Area Forecast Discussion
Issued by NWS Portland, ME

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649 FXUS61 KGYX 221504 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1104 AM EDT Sun Sep 22 2024 .SYNOPSIS... Low pressure south of Cape Cod lingers begins slowly drifting southward today, and continues moving early this week. The low continues to bring high surf and minor coastal flooding impacts along the coastline today. High pressure builds southward across New England by early next week, bringing seasonable temperatures and dry conditions. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Update...Surface trof has stubbornly continued to produce showers thru the night but is finally relenting to drier air from the east. The last few showers are drifting southeast away from the Seacoast at this hour. Along the leading edge of the dry air push there are some light radar echoes. This enhanced convergence may result in some sprinkles...so I have added that to the forecast for a few hours...but no accumulation is expected. Previous... Low pressure south of Cape Cod slowly moves southward and away from New England today as high pressure begins to press southward into the area. An isolated shower can`t be ruled out early today across parts of southeast New Hampshire, but otherwise the rain from the system has come to an end. Clouds gradually thin and become more broken through the day, with sunshine increasing from north to south. Seasonably cool air remains in place with a steady northeasterly flow, keeping highs in the 60s across most of the area today. The northeasterly flow continues to bring elevated surf, and the threat of dangerous rip currents along the coast. Minor coastal flooding is expected once again for this afternoon`s high tide, and looks similar to yesterday`s tide.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Skies continue to clear through the overnight as the high continues to build in. With a cool airmass in place and lowering dew points, temperatures drop into the 40s across most of the area. Some upper 30s are likely across the northern valleys, and possible through some of the more sheltered valley locations outside of the mountains. Patchy fog is likely through the river valleys across northern and western areas overnight. The axis of high pressure becomes centered across New England tomorrow. Despite this, clouds will be on the increase as moisture from a system in the Great Lakes spills eastward through the ridge. The morning starts out bright, but clouds will be on the increase by late morning and put a cap on temperatures for the day. Highs top out in the mid to upper 60s across most of the area, but there is room to bring highs down a bit if the clouds arrive slightly earlier into western areas following a cool night. Large breaking waves and rip currents look to continue tomorrow from the offshore system. However, the coastal flooding threat will be dropping as the astronomical tides drop from their monthly peak. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The 500 MB pattern through next week across NOAM continues to become more blocky, especially over the E half of the continent and the N Atlantic. The cooler ridge that move in for early next week will be replaced by an approaching trough to our W, and which models close off /to differing degrees/ over the E CONUS Thu-Fri. So, the period from Wed-Fri looks unsettled, although unlikely to rain the whole period, still need to have models in batter agreement on the timing, and strength of the systems. Still, it should warm up in the mid levels mid-late week, but given the way things are setting up, it looks like onshore or NE flow may dominate, keeping temps cooler, but still fairly close to normal. Interestingly enough, it is around the time of the equinox, and there is almost no below freezing air at 850 mb S of the arctic circle, and no sign of a major cold air intrusion any time soon according tho the models. Monday and Tuesday should be partly to mostly sunny with highs mostly in the mid to upper 60s, and overnight lows mid 40s to low 50s. By Wed, as the 500 trough deepens equatorward out of ON/QC will begin to see the threat of some showers, but for now the best chance looks more Wed night. Highs on Wed may end up a few degrees cooler than Mon or Tue but still in the 60s. That upper level closed low then drift Se across New England and deepens Thu, which continue the threat for rain, and then may or may not produce a coastal low near S New England which moves offshore. Moisture in the column is fairly high by Friday, and the 12Z Euro brings a bullseye of heavy rain into New England, which does raise a red flag, as sometimes the models are onto something, but it is more of general signal to watch for heavy rain, that something to be taken too literally. Despite the rain, the warmer and more humid air will allow for highs mid 60s to around 70 at the end of the week. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... Short Term...Mainly VFR conditions prevail through tomorrow at most terminals. PSM, MHT, and CON see a period of near marginal MVFR ceilings this morning through the early afternoon, with brief MVFR restrictions possible at times. LEB is also an exception this morning with a brief period of fog possible around sunrise. Valley fog is then likely at HIE and LEB tonight, which then burns off by mid morning tomorrow. Long Term...While winds are likely to remain below SCA criteria the pulses of low pressure S of the waters over the next several days will keep the swell up near 5-6 feet through the middle of next week. && .MARINE... Short Term...SCA conditions continue with elevated seas from an offshore low pressure center. The low gradually moves away through tomorrow, but continues to bring 5-8 foot waves through at least tomorrow. High pressure gradually builds southward across the waters through tomorrow. Long Term...Mainly VFR expected Mon-Wed, although flight restrictions become possible by Wed night into Thu, as there is some potential for rain and low cigs. && .TIDES/COASTAL FLOODING... Tides are beginning to lower from their astronomical peak for the month. With an ocean storm still spinning south of Cape Cod...storm surge will continue to run between one half and one foot on northeast winds, along with breaking waves of 4 to 7 feet along the coastline. Another round of minor coastal flooding...splash- over...and erosion is likely from Portland south this afternoon. By tomorrow, astro tides look to be just low enough to keep water levels below flood stage, but it will still be close at Hampton. Beach surveys and Emergency Managers continue to indicate compromised dune systems along the coastline from our storms this past winter...which will limit natural protection. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...High Surf Advisory until 8 PM EDT this evening for MEZ023-024. Coastal Flood Advisory from 2 PM to 5 PM EDT this afternoon for MEZ023-024. NH...High Surf Advisory until 8 PM EDT this evening for NHZ014. Coastal Flood Advisory from 2 PM to 5 PM EDT this afternoon for NHZ014. MARINE...Small Craft Advisory until 8 PM EDT Monday for ANZ150-152>154. && $$ NEAR TERM...Legro