Cooney Athletic Field, MA Hourly Weather Updates

Key Messages

• Scattered showers and t-storms mainly for interior Southern New England this afternoon through sundown. A couple could produce small hail and gusty winds.
• Pleasant weekend with seasonably cool temperatures and comfortable humidities.
• Rain chances return late Sunday into Monday, followed by quieter weather through most of next week.

Discussion

... KEY MESSAGE 1...Scattered showers and t-storms mainly for interior Southern New England this afternoon through sundown. A couple could produce small hail and gusty winds.

Main concern for the rest of the afternoon into early tonight revolves around low-topped showers and thunderstorms. A rather potent shortwave disturbance is visualized in water vapor imagery early this afternoon near Ottawa ON, forecast to move southeast through New England into early tonight. Modest instability given dewpoints falling into the mid 50s is present across most of New England, but stronger forcing and the cool pocket of air aloft due to the shortwave is contributing to scattered convective showers across NY and VT. BUFKIT soundings show strong 925-700 mb lapse rates as well as strong mid-upper level flow aloft, but with low equilibrium levels around 25-28k and wetbulb zero heights on the order of 9000 ft. Have seen some lightning strikes in eastern Ontario, and anticipate some of these showers could blossom into scattered t-storms. With the cold profiles aloft, even stronger showers could produce graupel/"dippin` dots" hailstones, with deeper t-storms capable of hail up to 1" diameter with locally strong/gusty winds. The severe weather risk level has increased to a Level 1 of 5, but still think the risk storms become severe is on the low side. The best chance for storms is mainly from a FIT- ORH- PVD line south and west, with showers more likely into eastern MA. Showers/storms are expected to dissipate into the early-mid evening hours associated with sundown and passage of the shortwave disturbance.

Clearing skies overnight, which will bring a risk for patchy river valley fog as winds go light northerly. A big airmass change comes in tonight with much lower humidity levels and lows in the mid 50s to around 60, so a good night to crack open the windows!

KEY MESSAGE 2...Pleasant weekend with seasonably cool temperatures and comfortable humidities.

Beautiful weekend shaping up as a 1024 mb high pressure establishes itself over Southern New England Saturday, then begins to move offshore into Sunday. Full sun, light northerly winds and dewpoints falling into the 40s Saturday will bring a taste of early-autumn, with highs in the mid 70s to around 80 as 850 mb temps run around +7 to +10C. Very strong radiational cooling setup Saturday night, with widespread 50s for lows as ridge of high pressure centers itself overhead, to go along with patchy river valley fog. A bit more of an increase in cloud cover Sunday, with risk for showers developing late in the day on Sunday in western New England at earliest, but most of the daytime hours are dry.

KEY MESSAGE 3...Rain chances return late Sunday into Monday, followed by quieter weather through most of next week.

Sunday starts off under mid-level ridging with heights falling through the day ahead of an approaching shortwave trough in the flow. This will keep conditions dry most of the day Sunday with temperatures in the upper 70s/low 80s. There is general agreement across most guidance in rain arriving Sunday night, spreading from west to east. Expect batches of showers to continue through Monday. Can`t rule out an embedded storm or downpour with marginal instability around. With PWATs 1.5-1.8", brief heavier rain rates are possible. Mid-level winds will be strong enough to keep any heavier showers or storms moving if there are any. This should help minimize the risk for flash flooding. Can`t rule out isolated instances of flash flood impacts in poor drainage/urban areas given the potenial for embedded heavier downpours. This has been reflected in the WPC ERO as a Marginal Risk (Level 1 of 4). For total amounts, ensemble guidance shows a range of 0.25" to 0.50" across southern New England. Localized higher amounts are possible, especially within any downpours.

A cold front moves through the region by Tuesday with a drier airmass advecting into southern New England behind it. Conditions remain generally dry Tuesday and Wednesday with zonal flow aloft. Temperatures will likely be in seasonable ranges in the upper 70s to low 80s with dewpoints in the low to mid 60s keeping humidity leaning toward the more comfortable side. Ensemble guidance signal for a trend toward unsettled weather by late-week with chances for rain returning to the forecast.

Aviation

/00Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

00z TAF Update:

Tonight: High confidence.

Any remaining SHRA/isolated TS to weaken and move offshore by 03z with mainly VFR conditions. Latest guidance seems more favorable for MVFR- IFR patchy mist/fog development toward daybreak in interior river valleys (e.g. BDL) and perhaps at BED too. Light northerly winds.

Saturday and Saturday Night: High confidence.

VFR. N/NW winds 5-10 kt, with seabreezes near the coast during the daytime hours. Patchy river valley fog with IFR visbys overnight.

KBOS Terminal...High confidence in TAF. Main risk for a few brief showers in the vicinity of the terminal will be after 21z/22z until about 02z. Low risk for a rumble of thunder too. Odds favor sea breeze remaining offshore this afternoon...but we do expect one to develop on Sat.

KBDL Terminal...High confidence in TAF. Better chance for TSRA after 19z thru sundown.

Outlook /Saturday Night through Wednesday/...

Sunday: VFR. Breezy. Slight chance SHRA.

Sunday Night: Mainly VFR, with local IFR possible. Breezy. SHRA, slight chance TSRA.

Monday: Mainly VFR, with local IFR possible. Breezy. Slight chance SHRA.

Monday Night through Tuesday Night: VFR.

Wednesday: VFR. Breezy.

Watches / Warnings / Advisories

/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None.