NWS Forecaster Discussion
BOX
Area Forecast Discussion National Weather Service Boston/Norton MA.
000 FXUS61 KBOX 101044 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 644 AM EDT Sat Jun 10 2023 .SYNOPSIS... Areas of morning fog burn off and gives way to partial sunshine and milder temperatures this afternoon. The main threat for diurnally driven showers Saturday afternoon will be confined to eastern Massachusetts. A warming trend Sunday with a low risk for a few afternoon showers in the interior, otherwise dry weather prevails. Then the weather pattern turns unsettled again for much of the upcoming week with the risk of showers each day. Temperatures will be seasonable for much of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 630 AM update... Forecast remains on track at this hour. Radiation fog has developed across the fog prone areas in southern New England this morning. Additionally, some low stratus is lingering over the east coastal areas. Expect both fog and low stratus to lift by mid to late morning in response to surface heating. See previous discussion for more details on todays forecast. No changes have been made with this update. 345 AM update... * Scattered afternoon showers not as widespread as Friday * Milder temps this afternoon with highs 70-75, cooler coastline Closed low over Nova Scotia early this morning providing a moist cyclonic flow across SNE, resulting in periods of clouds and a few sprinkles from time to time. Light winds have resulted in areas of radiational fog. In addition, stratus and fog have come onshore into northeast MA, including Boston. However, strong June sunshine will burn off areas of fog and low clouds by late morning. This surface heating combined with cold air aloft (-22C at 500 mb) and cyclonic flow will result in SCT-BKN diurnal clouds to form beginning late morning into the afternoon. This should be sufficient for scattered showers and an isolated thunderstorm to develop. The focus for convection will be across eastern MA given proximity to the departing cold pool aloft. As the closed low exits thru the maritimes, rising heights and warming temps will occur from west to east this afternoon. This will diminish the shower threat from west to east. Hence, driest weather today will be across CT into western MA. Overall, not nearly as wet as yesterday. Warming temps aloft combined with partial sunshine will result in milder temps today than previous days, with highs 70-75, except mid to upper 60s across eastern MA due to cooler onshore flow. Light NW winds except onshore along the coast. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... 345 AM update... * Mainly dry/tranquil weather * Warming trend with highs Sunday in the upper 70s & low 80s Saturday night... Upper trough continues to move east and away from the region as a mid level ridge axis approaches. This will result in dry/tranquil weather Saturday night. Low temps will bottom out mainly in the upper 40s to the middle 50s. Light/Calm winds may promote patchy ground fog late in the typically prone locations...but not expecting anything widespread. Sunday... Short wave ridging provides mainly dry weather, although can`t rule out a few spotty showers in the WAA pattern as the ridge axis slides east. More clouds than sun in the WAA pattern, but warming airmass with +18C to +20C at 925 mb supports highs in the upper 70s to lower 80s, with a few mid 80s possible in the CT River Valley. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... 345 AM update... Highlights * Seasonable temperatures next week * Another wet and unsettled weather pattern for much of next week Next Week We return to a wet and unsettled weather pattern next week as cyclonic flow aloft is set to dominate the weather in southern New England through at least Friday. An upper-level low over The Great Lakes on Monday will slowly progress east through mid-week. This setup will support mainly west/southwest flow over southern New England. Thus, temperatures will be warmer than last week and somewhat seasonable with daily highs/lows in the mid-upper 70s/upper 50s-low 60s respectively. Can`t rule out touching 80 on a couple of days either. The wettest period looks to be Monday afternoon through Tuesday night when a cold front pushes through the region. Ahead of the frontal passage, strong southerly flow will advect an anomalously moist air mass into the region with PWATs surging to values just below 2 inches. This would be about 175 percent of normal for this time of year. Given the surplus of moisture and strong forcing associated with the frontal passage, it`s likely that most of southern New England experiences a good soaking of much needed rainfall. Half an inch to an inch of rain should be observed across much of the region between Monday night and Tuesday evening with the bulk of precipitation occurring overnight Monday. Tuesday and Wednesday will feature more spotty/diurnally driven showers with no washouts in the cards at this time. Look for improvements Thursday and Friday as the trough axis associated with the upper-low shifts east of the region. Because we will still be beneath an upper cold pool at the end of the week, there will remain lower chances for diurnal showers on Thursday and Friday. Unfortunately there are no promising signals beyond Friday that suggest a significant pattern change. Cyclonic flow looks to be in the cards once again next weekend which will lead to more clouds and daily chances for at least spotty precipitation. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 12Z TAF Update... Today...Moderate Confidence. Mainly VFR after any low clouds/fog patches burn off by mid-late morning. Brief localized MVFR conditions are also possible in the afternoon...mainly across eastern MA in scattered showers and perhaps an isolated t-storm or two. Light NW winds except for sea breezes developing along portions of the immediate coast. Saturday night...High Confidence. Mainly VFR outside any localized patchy ground fog that may develop in the typically prone locations toward daybreak. Light SW Winds Sunday...high confidence. VFR, dry weather and SSW winds 10-15 kt. KBOS Terminal...Moderate Confidence in TAF. IFR/LIFR conditions this morning will slowly improve to VFR by 15-16z. Then isolated -SHRA/-TSRA from 15z-20z followed by dry weather. Light north winds early this morning shift to east by midday. KBDL Terminal...High Confidence in TAF. VFR, dry weather and light winds. Any afternoon -SHRA should be well to the east in RI and eastern MA. Outlook /Sunday Night through Wednesday/... Sunday Night: VFR. Slight chance SHRA. Monday: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA. Monday Night: Mainly MVFR, with areas IFR possible. Breezy. SHRA likely, isolated TSRA. Tuesday: Mainly MVFR, with local IFR possible. Breezy. SHRA likely, isolated TSRA. Tuesday Night: VFR. Breezy. Chance SHRA. Wednesday: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA, isolated TSRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 345 AM update... Saturday through Sunday...High Confidence. Weak pressure gradient will keep winds/seas below small craft advisory thresholds through Sunday. A few nearshore thunderstorms possible this afternoon along the eastern MA coast. The only other issue will be patchy dense fog Saturday morning, which will burn and lift by late morning. Outlook /Sunday Night through Wednesday/... Sunday Night: Winds less than 25 kt. Slight chance of rain showers. Monday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Monday Night through Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely, isolated thunderstorms. Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Nocera/RM NEAR TERM...Nocera SHORT TERM...Nocera LONG TERM...RM AVIATION...Nocera/RM MARINE...Nocera/RM