Area Forecast Discussion National Weather Service Buffalo NY Sun Aug 2 2020
.SYNOPSIS... A cold front will move east across the region this evening with a chance of showers and isolated thunderstorms. Unsettled weather will remain over the region for the next few days as weak disturbances pass through, while a tropical system rides up the coast.
.NEAR TERM /THROUGH MONDAY NIGHT/... Low pressure moving northeast into Southern Quebec will support some unsettled weather across the area through the first half of tonight. Most showers however will be short-lived. A cold front south of the low will move east across the region overnight with a lowering threat for showers with time.
Another weak frontal boundary will approach the region on Monday, leaving the region in a somewhat unstable environment with daytime heating and locally generated lake breeze boundaries providing focus points for afternoon and evening convection. By Monday night, there may be some convection/and or rainfall heading toward Central NY. This would be distantly associated with tropical moisture streaming north (well) ahead of Isaias.
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... A shortwave trough will traverse through the base of the upper level longwave trough Monday night into Tuesday. The shortwave will enter an area of vorticity which should promote the development of a surface low over the northern Ohio Valley before tracking northeast across the eastern Great Lakes. Meanwhile, Tropical Storm Isaias will continue its path northeast along the Eastern Seaboard entering the northern Mid-Atlantic/southern New England region Tuesday afternoon. As such, the interaction between these two surface lows will continue the likelihood for showers and storms throughout the day on Tuesday.
By Tuesday night, the two surface lows will have began to merge, which will help transition Tropical Storm Isaias to extratropical. The newly formed broad area of surface high pressure will drift northeast into New England throughout the day on Wednesday. As the low exits the region, a large area of surface high pressure will build in. While the high pressure will be knocking on our western door step, the forecast area will remain under enough of an influence from the exiting surface low to diminish the chances for showers from southwest to northeast throughout the day on Wednesday.
The aforementioned bubble of surface high pressure will push in and eventually dominate overhead of the region on Thursday, which will make for a primarily dry day and night.
Temperatures throughout the period will range in the 70s with a few places reaching 80. Cold air advection will continue behind the surface cold front on Wednesday, making it the coldest day of the period with highs ranging in the low to mid 70s. Otherwise both the opening and closing of this period (Tuesday and Thursday) will have highs that climb up into the mid to upper 70s with a few places reaching 80.
.LONG TERM /FRIDAY THROUGH SUNDAY/... During this period heights aloft will slowly increase, with temperatures at 850 hPa gradually warming. This will bring low chances for showers and thunderstorms, with day to day warming. The greatest chance for afternoon convection will be Friday - Saturday when a diminishing shortwave slowly drifts across the Eastern Great Lakes. Temperatures will average a few degrees above normal.