Severe thunderstorms likely in the Finger Lakes Monday afternoon

finger lakes weather forecast monday june 21 2021 severe thunderstorms tornado watch
Intense thunderstorms are likely this afternoon with constant lightning, numerous cases of damaging winds and large hail, and possibly a tornado or two. [Photo by Coleen Foley]

Severe Event Details

A severe thunderstorm event is likely in the Finger Lakes today, possibly reaching an intensity that we only see every couple of years.

It takes a lot of pieces to line up right for a severe thunderstorm event to unfold. Today, many of those factors look favorable for severe thunderstorms.

Without going too much into technical jargon, severe thunderstorms need moisture, instability, a trigger, and differing winds through the low and mid levels of the atmosphere. All these factors will be present at moderate to high levels today.

Early this morning, there are two batches of thunderstorms I am watching. The first is moving quickly through the northern Finger Lakes. The second is across Lake Erie and northern Ohio.

Both areas are weakening and should dissipate by mid-morning. The storms to the west should pivot northeastward and its associated cloud cover will move into western New York for the mid-morning hours.

For the Finger Lakes, sunshine will mix with some clouds through the morning and into the midday hours. The more sun, the more heating we get. This will contribute to instability, which allows storms to rapidly grow.

By the early afternoon, temperatures will be in the upper 80s and low 90s. Non-thunderstorm winds will be gusty from the south and southwest. A cold front will be approaching from the west at the surface, while wind speeds aloft increase.

Thunderstorms may start to pop as early as noon, but most of the activity will take place after 2 PM. Some of these thunderstorms will become intense, with constant lightning, torrential downpours, and severe weather.

All modes of severe weather are possible today. Several to numerous reports of damaging winds and large hail are likely. There is a higher than normal chance for a tornado as well, especially before 3 PM.

I suspect that a tornado watch will be issued for the region by the early afternoon. A tornado watch is issued over a large area for several hours and means that thunderstorms capable of producing tornadoes are possible. If a tornado watch is not issued, a severe thunderstorm watch will be instead.

Many severe thunderstorm warnings will likely be issued, and a couple of tornado warnings may be needed as well. Warnings are issued for small areas for 45-90 minutes and mean severe weather is occurring. Warnings need to be taken seriously and actions taken to remain safe.

Initially, the thunderstorms will be individual cells or small clusters of cells. As we get into the mid and late afternoon, the storms will congeal into broken lines of storms. Most of the storms should move east by 5 or 6 PM.

I will have frequent live updates as the storms unfold and possibly even some live video during the event. Be sure to check back frequently for updates. All updates will be posted on FLXweather.com and the Finger Lakes Weather mobile app.

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finger lakes weather 7-day forecast monday june 21 2021
This graphic represents an average over the entire Finger Lakes region. Localized variations should be expected. Click to enlarge.

Rest of the Week

The cold front will move through this evening and temperatures will nosedive. By Tuesday morning, temperatures will be in the mid 50s. Skies will be cloudy, and a few showers will be possible over the far southeastern Finger Lakes.

Eventually, the sun will increase Tuesday afternoon. Breezy northwest winds will hold temperatures to the upper 50s and low 60s.

Skies will clear Tuesday night and temperatures will range through the 40s by Wednesday morning.

Wednesday will start with sun, but the sky will fill with puffy cumulus clouds by the late morning and into the afternoon. No rain is expected, though. Winds will weaken and highs will get back to the upper 60s and low 70s.

Thursday and mostly of Friday look sunnier, with highs Thursday in the upper 70s and low 80s, while Friday reaches the low and mid 80s.

The next chance for rain will not come until next weekend.

More Information:

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finger lakes weather 7-day forecast monday june 21 2021
This graphic represents an average over the entire Finger Lakes region. Localized variations should be expected.

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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 and also run a goat milk soap business, Ye Olde Goat Cart. When not working or playing with the boys, he is probably out for a run through the countryside.

  1. […] Drew Montreuil from Finger Lakes Weather sees the storm severity “possibly reaching an intensity that we only see every couple of […]