7-27 Update - After searing heat, another dangerous storm set-up

Another hot, humid July day will load a lot of energy into the mix, so that later in the evening a line of storms will develop in the Ohio Valley. This is (again) one to watch, as the "D-word" (derecho) is again being floated about.

7-27 Update 2 (5:45pm) - The National Weather Service has us again under a Flash Flood Watch tonight, not taking any chances because of what happened last night. There is a Severe Thunderstorm Watch to our west-- the greatest risk for that kind of weather is going to be outside our area to the west (once the storms get here they will be knocked down a peg and losing sunlight fast). But, as a consequence the storms will translate from severe storm potential to big rainouts with loud thunder and vivid lightning. Flash flooding is nothing to sneeze at, and a lot of us are prone given the rain from last night. Keep an eye on the constantly updating maps below and be prepared to take action if you live near a traditionally rapid rising creek. I don't think the weather will be as bad as yesterday, but isolated spots will seem worse just because they might catch a storm this time as opposed to last night

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7-27 Update - The damage and impact reports from the event yesterday and in the overnight pretty-well tracked the forecast in the end. Here's a breakdown of what all happened:

Local Storm Reports - 7/26 to 7/27

Today is a new day, but we still are left with some lingering issues left over from the same line that has stalled out. There is an additional impulse of energy headed into the area later today that will be able to stir things up again. There is a "Slight Risk" of severe weather again for parts of our area:

Storm Prediction Center - Severe Weather Potential - Friday

This is not expected to be as big of a deal, but watch for some scattered storms to first pop up in the IL/IN area before watching it track eastward along with the low pressure system. These may hold together in an isolated fashion to our western zones, but if the Sun doesn't come out and warm things up, even then it will be a hard sell to get anything other than garden-variety 'manageable' storms.

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Updated below (most recent 6:00pm)

Get ready for an active evening... Welcome to your Thursday.

We've got several items on the menu today, so let's start right in with it.

- Heat Advisories Are Up

We're looking at temperatures soaring into the mid-90s today, bouyed by plenty of humidity as well. The wet ground will try to keep things from getting completely out of hand (the atmospheric data for the day would have given us upper-90s to near 100 with the drier ground of late June). However, bear in mind the atmosphere will get very juicy and ripe for storms to fire and maintain themselves, even into the night.

Folks that work outside for long hours of the day, be cautious: drink plenty of fluids, hit the shade, and take a break here or there when you can. Sunscreen is a necessity as well. Same goes for the football players that are getting ready for 2-a-days with pads.

- A Notable Severe Weather Threat (again) For Later This Evening

I encourage you to review the blog post from a few days ago, because it captured the event we ended up with fairly well. Compare the data to what we'll describe below, because there are several indications that this event will be worse than the one we already went through-- though for different people.

1. Strong mid-level dynamics

NAM - 500mb Chart - Thursday PM NAM - Mid Level Winds - Thursday PM

So, we've got another solid "short-wave" of vorticity (seen by the couplet of red and purple on the left-hand map) headed along the general southwest-to-northeast steering flow. In addition, the winds pick up fairly well between 5,000 and 10,000 feet. This will translate into a fast flow that keep storms well fed as they gobble up energy in transit. It will also provide ample opportunity for falling raindrops to harness that wind and bring it down to the surface, not a good thing either.

2. Another Front Provides Forcing And Lift

HPC - Surface Map - Thursday PM

This front will provide the initial lift-off for the storms we'll be watching, but once they sprout, the mid-level winds will carry them beyond the front and off to the races. The good news is that the steering flow is generally going to carry the storms in a WSW-to-ENE direction away from the tri-state area instead of right through it (like Tuesday). The bad news is that "somebody" is still going to be hit with this thing, and that still includes a piece of our area in the targeting sights.

3. Even Stronger Thermo-'dynamics' Than The Last Time

NAM - Available Storm Energy - Thursday PM NAM - Lifted Index - Thursday PM NAM - Wind Shear - Thursday PM

From left-to-right: The first map indicates available storm energy. Built up from today's temperatures in the 95-100 range in parts of the Ohio Valley, there will be more juice around compared to Tuesday; The middle map shows a more widespread propensity for the air to bubble upward-- the rising air gets storms bigger, taller, and badder; The right-hand map is about wind-shear (the difference in speed from the surface to 6,000 feet in the air). The good news is that the greatest shear is up toward NY-MA. It is out of our area, but that would be the first place I'd look for tornado possibilities.

Putting that together we've got yet another linearly fast flow locally, combined with frontal forcing entering a region of ripe storm-generating thermodynamics. The location where all of this phases together the best (for our area) is Ohio.

Yes, this does mean that a lof of us will be sitting there in steamy un-tapped skies wondering what all the fuss is about, but from a meteorological perspective the storm potential in the Ohio Valley and Mid-Atlantic begs a mention. Here's how the Storm Prediction Center is looking at it:

SPC - Severe Weather Probabilities - Thursday PM

A 45% probability is just about as certain as it gets-- so we'll be expecting an active pattern Thursday evening. The biggest threats as it relates to our area will be damaging winds (and that does mean power outages), and focused up in Ohio. The threat drops off significantly as you get south of I-64.

If there's another bit of good news I can pick out of this, it would be that these storms are going to move fluidly through any region, so the prospect of flash flooding should be on the lower side.

I'll be updating this post as time permits during the day today. If all goes well, we can keep these storms just to our north and out of our area and give someone else the headlines for a change.

Update (9:30am) - The latest severe weather outlook has been posted by the Storm Prediction Center, and here's the breakdown:

SPC - Hail Threat SPC - Wind Threat SPC - Tornado Threat

The strongest risk (for us) is still in interior Ohio, and the main threat is still gusty, damaging winds. However, it should be noted that we usually see severe weather even when we're in that other 'slight risk' yellow category, so we'll have to stay vigilant even into the overnight.

Update (1:15pm) - The destabilization of the atmosphere is progressing ahead of schedule, with the available storm energy now actually approaching 4000J/Kg instead of the modeled 3500. When the triggering lifting arrives from the west, we should see quite a powder keg of convection sprout up in a very short amount of time:

Visible Satellite Picture - 1pm

Inside the blue square lies a remnant outflow boundary that pushed ahead of the main cold front early this morning (as I've said before, thunderstorm lines love to rush out ahead after forming along fronts...as they die, their cloud boundaries can live on). It is here that the teeny tiny match should get tossed into the giant bowl of flammables (and soon too).

Update (1:30pm) - And with that, mere moments later, we get the pop! The Storm Prediction Center has now issued a Severe Thunderstorm Watch that covers almost all of Ohio, the western half of Pennsylvania, the Northern half of West Virginia, and a little sliver of Kentucky (which is a huge area to do all at once). From here on out, keep a close eye on the warnings map and the radar maps (both below and updating constantly).

Update (6:00pm) - The storms are now making their way into our viewing area. Folks in a line from Athens, OH down to Vanceburg, KY will be affected first, and the entire line has Severe Thunderstorm Warnings associated with it (see the maps below). Expect a burst of winds, driving rains, frequent lightning, and the possibility of hail. So far the storm reports coming from upstream are usual for an event like this (downed trees, power outages, etc.) Take precautions this evening, and have a plan for what you're going to do at the first ear-shot of thunder. Unfortunately this event looks to impact all four of our county fairs going on tonight, and the Pullman Square concert series in Huntington.

Following the initial line, the severity risk will drop for future storms. There will be more storms though, as the energy available in the sky has not been fully consumed by the initial line and there's clearly more thunderstorms forming behind it. Expect some loud boomers and frequent lightning at times into the night and even into tomorrow.

Feel free to post storm reports and local updates in the comments section so that we can all stay informed. Thank you very much for seeking out this blog for your weather-related needs :-)

Regional Radar/Satellite with Warnings Tracking

Accuweather Radar

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
Current Temperatures HD Doppler Radar Estimated Rainfall Active NWS Warnings
Click For Larger Click For Interactive Radar Click For Larger Click For Larger

Have a great day everyone!

-B

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