Area Forecast Discussion
Issued by NWS Portland, ME

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952 FXUS61 KGYX 100225 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1025 PM EDT Thu May 9 2024 .SYNOPSIS... A cool and unsettled weather pattern is expected through the next several days as a longwave trough gradually crosses the area. Although day-to-day details are relatively uncertain, there will be several opportunities for rain showers through this time. No days are expected to be washouts, however. Below- average temperatures are expected through the end of this week and this weekend, then will start to trend warmer next week. && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
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0222Z Update... A few showers, mainly over eastern New Hampshire, will diminish through midnight. Some patchy fog is still expected, however with slightly drier air attempting to enter the forecast area, it should be much less widespread than last night. Temperatures will drop into the 40s by morning. Update... A very gradual drying process continues from the north this evening with scattered to broken cloud decks across the region. Showers continue to form along the Maine and New Hampshire border early this evening. This is along and near an inverted trough over the forecast area. This precipitation should dissipate after sunset. By morning, expect temperatures to bottom out in the 30s in the north to the 40s across the south. Fog should remain less prevailent for the overnight period as compared to last night. Prev Disc... Not a lot of change with expectations for the remainder of this afternoon. Mostly cloudy skies for much of the area will continue with some showers around with CAMs favoring just either side of the ME/NH border for these. This is meshing well with what`s currently being observed on radar, so I have 40-60% stretching roughly from the Whites extending down into SW ME over the next couple hours. Closer to sunset expect a few of these farther west into NH. Accumulations will remain light ranging from a few hundredths to a tenth of an inch or so. These showers will dwindle for the most part by or just after sunset although can`t completely discount a couple continuing a little longer. Quiet conditions expected the rest of tonight for most of the area although there is a slight chance that far southern NH sees a little bit of light rain overnight and toward daybreak, but most model guidance keeps this mainly south. As far as cloud cover, northern and eastern areas will probably see some partial clearing this evening into tonight as the N/NE brings in some drier air, and these areas may reach the mid- upper 30s if enough clearing occurs. Elsewhere, lows are forecast to be in the lower-mid 40s.
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&& .SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY/... Weak high pressure center sets up to the northeast of the area Friday into Friday night resulting in a prevailing light east to northeast flow. Overall the atmosphere will be drier than today, but forecast soundings continue to show a decent amount of moisture aloft either side of 850mb, especially over into NH. So I think NH will stay mostly cloudy, particularly farther to the south and west one goes. As we get farther to the north and east over into western Maine, moisture isn`t as high, so there should be more sun. Similar to today, expect a some light shower activity through the course of the day, but amounts will be light, and most will remain dry. High temperatures will be in the 50s to lower 60s. Friday night looks quiet with partly cloudy skies. Temperatures are generally expected temperatures a couple of degrees either side of 40 but could be a bit cooler if skies clear out a little longer. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A long-wave trough overhead will define the extended forecast period, with embedded shortwaves providing periods of rain showers around the region. Temperatures will fall within seasonal norms, with below-average conditions under more maritime influence this weekend transitioning to near- or above- average as the trough shifts east and allows drier, warmer, continental air to filter in next week. Overall, not expecting any weather impacts besides perhaps some dense fog at times... though there is little confidence in where, when, or if that happens given the nebulous nature of the pattern at this time. Starting Saturday... low pressure will be tracking northeastward well offshore over the Atlantic, while high pressure sits over Maritime Canada. The flow regime promotes an east to northeast flow into the forecast area, and right now appears to be a fairly dry airmass with the exception of the sea breeze. This should make for a fairly pleasant day across the forecast area, with good mixing allowing for temperatures over the interior to warm to near 60. The coastal plain however sill see more of an onshore contribution, limiting temperatures to the 50s. The degree to which the sun makes an appearance will naturally have a bearing on sensible weather too... the fortunate news is that low clouds don`t appear to be much of a factor with dry low-level air, although mixed mid-level decks appear to be likely with partly to mostly cloudy skies expected. More overcast conditions may be present over western New Hampshire north into the mountains where moisture convergence is maximized, and where a few showers are possible as well. Upper level low pressure settles overhead by Sunday with a very weak pressure gradient, which will once again allow a sea breeze to develop amid light background flow. Though low confidence... there is model agreement with deeper moisture building across the region allowing for more cloud development Saturday night into Sunday. Model guidance is mixed for precipitation chances on Sunday, but in general increasing cyclonic flow and mixing should at least contribute a diurnal component to rain shower activity on Sunday. The upper level trough shifts east into Monday with shortwave ridging briefly building to start the coming work week. This should offer a brief period where we actually manage to have minimal precipitation chances... although timing that out may be a challenge in the short-wave driven pattern, especially as it turns a bit more zonal before another trough wanders in around mid-week. All in all, the trough shifting east brings the reasonable expectation for a warming trend, on average, early in the week as a southerly to southwesterly flow regime takes over. Current model consensus brings widespread 60s and 70s, coolest in the mountains where clouds are most likely and along the coast with a southerly component to flow. Though, increasing humidity and ripples in the upper wave pattern continues potential for rain showers... especially as a warm front overtakes the region, followed by potential for a more organized system around mid-week with the next long wave trough. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Short Term...Even though it will remain mostly cloudy through Friday night, the forecast has trended toward mostly VFR for the Maine terminals. For NH, there is more potential for MVFR ceilings through this evening and Friday along with some showers. However, coverage of showers is expected to be low enough that TEMPOS or prevailing SHRA will not be needed. Long Term...VFR likely to persist through Sat with light NE or E flow AOB 15 kts. Beyond that, forecast confidence in restrictions falls off a cliff, with potential for lowered CIGs Sat night through Sun along with -SHRA. The pattern in general from Sun into next week favors periodic restrictions, mainly CIG, and light flow allowing daily sea breezes. But, this is a particularly low-confidence forecast in terms of timing and day- to-day details. && .MARINE... Short Term...Low pressure east of the waters and weak high pressure to the north will temporarily tighten the pressure gradient through this evening with wind increasing to around 20 kt. Winds then diminish tonight into Friday and remaining out of the northeast with the weak high to the north and east. Low pressure emerges off the Mid-Atlantic coast Friday night, and winds may veer to more easterly but still remaining below SCA levels. Long Term...Light flow and quiet seas are expected over the extended forecast period with SCA conditions unlikely to occur. In general, winds this weekend will be NE, then will turn out of the SW to start the next week however daily sea breezes and a nebulous pressure gradient will muddy this progression a bit. The best chance for 25+ kt winds, right now, comes around Tue with a more organized system potentially crossing the region. && .TIDES/COASTAL FLOODING... High astronomical tides combined with around 0.5-0.7 feet of storm surge may push water levels to around minor flood stage around the time of high tide tonight. A Coastal Flood Advisory or Statement may be necessary, however any impacts will be very minor. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$