Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 182315 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 715 PM EDT Wed Oct 18 2017 .SYNOPSIS... High pressure over the Mid-Atlantic coastline will remain anchored there through the week, bringing dry weather, plenty of sunshine and above normal temperatures to our region. && .NEAR TERM /THROUGH THURSDAY/... IR satellite imagery showing completely clear skies across the area this evening. Clear, mild and dry conditions will continue through the overnight. There should be just enough of a gradient flow and dry boundary layer to greatly limit or prevent valley fog overnight across the western Southern Tier. Lows will range from the lower 50s on the lake plains to the mid 40s in the cooler Southern Tier valleys and Lewis County. Thursday, The strength of the mid level ridge will steer the next upper level wave well north of the Great Lakes through northern Ontario and James Bay. The weakening cold frontal trough extending southward from this system will sweep across western and north central New York during the afternoon. There will be little fanfare with this through as the airmass is so dry and surface ridge still remains in place. Looks like at best we`ll see a brief period of enhanced cloud cover with the trough, but that should be about it. Highs will again be above normal, with upper 60s in most locations and around 70 from the Genesee Valley into Central NY. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... A large upper level ridge and corresponding area of surface high pressure will slowly move over (and then east) of the Great Lakes region and Northeast US Thursday Night through Saturday Night. The result for Western and Central NY will be continued dry weather with above normal temperatures. With the high directly overhead Saturday Night, some valley fog will be possible in deep river valleys despite the overall dry airmass. But, with the growing season essentially over, there will be less available moisture from transpiration. So, the typical valley fog season is nearing its end. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... A progressive amplified mid-level pattern across the CONUS will bring changeable weather from this weekend into next week. Sunday a seasonably strong 500mb ridge over the East Coast with surface high pressure over the western Atlantic will bring another gorgeous day with plenty of sunshine across western and north central New York. Southerly flow will help temperatures run 15 to 20 degrees above normal with highs forecast to climb into the low to mid 70s. A change to cooler and more unsettled weather then arrives with the start of next week. A fast moving shortwave trough and surface cold front are forecast to shift into the western/central Great Lakes Sunday night. Differences in timing of when the front reaches western NY show up by Monday with the 12z GFS shifting the front over our region during the day Monday while the EC is about 12 hours slower holding it off until Monday night. Have taken down POPs a bit to low chance range on Monday favoring the EC timing then bringing likely POPs into WNY for Monday night. Temperatures will remain on the mild side Sunday night and Monday with strong cold advection not arriving until later in the week. Tuesday and Wednesday should feature unsettled conditons as the frontal zone stalls across our region and one or more waves of low pressure shift north along the front. Have included likely POPs for Tuesday as both GFS/EC models are in agreement with a surface low lifting north across New York. The GFS shows a potentially moisture rich airmass will move into place along the front with a connection to the Gulf of Mexico could push PWATs above an inch or more. WPC Day 6-7 QPF shows a swath of 1.25-2.5 inches of rain over western and central New York. Chance POPs are featured for Wednesday as the mid-level trough and cold advection support potential showery weather. Temperatures will run near normal (mid-upper 50s) Tuesday then below normal for Wednesday as 850mb temps dip to or below zero 0 which would support temps likely struggling to break above 50 in many locations. No snow is expected through Day 7/Wednesday but temps may cool enough Wednesday night for potential some wet snow to mix in in the higher terrain. Stay Tuned. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... VFR will prevail through Thursday as high pressure remains anchored over the Mid Atlantic States, with a ridge extending northward into the eastern Great Lakes. There will be enough gradient wind overnight to prevent river valley fog across the western Southern Tier. On Thursday a weakening cold front will move across the region during the afternoon and evening. This front will remain dry, with a few hours of clouds with bases around 5K feet. It will become quite breezy again Thursday, with gusts of around 20 knots for much of the area, and around 30 knots northeast of Lakes Erie and Ontario. Outlook... Friday through Sunday...VFR except for local IFR in river valley fog each late night and early morning. Monday...VFR/MVFR with a chance of showers. && .MARINE... Winds will increase again Thursday as the pressure gradient over the eastern Great Lakes increases. This will bring a round of Small Craft Advisory conditions to the eastern ends of the Lakes Erie and Ontario on a southwest wind for Thursday and Thursday night. Small Craft Advisory winds will also develop for the Buffalo Harbor and Saint Lawrence River. Small craft conditions may spread to most of Lake Ontario on a westerly wind as we move into Friday. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...Small Craft Advisory from 8 AM Thursday to 2 AM EDT Friday for LEZ040-041. Small Craft Advisory from 10 AM to 8 PM EDT Thursday for LEZ020. Small Craft Advisory from 8 AM Thursday to 11 AM EDT Friday for LOZ045. Small Craft Advisory from 6 PM Thursday to 11 AM EDT Friday for LOZ044. Small Craft Advisory from 11 AM to 8 PM EDT Thursday for SLZ022-024. && $$ SYNOPSIS...THOMAS/TMA NEAR TERM...HITCHCOCK/TMA SHORT TERM...ZAFF LONG TERM...SMITH AVIATION...HITCHCOCK MARINE...HITCHCOCK/TMA

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