textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- Gradual clearing today with a low chance of showers in parts of the interior. Drier into Wednesday.

- Generally becoming unsettled once again towards the second half of the week into the start of next week.

DISCUSSION

KEY MESSAGE 1...Gradual clearing today with a low chance of showers in parts of the interior. Drier into Wednesday.

Low pressure continues to pull off to the east and northeast today, which will allow for slow clearing, developing from west to east. Onshore flow persists as this low pulls further away from the region, which will likely keep temperatures near the coasts slightly cooler in the 70s. The rest of southern New England may reach the low 80s, as that's where clouds should scatter out sooner. With the clearer conditions inland, it will also be less humid as winds shift more northwest. A spot shower or two cannot be entirely ruled out across much of central MA into RI, CT this afternoon. Tonight should be calm with patchy fog possible and lows in the 60s.

Zonal flow persists aloft into Wednesday as an upper level low tracks well to our north across the Hudson Bay. Some guidance does indicate some shortwave energy moving within the flow across the region later Wed into Thu which could lead to a spot shower or two, however the more favorable parameters remain to our north and west.

KEY MESSAGE 2...Generally becoming unsettled once again towards the second half of the week into the start of next week.

A stronger shortwave within the flow aloft makes its way east heading into Thursday, bringing with it more favorable dynamics and moisture for showers. Discrepancies still remain regarding the wave's track across the ensemble and deterministic guidance, with the GEFS continuing to show higher probabilities for 24 hour rainfall of 0.1"+ extending into CT, SE MA, and RI while the ECMWF and Canadian ensembles continue to favor a more southern track. NAEFS guidance, notably, keeps the more anomalous moisture off to our south and east, though PWAT values reaching to around 1.5" are not out of the question.

Under the post-frontal airmass Friday with high pressure overhead, conditions will be drier overall. Temperatures will likely be in the low 80s and down to the mid 70s, particularly along the coasts where onshore winds will keep it slightly cooler. Conditions become unsettled once more, though, as we keep an eye on a deepening trough digging into the Great Lakes region towards the weekend period. Shortwaves moving along the boundary that may stall just off the east coast could bring chances for showers. Thunderstorms could be a possibility depending on if these waves could take advantage of daytime heat. More details will become apparent as we approach this timeframe.

AVIATION /07Z TUESDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

Through 12z...Moderate confidence

Pockets of IFR are continuing to develop across the region, with some areas reaching LIFR. Notably, coastal terminals have hit this sooner. Light E to NE winds continue over more coastal terminals with calm conditions persisting over the interior terminals.

Tuesday...Moderate confidence (ceilings)

MVFR to IFR conditions to start, with improvement to VFR from west to east between 17Z and 20Z. Improvements for terminals further east may be slower and may only top out to MVFR based on guidance, though VFR by 00z is a possibility for Cape/Islands terminals. Light N winds become more NW during the afternoon for the interior terminals, while onshore NE/E winds continues for eastern terminals, generally at 5-10 kt. Higher winds above 10 kt are possible for ACK.

Tuesday Night...Moderate confidence.

VFR across the interior, though MVFR towards the Cape/Islands, along with RI terminals, depending on how thick cloud cover remains. Otherwise, SCT to FEW at lower ceilings. ACK could see return of IFR conditions. Light NW to SW winds less than 10 kt with patchy fog possible.

Wednesday...High confidence.

VFR. WSW winds over much of the region, more SSW over the coastal areas all at 5-10 kt.

KBOS Terminal...Moderate confidence.

LIFR visby possible periodically early this morning through at least 08z. Exact timing of improvements to VFR lower confidence, but more likely between 16-19Z. SCT MVFR decks possible through the afternoon. Winds NE becoming E in the afternoon 7-10 kts.

KBDL Terminal...Moderate confidence.

MVFR conditions have just moved in to the terminal and are expected to continue through the rest of tonight into the mornings hours. Periods of IFR cannot be entirely ruled out for the early morning hours. Chance of fog remains.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: VFR.

Thursday: VFR. Slight chance SHRA, slight chance TSRA.

Thursday Night through Friday Night: VFR. Slight chance SHRA.

Saturday: VFR. Chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Through Wednesday Night...Moderate confidence.

Low pressure continues to shift farther off to the east. Seas diminish more to 2-4 ft across the coastal and nearshore waters. Ocean waters off to the east may take longer to drop off as they may get to around 5-6 ft heading into tonight. By Wednesday, seas fall to 2-3 ft across all waters. Winds through this period remain generally under 15 kt outside of occasional gusts in the afternoons. More N winds shift W, then S tonight, then more SW by Wednesday night.

A higher rip current risk is expected for east-facing beaches where a Rip Current Statement is in effect from 8 AM this morning through 8 PM tonight.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: Winds less than 25 kt.

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

Thursday Night: Winds less than 25 kt. Chance of rain showers, slight chance of thunderstorms.

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...High Risk for Rip Currents from 8 AM EDT this morning through this evening for MAZ007-015-016-019-022-024. RI...None. MARINE...None.