Area Forecast Discussion
Issued by NWS Binghamton, NY

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891 FXUS61 KBGM 221721 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 1221 PM EST Wed Feb 22 2017 .SYNOPSIS... A southwest flow of mild air will be over our area into the weekend. This will bnring temperatures well above normal for February. Weak areas of low pressure will bring a low chance of showers from time to time before a stronger system brings widespread rain on the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Updated at 1130 am. Scattered showers continue moving across northeast Pa late this morning with mainly dry weather to the north. Lots of breaks in the cloud cover have developed over the Finger Lakes and these should work east across the rest of the area later this afternoon. Temperatures are on track to reach the 50s in all areas. Previous discussion is below. Updated at 9 am. Quick grid update to raise pops in northeast Pa where a few showers have been moving across the area. Latest high resolution guidance showing these showers moving off to the east later this morning. Rainfall amounts will be a tenth of an inch or less. Previous discussion below. Weak little waves ripple along in the westerly flow while a diffuse trof lingers in the area. This will bring low chance pops to parts of the area today. HRRR shows the best chance for any rain would be over the estrmem north...and over the southern third pf the forecast area. Amounts will be quite light in any event. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... Deep southwest flow aloft will keep the easterly movement of surface features slow through the area. Frontal boundary running from the mid Mississippi valley to the Great Lakes will creep eastward as upper system race northeast in the upper flow. This will keep a risk of showers at times...but more importantly keep mild air over the forecast area through the short term. Expect very little change in the weather through Thursday with the upper ridge holding firm. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Southerly flow ahead of a strong midwestern low pressure center will pull the +15C 925mb isotherm to the NY/PA border on Friday. With a warm front to our north and a cold front approaching from the Ohio Valley, mainly cloudy skies will be over our forecast area with a few showers expected. Appreciable breaks of sunshine would allow temperatures to make a run at 70 degrees, but this seems unlikely. Even with the cloud cover most areas will reach the lower 60s Friday afternoon. A strong cold front will move through NY/PA on Saturday. Heavier showers are expected along the front, including a slight risk for a few thunderstorms in the abnormally warm/humid airmass. PWATs are north of 1 inch, so we will need to watch for downpours in heavy rain showers. Much colder air filters down from Ontario Saturday night into Sunday, changing rain showers over to snow showers. After wintry temperatures return on Sunday and Monday, a temporary mild spell is forecast ahead of another approaching cyclone, beginning on Tuesday. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... Despite the light winds and scattered showers VFR conditions will prevail over the region for much of the TAF period. Occasional MVFR ceilings are possible in SYR and RME for the next few hours. Conditions continue into Wednesday with little change with a weak southwest surface flow and ridging aloft. Some MVFR ceilings are possible aft 00Z as the sounding stabilizes and moisture gathers below a weak inversion. OUTLOOK... Thursday through Thursday night...Mainly VFR, except possible spotty rain showers/brief restrictions Thursday onward. Friday through Saturday...Restrictions from rainy frontal system. Sunday...Possible restrictions from lake effect snow KSYR-KRME. && .HYDROLOGY...
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1215 PM UPDATE... Significant warmup with increasing humidity still appears to be a high confidence forecast as low pressure tracks to our west with a deep southwest flow setting up. The melting of the remaining snow pack therefore seems pretty likely. The upper reaches of the Susquehanna and Delaware basins should lose generally 1 to 2 inches of SWE with some basins potentially higher. There may be some limitation to a complete melting of the deepest snow cover over N. Oneida county, but still expecting at least half of that SWE will come out, which could easily be 3 inches. This water alone is likely to push gauge monitored tributaries and headwater rivers above their posted action/caution stages. Additional rainfall would introduce the possibility for minor flooding of the typical Spring melt season flood prone rivers and streams. The Meteorological Model Ensemble Forecast System does indicate a chance for minor flooding occurring at these more sensitive forecast points along the Chenango, Tioughnioga and W. Branch Delaware well as some of the most sensitive locations on the main stem Susquehanna. The chance for any flooding is highly dependent on forecast rainfall, which in our opinion, may be overdone at this time as the current track of the surface low would suggest that the warm frontal rainfall on Friday-Friday night should be pretty light. The trailing cold front expected on Saturday could make up for that as it plows into an anomalous PWAT environment, but models need some time to sort that out. Bottom line is that the remaining melting snow will get flows within striking distance of exceeding bankfull stages and any properly located rainfall, in excess of about an inch, would get a few of those more sensitive rivers to top flood stage. Official forecasts show the river trends nicely, but are currently valid only until 12Z Saturday. Crests would be later Saturday, or Sunday. For now, we will remain conservative in our messaging of this event, but our partners might want to dust off any flood hazard and mitigation plans at this time.
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&& .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...DGM NEAR TERM...DGM/MSE SHORT TERM...DGM LONG TERM...DJP AVIATION...DGM/MLJ HYDROLOGY...JAB is the U.S. government's official web portal to all federal, state and local government web resources and services.