textproduct: Boston / Norton

WHAT HAS CHANGED

A High Risk for rip currents was issued for south-facing ocean beaches today. Those heading to the coast should exercise caution.

KEY MESSAGES

- Showers and extensive cloud cover lead to a cooler-than- normal and quite humid day. A High Risk for rip currents remains in effect for south-facing ocean beaches.

- Mainly dry Tuesday, with only isolated showers possible across eastern southern New England. Seasonable temperatures continue, with a High Risk for rip currents along east-facing ocean beaches.

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

DISCUSSION

KEY MESSAGE 1...Showers and extensive cloud cover lead to a cooler- than-normal and quite humid day. A High Risk for rip currents remains in effect for south-facing ocean beaches.

Showers early this morning will continue into the afternoon, though coverage should be lower than earlier today. Southern New England is situated between two areas of low pressure, with the strongest forcing displaced to the north and south of the region. As a result, it may be difficult to fully capitalize on the higher PWATs of 1.8 to 2.0 inches across the region. Nevertheless, periodic showers will continue through this morning and afternoon.

The threat for heavy rainfall remains low. While an isolated heavier downpour cannot be ruled out, widespread heavy rainfall is not expected. Flooding is also a very low threat, with the primary concern limited to localized urban or poor-drainage flooding. Rainfall amounts have trended lower across interior southern New England, generally ranging from one-tenth to two-tenths of an inch, while areas along and east of I-95 may receive around one-quarter to one-third of an inch. Localized higher amounts, potentially approaching one-half inch, remain possible beneath areas of weak convection.

One final round of showers, and perhaps a thunderstorm or two, is possible with the passage of a cold front. However, abundant cloud cover will limit instability across much of southern New England. The greatest potential for thunderstorms will be across eastern New York, far western Massachusetts, and far northwestern Connecticut, where MUCAPE may exceed 800 J/kg. Instability decreases considerably farther east.

Given the cloud cover and onshore flow, highs today will only reach the lower to middle 70s across eastern Massachusetts, Rhode Island, and eastern Connecticut. Farther west, temperatures climb into the middle to upper 70s. Dew points in the upper 60s to lower 70s will make it feel quite humid. While it will not be a hot day, it will certainly feel sticky.

It will not be an ideal beach day, but it is important to note the High Risk for rip currents along south-facing ocean beaches. 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...Mainly dry Tuesday, with only isolated showers possible across eastern southern New England. Seasonable temperatures continue, with a High Risk for rip currents along east- facing ocean beaches.

Somewhat drier air advects into the region from the northwest late tonight into Tuesday, with PWATs lowering to around 1.3 inches by Tuesday afternoon. A weak area of surface low pressure east of Cape Cod, along with lingering weak forcing, may produce an isolated shower or two, mainly along and east of a KIJD-KORH-KFIT line. Otherwise, Tuesday will feature a mix of sun and clouds with seasonable temperatures in the lower to middle 80s. The eastern Massachusetts coast will likely remain a few degrees cooler, with highs in the upper 70s due to continued onshore flow.

A High Risk for rip currents is expected along east-facing ocean 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 3...No washouts expected, though several opportunities for showers return from mid to late week.

The flow aloft becomes generally zonal Wednesday through Friday, with a stronger shortwave trough moving through eastern Canada late Wednesday into Thursday. A leading shortwave may trigger a few showers late Wednesday night, though much of Wednesday should remain dry. The primary shortwave and an accompanying cold front move through Thursday, providing better lift along with PWATs increasing to around 1.5 to 1.7 inches. This should bring an increased chance for showers, though widespread or continuous rainfall is not expected.

High pressure is then expected to build eastward, bringing mainly dry conditions. However, model guidance continues to indicate the potential for a boundary to stall offshore, with a series of embedded shortwaves moving along it from Friday into the weekend. This could result in periodic chances for showers, and perhaps a few thunderstorms, with the greatest risk generally focused across the south coast and Cape Cod and the Islands.

Wednesday will be the warmest day of this period, with highs in the middle to upper 80s and tolerable humidity as dew points remain in the 60s. Temperatures trend downward by a degree or two Thursday and Friday, with cooler conditions expected this weekend as highs generally range from the upper 70s to near 80 degrees.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

Today...Moderate confidence in trends, lower confidence in timing.

Periods of SHRA during the early morning hours become more scattered through the morning and afternoon as the steadier precipitation shifts east. Cannot rule out an isolated TSRA during the afternoon as a cold front approaches, though limited instability should keep coverage sparse. IFR to MVFR ceilings are expected this morning, with gradual improvement during the afternoon. Confidence remains low regarding the timing and extent of improvement. Southeast winds early become east, then northeast during the afternoon, eventually shifting to the north by 00Z Tuesday.

Tonight...Moderate confidence in trends, lower confidence in timing.

SHRA gradually end, though IFR conditions may persist overnight with areas of DZ and pockets of FG. 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.

VFR early, becoming MVFR after 10-12Z with SHRA. Ceilings should generally remain low-end MVFR, though periods of IFR conditions are possible, especially after 15Z with continued SHRA. Southerly winds become east-southeast by 10Z, then shift to east-northeast late this afternoon.

KBDL Terminal...Moderate confidence.

Conditions oscillate between MVFR and IFR with periods of SHRA throughout the day. Light east-southeast winds.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Wednesday Night: VFR.

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

Thursday Night: VFR. Chance SHRA.

Friday: VFR.

MARINE

Forecaster Confidence Levels...

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

Through Tuesday...Moderate confidence.

A weak area of low pressure moves south of the waters today, then shifts east of the waters Tuesday. Southeast winds around 20 kt this morning become easterly this afternoon, with gusts up to 25 kt. Seas build to 4 to 6 ft, with isolated seas up to 7 ft possible across the outermost southern waters, though confidence in widespread 7 ft seas is low. Small Craft Advisories have been modified to reflect the latest forecast, with the advisory across the eastern waters canceled due to a downward trend in both winds and seas. Conditions improve Tuesday as the low shifts farther east. Seas subside to 2 to 4 ft, with light northerly to north-northwest winds generally less than 15 kt.

Outlook /Tuesday Night through Friday/...

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

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.

Friday: Winds less than 25 kt. Slight 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 MAZ023-024. RI...High Risk for Rip Currents from 8 AM EDT this morning through this evening for RIZ006>008. MARINE...Small Craft Advisory from 8 AM this morning to 8 PM EDT this evening for ANZ232. Small Craft Advisory until 8 PM EDT this evening for ANZ233>235-237. Small Craft Advisory from 8 AM this morning to 2 AM EDT Tuesday for ANZ254. Small Craft Advisory until 2 AM EDT Tuesday for ANZ255-256.