336 FXUS61 KBUF 160724 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 324 AM EDT Thu May 16 2024 .SYNOPSIS... High pressure centered over Hudson Bay will nose southward across our region through Thursday night. While this will support mainly fair dry weather over our region, a few showers will still be possible south and east of Rochester. A poorly organized frontal boundary will then promote some shower activity Friday into Saturday. Meanwhile, above normal temperatures and relatively humid conditions can be expected into the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A broad 500mb trough overhead will begin to close off as it slides east into southern New England overnight. While there may be an isolated light shower south east of Lake Ontario, the bulk of the region will be precipitation free. The most impactful weather will come with the expansion of fog that will has developed overnight causing areas of reduced visibility, especially south of Lake Ontario. Otherwise, the cloud cover will limit radiational cooling tonight with lows in the mid 50s. A diffuse area of surface high pressure and a mid level ridge will build into Western NY during Thursday. This will bring mainly dry weather to the region, although there may be a few showers across the Finger Lakes and east of Lake Ontario, especially midday into the afternoon where there will be some instability developing under the weak ridging aloft. Temperatures will remain above normal, with highs in the upper 60s to lower 70s. The ridge will strengthen Thursday night, providing fair and rain free weather overnight with lows mainly in the low and mid 50s. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... A shortwave trough will ripple over a diminishing mid level ridge this period, promoting more coverage area to showers and a few thunderstorms, especially in the Friday night to Saturday timeframe. Instability grows to around 500 to 750 J/KG of MUCAPE and this could bring a few thunderstorms, mainly later on Friday into Friday evening. Just a lingering shower or isolated thunderstorm for the remainder of Saturday behind the shortwave trough. If some clearing over Lake Ontario develops, and a lake breeze boundary forms, could see a few showers forming south of the Lake, in convergence with a general light southeast synoptic flow. Similar airmass this period, with 850 hPa temperatures between 10 and 12C through the afternoon will allow for low to mid 70s across lower terrain, and around 70F for inland higher terrain. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... To begin this period a mid/upper level low will be off the Carolina coastline, with weak ridging aloft over our region. Much of the shower activity will remain to our south, leaving most of Sunday through Tuesday dry with a fair amount of sunshine. A deeper shortwave trough will cross the Plains and near our region Wednesday. Increasing moisture in the southern flow, and warmth aloft will increase instability, that along with lift ahead of the incoming trough will greatly increase the chances for showers and thunderstorms. Later Tuesday night and into Wednesday will be the most favorable timeframe for showers and thunderstorms this period. Temperatures several degrees above normal Sunday and Monday, will become even more above normal ahead of the trough Tuesday and Wednesday. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... VFR weather holding on east of Lake Ontario where moist cool northeasterly flow off Lake Ontario is not a factor, however MVFR conditions are expected to develop at KART late tonight as well. A different scenario across areas south of Lake Ontario where low stratus and fog have developed across just about all areas from the Finger Lakes westward with widespread IFR/LIFR/VLIFR conditions across the TAF sites south of Lake Ontario that will persist through within an hour or two after sunrise, before slow improvement begins. Conditions will only slowly improve through Thursday morning, especially south of Lake Ontario. High pressure and drier air will finally work in through the second half of the day with conditions improving to VFR from west to east through the afternoon and lasting into the evening and overnight. Outlook... Friday...VFR/MVFR. Showers likely late. Saturday...Areas of MVFR with showers likely. Sunday...Mainly VFR with a chance of showers. Monday...VFR. && .MARINE... Generally light winds will continue through the remainder of the week. Northeast winds in the 10-12 knot range will produce mainly light chop on Lakes Erie and Ontario through the remainder of the overnight. Otherwise, light winds will return Thursday as weak high pressure builds over the eastern Great Lakes. An offshore flow will then develop Thursday night and Friday with gentle to moderate southeasterly breezes in advance of the next system approaching from the west. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...RSH NEAR TERM...Apffel/JM/RSH SHORT TERM...Thomas LONG TERM...Thomas AVIATION...JM MARINE...Apffel/JM