Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 281742 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 142 PM EDT Fri Apr 28 2017 .SYNOPSIS... High pressure over the region will be responsible for a pleasant, but cooler day with some sunshine. A frontal boundary will push towards our region tonight, and linger over the region through the weekend, with clouds and periodic light rain showers. && .NEAR TERM /THROUGH TONIGHT/...
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Clouds continuing to erode with only some passing clouds level clouds across the region this afternoon. The afternoon will remain comfortable with temperatures in the 60s to lower 70s with lower humidity values. Winds will be light from the southwest, though an occasional gust to 25 mph will be possible. As moisture increases from the midwest late this afternoon, clouds will again begin to form and fill in across western New York. Tonight another cold front will sag across the region, this from an area of low pressure near James Bay. As moisture increases from the south a few light rain showers will be possible, especially south of Lake Ontario. Lows tonight will drop back into the low to mid 50s.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... A baroclinic zone will become established across the forecast area Saturday and Sunday as we will be sitting on the northern periphery of a ridge just off the southeastern coast. Weak waves will ripple along this frontal boundary promoting a chance of showers through much of the weekend. The steadiest precipitation will develop across southern Ontario Saturday night into Sunday along an axis of warm air advection in the mid-levels. Our region will be to the south of this steadier rain, with more convectively driven showers across our area. Warmer air aloft will lead to elevated instability with a few thunderstorms are possible. However the weekend will be far from a washout as overall forcing is weak and sporadic across our region. Temperatures will continue to average above normal on Saturday, with highs mainly in the 60s across the region. The surface frontal boundary will strengthen Saturday night with increasing winds and a sharper temperature contrast. Cold air advection will drop temperatures to the upper 30s to lower 40s north of the I-90 corridor from Buffalo to Syracuse, with temperatures remaining around 50 across the western Southern Tier. By Sunday the boundary will evolve into a warm front pushing northward as a deep low pressure system develops across the central plains. A sharp temperature difference can be expected across the region as the warm front moves northward with highs in the low 50s in the North Country and along the lake Ontario shoreline to the mid to upper 70s across the western Southern Tier. By Monday, the anomalously deep low pressure system will track through the upper Great Lakes while pushing a strong cold front across the region Monday. Model consensus keeps the area mainly dry Monday morning, with showers and thunderstorms likely Monday afternoon and evening. Forecast wind profiles support organized convection, but it is uncertain if instability will be ample to support widespread severe weather. This does suggest at least a potential for strong to severe thunderstorms along with locally heavy rainfall. Showers and thunderstorms will taper off from west to east late Monday night. Summer-like temperatures will also return to the region with highs in the upper 70s to lower 80s. This is warmer than consensus guidance which is probably too cool considering 850mb will be around +15C. && .LONG TERM /TUESDAY THROUGH THURSDAY/... An unseasonably deep surface low passing northwest of our region will help usher in much cooler weather with below normal temperatures expected. This airmass will arrive behind the cold front on Tuesday along with a chance of some scattered showers and gusty winds. Strong cold air advection with a source region over central Quebec will lower 850mb temps to around zero. This will result in highs only in the 50s on Tuesday. 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. Winds will slacken off Tuesday night with below normal temperatures then remaining in place Tuesday night through Wednesday and likely Thursday with continued cold air advection as a mid-level trough axis shifts east across our region followed by another trough digging into the central states. Cool air instability showers will be possible through Wednesday with the coldest core of below normal air aloft passing by. Have continued low to slight chances of showers for this. On Thursday medium range models show the digging trough over the central states will kick off a surface low along the Appalachians midweek which could lift some showers into our forecast area from the south by Thursday. Lows Tuesday and Wednesday nights look to dip into the upper 30s to low 40s then highs on Wednesday and Thursday only rising into the low to mid 50s. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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Widespread VFR conditions this afternoon with only some passing cirrus level clouds. Winds will be light, though some occasional southwest gusts to 20 knots will be possible, northeast of the lakes. Tonight clouds will thicken as a frontal boundary drops across the region. Initially these clouds will be mid level, but as moisture increases across the So. Tier, some IFR CIGS will be possible late tonight. Outlook... Saturday...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.
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&& .MARINE...
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Waves will approach 2 feet on the eastern waters of the Great Lakes this afternoon. A frontal boundary will become draped across the Lakes to start this weekend, though winds and waves will remain light and minimal. Looking a bit further out, strengthening easterly winds may bring Small Craft Advisory conditions to the western lake waters for Sunday. Another, stronger storm system may bring another round of thunderstorms early next week, with gale force winds possible behind a cold front on Tuesday.
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&& .TIDES/COASTAL FLOODING...
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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 and Orleans counties. There is still considerably uncertainty concerning wave heights since even a slight shift to the more easterly direction would push the highest waves to the Canadian shoreline.
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&& .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...THOMAS/TMA NEAR TERM...THOMAS/TMA SHORT TERM...APFFEL LONG TERM...APFFEL/SMITH AVIATION...THOMAS/TMA MARINE...THOMAS/TMA TIDES/COASTAL FLOODING...Apffel CLIMATE...THOMAS

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