Sydney Claridge

There are already dewpoints in the mid-to-upper 60s on the northwestern side of where these storms are expected to form. I doubt they will have that much of an effect for later on, although I guess sinking air could suppress storm development behind them (Steve McCauley was referring to this possibility if morning storms formed over DFW, which has not happened). We will probably get a separate watch later on.

The solution on the 18z NAM3k seems to hint at the possibility of a localized outbreak in/near DFW; I definitely do not want to see that solution verify. The earlier 12z run pops the storms further east, though. The 18z HRRR solution fails to initiate convection over DFW/North Texas in the afternoon, but could spell trouble up near Oklahoma City with storms firing on the triple point. EDIT: That trend towards afternoon storms is concerning to say the least. We will have to see how the observations play out tomorrow.

What is interesting about DFW-area tornado history seems to be that several of our worst outbreaks in recent memory have occurred on more conditional days that are not a moderate or high risk. Seeing something like a 10% hatched risk over DFW, as such, definitely gets my attention. December 26, 2015 was only an enhanced risk day (10%, not hatched), and the October 20, 2019 tornadoes occurred largely within a slight risk (there was an ENH further northeast). The April 3, 2012 tornado outbreak occurred near and within an enhanced-equivalent (10%, not hatched, considered a slight risk at the time) tornado risk, but an outflow boundary helped to back the winds that day. I believe that our last high risk was back in April 2007, and it largely busted. I am in no way saying that tomorrow will be like 12/26/15, 10/20/19, or 4/3/12. But there is the low probability that such an outcome could occur; there have also been hatched risk days that have failed to produce tornadoes (or failed to verify at that risk level, such as what happened to the MDT for tornadoes in the southeast on 4/19/20). Any conditional tornado event can produce tornadoes, but the risk is fortunately conditional. Several of the worst DFW tornadoes in recent memory have occurred on otherwise-conditional days, however, and mesoscale factors were largely to blame (as on 4/3/12 and I believe on 10/20/19 as well). Of course, we could see a downgrade or upgrade for Day 1 as the risk becomes more clear in the hours to come.

I guess there could be some northwest flow events in the Southern Plains even if we wind up with that pattern, provided there is enough moisture available to fuel severe thunderstorms. There was northwest flow severe earlier this month in the Midwest and Great Lakes states, even though northwest flow is not normally favorable for severe thunderstorms there until the summer. Northwest flow is not the most ideal for tornado activity, but it might at least be something. You would think that with cooler-than-normal water temperatures off the U.S. and Mexican Pacific coasts and warmer-than-normal temperatures in the Gulf of Mexico that we would be more prone to western troughing and eastern ridging.

15% hatched Day 3 Slight risk for DFW down through central Texas. SPC currently anticipates veer-back-veer wind profiles over the highest risk area, with large hail as the primary risk.

Definitely some good news as this storm approaches the I-59 corridor. But this storm could be cycling and has taken somewhat of a left turn. Could spell trouble for the southernmost parts of Hattiesburg (US-98 corridor) if this storm is only cycling.

As for those cells northwest of Hattiesburg, the one east of New Hebron is probably the one to watch, being by itself and all. I definitely do not want to see those smaller cells over Bassfield and Sumrall go severe, given that they are on track to affect areas hit hard by last Sunday's tornadoes (including Soso). Also keep an eye on that supercell south of Forest, MS. It has a prominent hook but seems to lack strong rotation at this time.

Interesting enough SPC includes a significant hail risk today (4/19) for half of the DFW Metroplex, primarily Dallas and Collin counties eastwards.

Would definitely be interesting to see the severe storm potential start to move further north. So far, the Gulf Coast states look to remain prone to severe thunderstorms and tornadoes for the next couple of weeks. Given what happened in Mississippi on Easter (and with said areas still recovering), it would be nice to get the severe storm potential away from that area. But they have another significant risk for tornadoes tomorrow (also including Louisiana once again, so still relevant to this subforum), and the 22nd and 23rd are also looking like potential severe weather days in that same area once again. With all that warm water in the Gulf, it would not surprise me that whenever the severe storm potential marches north, that things could get intense with plentiful low-level moisture. As for the traditional Tornado Alley, this is a Dixie Alley pattern, but parts of Texas may get in on the action (I don't want to necessarily rule out the I-35 corridor or the Southern Plains of TX/OK completely, especially if the storm systems come in northwest of where they are modeled, but everything looks like it will be east of there). I'm just a little surprised that it has remained quite cold in the Midwest and Great Lakes regions, but they will probably get their turn for severe storms once this warm, humid air can move further north than Dixie.

Storm moving into Birmingham looks like more of a straight-line wind threat, at least for now. What might be interesting is if this storm has left behind an outflow boundary that the storms approaching from the SW could exploit. Overall storm mode continues to look really messy, however.

Correlation coefficient might be suggesting debris north of Holt as well.

Storm in the Tuscaloosa/Northport area seems to have that supercellular look to it. EDIT: just as I said that a severe thunderstorm warning comes out. Storm motion is towards Birmingham, although the orientation of the polygon is pointed more towards Hoover and the southern Birmingham metro area (possibly taking into account a right turn).

Definitely a couplet on that storm. May need a tornado warning soon.

Tuscaloosa reporting 72/70, so there is plenty of humidity around. While the circulation near Union is weakening, the situation could change quickly given other parameters.

Couplet on lead cell is moving towards Union, AL; second cell has a couplet moving towards Emelle, AL.

Rotation also ramping up north of Meridian, about to cross over into Alabama.

Surprised those storms from Meridian to Tuscaloosa are not stronger. Inflow should be somewhat unimpeded. Not that I would want them to be any stronger; I have relatives of my family that live in the Eutaw, AL area.

Baton Rouge seems to be on the back edge of the discussed activity. Storms out by Hammond look to be more of a concern.

Lead cell just a left turn and is now headed for Meridian, that's is why that tornado warning is oriented the way it is.

Tornado emergency wording taken off of the lead cell NE of Pachuta. Now just states "severe thunderstorm capable of producing a tornado." EDIT: Actually both cells are no longer tornado emergencies, but the warning for the second cell near Taylorsville says that there is a confirmed tornado.

Possible debris ball between Macon and Brooksville, MS.

Low-level lapse rates are better ahead of that line in southern Louisiana (now moving through the Lafayette/Baton Rouge areas). This might be one area to watch.

Those cells down by the Gulf Coast, currently moving over Lafayette, LA, also have my attention right now.

Looks like we might be seeing initiation there. If so, that would be very concerning, but it might not mature until it passes the Jackson area (but you never know).

Moderate risk remains intact for the 1630z outlook. Concerns about convection surging ahead of the surface-based instability precludes a high risk upgrade. MDT extension into TN is for a 45% hatched wind risk; the 15% hatched tornado risk stays south of the TN/AL border.