318 FXUS61 KBOX 082328 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 728 PM EDT Sat Jun 8 2019 .SYNOPSIS... High pressure will bring a chilly night tonight and comfortably warm weather Sunday. A cold front will approach Monday afternoon into Tuesday, bringing showers along with isolated thunderstorms that may produce locally heavy rainfall. High pressure moves across Tuesday night through Wednesday. Another round of showers and isolated thunderstorms pushes in Wednesday night, along with locally heavy rainfall at times, which will linger into Friday as another front slowly moves across. A few showers may linger into next weekend. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 715 PM Update... High pressure ridge remains across New England this evening. Noting generally clear skies at 23Z, except for a few spots reporting high thin patchy clouds with light E-SE or calm winds. Quite a wide range of temps, from the mid 60s to near 70 along the immediate coast with light onshore winds to the lower 80s across N central Mass to the mid and upper CT valley. Near term forecast on track, with mainly clear skies overnight. Winds will drop off by around 02Z, followed by quickly falling temps thanks to radiational cooling. Have updated to bring near term conditions current. Previous Discussion... High pres in control tonight with clear skies and light winds. Another night of good radiational cooling will result in a chilly night with lows ranging from the dropping to the mid 40s to lower 50s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Sunday... Mid level ridge builds across New Eng while surface high shifts off the coast. Another beautiful day with sunshine and comfortably warm temps. With winds turning more southerly in the afternoon, warmest temps will be across the Merrimack and CT valleys with highs 80-85. Cooler toward the south coast with highs in the 70s. Dewpoints in the 40s. Sunday night... High pres moves offshore but ridging extends west into New Eng. Another night of clear skies and light winds with lows dropping to the upper 40s to mid 50s across SNE. && .LONG TERM /MONDAY THROUGH SATURDAY/... Highlights... * Showers will push across the region from midday Monday through Tuesday afternoon, a few thunderstorms with locally heavy rainfall possible * High pressure brings dry, pleasant conditions Tue night and Wed * More showers with locally heavy rain possible Wed night into Fri, isolated thunder Thu into Thu evening * Spotty showers may linger into next weekend Details... Monday and Tuesday... 12Z model suite all signaling the slow exit of high pres off the New England coast before passing S of Nova Scotia Monday morning. Noting high amplitude H5 long wave trough from Baffin Bay to mid Atlc coast with surface frontal system. Leftover ridging lingers across eastern areas, while leading edge of rainfall pushes into the CT valley around midday, then slowly shifting E through the afternoon. With good S-SE wind flow in place at the surface through the mid levels, will see deep moisture transport across the region with the approach of a cold front and associated low pres out of the Great Lakes. GEFS ensembles signaling 2-3 SD above PWAT plume moving across the region Mon night into Tue, with GFS showing PWATs of 1.9 to 2.1 inches. Models also signaling good instability with TQ values in the upper teens, K indices in the mid 30s and SLIs around -1. Have mentioned isolated thunder in the forecast, along with chance of heavy rainfall. For now, have QPF amounts from around 0.5 inches up to around an inch, highest across the CT valley region. Cold front should slowly cross the region Tuesday, with winds shifting to W from midday across the CT valley through the afternoon. Should see improving conditions, though leftover showers may linger across Cape Cod and the islands through most of the day. Expect highs on Monday in the 70s, possibly touching 80 across the interior Route 2 corridor, with cooler temps along the S coast with the onshore wind. On Tuesday, will see temps several degrees cooler as H85 and H925 temps fall through the day. Highs may not reach 70 across the higher inland terrain as well as the outer Cape and the islands. Wednesday... High pressure will build across the region out of the Ohio and central MS valleys brings another mainly sunny day across the region. With NW winds in place, will see temps close to or just a bit below seasonal normals. Locally onshore winds will keep temps cooler along the immediate shoreline. As the high shifts E, winds shift to southerly during the afternoon. May see some clouds approach western areas late in the day. Wednesday night through Friday... H5 cutoff low across Hudson Bay with long wave trough extending S across the Gulf states. So, will see increasing SW flow aloft, transporting Gulf moisture up the eastern seaboard. Models signaling mainly low pres center across the Great Lakes by 12Z Thu, though some model spread on this position, while another low forms near the mid Atlc coast. Some question how quickly the western Atlc high will push offshore, but for now leaned toward a blend of available guidance. Should see scattered showers push into S coastal areas by around midnight Wed night, then spreading N-NE through the remainder of the night. With onshore flow in place, could see some heavy downpours once again especially during the day on Thu. Have QPF amounts from 0.7 to 1 inch, with potentially heaviest rainfall during the day Thursday. May also see some enough instability along coastal areas for some isolated thunderstorms Thu afternoon/evening. Even as the low passes, the main front will be slow to cross as it is caught up in the high amplitude mid level trough, so widely scattered showers may linger into Friday. Temps will run below seasonal levels. Friday night and Saturday... Quite a bit of uncertainty as to how quickly the mid level trough crosses the Great Lakes toward the NE. The GFS is most aggressive in bringing H5 cutoff low out of Hudson Bay, further S than most of the other model guidance. In any event, troughing looks to linger into next weekend, with some diurnal showers possibly developing Saturday. Can't rule out spotty showers anytime during this timeframe, however. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/...High confidence. Expect VFR conditions through the period. KBOS Terminal...High confidence in TAF. A brief sea breeze is possible Sunday afternoon, but winds will become more southerly. KBDL Terminal...High confidence in TAF. Outlook /Monday through Thursday/... Monday: Mainly VFR, with local MVFR possible. Chance SHRA. Monday Night: MVFR/IFR conditions possible. Breezy. SHRA, isolated TSRA, patchy BR. Tuesday: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA, isolated TSRA. Tuesday Night through Wednesday: VFR. Wednesday Night: Mainly VFR, with local MVFR possible. Breezy. SHRA likely. Thursday: Mainly MVFR, with areas VFR possible. Breezy. SHRA likely. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/...Moderate confidence. Tranquil boating conditions with high pres over the waters providing light winds and seas. SE to S winds up to 15 kt on Sunday. Good vsbys. Outlook /Monday through Thursday/... Monday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Rain showers, isolated thunderstorms, patchy fog. Tuesday: Winds less than 25 kt. Local rough seas. Rain showers, isolated thunderstorms. Tuesday Night through Wednesday: Winds less than 25 kt. Seas up to 5 ft. Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely, patchy fog. Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Rain showers likely, isolated thunderstorms, patchy fog. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...KJC/EVT NEAR TERM...KJC/EVT SHORT TERM...KJC LONG TERM...EVT AVIATION...KJC/EVT MARINE...KJC/EVT