textproduct: Gray - Portland

SYNOPSIS

High pressure briefly builds in from the southwest today before shifting south as low pressure tracks across Quebec tonight. Saturday will be warmer behind a warm front with a cold front crossing Saturday night. Mostly dry weather will close out the weekend before the next low pressure system crosses Sunday night through Monday. A cold airmass then builds into the eastern US behind the system through mid week.

NEAR TERM /THROUGH TODAY/

Gusty winds have diminished early this morning as high pressure has started to build in from the southwest. Today will start off with a mix of sun and clouds while an approaching warm front will lead to increasing clouds this afternoon. Highs will be around 40 degrees across the north and into the low 50s. The approaching warm front will bring increasing chances for precipitation across the north this afternoon. The higher terrain likely see period of snow and if precipitation arrives after sunset some northern valleys could see a brief light wintry mix.

SHORT TERM /TONIGHT THROUGH SATURDAY/

Better forcing arrives this evening through the first half of tonight. This will lead to mainly rain overspreading the rest of the area with temperatures taking on a non diurnal trend. QPF will be light with amounts mainly less the 0.25 inches with higher amounts in the mountains.

The warm front pushes through the area Saturday with westerly winds allowing some breaks in the clouds and temperatures climbing into the low 60s to upper 50s south of the mountains. Other than some mountain showers Saturday is looking mainly dry.

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

Long Term Update: Focus in the long term continues to be an active pattern featuring a quick system late this weekend into Monday. Longwave centered over Hudson Bay will continue to pivot disturbances through the region. Main system will be a sharpening wave across the Great Lakes into Sunday, with surface low pressure deepening along the St. Lawrence River and the Northeast. Great jet dynamics will support a rapidly deepening system, but the trough remains positive/neutral. This results in primary low being quite progressive.

NBM ptype probs and thermal profiles continue to support mainly a rain/snow event for the area. Snow is most likely north and west of the ridges where cold air will be dug in and protected from onshore flow Sunday and Sunday night. However accumulation may end up being elevation dependent pending final solution.

Substantial jet through the base of the trough from the South into New England will aid in moderate moisture advection, with IVT peaking as mid level jet sweeps off the Maine coast. Thus current timing keeps the region out of a more damp solution.

Previous Discussion: Key Message: Active weather pattern in store into next week. Temps remain near to below normal keeping snow possible for the higher terrain. Impacts: No significant weather impacts anticipated thru this weekend. Early next week system may bring some wintry weather to the mtns with the right track.

Forecast Details: Ensemble guidance shows the Sun/Mon system being driven by a rather strong trof for this time of year...especially at the southern end of the trof. Both the upper jet and temps in the trof are along the lines of a once in a decade or even once in a generation event for mid November. This kind of guidance indicates a potentially strong system. This is more or less what cluster analysis shows as well. There is relatively small difference in timing across ensemble members...but what differs is strength and the resulting QPF. Right now there is not much to do with that portion of the forecast. With timing fairly close...NBM PoP looks fair and I am fine with likely to categorical PoP with the initial warm advection wave of precip. With precip falling largely outside of our QPF period...I am not too concerned with precip type a chance of rain or snow into the foothills describes the range of outcomes at this point.

Temps overall do appear to be cool enough thru the extended to continue upslope snow showers and potentially cool enough with the early week system to continue building snowpack in the mtns.

AVIATION /04Z FRIDAY THROUGH TUESDAY/

Short Term...Mainly VFR through today with increasing clouds this afternoon. A period of light rain and lowering cigs will likely bring at least MVFR across the area into Saturday morning. Conditions likely improve to VFR by Saturday afternoon.

Long Term...Ceiling restrictions likely increase in area west to east as Sunday progresses. MVFR is likely, with IFR also possible accompanying RA and some SN in the western mountains. This continues into Monday before storm system lifts north out of the region.

MARINE

Short Term...Low pressure passing to the north will bring increasing SW to S flow with SCA conditions likely by this afternoon. SCA winds continue into Saturday morning before shifting offshore while seas remain elevated into Saturday afternoon.

Long Term...SCA conditions likely accompany a storm cutting up interior Maine Sunday into Monday. Once this storm moves north, stronger west winds pick up over the waters Tuesday resulting in the possibility for Gale conditions into at least Wed morning.

TIDES/COASTAL FLOODING

High astronomical tides will be peaking during the late morning high tide today. Offshore winds have produced a negative surge while winds will shift out of the southwest early this morning and south this afternoon. The latest guidance keeps water levels below minor flood stage. Have opted to issue a Coastal Flood Statement as water levels peak at 11.8 ft MLLW at Portland and some onshore component of winds could lead to water levels approaching minor flood stage along the Mid Coast.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory from 4 PM Friday to 10 AM EST Saturday for ANZ150>154. Small Craft Advisory until midnight EST tonight for ANZ151-153.