Severe WX Severe Weather Threat 3/14-3/16

[KevinH]

Has there ever been a case where models downtrended heavily before a potential tornado outbreak but the event itself over performed the models as if they were just wrong outright?

I think that has happened a number of times over the years. I think D3 is really where people really want to start paying attention. Things have been tricky (read: highly conditional) on some D1 threats with high ceilings in the past. When it comes to weather, nothing is ever REALLY 100% guaranteed unless and until it actually happens LOL (regardless of what models and weather weenies say in the days leading up to an event).

 

[ColdFront]

ICON 18z is another run bringing a marked decrease in moisture quality, particularly for Friday.

I do think its a good idea not to over analyse every single model run and can understand where people are coming from on here warning against it. At the same time you are looking for existing trends, and whether each new output follows that trend. We most definitely have a trend - decreasing moisture - and ICON 18z plus the rest of the models for the last day fit that. And acknowledging/discussing a current decrease in severe threat doesn't mean you are not aware of the fact things can quickly swing the other way. Maybe I am just being optimistic.

Yep. We’ve been seeing a marked downtrend on moisture on Friday, especially the GFS. Which is why I’ll be very intrigued to see the 18z Euro. I mean, I don’t see anything wrong at all with pointing this out.

 

[Mrgolfman7070]

No, do not write this threat off, at least at this stage.

If the shear and cape will be higher to offset lower dewpoints, then I would agree with you for Friday night into Saturday. I know currently we are in 30% risk, but probably that will shift in tomorrow update. We want some action in our area lol. It's been a while

 

[JPWX]

I might be totally stupid here, but all 3 global models have a sub 980mb pressure and very robust trough Friday going into Saturday. Folks, the ONLY model that has started to have moisture issues is the GFS.

 

[ColdFront]

18z GFS is rolling in

 

[Clancy]

I might be totally stupid here, but all 3 global models have a sub 980mb pressure and very robust trough Friday going into Saturday. Folks, the ONLY model that has started to have moisture issues is the GFS.

Irrespective of moisture return and dews, can we just appreciate those troughs? Amazing structure.

 

[slenker]

Yep. We’ve been seeing a marked downtrend on moisture on Friday, especially the GFS. Which is why I’ll be very intrigued to see the 18z Euro. I mean, I don’t see anything wrong at all with pointing this out.

Of course there’s nothing wrong with pointing this out. I am just not a fan of people seeing a downtrend (albeit somewhat significant, but still) and immediately writing it off as a nothing-burger when we’re still 4-5 days out.

 

[JBishopwx]

Jackson AFD:

Updated Jackson AFD:
Late week through the weekend: By far, it appears the most impactful weather this week will occur in the late Friday through Saturday time frame with two distinct rounds of severe weather expected. A powerful shortwave trough will traverse the Plains and move into the MS Valley Friday into Friday night. As this happens, strong cyclogensis will bring substantial height falls into the area with and support thunderstorm development over northwest portions of the area, especially by late Friday into Friday evening and overnight (This being "Round 1"). High levels of instability and wind shear will support severe supercell development capable of tornadoes, damaging winds, and large hail. Uncertainty exists with how far southeast the threat will extend through Fri night as initially there will be a strong capping
inversion that limits tstm potential. So while the current graphic messaging for the Friday night period includes the entire area with at least a slight severe risk, the southeast portions of the area, particularly the Pine Belt region, will most likely not get any storms until Saturday ("Round 2") when the next wave of convection develops. The bulk of the forecast area should be impacted by severe weather and perhaps flooding threats Saturday. Some guidance indicate the impacts will be felt most over eastern MS, while others hold the second wave back some and affect more of the area. These details will get ironed out as we get closer, but for now, would generally expect a high impact severe weather/heavy rainfall event Saturday as there will continue to be a considerable amount of instability/deep layer shear and strong ascent. The difference with Saturday is that there will be more forcing and less capping, so there may be more numerous storms and more severe coverage with not quite as high of a ceiling for intensity, but would not want to make that determination this far in advance. Depending on how much the second round hangs back, training of storms and heavy rainfall be a greater concern. Have held off on putting out a heavy rainfall graphic with most focus on the severe weather, but this will be something to monitor along with gradient wind impacts as well. The storms could linger into Saturday night before strong cold advection brings in drier and cooler air for Sunday.

 

[andyhb]

Friday's threat is really looking less significant at this point, there's no denying the shift across guidance for that lead wave Wednesday to be more disruptive to moisture return.

 

[Clancy]

Jackson AFD:

If it is a rain-heavy event, could foresee something that loosely resembles 4/12/2020 purely in the sense that we had extensive convection across the northern parts of MS/AL/GA that resulted in some very nasty storms south of said convection.

 

[ColdFront]

Friday's threat is really looking less significant at this point, there's no denying the shift across guidance for that lead wave Wednesday to be more disruptive to moisture return.

100% - the trend has been undeniable.

 

[UK_EF4]

I might be totally stupid here, but all 3 global models have a sub 980mb pressure and very robust trough Friday going into Saturday. Folks, the ONLY model that has started to have moisture issues is the GFS.

I agree its important to stay weather aware and up to date with the forecast - things can and do change. But it's undeniable *all* models have seen decreases in moisture return.



Of course, there is a still a threat of significant severe weather, but this really isn't the same caliber setup models were showing yesterday and Saturday. Return to previous output isn't completely out of the question at this range, though.

 

[Bulkshear]

I might be totally stupid here, but all 3 global models have a sub 980mb pressure and very robust trough Friday going into Saturday. Folks, the ONLY model that has started to have moisture issues is the GFS.

I concur with your observation.. Something seems off with how quickly some people are really downplaying this now due to their perception of the model information. I think the big picture is being overlooked.

 

[ColdFront]

I concur with your observation.. Something seems off with how quickly some people are really downplaying this now due to their perception of the model information. I think the big picture is being overlooked.

I mean that’s an astute observation if some of us “weenies” are calling out the moisture issue. But when a professional meteorologist is doing it too then there’s some credence to it.

Like it’s just undeniable there’s been a downtrend for A major tornadic threat on Friday. Severe weather? No. But high potential outbreak? Yes.

 

[Bulkshear]

I mean that’s an astute observation if some of us “weenies” are calling out the moisture issue. But when a professional meteorologist is doing it too then there’s some credence to it.

Like it’s just undeniable there’s has been a downtrend for A major tornadic threat on Friday. Severe weather? No. But high potential outbreak? Yes.

No I am taking the position that’s it’s too early to be looking at it from that perspective. Yes a professional meteorologist did point it out. I’m not saying you should not take note and observe. That being said it’s way too soon to go from high end threat to oh it’s moisture starved in a matter of a few runs 5 days from the event.

 

[ColdFront]

18Z GFS actually makes Saturday look potent now. We may be entering the flip flop stage now.

 

[MMWX]

18Z GFS near Wicker, MS (Along I-20)

Moisture is no problem here.

 

[Clancy]

While Friday might not be as potent as previously modeled in more recent runs, I'm still quite concerned about Saturday afternoon. That's just not the kind of thing you like to see. 18Z kicks up that LLJ sooner while moisture and instability still abounds. Throw in that secondary low and you could be looking at a very nasty situation for the Deep South.

 

[ColdFront]

While Friday might not be as potent as previously modeled in more recent runs, I'm still quite concerned about Saturday afternoon. That's just not the kind of thing you like to see.

You must be like me Clancy. Setting there waiting for that square to turn blue on pivotal haha

 

[Clancy]

You must be like me Clancy. Setting there waiting for that square to turn blue on pivotal haha

I love me some pixel-staring contests, that's for sure!