Severe Thunderstorm Outlook: Friday, May 15, 2020

finger lakes weather forecast severe thunderstorm outlook friday may 15 2020
A warm, humid airmass will prime the atmosphere for severe thunderstorms ahead of an afternoon cold front. Widespread thunderstorms are expected with numerous severe thunderstorms.

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A warm front will lift through the Finger Lakes this morning. A few showers may accompany the front, followed by at least partial sunshine through the late morning and early afternoon hours.

By the mid-afternoon, thunderstorms will start to develop over Western New York. These storms should quickly intensify in the warm, humid air and will organize into either small line segments or one large line of storms.

The storms will move quickly to the east, bringing damaging winds, large hail, frequent lightning, and perhaps a brief tornado or two in addition to localized flooding.


The following severe weather alerts are *predicted* to be issued later today:

– A Severe Thunderstorm WATCH (highly likely) and/or a Tornado WATCH (50-50 chance). A WATCH means that conditions are favorable for severe thunderstorms/tornadoes. Watches are issued over large areas for several hours at a time.

– Many Severe Thunderstorm WARNINGS (highly likely). Severe Thunderstorm Warnings are issued over small areas for around an hour at a time to warn of ongoing damaging winds or large hail.

– One or two Tornado WARNINGS (most likely east of the FLX). Tornado Warnings are issued over small areas for around an hour at a time to warn of a radar indicated tornado or a reported tornado on the ground.

– One or two Flash Flood WARNINGS (most likely in southeastern FLX). Flash Flood Warnings are issued over small areas for several hours to warn of excessive rainfall causing rapid and dangerous flooding.


Thunderstorms will start to develop around 3 PM to the west of the Finger Lakes. By 7 PM, thunderstorms should be exiting the eastern parts of the region, or weakening below significant severe status.


Temperatures will peak in the low and mid 70s Friday afternoon with dewpoints between 60-65 degrees. This will result in a moderately unstable airmass capable of supporting numerous severe thunderstorms and rapid development.

finger lakes weather forecast friday may 15 2020 severe thunderstorm map
Click to enlarge.


LEVEL 3 THREAT- Numerous reports of damaging winds are expected. Most of these reports will involve scattered trees and wires down, resulting in several power outages. A microburst or two is possible, resulting in widespread significant tree damage over a small area. Some isolated structural damage is also possible. Top Winds expected: 70-80 mph


LEVEL 3 THREAT- Numerous reports of large hail are expected. Most of these reports will be for hail sizes between ½” and 1.5 inches. Hail at these sizes can dent cars, damage or destroy plants, and cause minor structural damage. One or two reports of larger hail are possible.


LEVEL 1, LOCALLY 2 THREAT- Most likely, there will not be a tornado in the immediate Finger Lakes area. However, a tornado or two will be possible in the Mohawk Valley, due to stronger tornado indicators in that region, and a climatological preference for tornadoes in that area due to topographical effects.


LEVEL 1, LOCALLY 3 THREAT-Thunderstorms should move quickly, but still may put down over an inch of rain in a short time. The majority of the Finger Lakes region is able to withstand such rainfall rates. However, the Southern Tier, and in particular Cortland and Tioga counties may exceed their flash flood numbers. Any flooding today should be localized with minor to moderate impacts.


Frequent lightning is expected with the thunderstorms. All lightning is dangerous. Seek shelter once thunder is heard. Lightning can and often does strike out ahead or behind the primary storm, sometimes even when it is not yet raining.


High- There is strong agreement among all models that thunderstorms will become widespread across the region, including severe thunderstorms. There is also strong agreement on the evolution of these storms and a higher risk for severe weather over the eastern half of the region.

Thunderstorm events are never 100% certain though, and each event often has its own unique subtleties and surprises that will not become clear until the event unfolds. It remains impossible to pinpoint when, where, and with what intensity a thunderstorm will strike hours in advance.


– A few rumbles of thunder may be possible Monday, but with no severe weather expected.

– A warm, humid weather pattern is expected towards the end of May, which could lead to additional thunderstorm chances. It remains far too early to pinpoint any particular threat, though.


  • A LIVE BLOG IS NOW POSTED will be posted early this afternoon with constant updates and answers to your questions throughout the event.


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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. When not working or playing with the boys, he is probably out for a run through the countryside.