Area Forecast Discussion
Issued by NWS Buffalo, NY

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032 FXUS61 KBUF 011837 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 237 PM EDT FRI JUL 1 2016 .SYNOPSIS... It will be a beautiful Fourth of July weekend across the region... as expansive high pressure over the Upper Mississippi Valley will gradually build across the Ohio Valley. This will promote sunny skies for all three days of the holiday weekend along with day to day warming. && .NEAR TERM /THROUGH SATURDAY/... A cold front crossing the Lower Great Lakes will keep unsettled weather in place across the bulk of Western and North Central New York through the remainder of the afternoon into the early evening hours. The front...which was crossing the eastern half of Lake Erie at 18z...will make its way across the remainder of the forecast area by 00z. A southwest lake breeze is strengthening ahead of the front... and while this will help to shield parts of the IAG Frontier through nightfall...the remainder of the region will have the risk for strong thunderstorms. The airmass...which was initially stabilized by the passing of this mornings showers...has had several hours of partial sunshine to allow SBCAPEs to recover to more than 500 j/kg. As the front encounters this increasingly unstable airmass...we can expect more storms to fire up...particularly over the Southern Tier...Genesee Valley and portions of the Finger Lakes. 0-6km shear in this area will be in the vcnty of 40kts...so strong to severe storms will be possible. Meanwhile...the line of showers and thunderstorms that moved across the far western counties during the morning and midday will cross the Eastern Lake Ontario region through 21z. This should limit the threat for severe weather with the actual cold frontal passage...as there should be little time for renewed destabilization. Tonight...the cold front will exit the region while expansive high pressure over the Upper Mississippi Valley will gradually make its way across the mid Western states. Notably drier air will be circulated into our region in the process...and this will lead to the return of fair weather along with more comfortable temperatures. The mercury will drop into the low to mid 50s for most areas... with 40s anticipated for the bulk of the Southern Tier. For Saturday...the large area of high pressure centered over the Mid Western states will expand across the Lower Great Lakes. While a subtle shortwave embedded within the cyclonic upper level flow could touch off a brief shower across the North Country...the remainder of Western New York will enjoy full sunshine with temperatures only climbing into the 70s. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... A slow moving 500mb low over Quebec and ridging over the Northern Plains states will yield a confluent flow over the Lower Great Lakes region through the remainder of the extended Independence Day Holiday weekend. This flow combined with weak surface high pressure will provide dry weather with mainly clear skies outside of some limited passing high clouds and limited diurnal cumulus. While temperatures will average near normal Sunday, slight warming aloft will lead to highs on Independence Day mainly in the low to mid 80s. Lows Saturday night will be on the cooler side with drier air in place but by Monday night a boost in dewpoints will lead to lows near or just above normal. && .LONG TERM /TUESDAY THROUGH THURSDAY/... The big story during the shortened work week next week will be on temperatures climbing well above normal. The upper ridging over the Central States on Tuesday is forecast to shift over the Eastern States by late week with 500mb heights building to 582DM or higher in response to a sharp shortwave diving across the Pacific Northwest. The GFS is more aggressive than the ECMWF building heights over 588DM. This difference is also present in 850mb Temps with the GFS showing +22C while the EC is below +20C. A warming trend in day to day temps is reflected in the official forecast based on the expanding ridging. High temps should run in the mid to upper 80s for most with at least low 90s across the warmer valleys possible Wed-Fri. Dewpoints climbing back into the 60s will bring a return of elevated humidity with muggy overnight temps only slipping back into the 60s mid to late week. In terms of rainfall, much of the week looks dry only furthering our current run of below normal precipitation. Models do show a potential for some showers and thunderstorms as instability and dewpoints build Thursday and Friday but timing of upper support from any shortwave troughs will be key in coverage. Have included slight/low chance POPs for now until the pattern becomes more clear late in the week. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... While VFR conditions can be expected to dominate the region this afternoon...there will be some showers and potentially strong thunderstorms to contend with. The greatest threat for strong convection will be over the Finger Lakes and eastern Lake Ontario regions...but given that a cold frontal passage is not expected until late afternoon...a thunderstorm will be possible for any TAF site. VFR conditions will then persist in the wake of the front tonight. The only exception could come in the Srn Tier valleys where a little fog could develop after 06z. Outlook... Saturday to Tuesday...VFR expected. && .MARINE... A cold front will cross the Lower Great Lakes late this afternoon and early evening. Gusty southwest winds will accompany this frontal passage over Lake Erie...then in the wake of the front...winds will freshen on Lake Ontario later tonight and Saturday. The stronger winds will support the current small craft advisories. As high pressure over the Mid West on Saturday builds across the Lower Great Lakes Saturday night and Sunday...winds and waves will lower. This will lead to more favorable recreational boating conditions as we work into the second half of the long holiday weekend. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Beach Hazards Statement until 11 PM EDT this evening for NYZ010-019-085. MARINE...Small Craft Advisory until 11 PM EDT this evening for LEZ040- 041. Small Craft Advisory from 11 PM this evening to 8 AM EDT Sunday for LOZ043>045. Small Craft Advisory from 11 PM this evening to 8 PM EDT Saturday for LOZ042. && $$ SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...SMITH LONG TERM...SMITH AVIATION...RSH MARINE...RSH

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