may be severe. Hot weather is expected to continue this weekend and an approaching cold front may bring us another round of scattered showers and thunderstorms sometime next Monday and/or Tuesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1 pm update...no major changes to the forecast. High pressure in control slowly slipping S/E allowing for present NW flow to gradually veer southerly late. Mostly clear conditions beneath an H85 airmass of around +8-10C lending to temperatures warming into the low 80s. Well-mixed boundary layer, will see dewpoints fall into the 40s to low 50s yielding relative humidity values down to 30 percent. Overall a fantastic day! && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Tonight... Similar conditions. SKC with weak pres gradient, leads to radiational cooling. Only caveat will be a slight increase in overnight mins due to a combination of moderated airmass and gradual increase in moisture with high pres center just E of the region. Lows mainly in the low 50s to low 60s. Thursday... High pres continues a slip to the SE. Return flow developing will lead to an increase in both low-level moisture and H85 temperatures to near +12C. Therefore, with sunshine outside of diurnal CU, expect highs reaching the upper 80s to near 90 away from sea breezes. Dwpts increase to mid-upper 50s and low 60s, still not too bad for July. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Highlights.. * Heat and humidity returns Fri, with some severe weather potential * Hot weather this weekend with highs mainly in the 90s * Another round of sct showers/thunderstorms possible sometime next Monday into Tuesday Details... Thursday night... Low level moisture continues to increase ahead of an approaching cold front. Mainly dry conditions expected to continue through much of the night. Small risk for showers across far western MA late. Patchy fog may develop late in the typically prone locations. Friday... We still have concerns about severe weather potential Friday into Friday night. The timing is not set, but currently favoring a typical diurnal pattern. While much of the day will be dry, it will become hot and humid. Model soundings continue to suggest the presence of an elevated mixed layer. Still need to see if this layer will develop, and arrive into our region in time to make a significant impact. It appears there should be plenty of forcing mechanisms and instability to support at least scattered thunderstorms. The strength of these thunderstorms is still in question. Saturday and Sunday... Consistent signal for another period of high heat and humidity. Winds appear to be strong enough to prevent an east coast seabreeze. The majority of this weekend looks dry right now, with a cold frontal passage early Saturday. Will need to determine how far south this front can get offshore before stalling. Monday and Tuesday... Very warm to hot temperatures likely continue with increasing humidity ahead of an approaching cold front. Depending on how far south the cold front make it and timing, there will be the risk for a round or two of scattered showers/thunderstorms during this time, but a washout is not expected. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Thursday Night/...High Confidence. 18z update... Rest of today... VFR. Will remove the mention of sea-breezes. Light NW flow dominant. Tonight into Thursday Night... VFR with winds turning W/SW. Could see gusts up around 15 kts along S-coast terminals for Thursday, perhaps as high as 20 kts into Thursday night. Increasing mid to high level cigs from the N/W late in the period. KBOS TAF...VFR. Do not believe at this point that a sea-breeze will become an issue for the terminal. KBDL TAF...VFR. Outlook /Friday through Sunday/... Friday...Moderate confidence. Mainly VFR. SCT SHRA/TSRA may result in TEMPO CIGS/VSBYs for the afternoon into evening period. SW gusts 25-30 kts into afternoon mainly along and S/E of the I-95 corridor. Saturday and Sunday...High confidence. VFR. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Thursday/...High confidence. 1 pm update...no major changes to the forecast. Mainly quiet boating weather through Wednesday Night thanks to high pressure building across the region from the W. NW winds veering out of the S/SW with time. Sea-breezes anticipated along the near-shore. Outlook /Thursday Night through Sunday/... Thursday...High confidence. Winds/seas mainly below small craft advisory thresholds most of the day. However, near shore southwest wind gusts of 20 to 25 knots and choppy seas are expected to develop along the south coast during the afternoon. Friday...Moderate confidence. Increasing southwest flow ahead of a cold front. This should allow wind gusts of 25 to 30 knots to develop Friday afternoon. Long southwest fetch will allow seas to build to between 4 and 7 feet, with the highest seas across the southern coastal waters. Saturday and Sunday...High confidence. Leftover swell will likely result in rough seas across the southern waters into the first part of Saturday. Otherwise, relatively weak pressure gradient should keep winds and seas below small craft advisory thresholds. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/Doody NEAR TERM...Sipprell SHORT TERM...Doody LONG TERM...Belk AVIATION...Belk/Sipprell MARINE...Belk/Sipprell

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