Area Forecast Discussion
Issued by NWS Portland, ME

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453 FXUS61 KGYX 201648 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1248 PM EDT WED JUL 20 2016 .SYNOPSIS... High pressure will build in from the west before settling offshore to the south of New England today. The high will then hold to the south of New England on Thursday. A warm front will approach from the southwest Thursday night, with warm and humid conditions settling in for the weekend. A cold front will slowly approach on Friday but will weaken and dissipate over the area on Saturday. High pressure settles back in Sunday. Another cold front approaches from the west early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Update 2...Minor adjustments to temperatures dewpoints and sky cover based on current observations. Rest of forecast on track. Prev Disc... At 06z...a 1025 millibar high was centered over southern Ontario province. A warm front was draped along the border of Ontario and Quebec province. For today...the surface high will build to our south while the weak warm front over Canada slides eastward and provides the forecast areas with some high and patchy mid clouds late today. It`ll be another warm day with comfortable humidity levels. Westerly flow should keep the seabreeze largely at bay with high temperatures ranging from 70s in the mountains to the lower 80s elsewhere.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Fair conditions will continue tonight as high pressure remains parked south of New England. We should see a slightly warmer night as return flow introduces somewhat warmer air back into the region. Lows will range from near 50 north...with 50s to near 60 south. On Thursday...the warming trend will continue on a westerly flow as the high remains anchored to our south. A weak impulse could bring a late day shower to the international border area.`ll be a partly sunny day with highs in the 80s...with a few 90 degree readings for southern New Hampshire and adjacent southwest interior Maine. Like today...humidity levels should remain in the comfortable range. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Chance of high impact Wx: Scattered severe storms possible Friday. 500 mb ridging to our south continue to be the dominant presence over the CONUS and adjacent oceans, holding the active jet north of the intl border. This will lead to a return to warn humid conditions by Friday and will continue into early next week. However, the area of weakness in the ridging remains across the NE US, with several rounds of weak troughing moving through during the long term forecast, and a couple threats for showers and thunderstorms. Friday will see the first of these threats for showers and storms as warmer and more humid air moves in from the south and west, and a weak 500 mb wave approaches from the west. Highs will reach to around 90 in southern NH and interior western ME, and low to mid 80s most everywhere else. TDs will rise into the mid 60s in many spots. This should produce enough instability combined with falling heights from wave aloft wave to produce thunderstorms in the afternoon, especially in the northern and western zones. There may be enough shear and wind aloft to produce some severe storms as well. Showers and storms will linger into the evening, and perhaps overnight as the frontal boundary slows and eventually stalls over the CWA. It`ll be a warm night with lows in the upper 60s in the south ranging to the low to mid 60s in the north. May see some slightly less humid and slightly less warm air mix down on Saturday as sfc wind shifts winds to the west, but overall not much of a difference as weak ridging builds back in quickly. Remnant surface boundaries could be the focus for another round of showers or storms Saturday afternoon with highs ranging from the low 80s n to around 90 in the south. Sat night may see mins a little lower than previous night but still mainly in the 60s. Sunday looks hot and humid in the south, with highs reaching into the low 90s, and mid 80s to near 90 in most other places, which will be followed by a warm humid Sunday night. The next chance of showers/storms will be on Monday afternoon and Monday evening as another 500 mb wave moves through. This may bring some relief from the heat and humidity on Tuesday. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... Short Term /through Thursday/...VFR with lcl ifr psb this morning and again Thursday morning in valley stratus and fog. Long Term...Possibility of both valley fog and coastal fog/stratus Thu night into early Friday, with Thunderstorms possible Fri afternoon and evening. VFR looks to [prevail over the weekend...with valley fog each night. && .MARINE... Short Term /through Thursday/...Winds and seas will increase a bit in southwest flow through Thursday...but remain below small craft threshold. Long Term...SCA likely Friday into Friday night, but winds seas below SCA Saturday and Sunday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ UPDATE...TFH is the U.S. government's official web portal to all federal, state and local government web resources and services.