Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 270945 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 545 AM EDT Thu Jul 27 2017 .SYNOPSIS... A cold front moves across the area today bringing scattered showers in the morning and possible thunderstorms in the afternoon. High pressure will nose into the region Friday and into the weekend as a low pressure slips south of the area. This high will remain established over the Northeast through early next week with an extended period of pleasant weather. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Update...Have increased PoP to likely for much of the Nrn two thirds of the forecast area as showers move thru this morning. Generally less than a tenth of an inch expected...with best chance for some clearing in the far NWrn zones where drier air is moving in from Canada. Previous discussion...A more uncertain forecast than usual in the near term this morning...as it looks like we have a couple rounds of precip in store. The first will continue crossing the region this morning. A lead s/wv trof is forcing an area of mainly light showers thru the Northeast. It is likely many locations will see rain falling...but less likely that they will see measurable precip. This shower activity will linger into the mid morning...especially farther S where the front will begin to lag as flow becomes more and more parallel to it. This all complicates the forecast...because the second round of potential precip is heavily dependent on daytime heating. A secondary s/wv trof is forecast to spark scattered thunderstorms after the morning clouds/showers move off. The more sunshine we see...I expect the better chance for and greater coverage of thunderstorms. At this time it looks like significant cloud cover may linger into the afternoon...so I shied away from likely PoP and this reflects the uncertainty. That being said...with a decent jet streak overhead sufficient shear will be in place for storm organization. If we can get some pockets of sun...a stronger storm or two is possible. With the uncertainty about that sun...SPC has pulled the remainder of the forecast area from the marginal risk. I have also trimmed the enhanced wording back to mainly Srn NH. If storms do form...gusty winds and small hail are possible...mainly in the 18 to 22 or 23z window. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Trof axis swings across the area tonight...bringing an end to the showers and storms as it shoves the cold front off the coast. Farther S the flow is more or less parallel to the front...so the tail end should stall in the vicinity of Srn New England. This may keep some clouds and possibly a stray shower around Srn NH. Surface ridging tries to nose into the region...but we remain in cyclonic flow aloft into Fri. This should keep the boundary layer fairly mixed overnight...and allow for diurnal cloud cover increases Fri afternoon. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A coastal low develops over DELMARVA Fri night then moves east northeast along the southern New England coast Sat into Sat night. Models continue in good agreement of the track and in keeping the northern fringe of the precipitation shield just south of the ME/NH coastline. An overcast day expected Saturday along southern and coastal areas while further north partly to mostly sunny skies expected. A light northeast breeze will keep temps mostly in the 70s Sat. By Sunday the coastal low will have exited well to the east allowing high pressure to build over the area allowing mostly sunny skies and seasonable temps mostly in the 75-80 degree range. A more zonal west to southwest flow aloft develops early to mid week allowing warmer temps to spread across the region. Generally dry conditions expected early to midweek except for maybe a few air mass afternoon showers or thunderstorms mainly in the mountains and foothills. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... Short Term...VFR conditions are expected to prevail thru Fri. An area of SHRA will move thru the forecast area this morning...the heaviest of which may bring a brief period of MVFR conditions. Ahead of the cold front this afternoon scattered TSRA are possible. These may bring MVFR or lower conditions...but coverage is uncertain enough to preclude mention in the TAFs at this time. Tonight into Fri high pressure tries to nose back into the region...and widespread VFR conditions return. Long Term...VFR conditions through the weekend and into next week. && .MARINE... Short Term...Winds and seas are expected to remain below SCA thresholds. The exception may be near 25 nm where a few 5 ft seas are possible late today in Sly flow ahead of the front. Long Term...SCA conditions may develop over the outer waters Saturday into Saturday evening as the coastal low passes southeast of the area, otherwise winds and seas to remain below SCA criteria. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro SHORT TERM...Legro LONG TERM...Marine AVIATION...Legro/Marine MARINE...Legro/Marine

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