The combination of plenty of mid summer-like humidity, the remnants of Hurricane Isaac and a favorable jet stream aloft will cause much needed rain across central New York the first part of tonight. The center of circulation of what’s left of Isaac will track over the south shore of Lake Ontario tonight and that will concentrate the very heaviest rains (2 inches or more) north of Syracuse. However, it is still likely in Syracuse rain totals will approach an inch by morning. With the threat for heavy downpours we’ll keep a close eye on some minor flooding over low lying areas.
By later tonight the low will head up toward northern New England so by daybreak the steadiest and heaviest rains will shift off to our east. There will likely be plenty of clouds and perhaps a shower Wednesday morning but with winds turning into the north our weather will improve. Those northerly winds will advect, or bring in, drier air from Canada and we should see an increase in sunshine.
Another system, a cold front, is forecast to arrive late Thursday. Ahead of the cold front, a surge of warm air will move into Central New York. As the cold front arrives, with the warm air in place, scattered showers and thunderstorms are possible.
Things still look a bit unsettled for the weekend. Thursday’s cold front will stall not too far to our south. Meanwhile, a storm system in the upper atmosphere will form somewhere over either the Ohio or Tennessee Valley. The counterclockwise flow around this low will bring moisture back north where it will interact with the stalled front. Our confidence is rising as to how this scenario starts out at the beginning of the weekend (showers and thunderstorms looking more likely) but the biggest question remains how quickly this system heads to our east.