311 FXUS61 KBOX 012032 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 432 PM EDT Mon Jun 1 2020 .SYNOPSIS... Any diurnal showers come to an end before midnight. Should be dry overnight and not as cool as last night, as high pressure builds in. Another shot for scattered showers Tuesday afternoon. Warm front lifts into southern New England late on Tuesday into early Wednesday bringing rain chances. A cold front will bring a chance of showers and possibly a thunderstorm on later on Wednesday. Dry and warm on Thursday. Another cold front will bring a chance of showers and thunderstorms Friday into Saturday. Dry, less humid, and cooler weather follows for Sunday and next Monday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 430 PM update... Highlights... * Any diurnal showers ending before midnight. Remains dry with warmer temperatures in comparison to this morning. Shortwave trough digs offshore tonight. A mid level ridge will build from the central Great Lakes into western New England by tomorrow morning. At the surface high pressure will nudge into southern New England from offshore of the Carolinas. Expect any diurnal shower activity to taper off as the sun sets. Best shot of showers this evening is across western MA and CT as things wind down. High pressure will also act to clear skies a bit across eastern portions of southern New England, however think clouds will linger across the west. Milder temperatures expected tonight especially when compared to the this morning. This is a combination of cloudiness expected and northwesterly warm air advection. Brought temperatures toward the 50th percentile of guidance, which yields lows ranging from the low 40s along the NH/VT/MA border to the low 50s along the coastal plain. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... 430 PM update... Highlights... * Increasing cloud cover as a warm front lifts into the eastern Great Lakes on Tuesday. Could see a few showers across southern New England during the afternoon. * Chance of rain showers across southern New England Tuesday night into Wednesday morning as the warm front lifts in. Tuesday... The mid level ridge slides offshore on Tuesday, while a shortwave digs from northern Ontario into the Ontario/Quebec border. A warm front will lift from the central Great Lakes into the Mid Atlantic and eastern Great Lakes. Ahead of the front will see cloud cover increase across the region. Do have some weak vorticity advection aloft. This in combination with the increasing cloud cover, near adiabatic low level lapse rates and some MUCAPE. Could see some scattered shower activity across the interior. Not expecting much QPF across southern New England with this shower activity - few hundredths at the most. Hard to pin point the exact location of these showers. Temperatures will be on an upward trend as warmer air advects in aloft. Will have winds shift to the west and southwest. This will advect 925 hPa temperatures of 10-15 degrees Celsius into the region. Highs range from the mid 60s to the mid 70s. Tuesday Night... Shortwave trough will dig from the Ontario/Quebec through southern New England. A warm front will lift into southern New England. This will bring cloudy skies and chances of rain showers Lots of differences amongst guidance on how widespread shower activity will be across southern New England. Have leaned toward the ECMWF/GEM guidance versus the drier NAM/GFS. Expecting surface winds to become more southwesterly, which will advect more moisture into the region. The GFS/NAM solutions keep winds more westerly, which keeps the lower levels drier and inhibits shower activity. Any showers that do move through will bring relatively light QPF. Only anticipating rain amounts of a few hundredths to a tenth of an inch. Warmer air will continue advecting into the region with westerly to southwesterly flow aloft. Expect 925 hPa temperatures of 12 to 17 degrees Celsius to move in. This will result in low temperatures in the 50s across southern New England. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... 430 PM update ... Highlights... * Chances of showers/thunderstorms Wed and again Fri/Sat. * Dry and warm Thu. * Dry, cooler, and much less humid Sunday and Mon. Overview... Fast upper level flow from the NW to W through midweek, then a deeper trough approaches Friday through Saturday night, exiting Sunday. At the surface, will have a cold front moving through on Wednesday and another one Friday into Saturday. Each will bring a chance of showers/thunderstorms, but the latter may be more widespread. Much drier air follows behind the upper trough for next Sunday and Monday. Wed/Wed night... A cold front will be moving through the region. The best instability is to our west and south, however. Strong WNW flow aloft...with 55-60 kt at 500 mb on GFS and closer to 70 kt on NAM. Supercell parameter is rather high in southeast NY and models anticipate any storms moving ESE from there. Have highest chances of showers and possible thunderstorms therefore over northern CT, RI, and southeastern MA and the southern coastal waters for Wed. evening. Highs Wed. will be in the lower 80s with dewpoints climbing to the lower to mid 60s ahead of the front. Thursday... Looks like the pick of the week with dry, post-frontal airmass overspreading the region. Mainly sunny skies and highs in the lower 80s with dewpoints in the 50s, making it more tolerable. Thursday night to Friday night...An upper level trough deepens as it advances from the eastern Great Lakes. Showers and thunderstorms are possible over the southern waters and spreading into southern RI and southeast MA toward daybreak. There is a better chance of showers and thunderstorms across the entire forecast area Friday and Friday night, with the approach of the front. The front will slow down in eastern sections as the upper trough deepens. This could lead to locally heavy rainfall. Too early to know if this will materialize or where. Despite cloud cover, temperatures should manage to climb to the mid 80s with dewpoints climbing back to the lower to mid 60s on Friday. Saturday...Some question as to how quickly the upper trough progresses east. The ECMWF briefly develops a closed upper low near NYC Saturday evening. Overall, expecting chances of showers or thunderstorms to mainly be in eastern areas, especially in the morning and early afternoon, then drying out. Highs near 80. Sunday and Monday...In the wake of the upper trough and surface front, we should have drier, cooler, and pleasantly less humid weather. Highs mainly 70 to 75 both days with dewpoints in the 40s. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 2030Z update... Thru 00Z...High confidence VFR conditions expected, but will have widespread diurnal cumulus. Expect ceilings between 4 to 8 kft. Still anticipating widely scattered shower activity, but uncertain on the coverage. Have covered the majority of terminals with a TEMPO group for when the best opportunity for a shower to move through is. Will continue to see gusty winds out of the NW across all terminals except for Cape Cod and the Islands. Will have local sea breezes which will bring differing directions. If a shower passes through a terminal then gusts may be as high as 25 to 30 kts. Tonight...High confidence VFR with any diurnally driven showers coming to an end. Best shot for these showers is across western MA and CT. Winds shifting to the W with speeds of 5 to 10 kts. Any gusty winds end as the mixed layer decouples. Tuesday...High confidence VFR conditions expected. Warm front approaches from the west, bringing increasing sky cover. Expect ceilings around 5 to 7 kft. A few showers are possible with no visibility restrictions anticipated. Tuesday Night...Moderate confidence Ceilings falling to MVFR limits with IFR possible late across the eastern slopes of the Berkshires. Chance of rain showers. No visibility restrictions anticipated at this point in time. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Wednesday through Saturday/... Wednesday: Mainly VFR, with areas MVFR possible. Chance SHRA. Wednesday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Thursday: VFR. Thursday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Friday: MVFR/IFR conditions possible. Chance SHRA, slight chance TSRA. Friday Night: MVFR/IFR conditions possible. Breezy. Chance SHRA, slight chance TSRA. Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA. && .MARINE... 430 PM update... High confidence in the forecast with southwest winds of 10-15 kts initially this evening shifting to the west and eventually the northwest late tonight. Will have gusts of 15-20 kts decreasing to 10-15 kts late. Seas 2 to 4 feet. Northwest winds quickly shifting to the southwest at 5-10 kts on Tuesday. Winds shifting to the south during the afternoon at 10-15 kts with gusts of 15-20 kts. Waves remaining below 3 feet. Outlook /Wednesday through Saturday/... Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Wednesday Night: Winds less than 25 kt. Local rough seas. Chance of rain showers. Thursday: Winds less than 25 kt. Local rough seas. Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Friday Night: Winds less than 25 kt. Seas up to 5 ft. Rain showers likely, slight chance of thunderstorms. Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...BL/GAF NEAR TERM...BL SHORT TERM...BL LONG TERM...GAF AVIATION...BL/GAF MARINE...BL/GAF