These details are provided by the NWS offices in Gray Maine, and the surrounding NWS offices in New York, and Massachusetts.  I have modified some of the technical stuff to help make it more understandable for the average reader.

Last update: 10/05 - 4:37 PM

NEAR TERM /TONIGHT:
Thunderstorms continue to develop over the waters remaining mostly stationary this afternoon, slowly drifting onshore over the New Hampshire seacoast and coastal York/Cumberland counties. Instability looks to drop off quickly over land with any thunderstorms weakening once they move onshore. Heavier showers move over the midcoast overnight bringing more rain to the area before clearing out near daybreak tomorrow. Cloud cover along the coast will keep temperatures warmer tonight with lows near 50 along the coast with clear skies to the north allowing temperatures to drop into the low 40s to upper 30s in the north.

SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT:
The coastal low that has been sitting off to the south over the last several days will finally start moving off to the east Thursday with winds turning from the southwest over the day. Showers across southern NH and coastal Maine will dissipate through the night with skies clearing in the early morning. Some fog may develop in the early morning along the Connecticut River valley, northern valleys, and some coastal bays with higher dewpoints and cool temperatures overnight. With sunshine and southwesterly flow, temperatures will warm into the 70s for most areas tomorrow, breaking the cool south warm north trend that had been in place over the last several days. Clouds begin moving in from the west tomorrow night as a cold front starts approaching bringing showers for Friday.

LONG TERM /FRIDAY THROUGH WEDNESDAY:
After a late-week warmup... a strong cold front pushes across New England Friday afternoon and evening, bringing showers and a noticeably cooler weekend. In spite of the active northern stream wave pattern, high pressure dominates most of the the extended forecast period with only low, brief chances for light showers beyond Fri/Sat as weak waves pass overhead. Temperatures rebound toward normal through the first half of the next workweek.

Starting Friday...a northern stream low over the Ottawa Valley will swing to a negative tilt, quickly sending a cold front across New England during the day. Warm southwesterly flow ahead of this will allow temperatures to warm into the mid 70s in the southern interior of NH up into SW ME by mid-day. Elsewhere temperatures will be more subdued in the 60s thanks to onshore flow/lingering low clouds over the Midcoast and greater cloud cover/shower chances in the mountains and further west.

Speaking of showers... chances will be increasing over the mountains/western zones Friday morning, with the front crossing the Connecticut River valley around mid-day and tracking east through the afternoon and evening bringing a chance of showers all the way to the coast... lowest chance being near the NH Seacoast, well removed from forcing which is concentrated to our north in Canada and highest toward the International Border. Given a fair amount of wind shear and potential for surface- or ML-based destabilization with surface heating, a line of convective showers is likely to form with the front... and may produce lightning. Given the strength of CAA(Cold Air Advection) I would expect a quick drop in temperatures and dew points behind the front toward the west with strong mixing, along with gusty west winds to about 20 kts.

CAA(Cold Air Advection) and west winds continue overnight into Saturday. Current guidance doesn`t have particularly strong winds with this system, not even deep enough to produce a good downslope... but winds should be strong enough overnight to prevent decoupling as skies clear south of the mountains and showers transition to the upslope variety in the mountains. Rain showers will likely transition to some graupel, snow, or a rain/snow mix by Saturday morning across the higher terrain and toward the International Border. Overnight lows are still forecast to be in the 30s to near 40... but again the wind should stave off significant frost issues where the growing season is active.

The weekend keeps cyclonic flow overhead but high pressure should be largely in control... ensuring classic fall-like conditions with brisk, breezy days in the upper-40s to near
60... and chilly overnights with lows mostly in the 30s. Abundant sunshine is expected outside of the mountains with the exception of some fair-weather cumulus, however upsloping flow keeps more clouds in the mountains themselves even after showers taper off Saturday. A reinforcing cold front looks to drop through the area late Sunday which would reinvigorate shower chances over the mountains... with rain potentially transitioning over to a mix or frozen precipitation overnight before ending. All in all we`re not expecting much accumulations between Friday and Sunday, <1"... so it`ll only be a taste of the season to come with little in the way of impacts.

Canadian high pressure moves overhead to start the next work week which leaves precipitation chances low and weather pleasant for the remainder of the forecast period. Temperatures should rebound somewhat with highs in the 50s to mid-60s... a little closer to normal, but still somewhat cool. This pattern does indicate cold overnights with frost potential as well... but the active upper levels have me hesitant to go all-in on the chillier solutions, so will stick to the multi-model blend for now. Should optimal conditions come together however the low-end of the statistical suite has widespread lows in the 20s and 30s.