textproduct: Gray - Portland

SYNOPSIS

Scattered showers will continue into tonight along with low clouds and fog. Clearing tomorrow except for a isolated shower across the interior in the afternoon. The Bermuda high will be in place through the weekend, supplying mostly dry and warm weather. The ridge breaks down for the start of the new work week, with a return of hit and miss showers. Heat will begin to build by the middle of the next week once again.

NEAR TERM /THROUGH TONIGHT/

This evening there is the diminishing chance for locally heavy rain north of the Whites and across the CT River Valley. Storm motion has been rather slow today with heavy rain showers anchoring on the terrain causing the heavier showers to drop close to 2" per hour rainfall. A few localized areas across Northern NH have received some heavy rain already today, so threat is if the same area gets hit again. Overall threat is very isolated, but a Flash Flood Warning can't be ruled out at this time as the mid- level short wave is still moving across the region. Second sensible weather impact is the potential for locally dense fog developing tonight along the coast. HREF props are showing a good push of low visibilities tonight and marine stratus is hanging along the coast today. LAMP guidance is also very low. Will have to see how dense the fog becomes tonight.

SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/

Weather Impacts: * No significant weather impacts expected * Dense morning fog on the coast can't be ruled out

Friday...Shortwave trough pushes through for tomorrow with westerly flow expected. Slightly drier air moves into the region with partial clearing expected as morning fog and stratus burns off. This should lead to clearing by the afternoon for all areas. CAM guidance shows potential for a few convective showers or weak storms over the terrain tomorrow afternoon. Overall areas coverage looks limited and severe parameters are weak. Not expecting and significant storms at this time but will let the night shift take another look.

Friday Night...Clearing is expected, with potential for some fog development. Overall no weather impacts expected with high pressure in control.

LONG TERM /SATURDAY THROUGH THURSDAY/

Overview: High pressure will be over the Gulf of Maine come Saturday morning. This will keep mostly dry conditions through the forecast area Saturday and Sunday, but will need to watch for afternoon showers or storms near stalled boundary to the west. Additional showers and storms will organize along a incoming cold front Sunday night through Monday. This front will lead to broad ridging into midweek, allowing for another potential stretch of day with hot temperatures.

Details: Saturday: While high pressure will be moving out of the Gulf of Maine through the day, onshore flow and high PWATs over the region will tend to bring afternoon showers or thunderstorms. Global models are hinting at a rather large footprint of QPF in NH through the afternoon and early evening. However in the absence of better jet dynamics and lifting feature, believe precip chances will lie close to topographic features vs. a widespread rainfall. This also aligns with diurnal trend of instability before coverage tails off in the evening.

Sunday-Monday: A cold front will advance eastward out of the Great Lakes Sunday. Ahead, onshore flow moderates temperatures w/ areas remaining dry through much of the afternoon. PoPs begin to increase into the evening hours as weak forcing arrives while any daytime instability remains. Presently little conviction on coverage here as low levels are dry.

Present rain chances focus on Sunday night-Monday associated with the frontal approach through Mon evening. Because the parent low drives north and occludes over Hudson Bay Sunday, forward progression slows. The result is precip influence from the boundary potentially through Mon night into Tuesday. There will be instability ahead of the front to bring the chance for thunder, mainly during the afternoon. Elevated instability will bring the chance for a few rumbles overnight and evenings as well.

On the heels of that weather maker, a return to hot temperatures appears likely should the front move through by Tuesday afternoon. Daytime highs into midweek could again top out in the upper 80s to lower 90s with dewpoints reaching the upper 60s to around 70 degrees.

AVIATION /19Z THURSDAY THROUGH TUESDAY/

Short Term...IFR and LIFR expected at most TAF terminals tonight as the marine layer surges back into the area with low ceilings and possible fog formation. Conditions improve by tomorrow morning

Long Term...MVFR to IFR ceilings return Friday night into Saturday morning. Additionally, stratus may build down during the late evening hours leading to vis restrictions due to fog. While fog will tend to thin into the Sat morning hours, ceilings remain MVFR to IFR through the day. LIFR is probable Saturday night along with additional fog development.

MARINE

Short Term...Fog is expected across the coastal waters tonight. Improving visibility is expected tomorrow through the weekend. Overall seas and winds will remain well below SCA conditions with high pressure in control.

Long Term...Conditions remain below SCA through the period. There will be the chance for marine stratus and fog to cause reduced visibility through this weekend and into early next week.

GYX WATCHES/WARNINGS/ADVISORIES

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