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Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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300 FXUS61 KGYX 161203 AFDGYX Area Forecast Discussion National Weather Service Gray ME 803 AM EDT Fri Aug 16 2024 .SYNOPSIS... Showers will be possible in the mountains today, but overall coverage will be less than the last couple of days. Hurricane Ernesto will pass well out to sea over the weekend, but that will not stop swell from moving into the Gulf of Maine. That could lead to a period of higher surf and rip currents into early next week. The weather after Sunday looks unsettled with showers and storms possible through much of early next week. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... Update...Minor changes to reflect latest observational trends. Previous discussion...Locally dense fog remains across the forecast area this morning...but visibility is slowly improving and leaving behind just low clouds. I will not be expanding the dense fog advisory...but will leave it in place thru sunrise. Some showers across eastern ME will drift into portions of the Kennebec Valley this morning but are not expected to make it much farther west than that. This afternoon we remain under the influence of the upper low still spinning over the Canadian Maritimes. However the lack of a clear forcing mechanism will likely confine showers to the mtns where differential heating and orographic lift can do that work. Lapse rates are weaker today and so convection overall will not have the same punch as the past couple of days. Will also see similar levels of wildfire smoke to the last several days. HRRR smoke model suggests the highest concentrations of near surface smoke will be north and west...away from marine influences. I have haze in the forecast for these areas. && .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SATURDAY/... Warm front will lift towards the forecast area tonight. North of the boundary onshore flow will prevail and as a result at the very least marine stratus will move back in tonight. Fog may not be as widespread as this morning however. Warm front aloft will be north of the forecast area Sat. At the surface it may hang up across NH. However the bulk of the forcing will be along the mid level front...and so showers are not expected to be widespread. WAA may allow for some convection...but I will keep PoP to isolated to widely scattered for now. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... At 500 MB, the weekend will start will a small area of ridging over New England as we sit between upstream and downstream trough and Ernesto to our SE. By Monday that trough shifts over the NE CONUS. And 500 MB flow on the downstream side tightens up a bit as it runs into ridging and absorbs Ernesto to our E, which makes Monday the day with the most dynamic forcing and the best chance for rain. The trough, and likely associated cold front swings through on Tuesday, with cooler and less humid air moving in for the middle of the week. However, will have that 500 MB trough lingering, which means a chance for some showers. By late week, should see some sfc ridging move in beneath NW flow aloft. Models seem a little more optimistic about the weekend, given the relative ridging overhead. Still cannot rule out a few SHRA/TSRA, especially if a greater amount of sun leads to increased instability. Highs on Sunday, with better onshore flow and more clouds, mainly run in the 75-80 range. Itll be more humid with Tds running in the mid to upper 60s, and overnight lows in the low to mid 60s. On Monday,, as that upper level trough starts to deepening a bit and a wave lifts out of the base of it, will see more in the way of SHRA/TSRA, and it`ll be more cloudy as well. Also humidity will be up with tds in the mid 60s N to the upper 60s and low 70s S. Highs will be closer to the mid 70s than 80 on Monday as well. SHRA/TSRA continue into Mon evening, but should start to wane somewhat after midnight, and the cold front may make into the mtns late so lows range from the upper 50s there to the low to mid 60s in the S. Tuesday and Wed will be cooler and drier as 950 temps drop below +10C, so highs will generally be in the 70s both days. The cooler air aloft and the 500 MB trough overhead will be enough for scattered daytime showers to develop, and perhaps a couple TSRA as well. Overnight lows will be more comfortable and range from the low 50s in the mtns to the mid to upper 50s in the S. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... Short Term...Areas of marine fog and stratus will continue to lift and move offshore, with VFR conditions are expected thru this afternoon. SHRA will be much more isolated today...and even then mostly confined to the mtns. HIE would be most likely to see any SHRA this afternoon...but even then confidence is too low to include in the TAF. Fog is possible again tonight...but low CIGs look likely again as a warm front lifts towards the forecast area. Long Term... While VFR is expected to prevail through the weekend, cannot rule out some brief flight restrictions due to SHRA/TSRA and then patch fog at night. Late Sunday night into Monday could some low stratus and numerous SHRA, plus a few TSRA, and will likely see MVFR with some periods of IFR through the day, with possibly some LIFR into Monday night. Expecting a return to mainly VFR Tuesday morning. && .MARINE... Short Term...Weak flow remains in place as the coastal waters are sandwiched between two systems. Light southeasterly flow will result and likely keep some of the marine fog and stratus lingering over the waters into tonight. Seas will begin to increase Sat as swell from Hurricane Ernesto reaches the Gulf of ME. At least for the first half of the weekend seas are forecast to remain below SCA thresholds. Long Term... Winds will not be an issue this weekend into early next week, but seas will increase, especially on Sunday and peak on Monday in long period swell from Ernesto. Seas away from the coast could push to almost 10 ft, while near shore waves could reach to around 6 ft. The seas will begin to subside late Monday night and Tuesday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro SHORT TERM...Legro AVIATION...Legro/Palmer