027 FXUS61 KBOX 061104 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 704 AM EDT Mon May 6 2019 .SYNOPSIS... High pressure will build across the region with a return to mostly sunny skies this afternoon. The high will push offshore late tonight. A cold front will shift southeast, bringing an area of showers and the threat for isolated thunderstorms on Tuesday from mid afternoon through early evening. High pressure returns Wednesday with dry and seasonable weather, then occasional rain and cooler temperatures are expected later Thursday into Friday. The weekend could end up being dry prior to another shot of wet conditions into early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 7 AM update... Showers have moved offshore, but still lots of stratus lingering across eastern MA and RI while clearing has developed in the CT valley. Cross sections indicate low level moisture hangs in the coastal plain this morning but then decreases, leading to clouds giving way to increasing sunshine by midday and into the afternoon. In western MA/CT, sct-bkn diurnal cu will develop later this morning into the afternoon where axis of 850 mb moisture sets up. Wide range in temps today with NE flow in place. Highs will be in the 50s in east coastal MA, warming to near 70 in the CT valley, and low to mid 60s elsewhere. Gusty NE winds 20-30 mph over the Cape/Islands will diminish this afternoon && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Tonight... Bubble of high pres sets up across eastern areas this evening, so should see mostly clear skies. May see a few more clouds across the E slopes of the Berkshires early tonight, which will start to push eastward overnight. The mid level steering flow remains nearly zonal, so the next approaching system will start to push SE out of upstate NY after 06Z or so. Will see mid and high clouds start to increase during the early morning hours. Expect overnight lows mainly in the 40s, but could hold near 50 across the lower CT valley. Tuesday... Clouds will continue to increase Tuesday morning with S-SW winds in place. It will be a mild day with highs mainly in the mid 60s to around 70 except in the upper 50s to lower 60 along the S coast with the onshore wind. A cold front continues to shift SE during the day, so precip will push into NW and N central Mass by mid-late morning. Also noting some marginal instability ahead of this front, with K indices in the lower 30s, Total totals around 50 and TQ values in the upper teens. However, as this front shifts SE, it will mover into a somewhat more stable airmass. Can not rule out some isolated convection, so have mentioned isolated thunder during the afternoon. Would not be surprised to see some brief heavy downpours with a band of PWATs up to 1-2 SD above normal. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Highlights... * Lingering showers/isolated t-storm south of the Pike Tue evening * Dry and seasonable Wed * Wet weather by late Thu into Fri with cooler temps * Mainly dry next weekend Tuesday night and Wednesday... Cold front will be moving south across SNE and exiting the south coast near midnight. The marginal afternoon instability is lost during the evening, but scattered showers and an isolated t-storm are possible Tue evening, especially south of the Pike as the front moves through with deep moisture axis. Drying out overnight. High pres builds to the north Wed with ridging extending south into SNE which will bring dry weather and seasonable temps, cooler than Tue. Plenty of sunshine expected, with some diurnal CU given shallow low level moisture. Chilly night Wed night as high pres settles over New Eng. Potential for some 30s in the favorable radiational cooling locations, but increasing mid/high clouds should prevent frost. Thursday into Friday... Pattern favors rain and cooler temps as warm front approaches from the SW with cool high pres moving east of New Eng setting up easterly flow. Thursday starts out dry with high pres providing low level dry air, but deep moisture and overrunning of frontal boundary should bring some rain Thu afternoon, especially to western New Eng with SE New Eng possibly remaining dry. Best chance of a soaking rain will be Thu night into Fri, with risk for some convection and isold t-storms Fri afternoon/evening as elevated instability develops within low level theta-e ridge ahead of approaching mid level trough. Pre-frontal showers linger into Fri night then cold fropa should clear things out overnight. Temps likely fall into 40s Thu afternoon in the west after rainfall onset given wet bulb cooling processes. Tricky temp forecast for Fri as warm front approaches. Will depend on position of the boundary with temps warming into 60s to the south of the front and holding in the 40s to the north. Best chance of milder temps Fri will be south of the Pike, with 40s possible for northern and NE MA. Saturday and Sunday... Looks dry Sat as cold front is offshore with drier W/NW flow and temps near or a bit above normal. Greater uncertainty for Sunday with possible weak wave and moisture/rainfall lurking to the south. Cooler temps Sun with onshore flow. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...Moderate confidence. Today... MVFR/IFR stratus across RI and eastern MA will improve to VFR by 15-16z with clearing skies. BKN cigs 4-5k ft develop in western MA/CT by late morning. N/NE gusts to 25 kt over Cape/Islands this morning, diminishing this afternoon. Tonight... VFR. N-NE winds up to 10-15 kt across Cape Cod and islands early, otherwise light/variable becoming S-SW overnight. Tuesday... VFR through midday. Cold front approaches. SCT -SHRA push into N central/W areas at midday, then shift SE through the afternoon. Conditions lower to MVFR to local IFR from NW-SE. SW winds 10-15 kt. KBOS Terminal... Moderate confidence. MVFR to brief IFR CIGS/VFR VSBYS through mid morning, then should improve to VFR. N winds around 10 kt for the morning push. VFR with E winds around 10 kt for the afternoon push. KBDL Terminal... Moderate to high confidence. VFR. Light N winds this morning becoming light E this afternoon. Outlook /Tuesday Night through Friday/... Tuesday Night: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA. Wednesday through Wednesday Night: VFR. Thursday: Mainly VFR, with areas MVFR possible. Breezy. Chance RA. Thursday Night: MVFR/IFR conditions possible. Breezy. RA. Friday: Mainly MVFR, with areas IFR possible. Breezy. RA likely. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...High confidence. Through 12Z... As low pressure passing SE of the 40N/70W benchmark early this morning, will see NE winds gusting to 25-30 kt across outer Cape Cod and Nantucket through around 12Z. Will also see leftover lowered visibility in showers and patchy fog, but should push offshore by around daybreak. Today... NE winds will linger across Cape Cod and the islands, gusting up to 25-30 kt most of the morning before backing to N and slowly diminishing this afternoon as low pressure pushes further offshore. Small Craft Advisories up for most waters. NE winds 15-20G25kt highest Cape Cod and Nantucket waters weaken and become northerly during the afternoon as Georges Bank low moves out to sea. Visibility around 3 to 5 miles in morning with drizzle and fog, improving into the afternoon hours. Tonight... High pressure ridge builds across the waters which will bring tranquil boating weather. Winds will diminish, but seas will remain up to 5-7 ft on the open waters, though will subside late tonight on the outer waters S of the RI coast. Tuesday... Winds will shift to SW ahead of an approaching cold front. Expect wind speeds up to 10 to 20 kt, highest during the afternoon on the eastern open waters. Gusts will increase up to around 25 kt as well. Seas will remain up to 5-6 ft on the eastern waters. Visibility lowers as showers push SE during the afternoon. Isolated thunderstorms possible. Outlook /Tuesday Night through Friday/... Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain. Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Rain likely. Friday: Winds less than 25 kt. Areas of rough seas. Rain likely. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ232. Small Craft Advisory until 1 PM EDT this afternoon for ANZ233- 234. Small Craft Advisory until 2 PM EDT this afternoon for ANZ235- 237. Small Craft Advisory until 6 PM EDT Tuesday for ANZ250-254-255. Small Craft Advisory from 5 PM this afternoon to 6 PM EDT Tuesday for ANZ251. Small Craft Advisory until 4 AM EDT Tuesday for ANZ256. && $$ SYNOPSIS...KJC/EVT NEAR TERM...KJC SHORT TERM...EVT LONG TERM...KJC AVIATION...KJC/EVT MARINE...KJC/EVT