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Area Forecast Discussion
Issued by NWS Binghamton, NY
Issued by NWS Binghamton, NY
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183 FXUS61 KBGM 180757 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 357 AM EDT Sun Aug 18 2024 .SYNOPSIS... An upper level system brings showers and thunderstorms today, with risks for locally heavy rainfall and perhaps gusty winds in the strongest cells. Showers and a chance of thunder will linger into Monday, in time pressing mainly east of Interstate 81. Drier and cooler conditions will arrive Tuesday, with fair weather persisting for much of the week ahead. && .NEAR TERM /THROUGH MONDAY NIGHT/... 355 AM Update... Main concern today will be the potential for locally heavy rainfall in showers and thunderstorms that redevelop this afternoon through early evening. Also, a few of the strongest cells could turn severe in Northeast Pennsylvania and bordering counties of New York. Small clusters of showers lost their lightning upon reaching our Central Twin Tiers zones as well as Pike-Sullivan-Delaware counties given nocturnal timing. Cells in Central Pennsylvania continue to have lightning, and we will monitor their progress this morning. However, primary attention will turn to renewed diurnally- driven convection later today, especially afternoon-early evening. Axis of instability will initially enhance along or just west of the I-81 corridor, then shift slowly east with time. Axis of instability will be situated along an amorphous shallow stationary front roughly up the Wyoming Valley and Poconos to Catskills. This setup can sometimes lead to trouble, due to a shallow layer of southeast flow with slight veering just above it. The Storm Prediction Center thus has brought in a marginal risk for severe thunderstorms across Northeast PA to the eastern Southern Tier and Catskills counties. HREF modeling and model soundings indicate 0-1km helicity values of 50-100 m2/s2. Though amount of heating is in question today because of cloud cover, the shallow shear and low Lifting Condensation Level (LCL) environment supports at least a small potential for severe cells, and indeed SPC also indicates a 2 percent risk for isolated tornadoes within 25 miles of a point. Our region will also reside in the left exit region of an upper jet aloft, which will provide forced ascent as an extra nudge to any diurnal heating from below. The bigger overall risk for the area, however, will continue to be potential for locally heavy rainfall. This is especially the case for locations that have already had recent rains. Meso- beta element vectors, that is cloud layer velocity vector minus low level jet vector, become very short late today east of I-81, suggesting potential of training or backbuilding of cells. Add to this Precipitable Water (Pwat) values of 1.50-1.75 inches, and locations that get either multiple cells or a slow moving axis of rain could exceed what the ground can handle which would allow water to quickly run off. The Flood Watch was expanded to include all of Northeast Pennsylvania, as well as the Southern Tier to Sullivan County in New York, through this evening. These areas have somewhat better potential for localized flash flooding, but even counties outside the Watch could have isolated excessive rainfall. If potential and confidence increase farther north, the Watch could still be expanded. Monitor the forecast for updates. After this evening, activity will press east and/or wane with loss of heating. However, the upper low pressure system ultimately driving our current unsettled pattern will only slowly edge east on Monday. This will trudge a cold front across the region Monday, with a final round of showers and chance of thunderstorms. Rain amounts will tend to be less than today, yet much of the area will also be even more sensitive to additional rainfall, and thus isolated excessive rain still cannot be ruled out though mainly east of Interstate 81. Behind the front, cooler air will start to advect in during the afternoon, sending temperatures all the way down into upper 40s-mid 50s by dawn Tuesday. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... 310 AM Update: A cold front will help push remaining showers through the region Monday night. The best chances will be east of I-81, especially over the Catskills. Some instability will support thunderstorms during the late evening as well. While some lingering showers may remain Tuesday morning, most of the region will be rain-free as cool, dry fills in behind the front. Some spotty showers cannot be ruled out over north-central NY as wraparound moisture from this stacked low will try to nudge its way into the region. That will be the case for Tuesday night as well. Temperatures will fall into the upper 40s to mid 50s Monday night. Tuesday will be noticeably cooler as temperatures will only climb into the 60s, though some valley locations may just reach 70. Tuesday night will be chilly as well as most will be in the 40s. With mostly clear skies over the region, temps were slightly reduced below guidance. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... 310 AM Update: Moisture from this pesky low pressure system will once again make an effort to push in from the north. Because of this, there may be some spotty showers on Wednesday as well. Since instability will be lacking, thunderstorms are not expected. Eventually, a ridge of high pressure will win out and gift us with an extended period of quieter weather. The next chance for rain won`t be until later this weekend, and even then, that is questionable. The long term will be pleasant with highs in the 70s and lows in the 50s. Temperatures due trend warmer throughout the week, so 80s return just in time for the weekend. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... MVFR to fuel alternate required ceilings will persist the remainder of the night through morning from moist southeast flow. As ceilings attempt to lift in afternoon, there will also be heating-driven development of showers and thunderstorms. Thunder chances are too iffy at this time to specifically include in TAFs for KELM-KITH, but farther east there is more confidence thus TEMPO CB groups have been introduced KSYR-KBGM- KAVP-KRME. In the wake of showers-thunder, expect MVFR to fuel alternate ceilings to redevelop in the evening, with potential for IFR. .Outlook... Late Sunday Night into Monday morning...Likely fuel alternate required to IFR ceilings. Monday midday through evening...Scattered showers and thunderstorms with resultant occasional restrictions. Tuesday through Thursday...Mainly VFR as high pressure gradually builds across the region. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Flood Watch through this evening for PAZ038>040-043-044-047- 048-072. NY...Flood Watch through this evening for NYZ022-024-055-056-062. && $$ SYNOPSIS...MDP NEAR TERM...MDP SHORT TERM...BTL LONG TERM...BTL AVIATION...MDP