Severe WX Severe Weather Event April 13-14, 2019

[warneagle]

Good lord. 12Z 3K NAM has at least one nasty streak of UH across the ARLATEX tomorrow afternoon/evening.

HRRR has oversold a couple events this year but did pretty well with 3/3. Even half of what it shows would be bad.

Yeah the 3km NAM isn’t quite as aggressive with the prefrontal convection and still has some of the VBV issues that aren’t really there on the HRRR for the most part.

 

[Kory]

Yeah the 3km NAM isn’t quite as aggressive with the prefrontal convection and still has some of the VBV issues that aren’t really there on the HRRR for the most part.

With the kind of upper level diffluence over the warm sector, I don’t see how we DON’T have discrete pre boundary convection.

 

[South AL Wx]

Latest timing from BMX. The bad thing about the timing is that the severe storms may occur during Palm Sunday church services, especially for central and eastern areas:

 

[CheeselandSkies]

Shreveport's local AFD is one of the more ominous I have read in several years, and rightly so with the parameters that are setting up.

 

[Richardjacks]

Latest timing from BMX. The bad thing about the timing is that the severe storms may occur during Palm Sunday church services, especially for central and eastern areas:

I think this shows the lack of confidence in the timing and how that timing is very important when it comes to CAPE. For example, if there are storms in west alabama at 2am, does that line keep moving or slow down? If it stays west of I-65, there could be a significant risk for midday in central/eastern areas...what if it stays west of the state line through 6am? Storms will not reach I65 until around 10-11am, we could be looking at a much higher risk from there east.

 

[kcyalater]

I think this shows the lack of confidence in the timing and how that timing is very important when it comes to CAPE. For example, if there are storms in west alabama at 2am, does that line keep moving or slow down? If it stays west of I-65, there could be a significant risk for midday in central/eastern areas...what if it stays west of the state line through 6am? Storms will not reach I65 until around 10-11am, we could be looking at a much higher risk from there east.

These kinds of timing issues have to drive mets mad. The potential is there for a fair amount of risk, but its dependent on factors that will not be worked out until hours before the show starts in Alabama.

 

[Kory]

ARW/NSSL and now the GFS are picking up on convection firing off during the evening hours over Western and NW AL well ahead. I think the models are under estimating the prefrontal convection looking at the forcing and upper level diffluence.

 

[NorthGaWeather]

NWS Peachtree City as of this morning has damaging winds as primary threat with “a few tornadoes can’t be ruled out”. Is there a limiting factor making a tornado threat less obvious for North Georgia? Maybe storms along the cost robbing us of instability?

Tornadoes will be possible. Instability will be a possible issue, but I don't think it'll be because of coastal convection. More of a timing and meager lapse rates problem. I don't think we'll have an issue maintaining severe convection, however that's the possible caveat to me.

 

[TornadoFan]

Yikes.

 

[apocalyptic_pleasures]

I think this shows the lack of confidence in the timing and how that timing is very important when it comes to CAPE. For example, if there are storms in west alabama at 2am, does that line keep moving or slow down? If it stays west of I-65, there could be a significant risk for midday in central/eastern areas...what if it stays west of the state line through 6am? Storms will not reach I65 until around 10-11am, we could be looking at a much higher risk from there east.

Sounds like if we don't want severe in Alabama then we want to get this thru as early as possible. Any risk of more storms firing if the line moves thru too soon?

 

[Richardjacks]

I think the risk would be less due to rain cooled air and leftover stratus....shear will be decreasing later before the environment recoups.

 

[Joey B]

FXUS64 KJAN 121656
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
1156 AM CDT Fri Apr 12 2019

...SEVERE WEATHER OUTBREAK SATURDAY AFTERNOON AND SATURDAY NIGHT...

.UPDATE...
Updated for morning discussion.

&&

.DISCUSSION...

The near term forecast update doesn't feature many changes with
lingering showers along the stalled boundary. We still expect
storms to redevelop with return flow late this afternoon and
evening, and a marginal risk for severe storms has been added for
this period as CAM guidance is suggesting the potential for
intense updrafts with hail potential. Looking ahead to the
expected severe weather outbreak late Saturday into Saturday
night, the most recent guidance suggests the greater severe
probabilities could expand eastward...more on this later in the
afternoon. /EC/

IEM :: AFD from NWS JAN https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=AFDJAN&e=201904121656

 

[Justin Hindman Hindy]

Just a foolish statement.

Let me rephrase that. West of I 65, but if the cape is underdone and it slows a little, could be a red letter day

 

[warneagle]

New day 2 should be up shortly. Not sure if we should be expecting any changes (I assume not).

 

[South AL Wx]

New day 2 should be up shortly. Not sure if we should be expecting any changes (I assume not).

Looks about the same as far as the MDT risk area. It does look like the ENH risk was expanded a little farther to the east, into far western Alabama:

 

[Richardjacks]

since this goes to 7am, this follows BHM outlook with just a little adjustment. From new day 2:
Some lingering questions about the tornado risk remain due in part
to some conditional factors yet to occur. However, it appears the
tornado risk may maximize in 2 corridors. First, a diurnally
focused tornado risk (primarily supercellular) across northern LA
into far southern AR vicinity between 3-9pm. A second area of
potential concern may focus from northeast LA near the MS River
east-northeast across central and into parts of northeast/east MS
during the evening into the overnight. A mix mode of supercell/QLCS
or hybridization of the two within a convective line are possible.
Along with damaging gusts, strong tornadoes may also occur with a
few of the most intense storms. While the pre-frontal, cellular
convection should diminish overnight, a semi-organized band of
storms -- with embedded rotating updrafts and continued
severe/tornado potential -- will move across the central Gulf Coast
states through the end of the period.

 

[warneagle]

I think the hail probs also decreased from 30 to 15

 

[Kory]

I think the hail probs also decreased from 30 to 15

Too much cloud seeding and not isolated enough convection.

 

[weunice]

Last few times we had a high end setup in this part of the country (north LA) we got MORE convection than was expected that choked things off. Is this a possibility here? Is that part of the uncertainty with this setup?

 

[Richardjacks]

Yes, I think that is a possibility...but I wouldn't say likely