textproduct: Boston / Norton

WHAT HAS CHANGED

A Rip Current Statement has been issued for east-facing beaches from 9 am to 8 pm Tuesday.

KEY MESSAGES

- Fair and less humid Tuesday with gradual clearing. A high risk of rip currents develops across east-facing beaches by Tuesday afternoon.

- No washouts expected, though several opportunities for showers return from mid to late week.

DISCUSSION

KEY MESSAGE 1...Fair and less humid Tuesday with gradual clearing. A high risk of rip currents develops across east-facing beaches by Tuesday afternoon.

Gradual clearing develops from W to E Tuesday as low pressure slowly pulls away from the region. Guidance shows areas of low clouds and fog lingering for much of the day across coastal areas with the help of cyclonic onshore flow. Thus, expecting high temperatures to stay in the lower to mid 70s for coastal areas, and perhaps even the upper 60s for the outer Cape. It will be quite humid closer to the coast with onshore flow advecting moisture inland. Elsewhere, it will be drier as the flow turns to the NW through the day. Further inland, it looks to be a warmer and drier day with highs in the low to mid 80s. Heat index values climb into the upper 80s to near 90 for a time Tuesday afternoon. For those heading to the beach Tuesday afternoon, a Rip Current Statement is in effect for east-facing beaches Tuesday. Those heading to the beach should remain aware of local conditions and check with lifeguards or beach staff regarding rip current risks at their specific location.

KEY MESSAGE 2...No washouts expected, though several opportunities for showers return from mid to late week.

Generally zonal flow aloft prevails Wednesday while an upper level low tracks well north across the Hudson Bay. Conditions are likely to stay dry during the day with temperatures in the low to mid 80s. A weak piece of shortwave energy shifts in from the west later Wednesday. While the better forcing remains further north and west, there is a low probability for an isolated shower in western MA Wednesday night.

Another shortwave in the flow moves through Thursday accompanied by better ascent and plume of above normal moisture to support showers. There is still some uncertainty across guidance with the track of the wave. The ECMWF (ens and deterministic) leans toward a more southern track with the higher ensemble probabilities (60-80%) for any rain accumulation extending across the south coast to southeast MA, and Cape/Islands. The GEFS/GFS has shown a wider footprint of showers with similar probabilities across all of southern New England. Any amounts are likely to range from a trace to a few tenths of an inch.

We'll be in a post-frontal airmass Friday resulting in slightly cooler temperatures in the mid 70s to low 80s and a downtick in humidity. The eastern coastal areas will likely end up on the cooler end of that temperature range given the easterly onshore flow. High pressure builds in from the west bringing dry conditions to most of the region. However, there are indications across model guidance of a boundary stalling off the east coast with a series of embedded shortwaves riding that boundary Friday through the weekend. This may bring periodic chances for showers, perhaps some thunderstorms if the waves align with diurnal heating. The higher risk for showers will the for south coast extending to Cape Cod/Islands.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

This afternoon into Tonight...Moderate confidence in trends, lower confidence in timing.

Pockets of IFR developing as winds shift to the SE and E, mainly across coastal terminals. Potential for LIFR for the Cape and Islands overnight. Light northerly winds, becoming calm across the interior.

Tuesday...Moderate confidence.

MVFR to IFR conditions to start, with improvement to VFR from west to east between 15Z and 20Z. Eastern terminals, including Cape Cod, may experience a later improvement to VFR, possibly not until 22Z to 00Z. Light northwest winds across the interior, with north to north- northeast winds across eastern Massachusetts at less than 10 kt.

KBOS Terminal...Moderate confidence.

MVFR until 21z, then IFR with SE winds shifting to the E after 00z. IFR conditions continue overnight with winds shifting to the NE and eventually N after 12z.

KBDL Terminal...Moderate confidence.

MVFR conditions through the overnight. Low chance for FG at the terminal. Light and variable winds.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: VFR.

Thursday through Friday: VFR. Chance SHRA.

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 Tuesday Night...Moderate confidence.

SCA conditions subside Tuesday as low pressure shifts farther east. Seas subside to 2 to 4 ft, with light northerly to north- northwest winds generally less than 15 kt. High risk of rip currents for east-facing beaches across E Massachusetts as well as the Cape and Nantucket.

Outlook /Wednesday through Saturday/...

Wednesday through 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 Tuesday morning through Tuesday evening for MAZ007-015-016-019-022-024. High Risk for Rip Currents until 8 PM EDT this evening for MAZ023- 024. RI...High Risk for Rip Currents until 8 PM EDT this evening for RIZ006>008. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ232>235-237. Small Craft Advisory until 2 AM EDT Tuesday for ANZ254>256.