Sydney Claridge

There is now a hailstorm capable of significant hail (2"+) about to move from southern Oklahoma into Montague and Cooke counties in north-central Texas.  Could even be some rotation trying to form on this storm.  If the current motion continues it may try to move towards Denton County (and the northern portions of the Metroplex) if it can hold together that long.

EDIT: severe thunderstorm warning for eastern Montague and all of Cooke County.  It is warned for 2-inch hail and 65 mph wind gusts (OK warning included concern for 3-inch hail).  Steve McCauley (on his Facebook page) is saying that the storms should be able to survive into (at least) the northern DFW area.

It will be interesting to see if the cap kills off those severe storms in southern Oklahoma in the next few hours.  If not, they are headed straight down I-35 for DFW.

This pattern would have been good for winter in the Northeast, too bad it came too late.  At the same time however, western ridging in the winter would have meant reduced mountain snowpacks and worse drought.  A return of the Pacific "blob" would be good for big-time Northeastern snowstorms but very bad for western water supplies, especially outside of the coastal Pacific Northwest where the warmer water can serve to increase the amount of moisture available to a storm system.

Eastern troughing and western ridging has killed severe weather seasons in many recent years.  If I recall correctly, 2013 had somewhat of a late start to the Plains severe weather season, but once it got going in May, we had some very powerful tornadoes in Oklahoma, including the most recent EF5 on record (Moore, OK), not to mention the El Reno tornado (that would also have been an EF5 if it had it hit structures).  There have been strong and violent tornadoes in Dixie Alley so far, and a persistence of the eastern troughing pattern would lead me to believe that areas on the southern and eastern flanks of the trough, namely Dixie and the Carolinas, would remain prone to potential tornado events through May, especially with warmer-than-average Gulf of Mexico water temperatures.  Perhaps with some northward shifts into the Ohio Valley and southern Great Lakes region as warmer air gains a foothold in that region.

The Plains might very well be stuck with northwest flow in this pattern.  Provided sufficient moisture, severe thunderstorms (and possible derechos) on the rim of the building western heat are a possibility, particularly if this western ridging/eastern troughing pattern continues into summer.  I would also watch to see if the High Plains EML gets advected further east into any regions favorable for severe weather that are on the southern and eastern rim of the troughing.  Western ridging that affects the Rocky Mountains and High Plains could be favorable for making a stronger EML, but this might also kill severe weather events as well, if the cap is too strong.

Definitely an area of strong winds southwest of Gainesville, moving towards the Metroplex.  I’m also wondering if that might be some rotation near Valley View?

90%/70% severe wind probabilities on that new severe thunderstorm watch, high odds but not enough for PDS.  If those odds were slightly higher (let's say >95/80) then I think they would have gone PDS.

There has already been a significant wind report out of Tulsa (65-75 mph wind gust at 51st/Harvard; listed as a 75 mph significant wind report by SPC).  If we get a derecho that might be where it starts, so I would expect areas to the east of DFW to be at the highest risk for getting a derecho today (the OK/AR/MO border region is also a climatological hotspot for derecho activity per SPC).  Remember that severe winds have to extend for at least 250 miles to get a derecho; that said, you can have an MCS with destructive winds that does not persist long enough to meet derecho criteria.

DFW itself will be impacted by the activity (either ongoing or yet to form) over central Oklahoma.  So far this activity has remained more discrete than that over northeastern Oklahoma (which has formed into a solid line).  Also note that helicity may increase between 01z and 03z based on RAP guidance (as seen on the SPC Mesoanalysis page), which also forecasts effective SigTor values as high as 9 over the DFW area as the storms arrive.  I'm not saying that there will be tornadoes (it seems unlikely, and SPC has only put DFW and much of north-central Texas in a 2% contour after all), but it might be a possibility with any discrete or semi-discrete cells once that helicity ramps up in a few hours.

I wonder what the odds of getting a tornado are for north-central Texas if there happen to be discrete storms around?  I know the supercell composite, helicity, and significant tornado values often do go up in the evening and at night (RAP on SPC Mesoanalysis shows this happening over north-central TX prior to the arrival of storms), but that storms often become more elevated at night as well.  The HRRR model also has the DFW area at the tail-end of the line of storms.

It always concerns me to see forecast values that high over a highly-populated area (DFW) with what could be some semi-discrete activity, but I have seen this happen before in the late spring and summer with few-to-no tornado reports.  This is also a northwest-flow scenario and there tend to be fewer tornadoes with that.  That said, I do wonder if we will see a derecho this evening.

3 minutes ago, TexMexWx said:

Getting very light radar returns in southeastern Tarrant county, might be nothing but the Denton-Collin County area seems to be strengthening in a matter of several minutes.

The area on the Denton/Collin county line may wait to mature until it reaches less-populated areas east of US-75, outside of explosive intensification (as mentioned previously).  But even then, Collin County east of US-75 has been growing rapidly, so there are still highly populated residential areas on that side of the county these days.  SE Tarrant County would be more of a concern, but high clouds have prevented satellites from seeing the status of the cumulus field down there so radar returns and on-the-ground observations are the best way to monitor storm development there.

4 minutes ago, TexMexWx said:

Dryline appears to be through western Denton and central Tarrant counties

Some light radar returns seem evident around Little Elm and western Frisco.  This might be the next storm to form.  The dryline looks to extend from Denton to Trophy Club down through Hurst and Alvarado.

4 minutes ago, Wmsptwx said:

Think dfw is okay at this point?

I would not put Collin or Dallas counties in the clear just yet, especially Collin County, depending on what happens in the Frisco area.

If that area in southern Denton County turns into a supercell soon it could spell big trouble for Collin County based on what is occurring with the activity in southern Oklahoma.  So far everything seems fine, but it would not take long for things to change.

A WFAA meteorologist mentioned that area (southern Denton County) for potential development.

Just now, cheese007 said:

Doesn't need to hold for much longer to spare DFW. Pete Delkus mentioned it was pretty thin in the latest sounding 

And hopefully it does hold.  As I mentioned, those temperatures in central/eastern Tarrant and southernmost Denton counties do have me concerned about the cap breaking.  There are mid-80s temperatures just ahead of the dryline, and temperatures behind the dryline are in the upper-80s to around 90.

Just now, TexMexWx said:

Was it forecast to get that high over there? Here in southern Collin county we're seeing temps in the low 80s and dewpoints in the low 70s in some spots. It might warm up beyond that too.

Those are generally personal weather stations (from Wundermap), but when I see a whole bunch of those averaging around a certain temperature I pretty much take it as fact.  I would keep an eye on southern Denton County right now, there seems to be agitated cumulus around 114 and I-35W (from satellite imagery) that looks like it could try to turn into a storm.

Not sure what the convective temperature is, but those mid-to-upper 80s temperature observations I am seeing in western Tarrant County (some of which may be behind the dryline now) are concerning me.  Maybe not for my location but for points to the east, should an updraft get going and then sustain itself.

I'm fairly confident at this point that I am not going to get severe weather at my location in west Fort Worth (just west of I-35W), unless something explosively develops in the next 30 minutes or so.  The dryline is very close and should pass over my location soon.  Dallas County, Collin County, and points east might not be so lucky though, if this cap breaks.

2 minutes ago, TexMexWx said:

Latest HRRR really tones down any notable activity until storms are east of the immediate DFW area

Excellent news for the Metroplex if that solution verifies.  Some of the temperatures in western Tarrant County continue to rise and are still ahead of the dryline (I believe the dryline is near or just west of the Tarrant/Parker county line).

6 minutes ago, cheese007 said:

Fwiw (and I say this as someone not far from where the tornado hit) the area south of 30, while more sparse, is also much less wealthy. Lots of poverty in that area

To be honest, if a tornado had to hit a residential area, I would rather it happen in a wealthy area like the Park Cities or Southlake given the COVID-19 situation and all.  It would be very costly for the insurance companies (like 10/20/19 was), but people with more resources would be less of a risk for spreading the virus in the aftermath of such a tornado and could more easily recover from the aftermath.

3 minutes ago, cheese007 said:

And that we just had a major tornado in the north Dallas area in October

Not to mention at least some of the model runs suggested that initial activity would be focused on the northern Metroplex.  There is a greater population in DFW north of I-30 than south of I-30, generally.

Some of the surface observations I am seeing in eastern Parker and western Tarrant counties have temperatures in the lower-to-mid 80s.  The big question is how much that cap can take before breaking.

For a moment it looked as if the intensity of those cumulus clouds west of DFW reduced in intensity, but it seems like the intensity is increasing again based on satellite imagery.  I can also see what is likely agitated cumulus (with my own eyes) just to my west.  If initiation occurs in the next hour or so it should be focused in eastern Parker, western Tarrant, southern Wise, and southwest Denton counties.

Those high clouds have moved out of the way and I now have full sunshine at my location in west Fort Worth.   The HRRR runs have predicted that potential supercell development could occur on the north side of those high clouds, likely out of that area of clouds that I highlighted in my last post.

Monitoring this area out by Mineral Wells for potential convective initiation that could affect the DFW area.

1 minute ago, 1900hurricane said:

Sharpening dryline is becoming evident in N TX with surface obs, rader, and visible imagery.

Definitely some agitated cumulus visible in the satellite imagery extending south of Wichita Falls.  If that extends under those high clouds (which it likely does) then this will be the area to watch for storm initiation that may affect the DFW Metroplex.

Convective initiation has now started in southwestern Oklahoma, west of Lawton.

And the brightening skies trend continues in west Fort Worth; I am now getting filtered sunshine on and off.  I'm assuming that the sunshine is filtered due to high-level clouds visible on satellite imagery.   SPC now says that a tornado watch is likely for N TX into S OK (see MD text in prior post).

EDIT: filtered sunshine became more consistent within the last few minutes.  I can now see blue skies off to the northwest; the clearing is now starting to affect the western portions of the DFW area.

Still socked in with clouds in west Fort Worth, but the skies seem a little brighter compared to an hour ago.  Temperatures have warmed into the lower 70s as well.

12 minutes ago, TexMexWx said:

Helicity doesn't look to be super high across north-central Texas, as was mentioned before, but the HRRR has been showing storms forming just west or maybe IN western parts of the DFW metro and tracking east over a still decent environment for the past few runs.

The CAPE values should be quite high whenever storms do develop.  100-200 m2/s2 of SRH (that model is saying roughly the same for 0-1km and 0-3km SRH) should be sufficient for potentially tornadic storms with the high CAPE present.

7 minutes ago, vwgrrc said:

well, i guess a positive outcome from this COVID thing is that a hail storm would potentially cause less damages across DFW now given there're much less business activities overall...

Not necessarily.  People still have homes and are occupying them.  Not everyone has a garage (or sufficient space) to place all of their cars inside or under cover.  Unoccupied businesses still have value. A big hailstorm over DFW will be an insurance nightmare no matter where it hits in the metro.  There will be fewer people outside who could get injured (which is the bright side here), but insofar as monetary damages are concerned there would be little difference in my opinion.

5 minutes ago, TexMexWx said:

Okay, that makes sense.

I meant to say dewpoints in the mid-to-upper 60s and edited my post accordingly.  A couple spots in central Texas (behind that area of developing storms) are reporting dewpoints around 70.  Provided that convective initiation occurs, I do not think storms will have any trouble turning severe with up to 4,000 J/kg of MLCAPE and 5,000 J/kg of SBCAPE modeled (although these high CAPE values are dependent on dews in the lower 70s).  A major hailstorm near or over DFW is a definite possibility this afternoon, and potentially a tornado or two (perhaps strong) as well.  Hopefully this does not happen.  There should be lower helicity along the dryline (compared to areas to the east) but there will be much higher CAPE.

I'm still socked in with clouds here in west Fort Worth at the current moment, but there does seem to be an area of clearing to the west just ahead of the dryline (precisely where the higher CAPE currently is).  As this area of clearing moves east I fully expect things to destabilize in DFW pretty quickly.  SPC Mesoanalysis forecast data (from the RAP) has the clearing arriving in DFW within the next two hours.