Severe threat increasing – a few tornadoes possible
UPDATE 7:35 pm EDT
So far there have been no confirmed tornadoes, although several tornado warnings were issued in the Mohawk Valley region. Many reports of damaging winds (either measured or reported damage) have been received by the SPC however. They have also issued Severe Thunderstorm Watch #296 for northeastern and central Pennsylvania and parts of southeastern New York (but not the New York City metropolitan area).
UPDATE 3:15 pm EDT
As expected, the SPC issued Tornado Watch #292 for most of the rest of upstate New York, excluding the areas north of the Adirondacks. Although a widespread tornado outbreak is not currently anticipated, a few tornadoes are certainly possible, particularly in the I-90 corridor from Rochester to Albany.
UPDATE 3:00 pm EDT
The SPC has issued Severe Thunderstorm Watch #291 for the areas near Lake Erie and Lake Ontario in upstate New York and northwestern Pennsylvania. No watch has been issued for central New York or the Finger Lakes region yet, that is where wind shear is somewhat stronger. Expect a Tornado Watch to be issued for those areas in the next hour or so.
The severe weather threat mentioned last night is materializing quite nicely, and may actually be a bit more than expected. The warm frontal boundary is working its way northward, and appears to be aligning itself well with the I-90 corridor from Buffalo to Albany. Along and south of that corridor in upstate New York and extreme northern Pennsylvania (as well as adjacent areas in Canada), severe weather looks to be primed for this afternoon and early this evening. A few tornadoes are possible as low level wind profiles are quite favorable for supercell development and rotation.
The Storm Prediction Center has issued a mesoscale discussion mentioning that a severe weather watch, most likely a tornado watch, is likely for much of upstate New York (excluding the northern part, where cloud cover is keeping the air mass more stable and cooler). Farther south of the frontal boundary across Pennsylvania and southward, thunderstorm activity may be strong to severe but much more isolated (a watch is not expected at this time), with temperatures in the low to mid 90s common in low elevation areas (and heat indices near 100).
If a warning is issued and a tornado threatens your area, it is advisable to take immediate safety precautions. Otherwise, it is best to keep an eye to the sky and listen for updated information should tornadoes form. It is amazing how many people can’t differentiate between a watch and a warning!
For more updates, my Twitter feed is @EternalWeather1.
Forecaster Craig Ceecee