textproduct: Boston / Norton

WHAT HAS CHANGED

A high risk for rip current statement has been issued for Nantucket on Monday.

KEY MESSAGES

- Outside a few showers/isolated t-storm risk into mid evening with the focus across the interior especially near and west of the CT River Valley. Areas of fog develop overnight which may become locally dense in spots.

- Drier with a return to seasonable temperatures this week. Rain chances return Thursday/Friday.

DISCUSSION

KEY MESSAGE 1...Outside a few showers/isolated t-storm risk into mid evening with the focus across the interior especially near and west of the CT River Valley. Areas of fog develop overnight which may become locally dense in spots.

The main cluster of showers that resulted in brief heavy rain along with a rumble or two of thunder has exited the eastern Ma coast earlier this afternoon. Behind this activity some subsidence and drier mid level air was allowing the lower clouds to begin to mix out from southwest to northeast. We will see a late rise in temps through early evening well into the 70s to perhaps near 80 in the CT River Valley as some peeks of sun try to develop. This will result in some modest instability developing with ML Capes approaching 1000 J/KG across parts of the interior. However...subsidence behind the earlier shortwave coupled with the main forcing well to our west will limit the additional risk. Nonetheless...a few showers and perhaps an isolated t-storm or two will be possible into mid- evening. The main focus for this activity will be across the interior and especially near and west of the CT River Valley closer to the upper level shortwave.

Otherwise...the main story later tonight will be for the development of fog some of which may become locally dense. Winds become light/calm overnight coupled with partial clearing, wet ground and dewpoints remaining in the 60s will set the stage for fog development. Some of the fog may become locally dense too. Low temperatures overnight will drop into the middle to upper 50s in the outlying locations...to the middle 60s in the urban heat islands of downtown Boston/Providence.

KEY MESSAGE 2...Drier with a return to seasonable temperatures this week. Rain chances return Thursday/Friday.

A post-frontal air mass ushers in drier conditions and warmer temperatures on westerly winds this week. As skies gradually clear from the dreary weekend, dewpoints will begin to drop slightly... into the upper 50s as opposed to the low to mid 60s we've been seeing. High pressure begins to slowly build Tuesday into Wednesday, prolonging the clear skies, drier weather, and warmer temperatures through the middle of the week. Expecting temperatures to return to seasonable, in the upper 70s to low 80s, and feel less humid thanks to the lower dewpoints through the end of the week.

Chances for rain showers return Thursday and Friday as a low pressure system develops over the Great Lakes and meanders east through southern Ontario. Some uncertainty remains regarding the onset of the showers as there's little consistency in the global ensembles on the actual placement of the low as it tracks through Canada; however, confidence has ticked up slightly in a later show of showers Thursday evening into the overnight period compared to yesterday's model runs.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

00z TAF Update...

Through Tonight...Moderate confidence in trends but lower confidence in specific timing.

A few additional showers and perhaps an isolated t-storm will be possible into mid evening, with highest chances across interior southern New England and particularly areas near and west of the CT River Valley.

Mostly MVFR-VFR conditions this evening; however, wet ground combined with light winds and dewpoints still in the 60s will likely result in areas of fog developing in the typically prone locations. Some of that fog may become locally dense overnight...while areas like KBOS end up going VFR. So a wide variety of conditions possible toward daybreak. Winds become calm/light SW tonight.

Monday and Monday night...High confidence.

Any leftover ground fog quickly burns off after sunrise Mon. Otherwise...VFR with SW winds of 7-13 knots with a few gusts up to 20 kts possible in the afternoon/evening hours. Mainly VFR conditions continue Mon night outside of any localized patches of ground fog that develop in those typically prone locations. Winds become calm/light SW Mon night.

KBOS Terminal...Moderate confidence in trends but lower confidence in specific timing.

KBDL Terminal...Moderate confidence in trends but lower confidence in specific timing.

Outlook /Tuesday through Friday/...

Tuesday: VFR. Breezy.

Tuesday Night through Wednesday Night: VFR.

Thursday: VFR. Breezy. Chance SHRA, slight chance TSRA.

Thursday Night through Friday: VFR. Chance SHRA, slight chance TSRA.

MARINE

Forecaster Confidence Levels...

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

Tonight through Monday night...High confidence.

The pressure gradient will generally remain weak enough to keep winds/seas below small craft advisory through Monday night. However...nearshore SW winds may gust into the lower 20 knots late Monday result in some decent chop for recreational boaters.

Outlook /Tuesday through Friday/...

Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.

Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft.

Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft.

Wednesday Night through Thursday: Winds less than 25 kt.

Thursday Night through Friday: Winds less than 25 kt. Chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...High Risk for Rip Currents from Monday morning through Monday afternoon for MAZ024. RI...None. MARINE...None.