textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast at this time. The aviation section was updated for the 18z TAFs.

KEY MESSAGES

- Dry weather continues through the evening before the risk for scattered showers and a few thunderstorms returns tonight into Friday.

- Some showers expected Saturday. followed by a warming and drying trend into early next week.

- Warm and humid mid week. Risk for some showers with a warm frontal passage sometime Wednesday into Thursday.

DISCUSSION

KEY MESSAGE 1...Dry weather continues through the evening before the risk for scattered showers and a few thunderstorms returns tonight into Friday.

High pressure continues to situate itself across the northeastern CONUS yielding rain-free conditions through this evening. Expect light southeasterly winds to persist with temperatures climbing into the upper 70s to low 80s.

However, this pattern changes as we head into tonight. As a weak surface low tracks across New England late this evening, an associated warm front will also move into the area allowing for the chance of showers and thunderstorms to progress from west to east. The risk for thunder remains quite low given the lack of instability present overnight, however some embedded rumbles of thunder over western MA are possible where a more favorable environment resides.

These showers will likely wash out Friday morning as the weakening low shifts further away. It'll feel slightly more humid on Friday with dewpoints in the mid to upper 60s. As another surface low tracks into the region on Friday, this will bring another chance for showers and thunderstorms in the evening/night. It looks like the convection will be fairly scattered and the severe threat remains isolated. Even though instability remains limited, the effective bulk shear looks impressive with values ranging from 40- 50kt. Therefore, the primary concern with thunderstorms that do develop will damaging wind gusts. It is worth noting that southern New England is also under a Marginal (1/5) risk for severe weather Friday.

KEY MESSAGE 2...Some showers expected Saturday. followed by a warming and drying trend into early next week.

Guidance continued to have a similar idea about a low pressure tacking along a cold front. However, the track of this low pressure and front were quite different. The NAM was the most aggressive keeping showers farther north across southern New England. Most of the guidance is farther south. Have the greatest confidence in showers towards the south coast of New England. Still thinking the timing could be off, and Saturday could turn out drier than the current forecast.

Dry weather is expected to return heading into the start of next week as high pressure associated with an amplified upper level ridge moves into southern New England. A warming trend also kicks off for the start of the work week, continuing into midweek. However, details on just how warm it may get are still uncertain at this time.

KEY MESSAGE 3...Warm and humid mid week. Risk for some showers with a warm frontal passage sometime Wednesday night into Thursday.

Increasing heat and humidity continues into the second half of next week. Much of this time is expected to remain dry, but there should be a period of showers with the passage of this warm front. The location details for these showers are not yet known.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Forecaster Confidence Levels...

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

18Z TAF Update...

This Afternoon through Friday Afternoon...Moderate confidence.

VFR conditions will persist through the evening with light southeasterly flow. Chances of showers and thunderstorms after 00Z increase from West to East as a weak surface low tracks across New England. The greatest risk for isolated thunderstorms remains in western MA between 08Z-12Z, therefore a PROB30 was noted in for KBDL to account for this risk. VFR ceilings will then drop to MVFR and possibly IFR heading into Friday morning. Also, there is a chance of fog along the south coast and a mention of BR was noted for KACK.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday through Tuesday/...

Saturday: Mainly VFR, with local MVFR possible. Chance SHRA.

Saturday Night through Monday Night: VFR.

Tuesday: VFR. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Through Friday...High confidence.

Light south-southwesterly winds persist through the afternoon, before shifting more southerly overnight. It's possible to see some breezier winds this evening (gusts up to 20 kt) across the waters. Seas should remain 2 to 4 ft. Showers and thunderstorms may start to impact the waters late tonight into Friday.

Outlook /Saturday through Tuesday/...

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

Sunday through Monday Night: Winds less than 25 kt.

Tuesday: Winds less than 25 kt. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...None.