891 FXUS61 KBUF 291828 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 228 PM EDT Mon Jun 29 2026 .WHAT HAS CHANGED... A Heat Advisory has been issued for the entire forecast area for tomorrow. Additionally, an Extreme Heat Watch has been issued for I- 90 corridor and Finger Lakes for Wednesday, Thursday, and Friday. && .KEY MESSAGES... 1) Dangerous heat and humidity is expected beginning tomorrow, and lasting through at least Friday. 2) Scattered strong to severe thunderstorms are possible tomorrow as a warm front lifts through the region. && .DISCUSSION... KEY MESSAGE 1...Dangerous heat and humidity is expected beginning tomorrow, and lasting through at least Friday. A Heat Advisory has been issued for the entire forecast area for tomorrow. Additionally, an Extreme Heat Watch has been issued for I-90 corridor and Finger Lakes for Wednesday, Thursday, and Friday. Guidance remains in lockstep on upper level ridging building across the eastern CONUS through Thursday...with the core of the ridge strengthening to near 600 dm while drifting east from the Tennessee Valley to the mid-Atlantic coastline. After that time...a series of shortwave impulses digging southeastward across eastern Canada will help to slowly buckle and flatten the ridge Friday through the holiday weekend...with its core correspondingly settling southwestward into the southern Plains/southeastern States. Under this regime...850 mb temps will climb to around +20C by later Tuesday afternoon...then will remain around or even a little above +20C through at least Thursday and possibly even Friday...before pulling back into the mid to upper teens next weekend. After a warm front lifts through the area tomorrow morning heat and humidity will then build in with highs reaching the upper 80s to low 90s. Increasing humidity will result in heat indices climbing to 95- 100 degrees for much of the area outside of the highest elevations and immediate lakeshore. Some locations around the Finger Lakes could top 100 degree heat index briefly tomorrow afternoon. Low level heights continue to build mid week as the upper level ridge strengthens. This will bring even hotter conditions to upstate NY. Widespread highs in the 90s are expected Wednesday through Friday, and readings will reach the mid to possibly upper 90s Wednesday and Thursday across the I-90 corridor and the Finger Lakes. It's here that an Extreme Heat Watch has been issued, where heat indices will likely top 105 degrees both afternoons. Heat indices will be slightly lower Friday, but the cumulative effect of 3+ days of high heat and humidity will extend the dangerous conditions through Friday afternoon. **Several other factors may make this potential heat wave more impactful such as the early summer season timing, very warm overnight temperatures (mid/upper 70s), Holiday week with many folks outside or vacationing, and the cumulative effect over several days.** KEY MESSAGE 2...Scattered strong to severe thunderstorms are possible tomorrow as a warm front lifts through the region. A warm frontal boundary will slide eastward early tomorrow morning through Western NY. Scattered showers and a few thunderstorms will develop along this boundary. Most CAMs show potential for a MCS to develop somewhere in eastern Ontario or southwest Quebec, and dive southward into NY later tomorrow afternoon. Strong wind shear (40+ kts) and moderate instability (2000+ J/kg MLCAPE) with support supercell structures within any cluster of storms that form, or any discrete cells that develop. SPC has upgraded portions of the North Country to a Slight Risk (2/5) for severe thunderstorms, with all hazards possible (damaging wind gusts, large hail, and isolated tornadoes). The biggest question that remains is where this convection will initiate, and where it will track into upstate NY, or if it tracks farther east into Vermont. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... Mid to high level clouds from a complex of thunderstorms upstream will increase in coverage across the region through tonight. A few showers along the leading edge of the area of thunderstorms may briefly move into western NY today, however confidence is low. VFR conditions are expected across the region through this evening. A warm front will move across the region Tuesday morning. Isolated to scattered thunderstorms are possible, however confidence is low on the timing and location of the storms. A brief period of IFR or below is expected in any heavy showers or storms. Outlook... Tuesday Afternoon...Mainly VFR with scattered showers/thunderstorms and localized flight reductions possible...with the greatest potential for these across the eastern Finger Lakes and North Country. Wednesday and Thursday...Mainly VFR. Friday and Saturday...Mainly VFR. Chance of showers and thunderstorms. && .MARINE... A warm front will pass across the region on Tuesday, with modest to moderate southwesterlies then following for the remainder of the week. The warm frontal passage may also bring the potential for at least a few showers and thunderstorms later tonight and Tuesday...some of which could produce locally higher winds and waves. && .CLIMATE... Dangerous heat and humidity are expected across western and north central NY this week. Here are the record maximum and high minimum temperatures for Buffalo, Rochester, and Watertown. 6/30 7/1 7/2 7/3 Buffalo, NY High Max 94(1963) 93(1963) 94(1966) 94(1949) High Low 73(1941) 75(1901) 75(1931) 74(1911*) Rochester, NY High Max 96(1964) 96(1901) 99(1931) 100(1911) High Low 72(2014) 76(1931) 76(1931*) 75(1911) Watertown, NY High Max 89(1977) 92(1967) 92(1966) 91(1966) High Low 73(2014*) 74(2014) 73(2002) 74(1973) Average Temperatures for June 30-July 3 Buffalo Max 79 Min 62 Rochester Max 82 Min 62 Watertown Max 78 Min 57 && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Heat Advisory from noon to 8 PM EDT Tuesday for NYZ001>008- 010>014-019>021-085. Extreme Heat Watch from Wednesday afternoon through Friday evening for NYZ001>006-010-011-013-014. MARINE...None. && $$ DISCUSSION...JJR/SGK AVIATION...HSK MARINE...HSK/JJR CLIMATE...