Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 141026 AFDGYX Area Forecast Discussion National Weather Service Gray ME 626 AM EDT Mon Aug 14 2017 .SYNOPSIS... Quiet and mild weather is expected today with a cold front expected to approach Tuesday with showers and thunderstorms possible during the afternoon. High pressure builds in Wednesday before another low pressure system affects the region Thursday into Friday with the potential for a period of heavy rain. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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630 AM Update...Little change to the going forecast early this morning. Mostly sunny skies are expected for the rest of the morning with steadily rising temperatures. Previously... A nice weather day looks to be had today as forcing for ascent looks to be nil with high pressure in place just to our east. Other than some cirrus clouds passing by and some daytime cumulus, the dry weather is expected with high temperatures within a few degrees of 80. An afternoon seabreeze is expected which will cool temps off on the coastal plain.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Quiet weather is once again expected to continue through tonight with relatively warm temperatures. On Tuesday, a short wave trough will approach from the west with forcing for ascent increasing during the afternoon. This, with moistening low levels will allow for shower and thunderstorm development during the afternoon hours. Instability and shear don`t look overly great for widespread organized thunderstorms, but a few thunderstorms are expected, with one or two marginally severe ones possible. Large hail and damaging winds will be the main threat, but instances of severe weather should remain localized. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... As we look to the middle of next week the pattern becomes dominated by an omega block aloft with a large high built to the west of Hudson bay across Manitoba and Western Nunavut. Balancing out the high will be low pressure over northern Quebec and Labrador which will serve to sling shot surface systems into our region from northern Ontario. By the end of the week, numerical guidance tries to break the block down, allowing for a wet surface low to push into the region to end the week. Starting Tuesday night thunderstorm coverage will decrease as the surface front moves through. High pressure will build into the region on Wednesday and crest over the region on Wednesday night. On Thursday low pressure will approach from the Great Lakes. Here`s where the timing of the upper level block breaking down will being to play a role. The faster solution allows for the rain to move into western New Hampshire by Thurday night while the slower break down delays the rain into Friday morning. Examining the variability in this end of the week system a bit closer we find that ensemble sensitivity shows this is all tied up in the strength of the low that gets ejected from the block. Current satellite imagery shows the block is just beginning to form and so it will be another day or so before we can get a better handle on the timing of this system. What is consistent right now is that all the deterministic guidance shows widespread rainfall with a tropical moisture source connection making this a system to keep your eye on for this week. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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Short Term...VFR conditions are expected today. Low clouds and stratus will be possible tonight, especially on the mid coast, as the low levels moisten. VFR conditions are expected on Tuesday after any stratus and fog burns off, but a few showers and thunderstorms may bring briefly lower conditions and gusty winds during the afternoon hours. Long Term... Thunderstorms will dissipate on Tuesday night. VFR conditions will continue through Wednesday and into Thursday. A storm system will approach Thursday night with IFR rain and fog for Friday morning.
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&& .MARINE... Short Term...Conditions are expected to remain below small craft thresholds through Tuesday. Long Term... Quiet conditions for the middle of the week as a high builds in. Hurricane Gert is expected to pass far enough off shore to keep most swell out of our area. At the end of the week, a storm system will cross the waters with small craft conditions possible as seas build. && .EQUIPMENT... The weather radar at Gray (GYX) will be down for maintenance until approximately through Tuesday, August 14th. During that time technicians will be installing important upgrades. This work has been scheduled to minimize any potential impacts to office operations. During the outage, radar coverage is available from adjacent radar sites including Burlington-Vermont (KCXX), Taunton- Massachusetts (KBOX), and Hodgdon-Maine (KCBW). Also, the radar at Albany (KENX) suffered a failure that has been attributed to azimuthal motor/gear issues. It is expected to be down for several days. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Ekster SHORT TERM...Ekster LONG TERM...Curtis

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