Area Forecast Discussion
Issued by NWS Buffalo, NY

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035 FXUS61 KBUF 290220 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1020 PM EDT Fri Apr 28 2017 .SYNOPSIS... A warm frontal boundary will push towards our region overnight, then will linger over the region through the weekend. This will result in scattered showers and a few thunderstorms, although much of the time it will remain dry and mild. && .NEAR TERM /THROUGH SATURDAY/... Overnight...a warm front over the Ohio Valley will push a bit closer toward our region...spreading in a decent likelihood of showers northward into the western Southern Tier during the overnight hours...with lower-end chances of showers extending as far north as Lake Ontario. On Saturday...most models stall the warm front near the Pennsylvania border...with the best chance for additional showers and perhaps a few thunderstorms during Saturday continuing to lie along the Southern Tier, with a much better chance for a completely dry day closer to Lake Ontario and the North country. Rising dew points will help keep temperatures mild tonight, with most overnight lows in the lower to mid 50s. Temperatures on Saturday will greatly depend on amount of sunshine or lack of cloud cover/precipiation, but for the most part still looks mild with most areas reaching the 60s. && .SHORT TERM /SATURDAY NIGHT THROUGH TUESDAY/... Saturday night into Sunday a developing low pressure system over the central plains will begin to influence the stalled frontal boundary across the area pushing it northward as a warm front. The warm frontal boundary aloft will move north of Lake Ontario Sunday, however the surface warm front will get hung up on on the south side of Lake Ontario, enhanced by the lake breeze off the relatively cooler lake waters. The main area of widespread synoptic precipitation will develop along the frontal boundary aloft north of Lake Ontario, while enhanced surface convergence along the surface boundary will continue to support scattered showers across western NY. There will also be a wide range in temperatures on Sunday with locations north of the I-90 thruway corridor markedly cooler than areas south across the western Southern Tier and southern Genesee Valley. Along the southern Lake Ontario shoreline and the Saint Lawrence valley temperatures will likely remain in the 40s to low 50s, while temperatures across southern portions of the state could push into the upper 70s. Rochester and Watertown will likely remain on the cooler side in the 50s, while Buffalo will be very near the transition with as much as a 20 degree temperature difference possible between the Southtowns and Niagara Falls. By Sunday night into Monday, the surface warm front will finally push north across Lake Ontario with deep southerly downslope winds developing across the region in the warm sector of the occluded low pressure system centered back across Wisconsin. 850 mb temperatures will again surge to +15 to +18C promoting temperatures reaching at least the upper 70s to low 80s, depending on cloud cover and timing of the impinging cold front. Showers will cross the region with thunderstorms likely Monday afternoon and evening. There will be ample shear to result in strong to severe thunderstorms; however, the main limiting factor will be how much instability can be realized ahead of the approaching front. This will depend on the timing of the front itself and how much sunshine can break through in the warm sector to destabilize the atmosphere. Will continue to mention the potential in the Hazardous Weather Outlook. The cold front and any associated convection will cross the region through Monday evening with cooler air filtering in it wake. A cooler airmass will be in place on Tuesday as the trough crosses the region. As the upper-level trough crosses the region on Tuesday enough moisture and ascent from the trough passage could spark some light showers across the region with the steep lapse rates aloft. Cloud cover will also linger under the trough, and with 850 mb temperatures to around 0C, high temperatures will be limited to the upper 40s/ low 50s in western NY to nearly 60 toward central NY. Tuesday will be a windy day, with a 45-50 kt 850mb flow potentially supporting advisory level gusts to 50 mph. Ultimately this will depend on the track and strength of the surface low, and if there is any sunshine to help mix these winds aloft to the surface. This threat of gusty winds is included in the Hazardous Weather Outlook. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... Cool and unsettled weather look to be the norm for most days over the next few weeks as a mean longwave trough remains in place over the Great Lakes and Northeast, with frequent shortwaves and associated surface lows bringing periods of showers and fresh deliveries of cool air. Tuesday night and Wednesday the deep upper level trough over the Great Lakes will move east across Quebec and weaken, but will still maintain enough influence across our region to keep below normal temperatures in place right through the end of next week. 850mb temps run from -2C to -4C Wednesday depending on model of choice, and only improve to around +1C by Friday. The weather will remain unsettled as well. Tuesday night and Wednesday the eastward moving trough will combine with cool air aloft and remaining wrap around moisture to support scattered showers, especially across the higher terrain with an added boost from upslope flow. It should briefly dry out Wednesday night as a bubble of high pressure builds over the eastern Great Lakes and New England. By Thursday and Friday of next week another trough is forecast to dig into the eastern US, and potentially phase and close off into a mid level closed low. An associated low will form along or inland of the east coast and move slowly northward. If this materializes, it will spread clouds and more showers into the region for the end of the week. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... A warm frontal boundary over the Ohio Valley will lift northward to the NY/PA border overnight...where it will then stall out through Saturday. Expect increasing/lowering clouds to spread across the region from southwest to northeast in advance of the frontal boundary...with some rain showers then following suit overnight across areas south of Lake Ontario...with the greatest coverage of these expected to be across the Southern Tier. Expect flight conditions to mostly be in the VFR range...though some MVFR/IFR will develop across the higher terrain of the Southern Tier/Finger Lakes later on tonight. On Saturday...expect scattered showers (and perhaps a few embedded thunderstorms as well) from time to time south of Lake Ontario...with the greatest chances of these again found across the western Southern Tier. Meanwhile...morning IFR/MVFR restrictions across the higher terrain of the Southern Tier/Finger Lakes will generally improve back to VFR...with VFR conditions prevailing elsewhere. Outlook... Saturday night...VFR/MVFR with a chance of showers and thunderstorms. Sunday...VFR/MVFR with a chance of showers. Monday...MVFR to locally IFR with showers and thunderstorms likely. Tuesday and Wednesday...VFR/MVFR with a chance of showers. && .MARINE... Waves will approach 2 feet on the eastern waters of the Great Lakes tonight. A frontal boundary will become draped across the lower Great Lakes to start this weekend, though winds and waves will remain light and minimal through the day Saturday and Saturday night. Strengthening east to northeasterly winds will likely bring Small Craft Advisory conditions to the western Lake Ontario nearshores for Sunday. Another, stronger storm system may bring another round of thunderstorms early next week, with high end small craft conditions likely returning on the lakes by Tuesday. && .TIDES/COASTAL FLOODING... East to northeast winds will increase Sunday, with waves building across western portions of Lake Ontario. This combined with already high levels on Lake Ontario has the potential to result in lakeshore flooding along the shoreline. The highest waves are expected in Niagara, Orleans and western Monroe counties. There is still uncertainty concerning the placement of the highest wave heights since even a slight shift to the more easterly direction would push the highest waves to the Canadian shoreline. && .CLIMATE... The last days of April will finish with above normal temperatures, warm enough that it will send our climate sites towards a top 10 warmest April on record. The degree of anomalous warmth has been greater towards the west, where climate site Buffalo may near the warmest April on record. Below are the warmest Aprils on record. Buffalo Rank....Value (F).....Year 1........51.3.........1921 2........51.1.........2010 3........51.0.........1955 4........50.9.........2008 5........50.8.........1878 Current April average temperature through April 27th: 50.3F Rochester Rank....Value (F).....Year 1........52.6.........1878 2........52.5.........1921 3........52.4.........2010 4........52.3.........2008 5........51.4.........1915 Current April average temperature through April 27th: 51.2F Watertown Rank....Value (F).....Year 1........49.1.........1987 2........48.7.........1955 3........48.7.........2010 4........48.3.........1968 5........48.2.........2008 Current April average temperature through April 27th: 47.4F Temperature records for Buffalo and Rochester begin 1871, while Watertown`s history is a bit shorter, with temperature records beginning in 1949. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...JJR/TMA NEAR TERM...JJR/TMA SHORT TERM...CHURCH LONG TERM...HITCHCOCK AVIATION...JJR/TMA MARINE...TMA TIDES/COASTAL FLOODING...APFFEL/TMA CLIMATE...THOMAS

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