289 FXUS61 KBGM 131522 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 1122 AM EDT Mon Aug 13 2018 .SYNOPSIS... A low moving across southern Pennsylvania will bring showers and thunderstorms to the area today, some with very heavy rain. The low will move into eastern New York on Tuesday and bring additional showers. && .NEAR TERM /THROUGH TUESDAY/... Unusual August setup as a closed upper low meanders eastward into Tuesday. Upper low is positioned over eastern Ohio this morning and will drift into Pennsylvania over the next 24 hrs. Deep tropical moisture lurking over the east coast and western Atlantic is set to be tapped by the southeast flow ahead of the low, and the upper divergence over eastern NY. This will develop a surface low that meanders into southwest New England by Tuesday morning. SHort term high resolution models are exploding precip over northeast PA this morning into central NY near that low level inflow and under the favorable upper jet. With model QPF ranging from a couple to isolated 5 inch amounts, and wet antecedent conditions, Flash Flood Watch seems prudent for the area, especially given the sensitivity to rain and the near term history, and the weak steering flow that will cause slow moving cells. At this time, most threatened areas are most of NEPA into the southern tier counties of NY. However, mesoscale modeling and the 12Z NAM suggest several other areas of very heavy rainfall setting up later today. The first is over northeast PA later this afternoon into the evening with new development of slow moving showers and storms. This activity is expected to move northwest into the Finger Lakes tonight resulting in another window for slow moving heavy showers and thunderstorms. With all that said, the flash flood watch was expanded into these areas. Also, the watch was expanded in time throughout the entire night given the expected persistence of localized heavy rain in the region tonight. Rain should taper off a bit this evening as some of the forcing for the convection is instability and heating related. Showers will fire again on Tuesday, but tropical inflow will have moved east by then. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... 350 AM Update... Though not completely rain-free, this period appears to be our best window for relatively benign weather. Upper low will start to open up into a wave while exiting northeast of the region Tuesday night. Lingering activity will be quick to diminish Tuesday evening, and temperatures will settle into the lower-mid 60s for lows. Decreasing clouds yet waterlogged ground could easily lead to temporary areas of fog Tuesday night-early Wednesday, but Wednesday itself looks mostly sunny in Northeast PA and at least partly sunny in Central NY if not indeed also more sun than clouds. Ridging will also boost temperatures well into the 80s for most of the region, which combined with still fairly humid dewpoints of mid to upper 60s will make things feel a bit uncomfortable. Even this supposedly tamer day could still produce a couple showers and thunderstorms in the afternoon, mainly in Central NY where a shallow boundary will skim by the region. Most of the area, and time, will be dry. Things will be quiet Wednesday night, with lows again in lower- mid 60s, and areas of fog probably forming again. && .LONG TERM /THURSDAY THROUGH SUNDAY/... 350 AM Update... Forecast adjusted towards latest multi-model blend with little change overall in the thinking. Confidence is now high enough to place some of Central New York into likely range for showers- thunderstorm chances Friday. Also, latest ECMWF for Sunday has backed away from its earlier solution that allowed a system to approach; thus as with Canadian/GFS models it does appear that the second half of the weekend will be generally dry. Previous discussion... Thursday and Thursday night: The frontal boundary will be meandering over our region with the exact location of the boundary differing on operational modeling and the respective ensemble guidance. Enough lift and moisture will likely be present for a few pop up storms in the afternoon and evening. Given some mid- level ridging ahead of the next front the 12Z GFS looks rather overdone with QPF and storm coverage Thursday. Modeling has trended slower overall with the timing of the next system holding off till almost Friday now. Another day with highs in the 80's and lows in the 60's. Friday through Sunday...A surface low pressure system/upper level trough will be approaching from the Great Lakes region and will head towards extreme southeastern Canada. Associated with this system will be a cold front. However, as is usual this far out, there are differences between various ensemble members regarding the timing of the passage of this front. Models have been trending towards most of the action occurring Friday afternoon. This will have to be monitored closely as we get closer to this period. Due to the uncertainty in the timing of the front and how far out this still is, decided to cap POPs for showers and thunderstorms to high-end chance rather than likely for now. Some lingering showers are possible Friday night into early Saturday, but this is once again highly dependent on the timing of the front. To account for this uncertainty, left in chance POPs for this time period. Otherwise, a drying trend should occur for the remainder of Saturday and most likely Sunday as well, as high pressure looks to gradually build in. The 12Z ECMWF shows another system approaching from the Great Lakes for Sunday, but left this out of the forecast for now since previous runs have not shown this with most other models keeping precipitation chances well south of the area along a stationary front. High temperatures during this period will remain nearly steady in the upper 70s to lower 80s. The most noticeable change will be the dropping dew points behind the passage of Friday's cold front, leading to a less humid weekend. Lows Friday night will be in the lower to mid 60s and lows Saturday night will be in the upper 50s to lower 60s. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... Low moving south of the area with deep moisture will keep showers over the area with scattered thunderstorms. This will result in MVFR ceilings and visibilities with spotty IFR conditions for much of the day and into the night. The rain is expected to become lighter after midnight but with the abundant moisture, IFR conditions are possible late in the period with light winds and a more stable environment. Light and variable winds through the period. Outlook... Tuesday through Tuesday night...Restrictions likely in occasional showers/thunderstorms. Wednesday through Thursday...Primarily VFR although brief restrictions possible in isolated convection. Friday...Restrictions possible due to showers and storms. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Flash Flood Watch through late tonight for PAZ038>040-043-044- 047-048-072. NY...Flash Flood Watch through late tonight for NYZ022>025-044>046- 055>057-062. && $$ SYNOPSIS...DGM NEAR TERM...DGM/MWG SHORT TERM...MDP LONG TERM...BJG/MDP/MWG AVIATION...DGM/DJN