textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes needed with this forecast update. Visible radar continues to show showers streaming in from the northwest, but as expected they really aren't amounting to much at the surface. The aviation section was also updated for the 00Z TAFs.

KEY MESSAGES

1. A warm front lifts through the region bringing both chances for very light rain this evening and overnight and near-record warm temperatures Wednesday.

2. A widespread soaking rainfall is possible for the late week into the weekend along a slow moving frontal boundary.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

A warm front remains draped across the forecast area this afternoon. Along and north of the boundary some very light rain continues. I do not anticipate much, generally less than a tenth of an inch, but the dampness and cloud cover will help to mitigate any new wildfire threat and allow crews to catch up with any ongoing fires.

As the front continues to drift north into Wed some very warm air is forecast locally. Model guidance is pushing the 925 mb temp forecast into the +16 or +17C range. This is good enough for high temps at least into the mid 70s. This is at least 20 degrees above normal and will be pushing record values, which can be found below in the Climate section.

KEY MESSAGE 2 DESCRIPTION...

Beginning Wed the upper low over the Midwest will begin to open up and shear out to the northeast. This will tend to leave behind the frontal boundary that will eventually slow to a crawl as it nears the East Coast. At the same time Thu into Fri a northern stream shortwave is forecast to drop into the Great Lakes and help close off another upper low. This will help keep the frontal boundary locked in place and help low pressure to develop along that front. This is forecast to zip north and bring a pretty solid rainfall event to areas in the vicinity. The maine question will be where this front stalls. As it stands right now that looks pretty close to our coastline. The chances for rain over the eastern half of the forecast area are pretty high, and probabilities over at least an inch of QPF are also fairly high. ECMWF EPS guidance continues to trend wetter, as does the GEFS even though it is slightly drier than its European counterpart. NBM PoP forecast looks pretty good for this range, especially since there is some timing uncertainty even if it does look like rain along the coast.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Through 00 Thursday: Generally VFR conditions expected despite some light rain moving into the forecast area. In the mtns some brief MVFR CIGs are possible this evening, but confidence is too low to include in the TAFs at this time. Any rain or showers looks like enough to avoid reducing VIS. Along the western Maine coast some low CIGs may begin to advect in off the Gulf of Maine this evening and overnight. RKD still looks like it will see a period of IFR ceilings tonight and I have thrown AUG in there as well as more guidance has trended that way. Guidance continues to show a lot of uncertainty for PWM so left any restrictions out of the TAFs as it may end up on the edge of the lower ceilings. Conditions return to widespread VFR Wed.

Outlook...

Thursday: VFR conditions expected. Some light rain or showers possible.

Friday-Saturday: Rain likely for eastern half of the forecast area. MVFR or lower conditions develop Fri and linger thru Sat.

Sunday: Returning to VFR conditions.

MARINE

Winds and seas are expected to remain below SCA thresholds thru the period. One window to watch will be late this week as low pressure develops along a stalled frontal boundary and zips northward along it. If the front is able to stall slightly farther west, that may introduce some gusty southerly winds and building seas for some of our waters east of Port Clyde.

CLIMATE

Temperatures will be 20 to 25 degrees above normal for parts of the forecast area, and are expected to approach daily records. The records for the local climate stations for November 4th are as follows:

PWM: 74 set in 1987 CON: 75 set in 1987 AUG: 74 set in 1990

GYX WATCHES/WARNINGS/ADVISORIES

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