389 FXUS61 KBOX 060714 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 314 AM EDT Sun Oct 6 2024 .SYNOPSIS... A ridge of high pressure will result in plenty of sunshine and pleasant temperatures today. A cold front moves through Southern New England very late tonight into Monday, bringing a period of rain showers and perhaps isolated thunderstorms. Trough and cold pool aloft mid week will support our chilliest stretch of Fall so far as morning lows drop into the 30/40s and afternoon highs crest in the 50s/60s. No significant precipitation is expected from Tuesday and beyond. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 315 AM Update... * Plenty of sunshine today at least away from the Cape and Islands with highs generally between 65 and 70 A ridge of high pressure will remain in control of our weather today. After a cool start...plenty of sunshine and a relatively dry airmass in place will allow for a nice recovery in temperatures. While it will be a few degrees cooler than yesterday...Highs should generally be in the upper 60s to near 70 although a few degrees cooler on the immediate coast with localized sea breezes. The only concern for today is that guidance indicates some low clouds that will attempt to back in off the ocean. Thinking the risk for these will mainly be across the Cape and Islands with a lower risk they flirt with the eastern MA coast for a time. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Key Points... * Showers move in from west to east between 2 & 10 am Mon * Period of widespread showers & iso t-storms possible Mon Details... Tonight and Monday... A mid level ridge axis will move east of the region tonight; allowing mid and high level cloudiness to overspread the region. An approaching shortwave will induce a modest southerly LLJ and a decent Pwat plume between 1 and 1.25 inches will advect into the region. As the forcing for ascent increases...expect showers to overspread the region from west to east roughly between 2 and 10 am Mon. A period of widespread showers is on tap for Mon...but the system is fairly progressive. So the back edge of the showers should move east of the CT River by early afternoon and reach the coastal plain by early evening. The mid level lapse rates are fairly steep and there is an instability burst with a few hundred J/KG of elevated Cape. So we did include the potential for isolated t- storms...which is also supported by the HREF thunder probs. While a period of widespread showers are expected...the short duration of the activity will probably keep most amounts in the 0.25 to 0.50" range. However...a few higher amounts are possible if any isolated t-storms are able to develop. Low temps tonight will mainly be in the upper 40s to the lower 50s. The clouds and showers will keep highs mainly in the middle to upper 60s on Mon. That being said...partial sunshine may develop across western MA/CT by mid to late Mon afternoon allowing highs to reach near 70 in the lower CT River Valley. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... * Cooler than normal temperatures develop mid week before ridging develops into next weekend * Rain chances look dismal from Tuesday and beyond with dry airmass in place Tuesday through Thursday... Welcome Fall! The long term forecast brings our first prolonged hit of below normal temperatures from Tuesday through Thursday as mid level trough and cold pool settle over southern New England and the cold front that brings expectant rain to the region moves seaward by 00Z Tuesday. The "540" line, what some forecasters view as the the official marker of "Fall", appears for the first time this season trough axis drops into SNE Wednesday; dipping as far south as the RI/CT coastline. Cold pool aloft peaks early Wednesday and Thursday mornings as 850mb temperatures drop a few degrees below zero (925mb temperatures linger in the low single digits Thursday AM). Given this, did take the opportunity to drop overnight lows mid week using a blend of CONSMOS and the current forecast to derive widespread lows in the upper 30s and low 40s; with some mid 30s possible across interior MA. Mid 30s will support the first kiss of frost for some areas. In addition to chilly morning temperatures, highs will only climb into the upper 50s and low 60s Wednesday and Thursday. Do expect diurnal cu development each day given aforementioned cold pool aloft. Friday into Next Weekend... Friday acts as a transitional period between cool and mild as trough shifts to the east. For Summer lovers, mid week's brief cool spell will drift into distant memory by next weekend as mid level ridging redevelops. Downsloping westerly flow and a continued dry air mass will aid in warming temperatures into the upper 60s and low 70s for Saturday and Sunday. Dry weather is expected to prevail with sprawling high pressure anchored over the eastern seaboard. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 06z TAF Update... Today...High Confidence. Mainly VFR. However...some marginal MVFR ceilings may roll in off the ocean this morning and impact parts of the Cape and Islands for a time today. Lower risk these marginal MVFR ceilings flirt with the BOS terminal...but will have to monitor. Light N winds shifting to the south this afternoon...but with sea breezes along portions of the immediate coast. Tonight and Monday...High Confidence this evening with moderate confidence overnight into Monday. VFR conditions dominate this evening. MVFR-IFR conditions should overspread most areas from west to east between 06z to 12z Mon along with widespread showers. This process may be 1 to 3 hours later towards the Cape and Islands. Widespread showers with the risk for an embedded t-storm or two will be possible on Mon. The back edge of the showers should be east of the CT River Valley by Mon mid afternoon and near the I-95 corridor by early Mon evening. Conditions to improve to VFR during the afternoon and approach the I-95 corridor by early evening. S winds 5-10 knots Mon am should shift to the NW across interior southern New England during Mon pm behind the cold frontal passage. KBOS TAF...Moderate confidence in TAF. Generally VFR conditions expected today. However...a period of marginal MVFR ceilings may flirt with the terminal for a brief time today...depending on how far west clouds are able to back in off the ocean. N winds shift to the E by early afternoon around 10 knots. KBDL TAF... High Confidence in TAF. VFR into this evening. Outlook /Monday Night through Thursday/... Monday Night: VFR. Breezy. Tuesday through Wednesday: VFR. Wednesday Night through Thursday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Today through Monday...High Confidence. Very distant tropical systems in the Atlantic will allow easterly swell of 3 to 6 feet to develop through Monday across the outer- waters. Therefore...small craft headlines are posted through Mon night. NE winds 5 to 15 knots should shift to the SE tonight. SSE winds continue on Mon with perhaps a few gusts near 25 knots across the outer-waters. Outlook /Monday Night through Thursday/... Monday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain showers. Tuesday: Winds less than 25 kt. Local rough seas. Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ250-254-255. Small Craft Advisory from 8 AM Monday to 8 AM EDT Tuesday for ANZ251. Small Craft Advisory from 4 AM Monday to 8 AM EDT Tuesday for ANZ256. && $$ SYNOPSIS...Frank/KS NEAR TERM...Frank SHORT TERM...Frank LONG TERM...KS AVIATION...Frank/KS MARINE...Frank/KS