April 19th Severe Event

[Bob's Burgers]

 

 ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 160845
   SPC AC 160845

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0345 AM CDT Thu Apr 16 2020

   Valid 191200Z - 241200Z

   ...DISCUSSION...
   Models have come into better agreement depicting a shortwave trough
   moving quickly from TX Sunday/D4 morning to GA by 12Z Monday/D5. Low
   pressure is forecast to develop over the Red River during the day
   Sunday, shifting east toward the lower MS Valley by 00Z. Ahead of
   the low, a warm front will lift north across the Gulf Coast states,
   with upper 60s F dewpoints likely into central MS, AL, and GA, with
   low 70s F along the coast. MUCAPE to at least 2000 J/kg is likely by
   18Z from TX into AL, with strong westerly winds aloft and 500 mb
   temperatures on the order of -10 to -12 C. 

   Storms are forecast to form relatively early over east TX, where the
   environment will support large hail and damaging winds. Supercells
   are possible initially, with an eventual MCS likely. A tornado or
   two will be possible despite marginal low-level shear. Meanwhile to
   the east, warm advection may support supercells well ahead of the
   MCS across MS, AL, GA, producing a tornado or two along with hail. 

   The primary severe risk in terms of coverage will likely be an MCS
   tied to the surface low as it quickly moves along the east-west
   instability gradient across LA, MS, AL and into GA. Significant
   convective feedback is present in the models, supporting the notion
   of a well-defined MCS with damaging winds. While SRH will not be
   very strong initially, it should increase after 00Z, with enhanced
   wind and/or tornado potential. The corridor of maximum threat will
   likely be adjusted in later outlooks.

[Jessy89]

 

ZCZC SPCSWOD48 ALL  ACUS48 KWNS 160845  SPC AC 160845  Day 4-8 Convective Outlook    NWS Storm Prediction Center Norman OK  0345 AM CDT Thu Apr 16 2020  Valid 191200Z - 241200Z  ...DISCUSSION...  Models have come into better agreement depicting a shortwave trough  moving quickly from TX Sunday/D4 morning to GA by 12Z Monday/D5. Low  pressure is forecast to develop over the Red River during the day  Sunday, shifting east toward the lower MS Valley by 00Z. Ahead of  the low, a warm front will lift north across the Gulf Coast states,  with upper 60s F dewpoints likely into central MS, AL, and GA, with  low 70s F along the coast. MUCAPE to at least 2000 J/kg is likely by  18Z from TX into AL, with strong westerly winds aloft and 500 mb  temperatures on the order of -10 to -12 C.   Storms are forecast to form relatively early over east TX, where the  environment will support large hail and damaging winds. Supercells  are possible initially, with an eventual MCS likely. A tornado or  two will be possible despite marginal low-level shear. Meanwhile to  the east, warm advection may support supercells well ahead of the  MCS across MS, AL, GA, producing a tornado or two along with hail.   The primary severe risk in terms of coverage will likely be an MCS  tied to the surface low as it quickly moves along the east-west  instability gradient across LA, MS, AL and into GA. Significant  convective feedback is present in the models, supporting the notion  of a well-defined MCS with damaging winds. While SRH will not be  very strong initially, it should increase after 00Z, with enhanced  wind and/or tornado potential. The corridor of maximum threat will  likely be adjusted in later outlooks.

Lordy I hope this isn’t like the past event.


.

[rnj79]

i'm just on the fringe in Baton Rouge!

[Orangeburgwx]

 

ZCZC SPCSWOD48 ALL  ACUS48 KWNS 160845  SPC AC 160845  Day 4-8 Convective Outlook    NWS Storm Prediction Center Norman OK  0345 AM CDT Thu Apr 16 2020  Valid 191200Z - 241200Z  ...DISCUSSION...  Models have come into better agreement depicting a shortwave trough  moving quickly from TX Sunday/D4 morning to GA by 12Z Monday/D5. Low  pressure is forecast to develop over the Red River during the day  Sunday, shifting east toward the lower MS Valley by 00Z. Ahead of  the low, a warm front will lift north across the Gulf Coast states,  with upper 60s F dewpoints likely into central MS, AL, and GA, with  low 70s F along the coast. MUCAPE to at least 2000 J/kg is likely by  18Z from TX into AL, with strong westerly winds aloft and 500 mb  temperatures on the order of -10 to -12 C.   Storms are forecast to form relatively early over east TX, where the  environment will support large hail and damaging winds. Supercells  are possible initially, with an eventual MCS likely. A tornado or  two will be possible despite marginal low-level shear. Meanwhile to  the east, warm advection may support supercells well ahead of the  MCS across MS, AL, GA, producing a tornado or two along with hail.   The primary severe risk in terms of coverage will likely be an MCS  tied to the surface low as it quickly moves along the east-west  instability gradient across LA, MS, AL and into GA. Significant  convective feedback is present in the models, supporting the notion  of a well-defined MCS with damaging winds. While SRH will not be  very strong initially, it should increase after 00Z, with enhanced  wind and/or tornado potential. The corridor of maximum threat will  likely be adjusted in later outlooks.

I guarantee that 30% moves further east this afternoon/tomorrow

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[Jessy89]

I think this one will stay a lot further south then the last


.

[Orangeburgwx]

I think this one will stay a lot further south then the last


.

Trend to watch is the placement of the low... Further North is climbs, more severe the chance

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[Bob's Burgers]

9 minutes ago, Orangeburgwx said:

Trend to watch is the placement of the low... Further North is climbs, more severe the chance

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here's the spread so far

 

[Bob's Burgers]

[Orangeburgwx]

That is from 6z though...

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[Orangeburgwx]

here's the spread so far
 

Tightest cluster is in NW Arkansas...

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[buckeyefan1]

2 minutes ago, Orangeburgwx said:

Tightest cluster is in NW Arkansas...

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You mean Mississippi 

[Orangeburgwx]

You mean Mississippi 

Yeah, thank you

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[Orangeburgwx]

How can the SARS be 100% TOR with hardly any CAPE?...

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[Bob's Burgers]

30 minutes ago, Orangeburgwx said:

That is from 6z though...

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yeah i mean the 12z gfs wasn't far enough out yet so i had use that 06z gfs. 12z gfs looks less impressive than the 06z gfs for sure

[Bob's Burgers]

also, hrrrv4 is back on COD, so get ready for 48 hour HRRR forecasts haha

[janetjanet998]

Just like last event, some models are picking up on a meso low SE of the main low days in advance...

and the new  GFS just in shows yet another one of these next Weds  afternoon/night across the deep south...

In addition to any discrete supercells,  likely more embedded fast moving spin ups  in a complex at night which can really pad the tornado count

106 confirmed from the last event so far

edit: per GFS, and yet another one next weekend ..has another tiny meso low ..

 

 

 

 

 

 

 

 

 

[Santa Clause]

This looks to be another high end severe event, given not quite as widespread or severe  as the last. Time for this all to play out, but lots of signs pointing toward severe weather Sunday.

[Orangeburgwx]

 

 

 

Just like last event, some models are picking up on a meso low SE of the main low days in advance...

and the new  GFS just in shows yet another one of these next Weds  afternoon/night across the deep south...

In addition to any discrete supercells,  likely more embedded fast moving spin ups  in a complex at night which can really pad the tornado count

106 confirmed from the last event so far

edit: per GFS, and yet another one next weekend ..has another tiny meso low ..

 

 

 

 

 

 

 

 

 

 

The one next weekend looks to be ugly for SC, this was the CAPE for my location at hr222 (if it holds serve... Which I doubt)but still need to monitor it

 

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[Bob's Burgers]

UKmet soundings out of Louisiana Sunday

 

[Orangeburgwx]

UKmet soundings out of Louisiana Sunday
 

All I can say is YIKES

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[janetjanet998]

DAY 3 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
0234 AM CDT FRI APR 17 2020  
  
VALID 191200Z - 201200Z  
  
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN  
TEXAS EASTWARD ACROSS THE GULF COAST STATES...  
   
..SUMMARY  
  
SEVERE STORMS ARE LIKELY SUNDAY ACROSS THE GULF COAST STATES. THE  
GREATEST THREAT APPEARS TO BE FROM LOUISIANA TO GEORGIA, WITH  
SIGNIFICANT SEVERE STORMS EXPECTED INCLUDING TORNADOES AND DAMAGING  
WINDS. LARGE HAIL IS LIKELY AS WELL.  
   
..SYNOPSIS  
  
A LOW-AMPLITUDE SHORTWAVE TROUGH WITH 60-70 KT MIDLEVEL SPEED MAX  
WILL MOVE FROM THE SOUTHERN PLAINS ACROSS THE LOWER MS VALLEY DURING  
THE DAY, AND WILL REACH THE EAST COAST BY 12Z MONDAY. PRECEDING THIS  
TROUGH, A BROAD AREA OF 50 KT MIDLEVEL WESTERLIES WILL EXIST ACROSS  
THE ENTIRE SOUTHEASTERN CONUS.  
  
AT THE SURFACE, MID-TO-UPPER 60S F DEWPOINTS WILL SURGE NORTH BEHIND  
A WARM FRONT, LOCATED ROUGHLY FROM SOUTHERN AR TO CENTRAL MS, AL AND  
GA BY 18-21Z. MEANWHILE, A DRYLINE WILL DEVELOP EASTWARD ACROSS TX,  
WITH A WEAK SURFACE LOW NEAR THE ARKLAMISS BY 00Z. AS THE SHORTWAVE  
TROUGH APPROACHES, SOUTHWESTERLY 850 MB WINDS WILL INCREASE TO 30-40  
KT DURING THE DAY, AND OVER 50 KT AFTER 00Z. THIS WILL RESULT IN AN  
EXPANSIVE AREA OF FAVORABLE MOISTURE, INSTABILITY AND SHEAR, WITH  
NUMEROUS SEVERE STORMS POSSIBLE THROUGH THE PERIOD.  
   
..EAST TX TO GA AND SC  
  
EARLY DAY STORMS ARE LIKELY TO BE ONGOING OVER NORTHERN MS AND AL  
RELATED TO WARM ADVECTION. THESE STORMS MAY POSE A HAIL THREAT  
INITIALLY. WITH TIME, THESE STORMS MAY TRANSITION TO SURFACE BASED,  
WITH AN EVOLVING THREAT OF DAMAGING WINDS OR TORNADOES FROM AL INTO  
GA COINCIDENT WITH A 300+ M2/S2 ESRH MAX.  
  
TO THE WEST, OTHER STORMS ARE LIKELY EARLY TO MIDDAY OVER EASTERN  
TX, BUT STORM MODE IS UNCERTAIN. GIVEN THE INCREASING LIFT,  
ESPECIALLY AFTER 18Z ACROSS LA AND MS, AN MCS WILL BE POSSIBLE. IN  
ADDITION, SUPERCELLS, POSSIBLY TORNADIC, MAY FORM AHEAD OF ANY MCS  
OVER LA AND MS. THE GENERAL MODEL TREND IS FOR UPSCALE GROWTH, AND  
THIS COULD BE A COMBINATION OF STORM MODES. AT ANY RATE, TORNADOES,  
DAMAGING WIND, AND LARGE HAIL WILL ALL BE POSSIBLE.  
  

[Snowstorm920]

Loaded gun sounding on the 12z NAM in southern Alabama 

 

[jpeters3]

The first NAM NEST is a similar story to last event.  Shows a very volatile environment over LA/MS at 2100-0000 UTC, but mainly grungevection with a trailing MCS, rather than discrete supercells.

Some very impressive looking forecast soundings though.

 

[DanLarsen34]

1 hour ago, jpeters3 said:

The first NAM NEST is a similar story to last event.  Shows a very volatile environment over LA/MS at 2100-0000 UTC, but mainly grungevection with a trailing MCS, rather than discrete supercells.

Some very impressive looking forecast soundings though.

 

Notice less VBV in this compared to one of the other posts. Crazy that we might be looking at another high-end event if things come together. 

[Quincy]

Looking at forecast soundings, the setup looks similar to last Sunday. If we were to nitpick, wind speeds may be slightly less impressive, although still favorable, along with modestly less steep mid-level lapse rates. On the flip side, relatively large 0-3km instability is progged, particularly south of I-20.

The warm front should end up verifying farther south than last week as well, which is evident in model progs and the SPC enhanced risk area.

Analog data is tempered slightly compared to last Sunday as well, but still supports at least an ENH and possibly another MDT risk outlook. 

[jojo762]

Per 12z NAM, a large severe weather outbreak appears to be evolving over much the of the southeastern states... Tornadoes (some strong), damaging winds, and large hail will all be likely.

0-1KM SRH on the order of 200-300m^2/s^2 will be prominent across most of the warm sector, atop  50-70kt effective shear, and unlike last week, instability will not be much of an issue with 2000-3000J/KG CAPE at any parcel of your choosing. Something, to me, that points to possibly greater tornado potential than last sunday is that 0-3km lapse rates are going to be much more impressive with 6-7C/km in forecast soundings across the region. 

Storm mode could be an issue, again though... Along with the potential for blobs of WAA precipitation INVOF of the warm front. Also a good possibility that the warm front barely makes it more than a few counties from the coast (especially in AL/MS), OR that late morning convection pushes the effective warm front further south via outflow... This would spatial confine the tornado threat to a much smaller area than the NAM would indicate.

Altogether, given various uncertainties with regard to extent of late morning warm sector convection, and northward extent of the higher theta-e air, it looks like a 10% sig tor type day, with the possibility of a MDT 15% if lesser detrimental late morning convection and coincident northward extent of warm front becomes more clear.

[TampaTwo]

If I had to make a call from 48 hours out, I would park myself in Hattiesburg MS and let it ride.....seems to be the best bullseye spot, although certainly not ideal for storm chasing visibility. 

[magpiemaniac]

1 hour ago, TampaTwo said:

If I had to make a call from 48 hours out, I would park myself in Hattiesburg MS and let it ride.....seems to be the best bullseye spot, although certainly not ideal for storm chasing visibility. 

And certainly not ideal for homeowners in the area either.  People just don’t need this crap right now.  They have enough on them already.

[andyhb]

Probably worth noting that while the progged warm sector on the models is not especially extensive in terms of northward extent, it is very extensive in the longitudinal (W-E) direction. This matters when you have a setup with westerly winds aloft.

[cheese007]

2 hours ago, jojo762 said:

Something, to me, that points to possibly greater tornado potential than last sunday is that 0-3km lapse rates are going to be much more impressive with 6-7C/km in forecast soundings across the region. 

Considering how prolific Sunday ended up being, that says a lot