Area Forecast Discussion
Issued by NWS Binghamton, NY

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000 FXUS61 KBGM 281143 AFDBGM Area Forecast Discussion National Weather Service Binghamton NY 643 AM EST Tue Feb 28 2017 .SYNOPSIS... Flow out of the south to southwest will surge temperatures well above normal today, and even more so into Wednesday. A strong storm system will cause showers and thunderstorms across New York and Pennsylvania Wednesday. Some of those storms could contain strong gusty winds and downpours. Colder air will follow for the end of the week. && .NEAR TERM /THROUGH TONIGHT/... 430 AM Update... Light precipitation early this morning could result in spotty ice in isolated parts of Central New York, otherwise this period will feature temperatures surging well above normal. High pressure is located offshore over the Atlantic, and southerly return flow around it is resulting in warm air advection. However, temperatures earlier tonight did manage to drop to near freezing in some pockets of Central New York. Meanwhile, left exit region of jet aloft, in tandem with warm air advection in the midlevels, is producing very light precipitation in Central New York early this morning. Coverage on radar looks more extensive than it really is, due to both bright-banding and virga on the periphery. The strip of light precipitation extends from about Penn Yan to Ithaca to Cortland to Norwich and Cooperstown. Though most locations are above freezing, the few spots around 32 degrees could have patchy ice. Later this morning we get into the unfavorable right exit region of the jet, and the resulting forced descent will tend to suppress activity. There will still be a chance of rain showers but most of the time conditions will be dry. Strong warm air advection will likely send temperatures not just well above normal but also at least slightly above model guidance as typically happens in southwest flow during late winter-early spring. We are expecting mainly mid 50s to lower 60s for highs. Pressure gradient will increase tonight as strong low pressure ejects from Central Plains into the southwestern Great Lakes region. Southerly winds will increase accordingly and become quite breezy at higher elevations, while holding temperatures from falling below upper 40s-mid 50s for most locations. Embedded waves within the southwest flow aloft will result in scattered showers overnight, though with some instability in the mid levels there could be a rumble or two. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... 445 AM Update... Main concern is for another threat of severe thunderstorms including potential for damaging winds and heavy downpours. As the saying goes, March comes in like a lion, though some could argue the lion actually arrived a few days early this past weekend. We are forecasting record high temperatures for the first day of the month, which is part of what will provide fuel for potential severe thunderstorms Wednesday afternoon-evening. Widespread mid 60s to lower 70s appears likely, surpassing daily records of 63 degrees in Syracuse, 60 degrees in Binghamton, and 68 degrees in Scranton (Avoca). The Binghamton and Avoca records were set in 1972, and the Syracuse one is front 1954. The Storm Prediction Center has upgraded Northeast PA and Southern Tier-Catskills NY into a Slight Risk for Severe Thunderstorms Wednesday, with at least Marginal Risk further north. There is uncertainty in the details as to whether or not clouds will break for additional heating, between a morning wave of showers-embedded thunder, and afternoon-evening thunderstorms along pre-frontal trough and/or cold front. However, it has become apparent that even if clouds stay quite persistent, the atmosphere will become unstable. Model soundings vary from a few hundred J/KG for Convective Available Potential Energy (CAPE) to almost 1000 J/KG; in almost all cases adequate for at least scattered thunderstorms. The tougher part is whether smaller clusters of showers-thunder will tend to break up organization. Hodographs are not as curved as the event we had Saturday, yet there is still some. Instead of strong southerly flow, it is more of a southwesterly direction, yet speed shear is again at very strong values. Models indicate that most of the 2km-6km layer will be southwesterly at 60-80 knots. Damaging winds will be the main concern with any storms Wednesday afternoon-evening, whether organized as a primary line or in segments. That being said, 0-1km helicity values are still in the 150-300 m2/s2 range and thus a tornado or two also cannot be ruled out. Another concern is potential for flash flooding. Flash flood guidance (that is, how much rain it would take in an hour to cause flash flooding to begin) is still very low for portions of South Central NY and Northeast PA due to the recent snow melt and also the 1-1.5 inches of rain this area received on Saturday. So, with saturated soils, a large portion of any additional heavy rainfall will become runoff. Overall rain amounts do not look especially high, and storms will be progressive, yet whatever does fall could come quick and heavy; possibly to the point of causing water problems. Precipitable water values are forecast to reach about 1.2 inches, or between 3 and 4 standard deviations above normal. This is actually slightly higher than the event we just had last weekend, yet as mentioned, thunderstorms will be more progressive (shorter- lasting) as well. After the front moves through Wednesday night, temperatures will drop sharply with showers-storms possibly ending as wet snow showers. There will also be strong, gusty winds behind the front on the synoptic scale due to strong pressure gradient on the backside of departing low. Temperatures bottom out in the upper 20s to mid 30s Wednesday night. && .LONG TERM /THURSDAY THROUGH MONDAY/... The northeastern U.S. still looks to be under a large-scale trough for the end of the week into next weekend. This means fairly cold temperatures (highs mainly in the 20`s and 30`s), along with frequent chances of light snow or flurries, especially later Thursday night into Friday, when a clipper type low is anticipated to track across southern PA or the Delmarva region. By later Saturday, a ridge of high pressure is expected to build across NY and PA, to bring a brief period of dry weather. Then, from later Sunday into early next week, an approaching warm front will ultimately bring milder temperatures, along with potentially some rain showers. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Mainly VFR/unrestricted conditions are expected today. By later this evening (02-04z Wednesday onward), an area of showers and lower ceilings could begin to impact KAVP, KELM, KBGM, and KITH. MVFR-fuel alternate restrictions were introduced at this point. KSYR and KRME will likely stay VFR longer overnight. S-SE winds will increase to 8-10 kt today, before becoming gusty at a couple of sites (20-25 kt gusts, namely KITH and KSYR) tonight. LLWS could become a concern towards 12z Wednesday, but we`ll opt to leave out of the terminals for now. OUTLOOK... Wednesday...Occasional restrictions likely in rain showers and thunderstorms. Thursday/Friday...Possible restrictions in snow showers. Saturday...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...MDP NEAR TERM...MDP SHORT TERM...MDP LONG TERM...MLJ AVIATION...DGM/MLJ is the U.S. government's official web portal to all federal, state and local government web resources and services.