textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Expect a few isolated showers around today with cooler temperatures. Warmer Tuesday with isolated showers or a stray storm possible.

- Forecast confidence decreases for late-week. Conditions more likely lean dry and warm, but we continue to monitor the potential for an offshore system to bring showers.

DISCUSSION

KEY MESSAGE 1...Expect a few isolated showers around today with cooler temperatures. Warmer Tuesday with isolated showers or a stray storm possible.

Another push of cold air gets ushered into today with northeasterly flow. This will bring cool day with cooler than normal highs in the upper 50s and 60s. Expect warmer temperatures in the CT Valley in the mid to upper 60s while onshore flow keeps the east coastal areas on the cooler side struggling to get into the low 60s. A weak quick- moving piece of shortwave energy drops across the region today. However marginal moisture will likely limit it to some isolated or "pop-up" showers in the afternoon.

Tuesday, the core of lower 500mb heights shifts east although southern New England still remains under the blocky upper trough. With the slight moderation in heights, temperatures should follow suite, warming a few degrees from Monday. This should support a more seasonable day with high temperatures in the low to mid 70s with local sea breezes. Coastal areas may end up a bit cooler in the upper 60s where the sea breeze sets up. There are indications across model guidance for another weak piece of shortwave energy shifting southward across the region resulting in another shot for pop-up showers in the afternoon. There are indications of marginal instability that will build with the help of the incoming shortwave and warmer temperatures. As a result, a few isolated storms can't be ruled out.

Wednesday trends mainly dry as an amplified ridge nudges in from the west while pushing the deep trough just barely offshore. This will begin the warming trend in temperatures. 850mb temperatures rise a couple degrees from Tuesday likely supporting highs in the 70s in most spots with the warmest temperatures in the valleys (75-80F).

KEY MESSAGE 3...Forecast confidence decreases for late-week. Conditions more likely lean dry and warm, but we continue to monitor the potential for an offshore system to bring showers.

Forecast uncertainty increases regarding the upper-level pattern heading into late week. Ensemble guidance shows general agreement that an amplified upper-level ridge will build east into the region, slowly pushing the deep trough further offshore. However, model spread increases concerning a potential closed low developing at the base of the trough near the Carolinas and tracking northward. While ensemble means currently favor this low to track well offshore (dry conditions), some deterministic and ensemble members across previous runs have suggested a closer track to the 40N/70W benchmark. If this closer track verifies, if could bring showers to the area Thursday to Friday in east locations (Cape and Islands). If it is dry as majority of guidance suggests, there is a signal for a strong ridge aloft to bring an anomalously warm airmass into the region. This may support summer-like temperatures in the low to mid 80s, perhaps nearing 90 in the CT Valley.

Details remain uncertain, but there is a consensus across ensemble guidance for a potential system to bring showers sometime Saturday.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

12Z TAF Update:

Through 00Z...Moderate Confidence in timing.

MVFR ceilings persist on NE flow thru at least 16z. It may potentially spread as far as BDL, though lower confidence. Potential for patchy IFR at BOS and Cape and Island terminals.

Today...Moderate Confidence (cigs/timing of improvements).

MVFR ceilings possible this morning with higher probabilities for the eastern terminals, but could expand as far as ORH. Patchy IFR possible along east coast terminals early this morning. Ceilings likely improving 15-18Z.

N to NE winds at 08-15 kts, strongest for coastal terminals. Period of gusts around 20 kts possible after 15Z-18Z mainly for coastal terminals. Low chance (< 10%) that an isolated -SHRA develops and makes is as far south as BOS before the morning. Low chance (< 10%) for an isolated shower in afternoon.

Tonight...High Confidence.

VFR. Light winds mainly from the W/WSW and more N for the Cape terminals.

KBOS...Moderate confidence in TAF trends. Hit-and-miss showers remain through midnight with very low risk of an isolated thunderstorm in the vicinity of the terminal. Stratus deck towards the Monday morning push could have lower bases.

KBDL...High confidence in TAF.

Outlook /Tuesday through Friday/...

Tuesday through Thursday Night: VFR.

Friday: VFR. Breezy.

MARINE

Forecaster Confidence Levels...

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

Through Tonight...High Confidence.

Remaining 5 ft seeing subside this morning. NE winds across the waters today less that 25 kts. Period of sub-SCA gusts 20-25kts possible mid morning through the afternoon across the waters.

Outlook /Tuesday through Friday/...

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

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

Wednesday: Winds less than 25 kt.

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

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

Thursday Night through Friday: Winds less than 25 kt. Seas up to 5 ft.

BOX WATCHES/WARNINGS/ADVISORIES

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