041 FXUS61 KBUF 101353 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 953 AM EDT Wed Oct 10 2018 .SYNOPSIS... Unseasonably warm and humid conditions will remain over the area through today. Chances for showers and storms then 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 TONIGHT/... A very warm and humid morning continues across Western and North-Central New York. Per the 12Z KBUF sounding, 850mb temperatures are about a degree less today than yesterday, Tuesday. With little change in temperatures aloft and expected daytime mixing, widespread high temperatures will reach the low to mid 80s again across the forecast area. The climate sites have higher record values today as compared to yesterday, so new record highs seem less likely. See Climate Section below for more details. Gusty SW winds to around 20 mph will also develop with daytime mixing. Looking at the bigger picture...A deep southerly flow over western and north- central New York will continue through this morning into today with a pressure gradient between high pressure shifting off the East Coast and low pressure approaching the Upper Midwest states. Skies are mostly clear and rain-free to start this morning with surface ridging extending across Upstate New York. Some low status over north-central PA is sneaking north of the border into the interior western Southern Tier. Tonight, a surface low will lift north across the central Great Lakes with an associated cold front approaching from the west. This front should be near or over WNY by daybreak Thursday. A leading 40+ kt low level jet ahead of the front will contribute to the first round of showers as it shifts northeast across western and central New York. A second round of heavier showers with some scattered thunderstorms are then expected to cross our region just ahead of or at daybreak Thursday. PWATs of around 2 inches will mean showers and thunderstorms will bring brief heavy downpours which have been mentioned in the weather grids. Basin average QPF tonight will run between a third and a half of an inch with locally heavier amounts. With the colder air behind the front not expected to arrive until later Thursday, and along with cloud cover and rain tonight, look for another night of mild temps. Lows will only slip into the mid 60s. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... Thursday a sharp mid level trough will move northeast across Ontario, with an associated surface low moving from the Nickel Belt of Ontario in the morning to the eastern shores of James Bay by early evening. An associated surface cold front will move quickly east across our region through the day. Model guidance continues to suggest the bulk of the rain will focus along and ahead of a pre- frontal trough. PWAT is very high at around 2 inches in the warm sector. Synoptic scale forcing will be weak however, with the stronger forcing displaced well north of our region closer to the path of the mid level trough. Instability will also be meager given the unfavorable time of day of the frontal passage, and the motion of any scattered thunderstorms that do develop will be quite fast. Given the mitigating factors above, any heavy downpours that do develop will be very brief at any one location, with the risk of any flooding very low despite the high PWAT values. The rain will end from west to east on Thursday, with rain ending by midday across Western NY and later in the afternoon east of Lake Ontario. There should be a few hours of clearing behind the cold front before wrap around and lake effect clouds start to develop during the late afternoon and evening. Temperatures will peak in the 70s in the morning just ahead of the front, then fall back through the 60s later in the day as cold advection sets in behind the cold front. It will be breezy, with wind gusts of around 30 mph common both ahead and behind the cold front. Lake effect clouds will continue to expand southeast of the lakes Thursday night as colder air aloft pours into the eastern Great Lakes. The airmass will initially be very dry in the top of the boundary layer, and this will likely prevent any lake effect showers from developing through the first half of the night despite the increasing lake induced instability. Towards Friday morning, background boundary layer moisture grows deep enough to support an increasing chance of lake effect rain showers. WNW flow will direct this chance of showers into the western Southern Tier off Lake Erie, and mainly Wayne to Oswego counties off Lake Ontario. Temperatures will drop into the mid to upper 40s by daybreak Friday. Cool WNW flow continues Friday as a longwave trough becomes established across the Great Lakes. This will continue to support plenty of lake effect clouds southeast of the lakes and periods of stratocumulus even away from lake influences. Moisture continues to be shallow in nature through Friday, which will limit lake effect rain potential despite 850mb temps of 0C to -2C. Expect a few scattered showers to continue Friday southeast of the lakes, with the best chances in the morning. Highs will be dramatically cooler than the past few days, with lower 50s at lower elevations and upper 40s for higher terrain. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Friday night and Saturday a clipper shortwave will move across the southern Great Lakes and northern Ohio Valley. Deeper moisture and weak forcing associated with this feature will bring a general increase in cloud cover and a chance of a few showers areawide. More importantly, it will introduce deeper moisture and a more favorable environment for lake effect rain showers as temperatures at 700mb drop significantly with the passage of a cold pool aloft. The combined influence of cooling mid level temperatures and increasing moisture will allow lake induced equilibrium levels to rise to over 15K feet. This will produce a more favorable environment for lake effect rain showers later Friday night and the first half of Saturday, with WNW flow favoring the western Southern Tier off Lake Erie and points southeast of Lake Ontario. Model point soundings suggest the boundary layer will remain too warm for any wet snow to mix in, even across higher terrain. The clipper moves off the New England coast late Saturday, with high pressure then building into the Ohio Valley and Mid Atlantic Saturday night. Associated drying and subsidence will force lake effect rain showers to slowly taper off and end southeast of the lakes. The longwave trough will reload across the Great Lakes early next week, with the leading shortwave and associated cold front moving through our region later Sunday and Monday. This will bring a chance of rain showers back into the region. Model guidance continues to suggest the possibility of a southern stream wave running northeastward along this frontal boundary and carrying some remnant moisture from Sergio into the Ohio Valley and Northeast States. If this were to occur, it would bring a better chance of more widespread rain late Sunday or Monday, but models continue to show plenty of run to run variability on this potential. Behind this system colder air aloft moves back into the region Tuesday with a chance of northwest flow lake effect rain showers. Temperatures will remain below normal most days through the weekend and early next week. The coolest days look to be Saturday and again Tuesday, when highs will struggle to reach 50 at lower elevations and stay in the mid 40s across higher terrain. Looking a little farther ahead, below normal temperatures are likely to continue through all of next week with a longwave trough well established across eastern North America. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... Dry mainly cloud and rain free weather will continue this morning with the exception of some low MVFR/isolated MVFR/IFR stratus extending north toward KOLE/KELZ from north-central PA. This should remain east of KJHW. VFR conditions will continue through today with some increase in low level moisture eventually allowing for BKN VFR cigs. SSW gusts to 18-20kts will be likely at most sites with daytime mixing. Tonight, a cold front will approach our region reaching just west of WNY near 12z Thursday. Look for showers to increase in coverage after midnight with cigs lowering to low VFR/MVFR at KBUF/KIAG/KROC. Scattered thunderstorms will be possible along the front. Outlook... Thursday...Areas of MVFR with showers and a chance of thunderstorms. Friday...Areas of MVFR/IFR southeast of the lakes in lake effect rain showers, VFR elsewhere. Saturday...A chance of lake effect rain showers and MVFR early southeast of the lakes, otherwise VFR. Sunday...A chance of MVFR conditions in rain showers. && .MARINE... High pressure will slowly shift off the East Coast with gusty SW winds but likely no marine headlines through today. 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. This will produce higher end Small Craft Advisory conditions on Lakes Erie and Ontario Thursday and Friday. && .CLIMATE... A very warm airmass will remain across our region right through today. Below are the record temperatures this period. New record highs were set for Buffalo and Watertown yesterday, with Rochester falling a couple degrees short. Rochester did however set a new record warm minimum temperature for yesterday. With warm temps this morning, new record warm minimum temperatures are possible for today. Buffalo... Date Record High/Year Record Warm Minimum/Year 10/10 85/1949 65/1879 Rochester... Date Record High/Year Record Warm Minimum/Year 10/10 89/1949 64/1914 Watertown... Date Record High/Year Record Warm Minimum/Year 10/10 82/1949 62/1949 && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Smith NEAR TERM...HSK/Smith SHORT TERM...Hitchcock LONG TERM...Hitchcock AVIATION...Smith MARINE...Smith CLIMATE...Thomas/Smith