Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
977 FXUS61 KBUF 031058 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 658 AM EDT Thu Jul 3 2025 .SYNOPSIS... A cold front moving through from the north will bring scattered showers and thunderstorms to the region at times through this afternoon. An area of high pressure will then bring dry and comfortable weather tonight through Independence Day. Heat and humidity will then build over the weekend, with more unsettled weather early next week. && .NEAR TERM /THROUGH TONIGHT/... Water vapor satellite imagery this morning indicates an upper level closed low churning over western Quebec. This trough will gradually sink further southward into the province through tonight, with its cold front coming through in pieces to bring periods of scattered showers and thunderstorms to the region. Confidence remains low in overall convective evolution including coverage and timing of storms, though the primary concern for stronger storms still looks to be from about mid morning through early afternoon as SBCAPE values build to 1000-1500J/kg and a cyclonically curved upper level jet streak on the backside of the trough moves in from the west, bringing effective shear values to 35-40kts. This could allow a few storms to develop stronger outflow winds or large hail, particularly in the corridor from the interior Southern Tier to the southern Tug Hill region across the Finger Lakes. SPC has maintained a Marginal Risk (level 1 of 5) in this region for the day, expanding it a just bit further westward overnight. The main trough axis and localized lake breeze convergence could also allow for a few thunderstorms across the Niagara Frontier during this timeframe, though deep shear values here look to be much lower with a corresponding lower severe risk. The the loss of daytime heating and passage of the primary cold front, any scattered thunderstorms will come to an end by this evening with quieter and cooler weather then expected to last through tonight. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... Expansive surface-based ridging will settle directly across our area on Friday...and this coupled with rising heights aloft will result in simply spectacular weather for the Independence Day holiday. Attendant subsidence and drier air will result in plentiful sunshine...with temperatures/humidity levels also rather comfortable (850 mb temps of +9C to +13C supporting highs in the mid-upper 70s...and surface dewpoints only running in the lower-mid 50s). The axis of the surface ridge will then only slowly drift southeastward Friday night...allowing for continued fair/dry and comfortable weather. During the rest of this period the surface ridge will then drift further southeastward and off the mid-Atlantic coastline...while the axis of broad upper level ridging crests across our region aloft. The increasing southwesterly flow on the backside of the departing surface ridge will help to pump warmer and at least somewhat more humid air back into our region...with highs on Saturday reaching into the mid-upper 80s in many areas...along with surface dewpoints climbing back into the lower half of the 60s. Coupled with daytime heating and a developing lake breeze boundary...cannot completely rule out an isolated shower/storm popping up southeast of Lake Erie Saturday afternoon...though dry weather should otherwise continue to prevail. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... On Sunday deep-layer ridging will remain anchored across the mid- Atlantic states...while a low-amplitude trough digs across the Upper Great Lakes. At the surface...an elongated/wavy frontal boundary across southern Ontario/Quebec will only slowly edge southward as its western periphery becomes more "wavy" in response to the approach of the above trough...resulting in the front remaining to our north through the day. In turn...this should result in another largely dry day...though again cannot completely rule out some isolated afternoon convection across Niagara/Orleans counties and northern portions of the North Country...which will lie closest to the slowly approaching boundary. The bigger story will be the very warm to hot and humid conditions...which could result in portions of the Niagara Frontier/Finger Lakes flirting with or reaching low-end Heat Advisory Criteria. After that...gradually amplifying (but still rather broad) troughing over eastern Canada will encourage the frontal boundary to slowly push southeast as a cold front and cross our region sometime during the Sunday night-Monday night time frame...with this feature bringing renewed chances for convection as it makes its way through our region. Following its passage...somewhat cooler and drier air should then filter back across our region through the balance of this period...resulting in a return to generally drier weather along with temperatures near early July normals. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... An upper level low over Quebec will slowly drift southward through tonight. A cold front tied to this feature will move through in pieces and bring periods of convection to the region through this afternoon. VFR weather will prevail outside of any convection, though within localized MVFR/IFR vsbys will be possible at times. Confidence in evolution of showers and thunderstorms remains low through this afternoon. PROB30 groups continue to be used to cover the potential for thunderstorms at the TAF sites during the windows when chances are expected to be greatest for individual sites. With the arrival of drier air and loss of daytime heating this evening, any leftover thunderstorm activity will likely taper off by 00z with mainly VFR continuing to prevail through tonight. Southern Tier valley fog is expected to develop overnight which could bring IFR or lower vsbys to KJHW. Outlook... Friday through Sunday...VFR. Sunday night through Monday...Chance of showers and thunderstorms with MVFR restrictions possible. && .MARINE... Westerly winds today will maintain a light chop on the waters as a cold front moves through. Widely scattered thunderstorms will be possible on both lakes at times through the afternoon. High pressure will then build across the Lower Lakes region tonight and Friday. Winds will shift northerly overnight behind the front with wave action gradually diminishing in the second half of the night. Generally light winds and minimal waves then expected for the Independence Day holiday. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...JJR/PP NEAR TERM...PP SHORT TERM...JJR LONG TERM...JJR AVIATION...PP MARINE...JJR/PP