Area Forecast Discussion

WHAT HAS CHANGED

No significant changes at this time, with the main focus remaining on this afternoon and evening's potential for severe thunderstorms.

KEY MESSAGES

1. Showers and storms continue to move into the area through this evening, with a severe potential across parts of New Hampshire.

2. A cold front slowly crosses on Sunday, bringing more chances for showers and a few thunderstorms.

3. A dry and seasonable start to next week will give way to a more unsettled second half with temperatures once again rising above normal and potentially posing a heat risk.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Showers and storms continue to move into the area through the afternoon and evening hours as a cold front approaches from the northwest. Temperatures continue to warm across New Hampshire, while a stalled front sits near the Maine/NH border. The cooler airmass across Maine limits the severe potential for late this afternoon and evening, with any convection likely to be elevated in the cooler airmass.

The focus for the greatest severe potential remains across southwestern New Hampshire where CAPE is building and shear is increasing. Damaging wind and large hail remain the primary concerns, with the potential for severe storms extending across southern NH. Severe storms can't be ruled out north and east of these areas, but chances quickly drop into the cooler airmass. The risk for severe storms ends late this evening as storms move offshore, but scattered showers remain possible into the overnight hours.

KEY MESSAGE 2 DESCRIPTION...

The front slowly crosses the area during the daytime tomorrow as low pressure tracks through southern Canada. Showers will be most likely across the north and mountains during the morning, and then move southward through the day with the cold front. Chances for precip gradually lessen as the front sags southward, but most people are likely to see some shower activity all the way to the coastline by late tomorrow afternoon.

Tomorrow also looks warmer for much of Maine as westerly flow overnight scours out the low level cool airmass to the east of the stalled front. With this set up, highs warm from the mid 70s through the foothills, to the low 80s along the coast and through southern NH. Highs in the 60s are expected across the north as the front moves through earlier in the day. The front then pushes offshore by late tomorrow evening, with clearing and drier conditions through the overnight hours.

KEY MESSAGE 3 DESCRIPTION...

A ridge begins to build in Monday and will slowly move eastward through midweek bringing a stretch of dry weather with building heat. Despite much of the area potentially seeing temperatures rise into the upper 80s and low 90s toward midweek, being on the downstream side of the ridge during this time should help to keep dewpoints bearable. However, as the ridge axis moves east of the area, a transition to west/southwesterly flow would begin to bring dewpoints up and start to introduce some heat risk in the late week time frame. The ECMWF and Canadian ensembles have an upper low diving out of Quebec and interrupting the ridge (currently on Thursday) which would bring with it a chance for showers and thunderstorms. The GEFS camp keeps the ridge, with all camps going back to a ridge building in Friday and Saturday. A more moist air mass looks to be in place for the second half of next week, so continued ridging would increase heat risk.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18Z Sunday... Showers move through all terminals this afternoon and evening, with brief thunderstorms likely at LEB, MHT, CON, and PSM late this afternoon into the evening. Outside of the showers and storms, VFR generally prevails at these terminals into tomorrow afternoon. HIE, AUG, and RKD stand the best chance to see IFR conditions overnight tonight with showers and low ceilings. Near MVFR ceilings look most likely at PWM. Ceilings improve through the morning Sunday, and then brief restrictions with scattered shower are likely from late morning at HIE, through the afternoon along coastal terminals. VFR then returns and likely prevails Sunday night.

Outlook... Monday-Tuesday: VFR conditions expected under mostly clear skies.

Wednesday-Thursday: Generally VFR conditions expected, but afternoon showers and/or thunderstorms may bring about TEMPO MVFR conditions.

MARINE

A cold front slowly moves southward, crossing the waters late Sunday afternoon and evening. Some seas to near 5ft are possible across the outer coastal waters tonight into Sunday in southerly flow around 20kt. Tranquil conditions are expected on the waters through next week as high pressure builds over the Gulf of Maine and only slowly moves eastward.

GYX WATCHES / WARNINGS / ADVISORIES

ME...None. NH...None. MARINE...None.