Area Forecast Discussion

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Dry with cooler than normal temperatures today and tonight.

- Seasonably warm temperatures return mid-week, continuing through Friday. A few showers possible sometime late Thursday into early Friday, otherwise mainly dry.

- Potential for a shift to an unsettled pattern with chances for rain for second half of weekend through early next week.

DISCUSSION

KEY MESSAGE 1...Dry with cooler than normal temperatures today and tonight.

Surface high pressure will be positioned the region today bringing dry conditions and mainly sunny skies. A cooler airmass will be in place with 925mb temperatures several degrees cooler than Monday. This will yield more "Fall-like" temperatures with high temperatures in the upper 60s and low 70s. Locations along the immediate east coast may even be cooler in the mid 60s as a result of the light easterly onshore flow. The high pressure center shifts offshore tonight shifting winds to the S then SW.

KEY MESSAGE 2...Seasonably warm temperatures return mid-week, continuing through Friday. A few showers possible sometime late Thursday into early Friday, otherwise mainly dry.

A strong upper level ridge/high remains positioned across the southeast CONUS mid-week, subtly building into the northeast mid- week. An upper trough in northern Canada will hold off any stronger ridging from building into the northeast, favoring a flatter/zonal pattern overall. This should support warmer temperatures advecting in within the SW flow. Highs Wednesday/Thursday rise back into the mid and upper 70s with 80s in the valleys (seasonably warm for mid- Sept). Surface high pressure should support mainly dry conditions Wednesday and Thursday.

Ensemble/deterministic guidance indicates potential for a weak shortwave trough to drop in from the northwest late Thursday into Friday. Ahead of this shortwave, a plume of anomalous moisture advects in from the west on Thursday. Across ensemble guidance, the PWATs run around 170-200 percent of normal or more directly put, PWATs 1.7-1.9". The anomalous moisture is being signal across NAEFS guidance as well. This building moisture will bring a more humid day for Thursday. There is some spread across guidance with regards to the timing of the showers; however, there is general agreement of the highest chances falling in the late Thu afternoon to early Fri morning timeframe. That timeframe should be able to be narrowed down as the details of the pattern become more clear as we go through the week. Despite the anomalous moisture, the weaker lift with this wave and later timing has limited the potential for widespread heavy rain. Ensemble QPF remains below 0.50" for most areas. We'll have to keep an eye on some embedded heavier showers that could bring locally higher amounts. A drier airmass pushes in behind the exiting shortwave Friday bringing dry conditions dominating by the afternoon. A cooler airmass sinks across the region by Saturday bring a return of Fall-like temperatures.

KEY MESSAGE 3...Potential for a shift to an unsettled pattern with chances or rain for second half of weekend through early next week.

Ensemble guidance hints at a transition to a more unsettled pattern for the second half of the weekend and into early next week. A low pressure system tracks eastward from the Great Lakes bringing increased precipitation chances more likely in the Sun-Mon timeframe. There indications of another wave or two bringing periods of rain for early next week as well. Confidence in precipitation chances and timing should increase as we get closer.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

06z TAF Update...

Through 12Z...High confidence.

VFR. Light N/NNE winds. Occasional gusts to 18 kts possible for Cape terminals through 08Z (HYA/ACK).

Tuesday...High confidence.

VFR. NNE winds this morning shifting to the NE at 5-10 kts. Interior terminals shift likely shift to the S/SSE early afternoon while coastal terminals shift to E/ESE in the afternoon then shift to the S/SSE 00-03Z.

Tuesday night...High confidence.

VFR. Winds becoming light S to SW. Patchy fog possible in valleys.

KBOS Terminal...High confidence in TAF. NNE winds shift to NE this morning then shift E/ESE 16-18Z at 5-10 kts. Winds shift toward the SSE/S around 00Z becoming S/SSW by 03Z.

KBDL Terminal...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: VFR.

Thursday: Mainly VFR, with local MVFR possible.

Thursday Night: Mainly VFR, with local MVFR possible. Chance SHRA, slight chance TSRA.

Friday: VFR.

Friday Night: VFR. Breezy.

Saturday: VFR.

MARINE

Forecaster Confidence Levels...

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

High pressure overhead today bringing light easterly winds today and tonight. Winds shift around to the S/SW overnight tonight into Wednesday as the high pressure center shifts offshore.

Outlook /Wednesday through Saturday/...

Wednesday through Thursday: Winds less than 25 kt.

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

Friday: Winds less than 25 kt. Slight chance of rain showers.

Friday Night through Saturday: Winds less than 25 kt.

BOX WATCHES / WARNINGS / ADVISORIES

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