000 FXUS61 KBOX 040210 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1010 PM EDT Sun Jul 3 2022 .SYNOPSIS... High pressure over the Great Lakes will move into the mid-Atlantic waters through Independence Day. Expect a seasonably mild Independence Day with clear skies, low humidity levels and coastal sea-breezes. Increasing mid to high clouds Monday evening but still tranquil weather into Monday evening. Tuesday looks to feature widespread, beneficial rainfall. Slightly below normal temperatures are expected for rest of the week with mainly dry weather. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 10 PM UPDATE... Clear skies and dropping temperatures (some already into the upper 50s!) No changes to the forecast at this time. PREVIOUS DISCUSSION... It's turned into a spectacular early July afternoon across much of Southern New England as surface ridge, mid-level dry air aloft seen on WV imagery and cyclonic flow aloft has led to decreasing clouds and falling dewpoints. It is still rather humid across the Cape and Islands but drier air to eventually filter in for the remainder of the afternoon. For tonight, ridging associated with a 1022 mb high pressure area over the Gt Lakes will continue to build into Southern New England. Clear skies, decoupling winds and deep dry air should support good radiational cooling. As lowest afternoon dewpoints were in the 60s across the South Coast, Cape and the Islands, this is one area where patchy fog may develop but it's still in some question. Following MOS-based approaches for min temperature population, expect lows in the low to mid 50s in the typical radiator sites and in the upper 50s to low 60s for the urban areas, Cape and Islands. One of those nights to give the A/C or central air a break! && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... 300 PM Update: Independence Day through Monday Night: Another beautiful day in store for Independence Day. Cyclonic mid- level flow associated with cooler 850 mb temps around +8 to +10C, while at surface, high pressure over PA to shift SE towards the mid- Atlantic waters. Full sun and deep mixing will support falling dewpoints and high temperatures in the lower to mid 80s. While a brief period of light NW winds is expected in the morning, expect coastal sea-breezes to develop by late-AM/early-PM near both coasts with developing W-SW winds later in the day. Given sea-breezes, expect a period of onshore flow and somewhat cooler temps near the coasts. Returning warm-advection pattern then ensues for Monday evening. Southerly flow brings increasing dewpoints into the 50s, to lower- mid 60s near the South Coast, Cape and Islands. Mid to high level moisture brings gradually increasing coverage of mid to high clouds, greatest to the north. So, increasing clouds toward partly cloudy but cloud bases should be above 10,000 ft. Somewhat milder lows than tonight in the upper 50s to mid 60s but still generally comfortable. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights * Looking unsettled on Tuesday with widespread rain possible. * Rest of the week looks cooler than normal but mainly dry. Tuesday... Confidence at this point is highest in rainfall chances on Tuesday into overnight Tuesday as a cold front slides through the region. While there certainly could be some thunder with a few hundred J/kg of MUCAPE along with 30-40 kt 0-6 km shear, severe weather does not look likely at this time due to poor mid-level lapse rates and lack of instability. Heavy rain or localized heavy downpours look more likely, however, with anomalously high PWATs of 1.5 to 2 inches and warm cloud layer depths of 3-4km. While there could be some localized ponding or urban poor drainage flooding, it looks like Tuesday will feature yet another opportunity for beneficial rainfall to further reduce our rainfall deficit. Wednesday into Sunday... After the cold front passage late Tuesday, the upper level pattern features a mean trough which will allow daytime highs during the remainder of the week to be below to near normal. For reference, typical daytime highs are in the low to mid 80s away from the immediate coast. From a climatological standpoint, we are fast approaching the highest average temps in the year. So no real big heat in the horizon during the hottest time of the year! Mainly stuck to blended guidance for this part of the forecast. While there may be opportunities for some unsettled weather sometime in the Friday/Saturday time frame, it is too early to say with certainty when and where that would occur. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 23z TAF Update: From 00z Monday through Monday Night: High confidence. VFR through the period; mid to high clouds arrive overnight tied to a warm front passing to our north. NW winds during the day around 4-7 kt; coastal sea-breezes for both coasts. Winds for the evening then shift to W-SW 4-8 kt. KBOS...High confidence in TAF. KBDL...High confidence in TAF. Outlook /Tuesday through Friday/... Tuesday: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA. Tuesday Night: Mainly MVFR, with local VFR possible. Windy with local gusts up to 30 kt. Chance SHRA, isolated TSRA. Wednesday: Mainly VFR, with local MVFR possible. Breezy. Wednesday Night through Thursday: VFR. Thursday Night: Mainly VFR, with areas MVFR possible. Slight chance SHRA. Friday: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 305 PM Update: Overall high confidence. Winds and seas through Monday night expected to be below SCA levels with favorable boating conditions through the period. NW winds tonight into early on Independence Day around 10 kt shift late on Independence Day to SW and increase to 10-15 kt for Monday evening. Seas mainly 3 ft or less through the period. Dry weather with good visibility. Outlook /Tuesday through Friday/... Tuesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of rain showers, isolated thunderstorms. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Thursday: Winds less than 25 kt. Thursday Night: Winds less than 25 kt. Slight chance of rain showers. Friday: Winds less than 25 kt. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Loconto/Chai NEAR TERM...Loconto/BW SHORT TERM...Loconto LONG TERM...Chai AVIATION...Loconto/Chai MARINE...Loconto/Chai