041 FXUS61 KBOX 021338 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 938 AM EDT Sat Sep 2 2023 .SYNOPSIS... High pressure will remain anchored over the southern offshore waters for the next few days. Tranquil weather with seasonable temperatures today, along with modest southerly breezes. Warming trend begins on Sunday, with summerlike heat returning Labor Day through Wednesday along with continued dry conditions. Elevated dewpoints could make it feel as if temperatures are in the mid-90s in a few locations. Rain chances return and temperatures decrease second-half of the week, though dewpoints remain elevated. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 9:30 AM Update... Patchy valley/river fog has dissipated in most locations, though remained tough through the top of the hour at Orange. We anticipate that this fog will lift quickly now at any remaining locations as daytime heating ramps up and winds begin to ramp up from calm to 10kt+. Otherwise, no wholesale changes made to the forecast with this update. 720 AM Update... Forecast remains on track. No changes in the latest update. 300 AM Update: Center of a 1026 mb high pressure area was located over southern coastal CT early this morning. Related ridging tied to it along with very dry low to mid-level air is allowing for clear skies and decoupled/calm winds. This is leading to development of river valley fog in localized areas in interior MA and CT, as well as around I- 495 in MA. Current temps were in the 50s for most, although worth noting that MVY's temperature was down to 44 degrees! Expecting another pleasant early-September day today as high pressure advects SE over the southern offshore waters. Couple differences compared to the forecast for yesterday. For one, SW flow stands to increase by later this morning, allowing for modest SW breezes to around 20 mph. It's also a little bit warmer aloft than the last couple days with 850 mb temps around the lower teens C range, so daytime high temps should be closer to the mid 70s to lower 80s with several hrs of sun. That said, a shortwave disturbance seen in morning mid-level water vapor imagery over the U.P. of Michigan will be moving into central NY later this afternoon. This will spread an increasing coverage of mid-level moisture and mid-level clouds later in the day into western sections of MA and CT. A number of the CAMs and the NAM depict some simulated reflectivity but inspection of model point soundings shows this is entirely mid-level moisture and profiles below 800 mb are unsaturated. So while we'll begin with full sun, expect gradually increasing mid to high clouds as the day wears on but the spotty QPF shown in some model solutions is overdone, especially in light of a few days of deep drying that had taken place. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... 300 AM Update: Tonight and Sunday: For tonight, ongoing mid-level shortwave and its associated midlevel cloudiness will continue to translate ESE through Southern New England for at least the first part of the night. However these clouds should depart offshore after midnight with returning clear skies. Will also note that dewpts start to rise more appreciably upon passage of the cloudiness, and while not super muggy, we will see return of low-60s dewpts to the region. So turning a touch more humid tonight and will have to watch if that moisture advection is enough to produce foggy areas outside of the otherwise favored river valleys; as of now think this isn't likely but bears watching. Lows should be several degrees warmer than the last few nights into the lower to middle 60s. Sunday starts to feel more summerlike with a return to increased levels of humidity, with high pressure still anchored to our south allowing for mostly full sunshine and dry weather. Dewpoints return into the mid 60s under continued warm/moist advection. There will also be less breeziness compared to today, so other than coastal sea breezes, nothing too much to take the edge off the warm/humid weather. Thus turning rather warm as 850 mb temps rise into the 14 to 16C range, with highs in the mid to upper 80s interior sites and upper 70s/near 80 along the south coast. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Highlights: * Summer heat returning Labor Day through Wednesday along with continued dry conditions. Elevated dewpoints could make it feel as if temperatures are in the mid-90s in a few locations. * Rain chances return and temperatures decrease second-half of the week, though dewpoints remain elevated. Overview... No major changes to this part of the forecast, as advertised the past several days we expect summer warmth and humidity to make a comeback. Synoptic setup; a vast mid-level ridge that was centered over the southern CONUS shifts east Monday and amplifies, extending northeast Tuesday and Wednesday. The ridge deamplifies late in the week, a mid-level trough approaches from the Great Lakes region Thursday into Friday. The dry and warmer weather continues for most of the week as surface high pressure remain in control, then becoming unsettled Thursday and Friday as a surface low approaches from the west. Monday through Wednesday... As mentioned above, this period of the forecast is dry, but PWATs are increasing. This will contribute to higher humidity. More interesting, is the return of the summer warmth, because Labor Day is widely known to be the "unofficial" end to summer. That said, am sure many people will returning to the A/C. Dewpoint temperatures return to the upper-60s and low-70s, air you can wear! And aloft the 925mb temperature increase between +22C and +26C, which are 3 to 6 degrees Celsius above what is typically normal for early-September. After reviewing the forecast profile on BUFKIT, the boundary layer is well mixed and dry. Monday and Tuesday features clear skies, but increased cloud cover likely Wednesday. That said, not expecting it will be cloudy, rather not wall-to-wall blue sky. High temperatures each afternoon are upper-80s and low-90s, but will be noticeably cooler at and near the coast. There temperatures during the afternoon are in the upper-70s and low-80s. As mentioned above, dewpoints are on the rise, this will make it feel as if it is hotter than the actual air temperature. The heat index could approach Heat Advisory criteria in a few spots like the Merrimack Valley, portions of Boston's metro west, and Connecticut River Valley. Something we will continue to monitor this weekend. Late Next Week... Temperatures cool late in the week with the return of clouds and rain chances. As the ridge breakdown a shortwave approaches from the west, POPs increase mid to late Thursday to slight chance and chance across western Massachusetts and Connecticut. Friday into next weekend a shortwave energy will rotate about a mid-level low that is centered over the eastern Great Lakes. On and off shower chances continue Friday into the upcoming weekend. Added cloud cover keeps temperatures cooler between the upper-70 and low-80s. But, dewpoints remain elevated in the upper-60s and low-70s. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today...High confidence. VFR with SW winds 5-10 kts. May see some 15-20 kt gusts after roughly 15-17Z. Should see some mid/high clouds push in toward 00Z. Tonight...High confidence. VFR for most with any gusty SW winds ending by roughly 23-01Z. Could perhaps see some valley fog across the Merrimack/CT River Valley. Uncertain at this point in how widespread it is, but could be MVFR/IFR. Sunday...High confidence. VFR. SW to W winds 5-10 kt, with local sea breezes on both southern and eastern coasts. KBOS TAF...High confidence in TAF. VFR with SW winds increasing to around 10 kt with gusts 15-20 kt by late-morning. Sea breeze remains offshore. Midlevel clouds arrive late afternoon to early tonight with decreasing SW gusts. VFR on Sunday with seabreeze development possible by 15z Sun lasting into 00z Mon. KBDL TAF...High confidence in TAF. VFR. SW winds increasing around 10 kt with occasional gusts to 20 kt. Outlook /Sunday Night through Wednesday/... VFR. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 300 AM Update: Overall high confidence. Issued small craft advisory for the far northeastern marine zones later this afternoon through early Sunday morning. SW winds increase around 10-15 kt to around 15-20 kt by later this afternoon, with gusts in the mid 20s kt range on the northeast waters. Seas should be around 2-4 ft on most waters, but may reach up to 5 ft on the northeastern outer waters. As the waters are pretty mild and the air is warming, expect mixing to be pretty shallow and gusts probably won't reach much higher than the mid to upper 20s kt range on the northeast waters. Winds and seas gradually decrease later tonight and overnight to around 10-20 kt SW gusts. Sub-SCA winds and seas anticipated for Sunday with gusts 10-15 kt and seas around 4 ft or less. Outlook /Sunday Night through Wednesday/... Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Sunday Night through Tuesday Night: Winds less than 25 kt. Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 8 AM EDT Sunday for ANZ250-251. && $$ SYNOPSIS...Loconto/Dooley NEAR TERM...Loconto/BL/KS SHORT TERM...Loconto LONG TERM...Dooley AVIATION...Loconto/BL/Dooley MARINE...Loconto/Dooley