Sunshine bakes Finger Lakes with heat and humidity

Late Summer Heat

A late season surge of heat and humidity will fry the Finger Lakes Tuesday and Wednesday with a hazardous combination of heat and humidity.

The sun has just come up and temperatures are starting the day anywhere from the upper 60s in the Southern Tier to as high as 77 degrees in Syracuse.

Expect temperatures to rise in a hurry this morning under mostly sunny skies and a gusty southwest wind.

Dewpoints will stay locked in the low 70s, making it feel extremely muggy and creating a potentially dangerous heat index this afternoon.

As temperatures push into the low 90s, the heat index will range from 95 to 100 degrees for most areas. Heat indices above 100 degrees will be in the northern Finger Lakes, especially in urbanized areas.

I expect only a few scattered clouds this afternoon. Wednesday will have a bit more in the way of cloud cover, but temperatures and heat indices will be very similar to today.

Thunderstorm Chances

This surge of heat is being spurred on by the interplay between low pressure just north of the Great Lakes and a high pressure system that is nosing into the Mid-Atlantic region from the south.

The high pressure system should keep the Finger Lakes dry both Tuesday and most of Wednesday, but it is not an absolute guarantee.

At least one weather model that I trust for thunderstorms shows a broken line of showers developing this afternoon roughly in a Corning-Ithaca-Cortland line. These southeastern areas should not expect to see rain today, but should also not be surprised if a brief shower or a clap of thunder passes by late in the afternoon.

The chances for showers and storms will be greater Wednesday during the late afternoon and evening as a cold front slowly approaches. These seem most likely over western and northern areas. A strong wind gust and frequent lightning will be possible.

Storms should weaken Wednesday evening with a few showers overnight as the front slides through.

Behind the Cold Front

The difference in the weather between Tuesday/Wednesday and Thursday could not be much greater.

Winds will change direction Wednesday night and will be from the north by sunrise Thursday morning. The north wind will quickly blow the heat and humidity to the south, leaving a rather cool day on Thursday.

In fact, high temperatures Thursday will be about 20 degrees colder than on Wednesday with most places struggling to get much beyond 70 degrees. Highs in the mid and upper 60s are not out of the question, especially near Lake Ontario where clouds and perhaps a couple lake effect rain showers will be most likely.

The north wind will turn to the east and southeast on Friday, cutting off the coldest air. Temperatures will moderate to a more seasonable level with highs Friday in the mid and upper 70s.

This weekend’s weather looks a bit unsettled with a few scattered showers or thunderstorms, but no major weather system to bring in more significant weather.