Subtle changes Thursday set stage for windy, stormy Friday

finger lakes weather forecast thursday september 20 2018 severe thunderstorms friday september 21 2018
The Finger Lakes will enjoy a nice Thursday, but behind the scenes, the weather will be getting ready for a busy Friday. [Photo by Helen Heizyk]

Nice Weather Thursday

The Finger Lakes is off to a cool, and in favored areas foggy start, but the atmosphere will start to warm up as a storm system takes shape over the middle of the nation.

This storm system is centered over the Kansas-Colorado border this morning, but a warm front extends eastward as far as southern Michigan. Meanwhile, high pressure is centered over northern New England.

The warm front should lift north-northeast today, staying west and eventually north of the Finger Lakes.

Some high, thin clouds and a few puffy cumulus clouds will develop today on the fringe of the front. A stray shower near Lake Ontario cannot be completely discounted either. The vast majority of the rain will stay over Canada and northern New York.

Winds will start the day light and variable, primarily under the influence of the high pressure. Later in the afternoon, a southeast wind will develop as air flows towards the front.

Temperatures will end up a bit warmer than yesterday and a fairly significant rise over this morning. Most areas should reach the mid 70s this afternoon. Dewpoints will remain low in the 50s.

The wind will begin to noticeably increase overnight as it turns towards the south in response to the front building into northern New York.

Temperatures will only drop slightly overnight with mid 60s for most locations. Dewpoints will come up into the low and mid 60s.

Windy, then Stormy Friday

The main story to start on Friday will be the wind. South winds will continue to increase and gusts could approach or exceed 40 mph during the day.

Cloud cover is a bit uncertain. Our region will be well south of the warm front and well east of the cold front, so there is a good chance for a decent amount of sun.

finger lakes weather daily weather map thursday september 20 2018 spc outlook day 2 friday september 21 2018
A warm front over the southern Great Lakes will pass west, then north of the Finger Lakes, setting the stage for a windy and storm Friday. The entire region in yellow shading has a chance for thunderstorms with damaging winds on Friday. Click to enlarge.

However, there could be some clouds and even a shower or thunderstorm during the morning as leftover storms from this evening in the Upper Great Lakes move east. Areas near Lake Ontario will again have the best chance at seeing one of these showers.

By the early afternoon, the confidence for sunshine increases. Temperatures will range from the mid and upper 70s across the Southern Tier and eastern Finger Lakes all the way to the mid or possibly upper 80s in the Rochester-Buffalo corridor.

Dewpoints will rise into the mid and upper 60s and the atmosphere will become laden with moisture.

Thunderstorms should start to fire over western New York by the late afternoon and will form into some sort of line. Whether this line is broken or more solid remains to be seen.

There may be minimal lightning with the thunderstorms, especially as they march east and persist into the evening hours. However, strong winds will be a threat even without lightning. With ample wind energy in all levels of the atmosphere, it will not take much to produce at least sporadic tree damage and power outages with the possibility of more widespread wind damage.

I also would not be the least bit surprised to see a tornado threat develop over the western Southern Tier (Chautauqua, Cattaraugus, Allegany counties), which seems to be a hot-spot for tornadic activity in these types of set ups.

The Storm Prediction Center has the entire region in its Level 2- Slight risk zone, but my feeling is that the further west, the greater the threat for organized severe weather. I will publish my own severe weather map tomorrow morning and will have updates throughout Friday afternoon and evening.

There could also be some isolated minor to slight flood problems due to the heavy rain. Thankfully though, the rain should be fast moving and brief enough to prevent any major issues.

Cool Weekend

Behind the thunderstorms, a cold front will quickly cross the region. Temperatures should be well into the 50s and possibly even upper 40s by Saturday morning.

Morning clouds will break for afternoon sun, but a breezy northwest wind will keep temperatures down Saturday.

Many areas will struggle to even reach 60 degrees Saturday afternoon.

Sunday morning will be perhaps the coolest morning yet this season, with upper 40s in the heart of the Finger Lakes and low to mid 40s elsewhere. Highs Sunday will be a touch warmer reaching the mid 60s. Skies should be quite sunny.

Monday morning will be similarly cold, but clouds will increase later in the day. High temperatures could return to the low 70s across the northern counties.

The next storm system will then roll in with rain along a warm front Tuesday and another windy, stormy cold front possible Wednesday.

Follow Meteorologist Drew Montreuil:
Meteorologist Drew Montreuil has been forecasting the weather in the Finger Lakes region since 2006 and has degrees in meteorology from SUNY Oswego (B.S. with Honors) and Cornell (M.S.). Drew and his wife have four young boys. When not working or playing with the boys, he is probably out for a run through the countryside.