Area Forecast Discussion
Issued by NWS Portland, ME

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401 FXUS61 KGYX 220226 AAC AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1026 PM EDT THU JUL 21 2016 .SYNOPSIS... Expect warm and humid conditions across the region tomorrow ahead of an approaching cold front. Showers and thunderstorms are expected to develop tomorrow afternoon and continue into the evening hours. Some of the storms could be severe. Another round of thunderstorms is possible on Saturday before more stable conditions move into the region on Sunday. Weak high pressure aloft will move over the region on Sunday and into Monday. Another impulse will move through late on Monday...bringing more showers and thunderstorms to the area before high pressure returns for Tuesday and Wednesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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1022pm Update: Forecast continues to be in very good shape this evening with gradually thickening upper level cloudiness. Slowed arrival of PoPs overnight some...but no other significant changes for the overnight period. A look at radar data from Environment Canada suggests the bulk of activity over Quebec may very well miss us to the north...but as the tongue of higher thetae at H8 builds into the region towards daybreak...still would not be surprised if a few showers/storms brush my northern zones. These trends would suggest the potential for a sunny start to the convective ingredient list for Friday...but lack of any good consensus beyond this suggests lots of uncertainty for severe potential later in the day. More certain...however...is a warm/humid/unstable airmass. 738pm Update: Only minor tweaks this hour...again to boost temperatures just a tad based on evening trends. 549pm Update: Updated near term temperatures and dewpoints to match late afternoon trends /included boosting temps a tad/ and also lowered sky cover for a few hours...with batch of cirrus overhead thinning for at time before more substantial convective anvil remnants work in from the west. Previous Below... Very humid air will be moving in quickly tonight. Our mid 50s dew points will become lower to mid 60 dewpoints by morning. Low temperatures tonight will be some 10 or more degrees warmer than last night. Lots of cirrus blowoff coming in from the thunderstorms in Canada. There may be some patchy valley fog late tonight in places but this should not be very wide spread. Can`t rule out some showers and maybe a thunderstorm in the mountains tonight as the humid air moves in.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Very humid and hot Friday with high temperatures in the lower 90s in southern New Hampshire and southwest Maine and mid to upper 80s elsewhere except the mountains where temperatures will climb into the lower to mid 80s. The big question is the chance for severe weather. SPC does have us in a slight risk. Conditions do seem favorable for severe weather in the afternoon into the evening hours. the will be a fair amount of debris clouds so that will limit somewhat the heating but we will have an incredibly moist environment to work with and any heating will help to quickly destabilize the atmosphere. Have mention some thunderstorms may be severe in the afternoon. With the front not really moving through until Saturday, Friday night will be another uncomfortable sleeping night with dewpoints remaining in the 65 to 70 degree range. Convection will likely linger into friday night. Low temperatures bottom out in the upper 60s to lower 70s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Frontal boundary stalls over the region Friday night and into Saturday. A weak upper level disturbance will pass through on Saturday and will provide enough instability to produce another round of showers and thunderstorms...although likely not as strong as what is expected tomorrow. Weak ridging aloft works its way into the region for Sunday and into Monday with northwesterly flow becoming more westerly by midday on Monday. An approaching cold front will generate showers and thunderstorms Monday afternoon. It is a bit too early to say with any certainty how strong they may be...but the system looks to be fairly robust with strong dynamics and could very well produce some severe weather across the CWA. Zonal flow aloft then remains in place for Tuesday and Wednesday with little in the way of interesting weather over New England. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Short Term /through Friday night/... Summary: A warm front will race north of the region tonight...with a cold front gradually settling towards New England on Friday. This will result in a gradually increasing chance for showers and thunderstorms, particularly by Friday afternoon and evening. Restrictions: VFR conditions will dominate the TAFs through at least 18Z Friday. Expect winds aloft and upper cloudiness to really limit fog potential at HIE/LEB tonight. Beyond this...shower and thunderstorm chances will increase Friday afternoon with isolated MVFR/IFR restrictions possible for brief periods. Will not add this detail in this TAFs yet given significant uncertainty in timing/placement of convection. This chance for restrictions will continue through the first half of Friday night...with more widespread IFR fog potential overnight Friday night...particularly in areas that experience shower/thunderstorm activity. Winds: Southerly winds around 5kts tonight will become southwest and increase to 12g20kts for the day on Friday. Southwesterly winds will diminish below 10kts Friday night. LLWS: Winds in the 1-2kft layer strengthen to around 30kts overnight tonight...in a sharpening inversion which will allow for a period of LLWS through daybreak before daytime mixing erodes the shear layer. Thunder: There is a very low chance of a thunderstorm LEB-HIE around daybreak Friday. Beyond this...there will be a chance for thunderstorms all locations Friday afternoon through Friday evening. Greatest threat will be away from the coastal plain...with isolated severe thunderstorms possible. Much uncertainty exists with timing/placement of thunderstorms...and thus have not explicitly added them to this TAF package. Thunderstorm activity will wane overnight Friday night. Long Term...Expecting strong to severe thunderstorms Friday night. They will likely cause some flight restrictions...but the situation will be variable. VFR conditions should return for Saturday...although there could be some scattered showers and thunderstorms that generate a few issues on that day as well. Sunday through early Monday should see VFR conditions with showers and thunderstorms once again possible Monday afternoon and evening. && .MARINE... Short Term /through Friday/...Small craft advisory for hazardous seas from 12Z Friday through 12Z Saturday. Long Term...Expecting strong to severe thunderstorms Friday night. They will likely cause some flight restrictions...but the situation will be variable. VFR conditions should return for Saturday...although there could be some scattered showers and thunderstorms that generate a few issues on that day as well. Sunday through early Monday should see VFR conditions with showers and thunderstorms once again possible Monday afternoon and evening. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory for hazardous seas from 8 AM Friday to 8 AM EDT Saturday for ANZ150-152-154. && $$ SYNOPSIS... NEAR TERM...Arnott SHORT TERM... LONG TERM... AVIATION... MARINE...

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