Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 221615 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1215 PM EDT Sat Jul 22 2017 .SYNOPSIS... A cold front will drop southward across the forecast area today with just a slight chance of a shower or thunderstorm. Temperatures will remain very warm. High pressure will settle over the region Sunday into Sunday night. Low pressure will approach from the southwest later Sunday night and for Monday and will deliver cooler temperatures and the likelihood of rain. Conditions will improve Tuesday and Wednesday as high pressure moves in. && .NEAR TERM /UNTIL 8 PM THIS EVENING/...
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1212 PM...minor ESTF update to reflect the current mesonet in near term grids. Prev disc... 900 AM...The cold front extends from the mid Maine coast westward through central New Hampshire into upstate New York. This boundary will only inch southward today and will provide the focus for widely scattered convection. Based on satellite trends...I adjusted cloud cover grids to reflect the dense high and patchy mid cloud traversing much of the forecast area along and to the south of the boundary. The latest mesonet was also ingested into near term grids for this ESTF update. Prev disc... 7 AM Update...Very little change to the going forecast. Continue to expect some mid and high clouds from time to time this morning, but it should remain dry. Isolated showers and perhaps a tstm still a possibility this afternoon but vast majority of locales will remain dry. Previously... A relatively weak cold front will push southward across the CWA today into this evening. Moisture and forcing for ascent will be limited so very little precipitation is expected, if any. We just have a 20 percent chance of a shower or isolated thunderstorm across central and a few southern zones. Most everyone will remain dry. Otherwise, temperatures will be quite warm again with highs well into the 80s at most locations, with a few 90 degrees readings possible in the far south.
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&& .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SUNDAY/... High pressure will settle into the region in the wake of the cold front tonight. This will bring cooler temperatures, with lows in the 40s expected in the the far northern zones. High pressure remains in control on Sunday although WAA aloft should foster an increase in clouds. Forcing for ascent with the next short wave trough looks to hold well to our west during the day so we do expect to remain dry. High temps should be a good 10 degrees cooler than those seen on Saturday. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... The week will begin with a trough in place over the northeast US. By Sunday night a strong short wave will dive southward around the main trough. As this moves through widespread rain will move in from west to east across the area on Monday. At the surface low pressure will develop south of New England. This will keep northeasterly flow in place at the lowest levels helping to keep temperatures lower than normal. Meanwhile the easterly flow into the mountains will help to ring out moisture. PWAT values climb to around 1.5 inches which in combination with the low level jet and saturated conditions should allow some areas of heavy precipitation across Maine on Monday. Most of the variability in this system is with the strength of the offshore low and the placement of the heaviest axis of precipitation. Showers will continue Monday night and into Tuesday especially in the mountains as the low moves out. The upper level trough will remain in place through Wednesday keeping the high temperatures once again in the upper 60s for Tuesday. By Wednesday surface high pressure begins to build in as the upper level trough moves out. Temperatures will begin to increase once again reaching the mid to upper 70s region wide. A cold front will approach on Wednesday night and cross the region Thursday. A region of fairly steep lapse rates in combination with mid afternoon timing will mean thunderstorms are likely and have added straight thunder wording for the daytime hours. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... Short Term...VFR today outside of some early morning valley fog. VFR conditions continue tonight and Sunday with river valley stratus and fog once again likely late tonight. Long Term... Sunday night will see most of the area move into MVFR or IFR Fog as log pressure develops. Monday will have widespread showers and rain with some thunderstorms possible. IFR conditions may persist throughout the day especially along the coast. Conditions will improve on Tuesday with mostly mountain shower activity and increasing ceilings to the south. High pressure builds back in for Wednesday. && .MARINE... Short Term /through Sunday/...A cold front will drop southward across the waters late today and tonight. Northerly wind gusts may briefly reach 25 kt tonight into early Sunday but the probability is a bit low to issue a SCA at this time. Long Term... A low will develop south of New England late Sunday night into Monday. This will bring increasing easterly winds to the waters with small craft conditions likely during the day on Monday. A strong low level jet may result in a few gusts to near 30kts especially in regions of heavy rain. High pressure will move in for Wednesday with subsiding winds and seas. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ ES is the U.S. government's official web portal to all federal, state and local government web resources and services.