447 FXUS61 KBUF 110511 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 111 AM EDT Thu Oct 11 2018 .SYNOPSIS... Unseasonably warm and humid conditions will remain over the area through tonight. Chances for showers and storms increase tonight ahead of a strong cold front that is expected to cross the area Thursday. Dramatically cooler temperatures will move into the area Friday through early next week. && .NEAR TERM /THROUGH TODAY/... Radar imagery showing the first area of rain moving into Central NY and the eastern Lake Ontario region. This will bring a 1-2 hour period of light to moderate showers with little chance of any thunder given the lack of instability or stronger forcing. PWAT values are very high at around 2 inches, but weak forcing and weak instability will prevent any heavy rain. From the Genesee Valley westward, expect mainly dry conditions through the wee hours of the morning with just a few stray light showers possible. A better chance of scattered showers will arrive shortly before daybreak with the approach of the cold front. Low pressure will track into southern Ontario through Thursday. A strong cold front will approach the region late tonight and move across the area Thursday morning. A southerly flow will continue tonight as the cold front swiftly moves eastward into the Ohio Valley. A 30-40kt LLJ ahead of this front will move across the forecast area from the Western Southern Tier to the North- Country overnight. It will be a mild night with low temperatures only in the mid to upper 60s. Those out and about tonight will notice the muggy and tropical airmass with PWATS at their climatologically maximum for mid- October and freezing levels near 14k feet. The cold front will be near the NY Lake Erie shoreline at 12z Thursday. The parent closed mid-level low will be moving east- northeast across the Upper Great Lakes and International border at this time. Daybreak Thursday the steady rain showers associated with the LLJ will be exiting east of the North Country, meanwhile showers will also develop along the cold front. Timing will be more favorable for destabilization further east, where showers and some thunderstorms along the front will reach the eastern Lake Ontario region early afternoon. There may be locally heavy rain with these storms, with an isolated strong to severe storm not completely out of the question. High temperatures will be reached in the morning across Western NY and around noon- time for the North Country. Temperatures will reach the low 70s during this time. Temperatures will likely be in the low 60s by late afternoon across the Niagara Frontier and Western Southern Tier. Cold air advection will occur behind the front Thursday morning and afternoon. Gusty winds 10 to 20 mph with gusts up to 30 mph expected behind the front. Low-level moisture will likely persist so expect a mostly cloudy day. Clearing will likely occur across the Niagara Frontier by evening. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... Thursday night and Friday...an upper level trough will be moving SE into the Dakotas with it's surface low near James Bay. A cold front tied to this low will already be well east of WNY with cold air advection in place. Meanwhile, Michael will be moving NE toward the Mid Atlantic coast but with little interest to WNY weather. Low level moisture will remain below about 5000' resulting in abundant cloud cover and possibly some lake effect sprinkles or showers ESE of the lakes. Dry air above this level should negate any significant rainfall amounts. Otherwise the main impacts through Friday will be the notably cooler weather with temperatures Friday struggling to top 50F. Friday night and Saturday...The upper level trough earlier over the Dakotas will move east across WNY during this time. This will allow moisture to increase throughout the profile, with at least a chance of showers everywhere, with the highest probability toward the Southern Tier. Lake effect showers should then linger into Saturday ESE of the lakes, with continued abundant cloud cover elsewhere. Saturday night...there is a possibility that some of the moisture may start to break up a surface ridge moves into the OH valley and then east through PA. If so, some clearing is possible with radiational cooling resulting in frost conditions inland from the lakes, with a freeze east of Lake Ontario. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... This period will open with a mid level wave and its attendant surface reflection passing by to our north across Central Ontario and Quebec Sunday and Sunday night...with its trailing cold front passing through our region between late Sunday and Sunday night. Out ahead of the front...Sunday should be mainly dry aside from some possible leftover lake effect rain showers northeast of the lakes...with a modest shot of warm air advection out ahead of the front also helping to push high temps back up into the mid to upper 50s. Sunday night shower chances should at least increase somewhat as the front passes through our region...though the exact coverage of these remains in question with the latest GEM suggesting a round of showers for all... the ECMWF completely dry...and the GFS lying in between these two extremes. Given the resulting forecast uncertainty...have elected to scale back a bit on the likely PoPs previously in place areawide... with these now restricted to the northern half of our area...where the front will have a little better support from its parent waves. In the wake of the cold front...the medium range guidance continues to suggest that a southern stream wave/possible remnants of Sergio may ripple northeastward along the boundary and bring our region another shot of showers sometime in the Monday-Monday night time frame... though considerable run-to-run and model-to-model variance also still persists in the timing and placement of this wave. Following a general consensus would suggest a slower overall approach and passage of this feature...and have trended the forecast in this direction with the bulk of its showers now indicated for late Monday and Monday night. Following the passage of this feature...another shot of colder but relatively dry air will then build across the region late Monday night and Tuesday...with some nuisance-type lake effect rain showers again becoming possible downwind of the lakes. As for temperatures...the twin shots of cold air advection behind the initial cold front and secondary southern stream wave will send temperatures back to below normal levels for both Monday and Tuesday...with highs both days only expected to range from the upper 40s across the higher terrain to the lower 50s across the lower elevations. After that it looks like a case of lather...rinse...and repeat for Tuesday night and Wednesday as another mid/upper level trough axis passes across the Great Lakes and Northeast...with its attendant surface low passing by to our north across Ontario/Quebec and pushing another cold front through our region. This next system should also be accompanied by a round of at least scattered showers as it passes through our area...with its attendant cooler temps aloft possibly also supporting some areas of lake enhancement. Otherwise temperatures will remain below normal...with highs on Wednesday again mainly in the upper 40s to lower 50s. && .AVIATION /05Z THURSDAY THROUGH MONDAY/... A cold front will approach the region late tonight and then cross the region on Thursday. The first batch of rain will continue to move through Central NY and the eastern Lake Ontario region through about 09Z. The low level airmass is initially unsaturated with this, so expect mainly VFR CIGS and VSBY. Farther west, areas of MVFR CIGS at lower elevations and IFR for higher terrain will expand through the rest of the night as the low levels saturate. A few scattered showers will develop towards daybreak as the cold front nears. The cold front will encounter increasing instability to the southeast and east of Lake Ontario during the midday and early afternoon hours, with a better chance for a line of showers and thunderstorms to develop. Some of these storms may contain gusty winds briefly. Behind the cold front expect MVFR CIGS to linger for an hour or two, and then scatter out to VFR as much drier air sweeps into the region. Low level moisture will move back into the area Thursday evening as lake effect clouds begin to develop. This will produce areas of MVFR CIGS Thursday night. Outlook... Friday...Areas of MVFR southeast of the lakes in scattered lake effect rain showers, VFR elsewhere. Friday night and Saturday...Lake effect rain showers and MVFR/IFR southeast of the lakes, otherwise VFR. Sunday and Monday...VFR/MVFR with a chance of rain showers. && .MARINE... High pressure will keep the winds and waves on the waters below marine headline criteria through this evening. A strong cold front will then cross the eastern Great Lakes Thursday. Southwest winds will become moderate to strong behind the cold front, and gradually veer to the northwest through Friday as much cooler air pours into the eastern Great Lakes. Small craft headlines were extended through late Friday with the persistent post-frontal winds. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...Small Craft Advisory from 8 AM this morning to 2 PM EDT Friday for LEZ040-041. Small Craft Advisory from 2 PM this afternoon to 11 PM EDT Friday for LOZ043>045. Small Craft Advisory from 11 AM this morning to 5 PM EDT Friday for LOZ042. && $$ SYNOPSIS...HSK NEAR TERM...Apffel/Hitchcock/HSK SHORT TERM...Zaff LONG TERM...JJR AVIATION...Hitchcock MARINE...Apffel/HSK/Smith