textproduct: Boston / Norton

SYNOPSIS

Warm and dry conditions Today and Thursday with above normal temperatures, then trending near seasonable for Friday. We then enter into a cooler and more unsettled weather pattern again for the weekend. High pressure brings dry weather for Monday, then turning unsettled again Tuesday.

NEAR TERM /UNTIL 6 PM THIS EVENING/

Key Messages:

* Warm and dry today with comfortable humidity and modest breezes

Broad low amplitude upper trough will settle over New Eng today with high pres building over mid Atlc region. Patchy stratus and fog will lift by sunrise, otherwise sunshine will mix with diurnal CU this afternoon as steep low level lapse rates develop with shallow moisture below the inversion. A few of the CAMs try to develop a few spot showers over the interior this afternoon, but current thinking is sub- cloud layer will be dry enough to preclude any showers with better chance to the north. Warming temps aloft and sunshine will result in a much warmer day today. 925 mb temps 18-19C will support highs 80-85, but 70s near the south coast and higher terrain.

Risk for dangerous rip currents will be greatest over south coast Nantucket beaches, with more a moderate risk for rest of south coast.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/

Key Messages:

* Dry and mild tonight * Breezy, warm and dry Thursday

Quiet weather tonight with dry W-SW flow. Under mainly clear skies lows will range from the upper 50s to lower 60s.

On Thu, passing northern stream shortwave across Canada will push a cold front south across northern New Eng and into SNE during the afternoon. Axis of higher PWATs will push south across SNE but westerly pre-frontal flow will limit low level convergence and instability axis is SW of SNE so expecting dry weather. Another warm day with low level temps suggesting a few degrees warmer than today with highs low-mid 80s and possibly some upper 80s CT-RI-SE MA, but low humidity as dewpoints mix out into the low 50s during peak heating. It will be breezy as well mixed boundary layer supports west wind gusts to 20-30 mph with a few higher gusts over higher terrain.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

Key Messages:

* Mainly dry and warm Friday

* Cool and wet weather Saturday and Sunday

* Mainly dry and warmer again Monday

Zonal flow aloft will lead to a rather unsettled pattern for Friday through the Weekend. However, guidance is still struggling to resolve the weakly forced features, leading to a continued low confidence forecast this weekend. Friday has the best chances of staying dry with subtle height rises and weak mid-level ridging. High temps rise into the upper 70s to low 80s with localized sea breezes keeping the coasts closer to the low 70s. Better forcing and moisture arrive just in time to bring us another rainy Saturday. Without a stronger shortwave moving through, guidance has been showing mixed signals between a total washout or hit-and-miss showers. Ensemble systems favor hit-or-miss showers, as 58% of the GEFS, ENS, & GEPS have less than a half-inch QPF. 27% of the ensembles have .05 to 1 inch of QPF, with 10% having greater than an inch. That leaves only 5% of the ensemble members showing a dry forecast for Saturday. High temperatures on Saturday are likely to struggle to top 70F, possibly staying in the low 60s. Sunday may end up as a drier day than Saturday, as much of the shortwave energy gets shunted south ahead of a more amplified shortwave dropping south towards the Great Lakes. Either way, Sunday will still be cool and cloudy due to the onshore flow. High temperatures are likely to struggle to top 70F again.

High pressure builds in for Monday, bringing a brief reprieve from the cloudy and wet conditions before unsettled weather returns yet again for Tuesday and Wednesday of next week. High temperatures are expected to gradually rise from the low to mid-70s on Monday and Tuesday, then increase to the low to mid-80s by Wednesday and Thursday.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

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

12z TAF Update...

Today...High confidence.

VFR. WSW-SW wind 10-20 kt. Smoke may cause hazy skies and possibly some light visby reductions this afternoon

Tonight...High confidence.

VFR. W wind 5-10 kt. Increasing westerly winds aloft will lead to wind shear concerns

Thursday...High confidence.

VFR. W wind gusts 20-30 kt developing.

KBOS Terminal...High confidence.

VFR with breezy SW winds today. Smoke could cause some light visby reductions this afternoon. Winds at the surface diminish with sunset, but winds aloft increase from the west up to 30-40 knots

KBDL Terminal...High confidence.

Radiation fog possible around the terminal this morning, burning off quickly after sunrise. VFR today with SW winds around 10 knots. Smoke could cause light visby reductions this afternoon.

Outlook /Thursday Night through Sunday/...

Thursday Night: VFR. Breezy.

Friday: VFR.

Friday Night: Mainly VFR, with local MVFR possible. Chance SHRA.

Saturday: Mainly MVFR, with local IFR possible. SHRA likely.

Saturday Night through Sunday: MVFR/IFR conditions possible. Chance SHRA.

MARINE

Forecaster Confidence Levels:

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

Today through Thursday: High Confidence.

Persistent SW winds through the period, Speeds 10-20 kt through tonight with some 25 kt gusts possible Thu over nearshore waters. 5 ft seas over southern waters will gradually subside this afternoon.

Outlook /Thursday Night through Sunday/...

Thursday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

Friday: Winds less than 25 kt.

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

Saturday: Winds less than 25 kt. Rain showers likely.

Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers.

Sunday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...High Risk for Rip Currents until 2 PM EDT this afternoon for MAZ024. RI...None. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ254>256.