Updates Below (most recent 10:30am)
It figures on being a wild Wednesday today... so lets get down to it.
The first sign of volatility is the general thought of going from near record highs 30-degrees above normal, down to 10-degrees below normal. This requires a large amount of energy in any season. Usually this means thunderstorms, or strong prolonged winds, or both.
|HPC - Wednesday Afternoon|
What a mess, right?
In the most basic terms, we've got a strong storm system (< 990mb is a good low pressure center for a storm). As we saw yesterday, the warm fetch of air has been good enough to get those 70s into our area. That's going to get things going pretty well as the cold air advances.
The most updated maps for severe weather tracking are below as the usually are, but I wanted to highlight the thinking from the Storm Prediction Center.
|SPC - Severe Weather Outlook||SPC - Severe Weather Reports - Tuesday|
What you see on the right are the storm reports from yesterday's action-- Much more wind reports than anything else, and nothing in the extreme. There were three tornado reports, but that's fairly isolated for an event of this magnitude. Today's expected severe weather zone has a similar consistency to it. You should be able to get an idea of what's going to be the concern today. The greatest threat zone is to our south, but we are all in the realm of possibility.
Here's what we're seeing in the model data regarding strong storms (from the NAM)...
|NAM - Storm Energy - Wednesday Early Afternoon||NAM - Lifted Index - Wednesday Early Afternoon||NAM - 0-6KM Shear - Wednesday Early Afternoon|
The first two maps are rather innocuous, showing limited storm energy and total storm lift. However, these numbers are above average for late January considering we should be in the dead of winter with very little convective cloud growth. It's that last map that should grab your attention. The shear values this afternoon are quite amazing. Well over 100 knots in a solid stripe up through the Ohio Valley. If this gets caught up into a developing storm, that can be trouble. Wind shear represents wind changing direction and speed with height. Just like when you shove an oar into the water while canoeing, we can get little spin-up eddies in the air just like you would going down-river. Most of the incredible shear will be trailing the storm line, but it's certainly possible we can have an instance or two where things phase well. If the shear lines up with a developing storm cell, there's two main things that appear: Gusty winds and tornadoes. Now, don't freak out; though this is an environment that can be conducive to tornadoes, more often than not it doesn't end up happening. Yesterday we saw two. Today may well see more, but there's no certainty that it will be folks in our area that will get them. One thing everybody should see is gusty winds. These winds can even gust up high enough to cause limbs to come down, so we will be watching for that too.
Pay close attention to the radar and the tracking maps today, particularly if we start getting reports of severe weather upstream. The prevalence and type of reports will be the clue we should be using to understand just how vibrant our weather ends up becoming when it gets here. As far as the timing of that is concerned, here's a look:
|NAM - Wednesday 4pm||NAM - Wednesday 10pm|
There's going to be some play in this timing, but I do think there's some opportunity for those who work outside to get some hours in during the first part of the day. But it's imperative that you keep an eye on the radar and get inside when the skies go downhill. Flash flooding is also a possibility with this system, as the models are trying to spit out > 1.00" of rain in short spurts under the thunderstorms.
As we said before, this is in advance of a large push of cold air that will fly through the overnight hours. Enough to change temperatures as much as 30-degrees from one morning to the next. It will be cold enough to snow on Thursday, and the prospects of black ice and flash freezing will be almost guaranteed. Be careful.
But for today, this blog post (and your attention) should be on monitoring today's weather, and staying safe where (and if) necessary.
Update (7:00am) - So here we go! The threat breakdown from the Storm Prediction Center:
|SPC - Hail Threat||SPC - Wind Threat||SPC - Tornado Threat|
The bulk of the severe weather dangers (of the worst kind) are going to be further to the south in the slightly better air (warmer dewpoints, etc.). The storm reports so far today have overwhelmingly been of the high wind reports (see below). This is expected to continue, but at the same time, nearly all of us should expect to encounter a severe thunderstorm or tornado Warning for their county. This is appropriate considering the system we have before us, but as far as tornadoes are concerned, it'll be heavy on precaution and not so much on verification. This means false-positives, but I don't want you to treat any Tornado Warning for your county like it's a false positive. Do the same sorts of things you should to stay safe, but I don't want you to panic. The tornadoes that may spin up in this type of environment are often eddies embedded within the advancing line of strong straight-line winds. In that scenario, everyone is receiving gusty winds, just someone happens to get the same winds in a rotating fashion. In the end, the difference is negligible. So, whether you're going to get hit with a very weak tornado, or a very strong wind gust, it is a good time to be on your toes. Respect the reports we've had upstream. The best news is that whatever we're going to see of the biggest impacts, they will pass through fairly quickly-- perhaps only a 20-30 minute ordeal. Then the rest of the day will be blustery, with that eventual cool-down we've been talking about.
Think smart, and we'll all be fine :-)
Update (10:30am) - The National Weather Service has expired/cancelled all the remaining tornado watches for the area, as the strong shear-based thunderstorms have pushed east. However, we're still going to experience gusty winds today, especially this evening as temperatures plummet. There have been widespread reports of 45-55mph gusts with that line that went through, and at the time we've had over 1000 people without power in Cabell, Athens, Kanawha, and Pike counties. All the damage reports are wind-related in our area, with no tornado reports expected.
|Regional Radar/Satellite with Warnings Tracking||
From the Storm Prediction Center (below): Click For a Larger Image
|Activity Overview||Storm Outlook||Watches||Potential Watches||Storm Reports|
|Temperatures||HD Doppler Radar||Estimated Rainfall||Active Warnings|
|Click For Larger||Click For Interactive Radar||Click For Larger||Click For Larger|
Have a great day everyone!