textproduct: Boston / Norton

WHAT HAS CHANGED

Extended the time of the Small Craft Advisory for the eastern waters to 18z today. Otherwise, the forecast remains on track.

KEY MESSAGES

- Dry weather will persist through the weekend. Warmer temperatures return for Thursday and Friday with gusty winds on Friday. Seasonable temperatures return for weekend.

- Transition to a more unsettled weather pattern by early next week, bringing periodic chances for rain. However, confidence in specific timing remains low.

DISCUSSION

KEY MESSAGE 1...Dry weather will persist through the weekend. Warmer temperatures return for Thursday and Friday with gusty winds on Friday. Seasonable temperatures return for weekend.

Mid-level ridging and surface high pressure will dominate favoring mainly dry conditions through the weekend. Clear skies will favor cool nights with likely the coolest night being tonight. A cooler airmass in place combined with light winds and mainly clear skies will favor efficient radiational cooling tonight. Temperatures are likely to fall into the 20s and 30s with the higher terrain, valleys, and usual radiator spots most favored for lows in the mid- upper 20s. Can't rule out a few spots in the interior dropping into the low 20s.

Dry and seasonably cool temperatures persist into Wednesday. Temperatures aloft trend a little warmer as a mid-level ridge shifts east which may nudge highs a few degrees warmer than Tuesday. The warming trend in temperatures continues into late- week resulting in 925mb temperatures warming to +11 to +14C. This will yield high temperatures in the mid-60s on Thursday alongside breezy NW winds. Despite the mid-level zonal flow Friday (ahead of our next weak wave), the westerly flow will support efficient mixing in the boundary layer. This will result in a gusty/windier day and likely the warmest day of the week with high temperatures in the upper 60s to low 70s. NBM continues to highlight probabilities 50-75%+ for temperatures 70F or greater with the highest probabilities for the valleys and I-95 metros. This is reasonable given the added factor of the warming downslope flow. A mild late-October day is looking likely.

Another moisture-starved shortwave and cold front moves overnight Friday. This will shift temperatures back into the low 60s for the weekend which is seasonable for late-October.

KEY MESSAGE 2...Transition to a more unsettled weather pattern by early next week bringing periodic chances for rain. Confidence in specific timing remains low.

Looking ahead to next week, ensemble guidance shows agreement with a transition to a unsettled weather pattern. This will feature series of shortwave troughs bringing periodic chances for rain. However, there is still a fair amount of spread across guidance in the details of the pattern including details of the pattern which has reduced confidence in the timing of rain chances through the week.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Forecaster Confidence Levels...

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

18z TAF Update...

Today and Tonight...High confidence.

VFR conditions. Northerly component winds for most of the terminals for the rest of the afternoon at 5-8 kts. E/ESE at BOS and NE for the Cape/Islands terminals. Occasional gusts to 18 kts possible for HYA/ACK through the evening. Winds diminish to very light/calm levels shortly after sunset tonight.

Wednesday...High confidence.

VFR conditions. Light wind patterns continue. Generally out of the N in the morning less than 6 kts then transitioning to SW in the afternoon after a period of more VRB winds. SSE winds possible at BOS for a period in the afternoon before becoming SW late afternoon/evening.

KBOS Terminal... High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Wednesday through Sunday/...

Wednesday through Wednesday Night: VFR.

Thursday through Friday: VFR. Breezy.

Friday Night through Sunday: VFR.

MARINE

Forecaster Confidence Levels...

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

Through Wednesday...High confidence.

NE winds this afternoon at 9-15 kts with a few gusts to 20 kts possible across the outer waters. Seas 2-5 ft with 5 ft seas confined to the outermost waters. Winds/seas continue to decrease this tonight with high pressure overhead. Light winds and seas 1-3 ft for Wednesday as high pressure persists across the coastal waters.

Outlook /Wednesday through Sunday/...

Wednesday through Thursday: Winds less than 25 kt.

Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft.

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

Friday Night: Winds less than 25 kt.

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

Saturday Night through Sunday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES

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