Area Forecast Discussion
Issued by NWS Boston, MA
Issued by NWS Boston, MA
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394 FXUS61 KBOX 220147 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 947 PM EDT Sat Sep 21 2024 .SYNOPSIS... The offshore low begins to move farther out to sea overnight and especially Sunday and Monday. While mainly dry weather is expected Sunday through Tuesday, cloudier conditions and onshore breezes are expected. Rain chances then increase again for midweek as a frontal system moves in from the Great Lakes. Temperatures will be below normal. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 945 PM Update: Forecast is on track and no changes needed. Western edge of the rain shield was slowly eroding and that trend will continue overnight as offshore/upper lows begin to head farther out to sea. Already seeing some dry air aloft work into region from north as surface ridging begins to take hold, but per high res guidance it should take most of the night to end on Cape Cod and Islands. So we should see more of an erosion of rain shield overnight as opposed to it moving completely offshore. Gusty N/NE winds will continue near coast. Farther inland, ridge of high pressure will continue to dominate overnight. Still a good amount of cloud cover but it remains dry. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Sunday... Continued improvement expected as offshore low pres continues to move offshore. Good drying in the column moves in from the north across the interior in the afternoon so clouds should give way to partly sunny skies here. However, closer to the coast, deeper moisture will be slower to depart so clouds will dominate across RI and eastern MA and can`t rule out a few lingering showers across SE MA and Cape Cod, especially in the morning. It will remain breezy near the coast as strong pressure gradient in place on NW periphery of the ocean storm. NE gusts to 20-30 mph expected along the coast, strongest gusts over the Cape/Islands. Another cool day with below normal temps, with highs mid-upper 60s. with some lower 70s in the CT valley. Sunday night... Surface and mid level ridging builds into the region Sun night with continued drying. Dry conditions expected with partly cloudy skies, but patchy fog and stratus may develop overnight. Lows will drop into the 40s, except low-mid 50s near the coast where a steady NE wind will continue. NE winds will diminish but still expect gusts to 15-25 mph along the SE New Eng coast. && .LONG TERM /MONDAY THROUGH SATURDAY/... Highlights... * Onshore surface flow much of the week will yield generally dreary conditions * Frontal system sometime mid to late week brings another chance for rain Low pressure that brought much needed rainfall to eastern southern New England over the weekend will continue to shift to our southeast, out into the more open Atlantic, early next week. While the low wont have a dominant effect on our weather for next work week, it will meander around the Bermuda area for a good portion of the week. For Tuesday and Wednesday, mid level ridging will build across the mid-Atlantic, leaving us in the northern fringes of the ridge, but onshore surface flow will counteract any expected warming effects from the ridge. Given onshore flow, expecting considerable cloudiness much of the week. Mid level cutoff low begins to develop mid week and its associated trough will cut south into southern Quebec and northern New England on Wednesday and Thursday. Front associated with this cutoff will bring our next best chance for rain. Trough remains draped over southern New England through at least Saturday, which will support unsettled, showery conditions to round out the work week and start the weekend. Temperatures look to respect the page turn from astronomical Summer to astronomical Fall, which occurs on Sunday the 21st. Highs will be below normal to start the week ranging from the upper 50s in the high terrain of western and central MA to the mid 60s to low 70s elsewhere the first half of the week. Gradual warming trend is possible late week, with widespread highs in the 70s expected Friday and Saturday. As mentioned by the previous forecaster, persistent onshore flow will lead to a continued risk for rip currents and high surf through at least Tuesday. With the Harvest Moon waning, coastal flooding concerns will decrease each day, though it is possible some splashover occurs during the Monday daylight high tide. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00Z Update Tonight...Moderate Confidence. MVFR-IFR conditions eastern MA and RI improving to VFR in NE MA, but MVFR persisting SE MA and RI. VFR CT valley but patchy late night fog possible. Rain gradually tapers off to scattered showers overnight in eastern MA/RI, but rain persisting Cape/Islands. Diminishing N-NE wind, but gusts 25-30 kt Cape/Islands. Sunday...Moderate Confidence. Mainly MVFR cigs central-E MA and RI and VFR CT valley. Scattered showers lingering Cape/Islands and SE MA in the morning. NE wind gusts to 25 kt Cape/Islands and up to 20 kt near the coast. Sunday night...Moderate Confidence. Mainly VFR, but areas of MVFR cigs may linger RI and SE MA. Diminishing NE wind. BOS TAF...Moderate confidence. MVFR conditions expected through most of Sunday until the evening hours when it should improve to VFR. Rain expected to subside around 08Z Sunday AM. BDL TAF... High Confidence. VFR through Sunday. Wind gusts up to 20 knots expected to return around 17Z, dying back down going into the rest of the evening. Outlook /Monday through Thursday/... Tuesday: Mainly VFR, with areas MVFR possible. Tuesday Night: Mainly VFR, with local IFR possible. Wednesday: Mainly VFR, with local IFR possible. Slight chance SHRA. Wednesday Night through Thursday: Mainly VFR, with areas IFR possible. Chance SHRA. Thursday Night: Mainly VFR, with local IFR possible. Chance SHRA. Friday: Slight chance SHRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight through Sunday Night... NE gusts to 25-30 kt will continue into Sun, especially across southern waters and waters E of Cape Cod with 8-10 ft seas over the outer waters. Winds will slowly subside late Sunday night but rough seas will continue. Outlook /Monday through Thursday/... Tuesday through Tuesday Night: Winds less than 25 kt. Rough seas up to 8 ft. Wednesday: Winds less than 25 kt. Areas of rough seas. Wednesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Thursday through Thursday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain showers. Friday: Winds less than 25 kt. Areas of rough seas. Slight chance of rain showers. && .TIDES/COASTAL FLOODING... Coastal Flood Advisory remains in effect for Sunday afternoon high tide. While astronomical tides remain elevated, the tides are slowly coming down from the peak Fri and Sat. With a 1-1.5 ft surge anticipated, we expect areas of very minor inundation or splashover during the Sun afternoon high tide for vulnerable shoreline roads across east coastal MA. The High Surf Advisory was extended through Sunday due to high seas and rough surf which will continue. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...High Surf Advisory until 8 PM EDT Sunday for MAZ007-019-020- 022>024. Coastal Flood Advisory from noon to 6 PM EDT Sunday for MAZ007- 015-016-019-022>024. RI...High Surf Advisory until 8 PM EDT Sunday for RIZ006>008. MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ230- 236. Small Craft Advisory until 8 AM EDT Monday for ANZ231-232-250- 251-254>256. Small Craft Advisory until 2 AM EDT Monday for ANZ233>235-237. && $$ SYNOPSIS...KJC/KS NEAR TERM...JWD SHORT TERM...KJC LONG TERM...KS AVIATION...KJC/Hrencecin/KS MARINE...KJC/KS TIDES/COASTAL FLOODING...KJC