077 FXUS61 KBOX 032319 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 719 PM EDT Mon Jun 3 2019 .SYNOPSIS... The dry weather will continue tonight into Tuesday afternoon, but with less wind. A warm front will bring scattered showers across the region Tuesday night and Wednesday. Another round of showers, along with scattered thunderstorms, will push across Wednesday night into Thursday. Large high pressure will bring mainly dry and beautiful weather Friday into the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 650 PM Update... With excellent low level mixing in place across most of the region this evening thanks to low level lapse rates around 9C/km, W-NW winds up to 25-30 kt up to H9 have been reaching the surface from around midday through the afternoon. Peak winds reported up to 30 kt at KFIT and KLWM, 29 kt at KCEF, KORE and KBOS and 27 kt at KEWB, KMVY and KBVY at 22Z. Also continue to note quite high dewpoint depressions and RH values from 25 to 30 percent across most areas as the drier air aloft mixes down. Will see the lapse rates lower by around 00Z or so and, even though noting a low level jet at H925 up to 30-35 kt passing across the eastern waters, should not mix down quite as much but may be enough to keep Small Craft Advisories going for at least a few more hours. Diurnal clouds have been tending to dissipate over the last couple of hours across the southern coastal plain as noted on latest observations and GOES-East visible satellite imagery, with leftover scattered cumulus clouds seen from N central CT into interior E Mass north and west. The most cloud cover remains across the Merrimack River valley westward to the Worcester hills and E slopes of the Berkshires. With the diminishing wind and loss of diurnal heating, clouds should continue to dissipate this evening in line with previous forecaster's thinking. Near term forecast pretty much on track, but have updated to bring conditions current. Previous Discussion... With sunset, the cumulus field should dissipate giving way to clear skies, and at the same time winds will continue to diminish. This as surface high pressure moves in to our south. Temperatures tonight will be quite a bit colder, in the 40s for most. Higher elevations will likely even dip into the upper 30s. It should be a good night for radiational cooling as we decouple, so have trended toward the colder guidance. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Sunny and dry for much of Tuesday before rain chances return. Dry northwest flow around the high to our southwest starts the day with light winds. As the day progresses we'll begin to see increasing clouds as moisture moves in on WAA with an approaching warm front. By Tuesday afternoon a plume of moisture (PWATS approaching 1") moves in coincident with a 35-45kt 850mb LLJ. This brings rain back into the forecast, spreading from west to east Tuesday evening into Tuesday night. The forecast continues to favor areas from the CT/MA border northward for the best chance of rain. This is where the best forcing and moisture is aligned. There's enough region-wide, though, to keep rain in the forecast for everyone. Rain continues overnight and should begin to taper off near daybreak. Low temps will be back in the 50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Highlights... * Expect scattered showers to linger through around midday Wed * Another round of showers moves in late Wed into Thu, along with a few thunderstorms at times * Showers linger Thu afternoon and evening, then should end * Dry conditions and seasonably mild temperatures forecast for Friday into next weekend Details... Wednesday and Wednesday night... As H5 cutoff low pressure lifts NE to the Maritimes Wednesday morning, the overall mid level steering pattern across the northern tier will tend to flatten out. The scattered showers across central and northern areas should slowly lift N during the afternoon but will linger N of the Mass Pike through most of the day. Expect the showers to be hit and miss, so should be dry for most areas. Another potent mid level short wave works eastward Wed evening as a surface reflection moves out of NY state into western New England overnight. Noting good elevated instability with this feature, with K indices in the lower-mid 30s, TQ values in the mid-upper teens and SLIs from zero to -2. As the frontal system and low approach overnight Wed night into early Thu morning, looks like best shot for convection anywhere across the region. May see some brief, locally heavy downpours mainly along the S coast where the best lift will cross. Expect temps on Wed to run close to seasonal levels, topping off in the 70s across most areas, though a bit cooler along the immediate S coast with SW winds in place. Thursday... The low should push offshore Thu morning, but clouds and scattered showers may linger as another weak short wave moves along in the W- NW steering flow. Have CHC POPs mainly across central and eastern areas through most of the day, but not a lot of moisture with it. The cold front will cross during the day, so may take a while for winds to shift to N-NW. Conditions should slowly improve across eastern areas early Thu night. Expect temps to run in the mid 70s to lower 80s away from the coast. Friday through Sunday... 12Z model suite and ensembles continue to signal the southern periphery of large high pressure extending SE out of Hudson Bay and western Quebec, while high amplitude H5 ridge builds from western Ontario into Saskatchewan late this week. H5 heights forecast in the 570 dm range through most of this timeframe. Expect high temps to run close to normal each day. Some models try to move a weak system out of eastern Ontario Sat night in the NW flow aloft, but at this point should remain N of the region. Meanwhile, a sprawling area of unsettled conditions extending from the northern Plains to the SE U.S. With the ridging across the northeast into eastern Canada, this should remain well S of the region through next weekend. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. Through Tonight... VFR. Dry weather with gusty W-NW winds up to 25-30 kt then diminishing after 02Z-03Z. Tuesday... VFR, dry weather and modest west wind 10-15 kt. Low risk of marginal MVFR-VFR late in the day in showers mainly western- northwest MA. Tuesday Night... Mainly VFR, with local MVFR possible. Breezy. Chance SHRA. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Wednesday through Saturday/... Wednesday: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA, slight chance TSRA. Wednesday Night: Mainly MVFR, with local IFR possible. Breezy. Chance SHRA, slight chance TSRA. Thursday: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA. Thursday Night: VFR. Slight chance SHRA. Friday through Saturday: VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. Tonight...W-NW winds up to 25 kt thru about 02Z-03Z, then trending downward. Seas up to 5 ft early, then subsiding. Dry weather and good vsby. Tuesday...Modest W-SW wind becomes NW in the afternoon. Seas 4 ft or less. Dry weather and good vsby. Tuesday Night...SW winds increasing to 15-20 kt. Gusts up to 25 kt, highest on the southern waters. Seas building up to 5 ft. Chance of rain showers. Outlook /Wednesday through Saturday/... Wednesday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Chance of rain showers. Wednesday Night: Low risk for Small Craft Advisory winds with local gusts up to 30 kt. Local rough seas. Rain showers likely, chance of thunderstorms, patchy fog. Local visibility 1 to 3 nm. Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. Thursday Night: Winds less than 25 kt. Local rough seas. Chance of rain showers. Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. Friday Night through Saturday: Winds less than 25 kt. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230>237-251. Small Craft Advisory until 4 AM EDT Tuesday for ANZ254>256. && $$ SYNOPSIS...EVT/BW NEAR TERM...EVT/BW SHORT TERM...BW LONG TERM...EVT AVIATION...EVT/BW MARINE...EVT/BW