National Weather Service Buffalo NY
655am EDT Monday August 26 2024
Synopsis
Expansive high pressure across the eastern Great Lakes to the Mid- Atlantic will support dry and very warm weather for most areas today and Tuesday. A few showers may cross across the North Country and Chautauqua county today, though believe the best chances for these showers will lie just outside of the forecast area. A cold front gradually slide south across the Great Lakes, supporting a chance of showers and thunderstorms late Tuesday night through Wednesday. Another cold front will usher into the region at the end of the week which will bring more unsettled weather of showers and thunderstorms.
Near Term - Through Tonight
Nighttime microphysics satellite imagery currently depicts mainly clear skies across western and north central New York. However, just outside of the area to the southwest a few showers and thunderstorms are diving southeast into northwest PA. Additionally, river valley fog has developed across the Southern Tier. As the morning progresses towards daybreak, shower activity will remain outside of the area with clear skies persisting across the forecast area. Additionally, valley fog will lift in the a few hours.
Dry weather will persist today as the surface high remains expanded from the eastern Great Lakes to the Mid-Atlantic. With the light winds across the area due to surface high, a few scattered diurnal cumulus will form along and inland of the lake breeze boundaries.
All of this being said, there is a slight chance for a few scattered showers across the North Country and Saint Lawrence Valley as a longwave trough spread across the northeast sharpens as another circulation drops south out of Quebec and into New England, dropping embedded shortwaves across the area. Most of this activity will lie northeast of the area though a few spotty showers/isolated thunderstorm can't be ruled out.
Additionally to the southwest, a few rounds of showers and thunderstorms will develop today along a warm frontal segment lying across lower Michigan into northeast Ohio/northwest PA. Similar to the activity across the Saint Lawrence, this activity will lie just outside of the area, however a few stray showers/isolated thunderstorms can't be ruled out across Chautauqua County.
Tonight, clear to partly cloudy skies will prevail areawide. Again, river valley fog will be possible across the Southern Tier.
Short Term - Tuesday Through Wednesday Night
Heat will build across the region Tuesday underneath a strengthening mid-level ridge extending across the central and eastern CONUS. Most high temperatures will reach the mid to upper 80s, with some lower 90s across the lower elevations of western New York. Humidity levels creep up a bit with dewpoints getting into the mid 60s to around 70 degrees. This will push the warmest heat index values into the mid 90s. Most of the region will be dry, with the outside chance of a shower or thunderstorm along any lake breeze boundaries.
The mid-level ridge will weaken Tuesday night and Wednesday with the approach of a cold front from the northwest. A lower confidence forecast with the potential for showers and thunderstorms increasing, however timing and overall coverage in question. Some model suggestion of a convective complex working through the lower Great Lakes Tuesday night with the potential for strong to severe storms, but how all this plays out is uncertain.
Wednesday, it will all depend on the positioning of the front, as it moves slowly south through the region. It will not be as hot with temperatures peaking in the upper 70s to mid 80s. The warmest readings will be found closer to the NY/PA line and Genesee Valley.
An expansive ridge Ontario and Quebec will bring a return to drier weather later Wednesday night.
Long Term - Thursday Through Sunday
On Thursday the center of large Canadian high pressure will slide across northern Quebec...with the southern periphery of this ridge draped across New York State. Meanwhile...Wednesday's frontal boundary will be stalled out across the Ohio Valley...and now appears as if it may remain in close enough proximity to keep a low potential for a few additional showers/storms across our area. Have inserted some slight chance Probability of Precipitation into the forecast to account for this possibility...with a cooler day otherwise expected with our region firmly embedded within the northeasterly flow in between the surface high and stalled out front. Highs should run mostly in the mid to upper 70s.
Forecast uncertainty then increases for the end of the week and next weekend as the medium range guidance continues to exhibit notable differences in the handling of the next mid-level trough and its attendant cold front...though these have diminished some over the last 24 hours. Amongst the big three operational packages...the GFS (Global Forecast System) is still weaker and slower with these features compared to the ECMWF (European Centre for Medium-Range Weather Forecasts) and GEM...though at the same time has also trended toward the latter solutions...which remain in fairly good agreement on bringing these and the next chance for showers/storms into our region on Friday... then sliding everything off to our east during Saturday. For now will continue to lean toward continuity/blended guidance and the latter scenario...while keeping Probability of Precipitation confined to the chance range due to the lingering uncertainty. With respect to temps...this would result in a somewhat warmer day on Friday with highs in the upper 70s to mid 80s...followed by slightly cooler temps in the mid 70s to lower 80s on Saturday.
Looking further ahead to Sunday...yet another mid-level trough may approach by the latter half of the weekend...though the guidance is at odds with respect to its amplitude and associated convective potential. Given the level of disagreement will just indicate some slight chance Probability of Precipitation for now...with high temps running very similar to those of Saturday.
Marine
Surface high pressure and a weak pressure gradient overhead will continue to support light winds and minimal wave action through Tuesday. The weak pressure gradient and strong differential heating will allow lake breeze circulations to develop, with local onshore winds developing each afternoon.
A cold front will move south across the Great Lakes late Tuesday night through Wednesday. This front will bring a chance of showers and thunderstorms, with locally higher winds and waves possible.
NOAA Buffalo NY Office: Watches - Warnings - Advisories
NY...None.
Marine
None.
