Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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882 FXUS61 KGYX 221904 AFDGYX Area Forecast Discussion National Weather Service Gray ME 304 PM EDT Mon Jul 22 2024 .SYNOPSIS...A warm front will push north of the area tonight. This front will remain near the area through midweek with waves of low pressure tracking along the front bringing rounds of showers and thunder through Wednesday. A cold front will push through the area on Thursday bringing another threat of showers and storms. High pressure builds in for Friday into the weekend for a return to dry weather. && .NEAR TERM /THROUGH TUESDAY/... A warm front continues to drift northward tonight as moisture increases with a building ridge off the East Coast. Scattered showers start to reach southern New Hampshire during the evening hours, but any appreciable rainfall holds off until after midnight tonight. The front looks to stall across interior areas, extending from central New Hampshire into central Maine. This area serves as the focus for the threat of some heavier rainfall and possibly localized flooding concerns. The threat looks low, and antecedent conditions are well positioned to absorb several inches of rain in most spots. It would likely be toward daybreak should several rounds of heavier downpours affect the same areas that any problems would start to arise. Elsewhere, showers looks likely through the overnight hours, but don`t look to be a widespread across southern coastal areas, or toward the Canadian border. Patchy fog likely develops along the coastline tonight and moves inland into central Maine as the moisture increases overnight. A few thunderstorms are also possible, but most of the rain likely falls without thunder tonight. && .SHORT TERM /TUESDAY NIGHT/... Most of the shower activity comes to an end during the morning hours, with mainly cloudy and humid conditions for the late morning to mid afternoon hours. Some breaks of sun are likely, especially across southern New Hampshire, which helps temps warm into the mid 70s to low 80s across most of the forecast area. Along the immediate coast and across the north see the coolest conditions, with highs likely topping out near 70 degrees. Patchy fog and low clouds may also linger much of the day along the coastline, especially toward the MidCoast. Isolated showers likely pop up in the afternoon, with the best chance across the higher terrain. This continues into the overnight hours tomorrow as a moist southerly flow helps to keep scattered showers ongoing at times in the vicinity of the stalled front. A few showers are possible outside of these areas as well, but most the looks to be rain-free with patchy fog. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Overview: Relatively progressive flow across the NE CONUS continues in the extended period with the beginning of the period east coast ridging being replaced by a mid-level trough by Thursday. 500mb ridging returns by the end of the weekend as a ridge amplifies over the Ohio River Valley bringing a return to above normal temperatures by the end of the period. Impacts: Overall low impact forecast period with the potential for dense fog on the coast during the day on Wednesday. Localized heavy rainfall and thunderstorms will be likely on Thursday as the cold front swings through, but current severe threat and flash flooding is relatively low. Forecast Details: Wednesday begins with south to southwest onshore flow which could bring coastal fog or marine stratus inland as the area is sandwiched between the approach Great Lakes trough and the slightly anomalous Bermuda high off the Eastern Seaboard. Strong moisture convergence over the mountains will most lead to inland showers and isolated thunderstorms, but looks to be isolated in coverage. Looks like a cloudy day overall with temperatures in the upper 70s along with humid conditions. By Thursday low-level flow becomes more southwesterly as the shortwave trough and surface cold front approach. Showers and thunderstorms will occur as a 120KT jet streak moves across the region. Shear profiles look good, so severe threat will depend on surface heating and how much cloud cover there is, which currently looks like plentiful, but will have to watch trends on heating potential. Cold front pushes through Thursday evening with slightly drier airmass in place. By Friday a few instability showers on NW flow could be possible in the mountains, with mostly sunny skies downstream of the mountains leading to a nice day. Weekend looks nice as surface and upper level ridging takes hold over the Northeast. It will be trending hotter though, with upper 80s for highs by Sunday. Dewpoints will remain relatively dry though through the weekend, so it will remain mostly comfortable. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... Short Term...VFR conditions end tonight as showers and low clouds move into the area after midnight. Coastal terminals, AUG and LEB likely see conditions drop to IFR late tonight. Interior terminals see conditions drop to mainly MVFR in showers. Fog is also likely at RKD and AUG. Conditions improve to at least MVFR by late morning tomorrow, except at RKD where low clouds linger most of the day. A period of VFR is likely at at least MHT, CON, and PSM during the afternoon. IFR conditions are possible again tomorrow night with low clouds, patchy fog, and scattered showers. Long Term...IFR conditions due to low ceilings could be possible on Wednesday due to a onshore flow marine push. Cold front and storms are expected on Thursday with tempo MVFR conditions for all TAF terminals. High pressure returns Friday into the weekend with no aviation weather impacts expected. && .MARINE... Short Term...A warm front lifts through waters tonight and stalls across New England. Locally dense fog develops overnight, and lingers into tomorrow night. Conditions remain below SCA levels. Long Term...Marine stratus and fog are possible on Wednesday over the coastal waters leading to visibility restrictions. By Thursday a cold front will approach with veering wind flow from the SW to NW by Thursday night. An isolated thunderstorm can`t be ruled out during the frontal passage. Offshore flow on Friday with surface high pressure building into the region. High pressure will dominate the weather pattern this weekend, with light flow becoming southwest by Sunday. Seas are expected to remain below SCA during this period. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Clair SHORT TERM...Clair LONG TERM...Dumont AVIATION...Clair/Dumont MARINE...Clair/Dumont