A Quick Note

This site is a work-in-progress, with such exciting things as a portal coming soon. Please excuse our mess.

Join the Community – Stormy Grove Discord Server!

Join Us!

A form's coming soon for anyone interested in joining the Nation. But until then, email stormygrove@gmail.com if you're real and classy enough to be interested. ;)

Have you gotten your Amazon shopping done today?

Mesonoptic FM

Shows featuring on-the-real news and views, stimulating intellectual conversations, video game chit-chat, tech talk, great music, and more - find 'em on The Stormy Grove's own Mesonoptic FM!

Get Tuned!

Good Organizations – United States

Jumpin’ January!

One of the common weather wisdoms in North Texas is that severe thunderstorms, a purview of warm weather practically unheard of in the wintertime in the northern half of the country, can happen any time of the year, due to our subtropical climate. Sure, they may be most common in the springtime, but never count out the day after Christmas and damn near Halloween.

As those articles demonstrate, that wisdom is very much true. And right now, it’s looking like it’ll be proven true once again today – Friday, January 10, 2020 CE.

The PC2 StormStalkers have been tracking and providing modest updates on an approaching storm system (low), which, a few days ago, looked like it was gonna bring some modest thunderstorms to the area yesterday, today, and some light wintry weather early Saturday. Then, the model guidance inched more and more towards severe weather…

Earlier in the week, this storm system was looking like it was gonna speed along, bringing just a marginal chance of severe thunderstorms to North Texas. But lately it’s been slowing down. What this means for North and Northeast Texas is, in short, higher and more widespread severe weather potential.

Let’s start with flooding. It’s been quite dry for a few weeks, and in fact, drought conditions have been slowly re-expanding across the region after being beaten back somewhat late autumn. So the soil moisture is low.

Soil moisture map of the United States. Texas, with the exception of part of the Panhandle and a tad of the Big Bend, is quite dry at the moment, to put it mildly.

With the exception of sandy desert soil, dry soil is eager to absorb water. If the low was going at the original speed it was clocked at as it was crossing the Pacific, the flooding risk would’ve been near zero since the forecast ~.25-1.5″ of rain would’ve been easily absorbed.

With the slowing of a storm comes, of course, higher rainfall totals. Now, we’re looking at the potential for 2-4″ of rain from the core Metroplex and points northeastward into southeastern Oklahoma, and up to 2″ elsewhere in the region–all falling mainly within a fairly short 1-3 hour period of time in any given location. This has the potential to overwhelm soils as well as urban drainage systems. Because of this, a Flash Flood Watch has been issued for Dallas and Tarrant counties, and counties points northeast, starting at noon today & ending at 3 AM tomorrow.

Now, let’s talk the other modes – large hail, damaging straight-line winds, and tornadoes. Another consequence of a slower-moving system, combined with timing, is that it can better assemble and “mix” the ingredients for severe weather. Counter-clockwise rotation around lows in the Northern Hemisphere means this west-to-east mover from across the Pacific will have more time to pull warm, moist air from the Gulf of Mexico and have it well-primed with morning & early-afternoon sunlight energy to clash well with its associated cold front. In fact, that’s been happening for the past day. This morning’s lows in North Texas will struggle to get below 65F/18.33C, which is incredibly warm for a low, even in a mild Texas January! Our normal highs this time of year are in the mid-50s F/~12C.

The morning will be calm, so if you’ve got business, try to take care of it then. Skies will be mostly cloudy, temperatures will linger in the 60s, and it’ll be absolutely juicy outside, so dress appropriately – it WILL feel like mid-spring. Winds will be quite breezy, 10-20 mph/16-32 km’h from the South.

It’s around noon that things will get interesting. The cold front will be idle (save for the temperature drop) until it’s about to a Childress/Abilene/Del Rio line that it will approach by about the aforementioned noontime. Non-severe storms may start along it by then, while activity has the potential to bubble up ahead of the front in North, Central, and South Central Texas.

It’s this “ahead” activity that would kick off the day’s severe weather. When you have a low with an associated front (usually, but not always, a cold front), and conditions are conducive to a squall line forming along the front (as they are today; more on that later), it’s the isolated storms that form in the thick of the juicy air up to sometimes as much as 250 miles ahead of the front itself that have the potential to become supercells – the strongest form of thunderstorm. Why? Well, unlike storm cells embedded in a line, they have a whole heaping helping of primed atmosphere ahead of them!

IF – and that’s the key word, as they may not – they form, as mentioned, it’d be in North, Central, and South Central Texas, a tad west of the I-35 corridor. They’d then move northeast (with some having the potential to turn and move more due east or even slightly southeast), bringing the potential of hail up to the size of – in today’s case – probably teacups or so, straight-line winds up to and exceeding 65 mph/105 km’h, and tornadoes, in addition to localized flooding.

the HRRR simulated-reflectivity model, starting at 08z Jan 10th [2am/0200 Jan 10th CST], showing potential development up to late afternoon/early evening. Note the isolated cells that form first, then “merge” into the squall.

As these supercells move eastward, the front itself will spawn thunderstorms that will quickly form into a solid squall line, likely along a Brady-Brownwood-Eastland-Wichita Falls geo-line, and then move eastward. With squalls like this, the highest hazard is straight-line winds. Hail is much less of a concern, but the potential is still there for up to 1-2″/2.5-5 cm hail in the most severe parts of the line. Brief “landspout” tornadoes are also possible, with exceptions (more on that in a bit). But this is where the flooding threat makes itself really apparent.

Back on May 5, 1995, an isolated supercell pummeled Tarrant County with a hailstorm that, for almost six years, held the record for costliest hailstorm in American (and perhaps world) history, until it was beaten in 2001 by one in St. Louis. This supercell was a frontal cell that formed in the juicy air ahead of the front’s squall. Almost always, the front’s squall catches up with, and absorbs, any supercells that formed ahead of it. This happened over Dallas County back then, causing major flooding.

A quick primer on SPC severe weather risk outlook categories…

And now the outlook maps…

SPC outlook issued just before midday CST (18Z) on Thursday, Jan 9…

…and the latest SPC outlook, issued a tad before midnight today (6Z). Note the “bubble” of Moderate risk that popped up first only for the Shreveport extended metro, before being extended to the entire ArkLaTexOma region and NE Texas.

A similar phenomenon is likely today. As the supercells approach about a US-75/I-45 line in the early evening – perhaps a bit further east – they’ll start to be absorbed into the squall and present a major flooding risk, especially for Northeast Texas. Current thinking is that the squall will still have a major tornado threat, due to being particularly intense – leaving a wide-open possibility that supercells form “embedded” in the line! It was “just” straight-line winds that led the “bubble” of Moderate risk to pop up as mentioned above, but after the latest model guidance on the squall’s potential, it was expanded.

Keep in mind that ANY category of severe weather potential is hazardous, and even “just” non-severe thunderstorms spawn lightning and can cause floods. It’s just that more intense, more widespread activity is *more likely* in deeper risk areas. Even in “just” slight/enhanced area, supercell potential is there!
After evening’s in full swing, the severe stuff will be in eastern North Texas, East, and Southeast Texas to take us into the night, leaving just light to moderate back-side rain over North Texas. By the time morning comes – about 4 AM – Louisiana will be the focus and we’ll be talking snow/ice potential…

After the core of the low arrives in East Texas in the early morning hours of Saturday with its associated light core rain, the cold air behind the front will spill down into North Texas, bringing temps in the 30s; lower 40s further South in the region, and hit up some of the leftover moisture. This will lead to scattered wintry mix showers (rain, sleet, snow) along and north of a Stamford-Breckenridge-Fort Worth-Dallas-Greenville-Texarkana line.

The ground temperatures will still be quite warm from today, however, so expect no real impacts (though still use caution traveling, as people here in Texas go into panic mode upon seeing any form of wintry precip falling!). There MAY be a VERY light “dusting” on elevated and grassy surfaces along and North of a US-380 line. This is within a 3-8am-ish timeline.

Skies will remain cloudy until about noonish or so, at which point they will clear out. Highs will still be cold – in the 40s; 50s south.

Leave a Reply

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>