035 FXUS61 KBOX 281054 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 654 AM EDT Tue Jul 28 2020 .SYNOPSIS... Hot weather will prevail for the next few days, although the humidity will decrease for the middle and end of this week. A weak cold front will bring scattered showers and thunderstorms Today. Mainly dry weather will follow for the rest of this week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 7 am update... No major changes to the forecast with this update. It's a very warm start out there; all four climate sites are currently on track to set a recored warmest low temperature for the day (barring a cooler temp later this evening). The cold front is currently draped across western NY as visible on satellite and the line of convection out ahead of it in eastern NY. The bulk of this line of stronger storms will most likely pass just north of us into VT but some showers and tstorms may make it into western MA...should be weakening as they enter a less favorable environment. Previous Discussion... Another day of heat and humidity is in store for southern New England. Heat Advisories continue across most of our region for heat index values of 95-100 degrees. Expecting moderate instability today between 1-2k J/kg. Primary axis of the low level jet should be displaced off to the east of our region. Winds more towards the mid levels will be more overhead. Mid level lapse rates should be nearly moist adiabatic. Not looking like a widespread severe weather day, but will need to monitor conditions as a few could become quite strong to severe. The main threats are straight-line winds and downpours, with a lower risk for hail. Timing-wise, can see showers start to bubble up late morning, with thunderstorms becoming increasing likely this afternoon and evening. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Showers and thunderstorms should diminish this evening with the loss of daytime heating. Not expecting a weakening cold front to move through southern New England until late tonight. Some signals this front could hang up towards the south coast of MA and RI late tonight into Wednesday. Maintained at least a chance for some late night showers and thunderstorms along this weak front. Drier air starts to arrive from the NW tonight, but thinking the lower dew points will struggle to reach the Cape and islands Wednesday. The mid levels should dry out, so thinking much of southern New England should be rain-free Wednesday. ABove normal temperatures continue tonight into Wednesday. However, there should also be just enough of a drop in low level dewpoints where we are just short of needing to extend Heat Advisories into Wednesday. It will be close though, so something to monitor with later forecasts. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Highlights * Trending not as hot and less humid * Isolated to scattered showers and thunderstorms possible on Thursday and Friday, but no washouts anticipated. Details... Temperatures... Better days are ahead, if you're not a fan of the heat wave we've been experiencing that is. As we move into the latter half of the week and weekend the synoptic patter transitions to one dominated by broad mid-level troughing over the northeast. As this happens height falls and cooler upper level temperatures will lead to a gradual "cool down"...quotes included because even so, temperatures will still feel very much summer-like. Some locations like Hartford and portions of eastern MA may even get one more day tacked onto the heatwave streak on Thursday (i.e. could reach 90 F once more), after which things remain around normal or slightly above normal for early August. By the weekend 850 mb temperatures drop as low at 12-14 C. All of this translates to highs in the 80s across the region; biggest drop in temps comes between Thursday and Friday with a cold frontal passage. Good news is dewpoints should be more comfortable during this period. Precipitation... Better confidence in the details/timing of rain chances early, decreasing as we reach the weekend and beyond. Big picture, though, indicates the best rain and thunderstorm chances Thursday into early Friday, then again around the start of next week. Firstly Thursday rain and thunderstorm chances linger beneath the broad trough/cold pool aloft and sfc trough. Between these lifting mechanisms and and plenty of moisture ahead of an approaching cold front we'll see shower and thunderstorm chances on Thursday into Friday. Ridging then builds in for the weekend keeping things mostly dry until the pattern breaks down again toward the start of next week when more widespread rain and showers returns. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 12Z update... Today...High confidence VFR with scattered showers and thunderstorms moving in due to an approaching cold front. As showers and storms move through will likely have brief MVFR/IFR conditions with gusty winds and heavy rain possible. Most likely outcome timing-wise is starting 14-15Z near Berkshires, reaching BOS/PVD around 18Z, and south coast by 20-21Z. Activity diminishes this evening as winds shift to W. Tonight...High confidence VFR. Still could have some lingering shower/storms across the south coast as a cold front stalls. If a shower or storm moves through, then could have brief MVFR/IFR conditions. Wednesday...High confidence. VFR. Light SW winds. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Wednesday Night through Saturday/... Wednesday Night: VFR. Thursday through Thursday Night: VFR. Slight chance SHRA, isolated TSRA. Friday: VFR. Slight chance SHRA. Friday Night through Saturday: VFR. && .MARINE... SW flow prevails through today with slowly building seas on outer waters, which reach near 5 ft today. Small Craft Advisories continue for marginal rough seas. An approaching cold front will weaken as it reaches coast tonight, but may still bring scattered showers or thunderstorms tonight into Wed. Outlook /Wednesday Night through Saturday/... Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers, isolated thunderstorms. Thursday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. Friday: Winds less than 25 kt. Slight chance of rain showers, slight chance of thunderstorms. Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. && .CLIMATE... Last occurrence of 100+ temperatures... BOS...07/22/2011 PVD...07/22/2011 BDL...07/21/2019 ORH...07/04/1911 Daily High Temperature Records July 27th BOS 98 in 1882 PVD 97 in 1940, tied 2020 BDL 98 in 2020, previously 96 in 1964 ORH 93 in 1892, 1940 and 1949 July 28th BOS 99 in 1949 PVD 95 in 1949 BDL 96 in 1931, 1949, 1970 and 2016 ORH 95 in 1892 Daily Warmest Low Temperature Records July 27th... BOS 76 in 1963 PVD 75 in 1995 BDL 73 in 1934 and 2003 ORH 73 in 1940 July 28th... BOS 78 in 1963 PVD 75 in 1919 BDL 74 in 1919 ORH 73 in 1931 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Heat Advisory until 8 PM EDT this evening for CTZ002>004. MA...Heat Advisory until 8 PM EDT this evening for MAZ004>007- 010>022-026. RI...Heat Advisory until 8 PM EDT this evening for RIZ001>007. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ254>256. && $$ SYNOPSIS...Belk/BW NEAR TERM...Belk/BW SHORT TERM...Belk LONG TERM...BW AVIATION...Belk/BW MARINE...Belk/BW CLIMATE...