Late Season Severe Thunderstorm Event
A squall line with damaging winds and possibly a tornado or two will develop Friday evening and race across the Finger Lakes for what may be the biggest severe weather event of 2018 for the Finger Lakes.
Late season severe weather events are not uncommon in our region, but typically follow a set pattern. Today’s event is a classic, textbook scenario.
A strong low pressure system is pushing east across southern Canada, helped along by an impressive jet stream. Warm, moist air is surging north ahead of the low on gusty south winds. A sharp cold front is clashing with this warm, moist environment to trigger thunderstorms.
The strength of the winds in all levels of the atmosphere is a typical characteristic of these events, which primarily produce damaging winds but can also lead to a couple of tornadoes.
Given similar set ups, which typically have minimal instability to work with, today’s instability is impressive.
Overall, my confidence is quite high in this event and I do not anticipate any significant changes to the forecast strength, hazards, or timing of this event. So let’s get to the details:
Severe Thunderstorm Details
Timing
Most of Friday will be quiet, albeit windy in the Finger Lakes. Thunderstorms will start to develop across far western New York around 6 pm. By 10 pm, the thunderstorms should start to weaken as they push into Central New York.
The prime tornado threat will be between 6-8 pm as the storms first develop. A smaller tornado threat will persist until the storms weaken around 10 pm.
Check your zip-code forecast for approximate timing of the storms in your location.
Hazards
Damaging winds are the primary threat today and drive the Level 3- Elevated Risk. I expect many reports of trees and power lines down and one or two reports of direct structural damage. I think peak wind gusts will be in the 60-80 mph range. A Level 4- High Risk would require a better chance for destructive winds over 80 mph.
The tornado risk is set at Level 2- Low, primarily for the western half of the Finger Lakes. This does not mean a tornado will necessarily touch down, but the potential exists and multiple tornado reports is not our of the question. The tornado threat further east is minimal, but still exists. The threat for tornadoes will be greatest in individual thunderstorm cells before the squall line organizes. Tornado climatology also favors southwestern New York and the I-90 Corridor between Buffalo and Rochester for tornadoes, but this does not mean other areas are not at risk.
Hail and flooding are minimal concerns today. A little small hail may be reported early on in the event, but most of the region should not see hail. Thunderstorms will have heavy rain, but should be moving fast enough that significant flooding issues should not occur.
Lightning will be a larger hazard for areas further west and early in the event. After dark, the amount of lightning should diminish. This could lead to situations where the storms arrive unannounced, catching people off guard.
Preparation & Safety
You can prepare for this event by making sure there are no loose objects that can be blown around.
Have a plan in place for what to do when storms threaten. Head indoors and stay away from windows.
If a tornado WARNING is issued, be prepared to seek shelter in the lowest level of your home in an interior room.
Remember the difference between a WATCH and a WARNING. A WATCH means that conditions are favorable for a given condition. A WARNING means those conditions are occurring. I would not be surprised if our area has a tornado WATCH issued later, and this will undoubtedly cause some confusion and unnecessary anxiety.
Typically, an evening severe weather event would mean less people would be outdoors and at risk. However, Friday evening in the early fall means High School Football. If you are heading out to a game tonight, stay weather aware and realize that storms may come up very suddenly and with little thunder and lightning to announce their arrival. Having a plan in place before the storms is key. Know where you will go to seek suitable shelter and do so before the storm arrives.
My coverage of this severe weather event will be constant once the storms develop this evening. I will be doing live video streaming (barring any significant technological problems). I anticipate live-streaming for the better part of 4 hours between 6-10 pm.
I will post a new blog post this afternoon by 5 pm, possibly sooner, where I can start posting updates. My live video feed will then be embedded within that post.
Please, share this no-hype, no-nonsense forecast with your family and friends in the Finger Lakes region. Help them to understand the true nature of the threats (yes, tornadoes are possible…no they are not an absolute) and the timing of the storms. Urge preparedness by putting plans in place beforehand, especially if you are outside tonight.+
