Area Forecast Discussion
Issued by NWS Portland, ME

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451 FXUS61 KGYX 231130 AFDGYX Area Forecast Discussion National Weather Service Gray ME 730 AM EDT Wed May 23 2018 .SYNOPSIS... A cold front will drop south across the area today producing scattered showers and thunderstorms across northern and eastern portions of the forecast area. High pressure will build into the region Thursday and Friday with very warm weather expected. A backdoor cold front drops into the region this weekend and will likely provide for some unsettled weather. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7am update... Minor adjustment for current temps. Some low clouds and fog in the CT valley will burn off quickly this morning. prev disc...One short wave trough passing through northern New England early this morning will bring an end to the shower activity early on. In the wake of this short wave trough downsloping flow will allow temperatures to rise well into the 70s and even lower 80s across central and southern zones. However, another short wave trough will graze northern and eastern zones today. Scattered showers and thunderstorms will likely be the result today...especially over Mid Coast zones. The most likely time period for this will be during the afternoon hours. Forecast thermodynamic profiles will be favorable for gusty winds and small hail in any thunderstorms. Have included this enhanced wording in the forecast for today.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Fair weather is expected tonight through Thursday with high pressure moving into the region. Temperatures on Thursday will be in the 65-75 degree range depending on location...warmest south. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... The week will culminate with the warming trend we`ve seen since mid week pushing high temperatures on Friday well into the 80s across the region. Overall looking like a hot, dry, and windy day on Friday. With forecast soundings supporting mixing to nearly 750mb (~7000 ft) have trended the entire forecast towards this concept and increased high temperatures, increased winds, and decreased dew points to reflect the drier and moving down into the region. Across interior southern NH 90F is possible. With westerly flow resulting in downsloping and helping to keep the sea breeze at bay have increased temperatures a bit above guidance for the entire region as we make our first run at 90F. Saturday afternoon a warm front will sag southward across the region. This will be a relatively weak boundary with little moisture however some afternoon showers or thunderstorms are possible. Have limited PoP to high chance as areal coverage is still uncertain. On Sunday we see north to northeasterly flow set up through the region as front becomes a backdoor front slipping southward. The result will be much cooler temperatures than the prior days with much of the area staying in the 60s or even upper 50s. The Ct River valley will be the exception where the mountains will prevent the northeasterly flow from arriving and the valley will assist in funneling warm air northwards allowing temperature to climb back to the mid 70s. Rain chances become increasingly likely on Sunday and into Monday. Here a low pressure system will move out of the Canadian prairies and help to induce widespread showers across the region. The exact timing and amount of precipitation are low confidence at this point due to the upper level flow. After the end of the week the high pressure aloft has moved east and split flow tries to develop with a cut off over the southeastern US. This continue to introduce a lot of uncertainty for the end of the weekend; uncertainty which is unlikely to be resolved for another 36 to 48 hours when the northern stream wave will begin to form over the Yukon. For now have left high chance Pops in for the entire Sunday - Monday period. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Short Term...Areas of MVFR conditions will give way to VFR this morning. VFR conditions are then expected today and tonight with the exception of localized MVFR conditions across the mountains and Mid Coast in scattered showers and thunderstorms this afternoon. Long Term... High pressure and warm conditions will keep VFR conditions from Thursday night into Saturday morning. Saturday afternoon some scattered convection may result in MVFR showers in the mountains. Further showers and lowering ceilings are expected on Sunday and remaining into Monday as low pressure begins to move into the region. && .MARINE... Short Term /through Thursday/...Winds and seas expected to remain below SCA level through Thursday. Long Term... Gusty westerly flow on Friday will bring the outer waters to SCA criteria as the pressure gradient between the departing low pressure and building high to our south increase winds. A backdoor front will cross the region on Saturday switching flow to the northeast. Periods of showers with fog possible on Sunday and into Monday. .FIRE WEATHER... Today and Tomorrow will be mostly dry. By Thursday RH values will fall to 25% across most of the area however the winds will be quite light. Friday will see gusty west to northwesterly flow around 25kt. These winds will help to mix down dry air from aloft with RH dropping to around 30% across southern New Hampshire. This will put southern NH near Red Flag criteria and will need to be watched for possible Fire Wx headlines. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Curtis SHORT TERM...Ekster LONG TERM...Curtis AVIATION... MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.