Area Forecast Discussion
Issued by NWS Portland, ME

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539 FXUS61 KGYX 232242 AFDGYX Area Forecast Discussion National Weather Service Gray ME 642 PM EDT Thu May 23 2024 .SYNOPSIS... A cold front will exit east of the region tonight. Drier air arrives Friday with mostly dry weather into Saturday. A frontal system brings chances for showers late Saturday into Sunday. A more organized system approaches for early next week bringing better chances for widespread showers late Monday into Tuesday. An upper level trough crosses the region Wednesday into Thursday with more scattered showers. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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640 PM Update...Dry air continues to gradually push eastward across the forecast area early this evening with dewpoint temperatures dropping into the the 40s across northern NH and the western ME mountains. Most of the precipitation is done, however we cannot rule out an isolated shower or thunderstorm on the ME coastal plain for the next 1 to 2 hours as SFC convergence and SFC dewpoint values around 60 still remain. Otherwise, expected the drying trend to continue. Previously... Update... Have coordinated with SPC and WFO CAR and have lowered the Severe Thunderstorm Watches for the remaining portion of the forecast area. A few showers and possibly a thunderstorm will be exiting off the Midcoast early this evening per latest radar trends and mesoscale models. Warm temperatures tomorrow along with very cold water temperatures along the coastal shoreline will combine for hazardous paddle craft conditions for tomorrow. Have coordinated with the USCG and WFO CAR to issue the Beach Hazards Statement for Friday. Otherwise, only minor changes to the near term portion of the forecast, mainly to remove damaging winds and large hail to the near term portion of the forecast. Prev Disc... The area of focus over the next hour or so will be the area of strong to severe thunderstorms heading for the Maine Midcoast with SPC Mesoanalysis indicating around 1500 J/kg of CAPE and 30 kt of effective shear. This supports hail the continued threat of hail in excess of 1" in diameter and damaging wind gusts up to 60 mph, and the Severe Thunderstorm Watch continues for Sagadahoc, Lincoln, Knox, and Waldo counties. Areas to the north and west where the line has already moved through, the Watch has been canceled although can`t rule out a stray shower or storm. There may also be some development farther south into Cumberland, York, and Rockingham counties where outflow interacts with the seabreeze, but the threat for thunderstorms is expected to be over for the most part by 6 pm, with a couple of showers remaining possible through sunset. The rest of the night will be quiet as drier air continues to move in behind the front. Skies will become mostly clear, and with winds being fairly light have gone a little cooler for lows with most being in the 50s, but northern areas may be able to reach the upper 40s.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Mostly dry and warm conditions are store in for Friday with an overall drier airmass, especially early in the day. By the late morning and afternoon, a mid-level trough swings through southern Quebec and sends another frontal boundary through northern New England. Moisture is very limited, so not really expecting much in the way of shower activity, except for in the western ME mountains where the moisture profile is a little more conducive (still only 20- 30% there). Temperatures are forecast to reach the upper 70s to mid 80s across the area, except a little cooler along the coast. Deep mixing will bring down higher winds from aloft, which will support breezy conditions at times to around 20-25 mph, possibly up to 30 mph on occasion. Northwest winds carry in drier air Friday night behind the front with high pressure building in from the north. Skies will become mostly clear, and with winds being fairly light, have blended in some cooler MOS guidance to account for radiational cooling. Aside from southern NH staying in the 50s, most should see lows in the 40s, but northern valleys could reach the mid-upper 30s, which could yield patchy frost if temps do manage to get this chilly. && .LONG TERM /SATURDAY THROUGH THURSDAY/... A significant transition of the trends in the synoptic regimes and therefore the long range portion of the forecast begins this weekend. For the overview, a trend towards cooler with more showers expected as we head into next week. We begin on Saturday where a west to northwesterly flow both at the surface and aloft will start out the day with dry and chilly conditions. A very narrow ridge of high pressure will then cross the region under mainly sunny skies during the day. In the afternoon, expect winds to become onshore near the coastline. A very weak trough will cross the region Saturday night into Sunday bringing a few scattered showers into the region. Any precipitation will be light and brief in duration. Latest models and ensemble solutions suggest the most breaks in the cloud cover will be over southern New Hampshire where temperatures may top out in the lower 80s. Much cooler conditions are expected over eastern portions of our forecast area. On Monday, a large scale upper level and surface low will cross the Great Lakes. This in term will allow for an increasing south to southeasterly gradient to develop over the forecast area in a warm air advection pattern. Increasing moisture will allow for scattered showers to become more widespread Monday night into Tuesday. It will remain on the seasonably cool side with temperatures mainly in the 60s. Seasonably cool and showers conditions will close out the middle to the end of the week next week with as a significant cold pool rotates over our region. The cold air aloft may allow for a snow shower or two to mix in over the top of Mount Washington by the end of the week as we approach and enter June. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... Short Term...Most showers storms will exit/diminish by 22-23Z this evening, but the higher potential for TEMPO restrictions will be at RKD and possibly AUG. Mainly VFR tonight, but patchy fog could impact LEB/HIE/AUG overnight. VFR expected on Friday with any showers looking to remain north of the TAF sites, and VFR is expected to continue Friday night. Long Term...Showers will arrive Saturday night and into Sunday with a higher potential for more widespread rainfall and flight restrictions early next week. An upper level trough will bring a few more scattered showers during the midweek period with pockets of IFR conditions at times. && .MARINE... Short Term...Winds and seas are expected to remain below SCA levels through Friday night. A few storms may move offshore into early this evening ahead of a cold front that will shift winds to westerly through tonight. Winds become more out of the SW late Friday morning and then more southerly ahead of another weak front that is forecast to cross the waters late in the day. Winds will turn more northerly Friday evening and continue out of the north or northwest through Friday night. Long Term...A northwest flow Saturday night will switch to out of the south on Sunday and continue through Monday and Tuesday. The gradient flow and winds will increase out of the southeast on Tuesday into SCA conditions. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Beach Hazards Statement from Friday morning through Friday evening for MEZ023>028. NH...Beach Hazards Statement from Friday morning through Friday evening for NHZ014. MARINE...None. && $$ NEAR TERM...Ekster SHORT TERM...Combs LONG TERM...Cannon