Severe WX Severe Risk 2/23-2/24 (2 Viewers)


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If the junky mess can stay at bay Saturday morning ... spc seems concerned with discrete super cells.... and with the strong over head jet 70kt.... I can see the concern ... that help clear out convection In front of the negative tilted trough ....
 
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Really surprised at the lack of interest in this threat to be honest .. guess 5 days away still.... but this could n should be the be weather maker this week if the models hold through rest week ... tornado threat has increased on today s 12 z runs particular ark la Tex most Arkansas north ms ... western tenn and even kentucky ... impressive jet.... 70kts least Today’s runs showed a larger warm sector to work with too ....
 

andyhb

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Norman, OK
There are a lot of pieces on the board for a fairly significant event here. BL moisture quality is one of them, most guidance agrees on getting mid-upper 60s dewpoints over a rather expansive piece of real estate from the Arklamiss and Mid South eastward into the TN Valley on Saturday afternoon. The timing of the trough is another, with it kicking negatively tilted and ejecting ENE right during peak heating on Saturday. The wind fields are obviously strong given time of year and intensity of the shortwave. Shear vectors are well aligned with the pre-frontal trough to encourage semi-discrete/discrete storm modes assuming initiation.

I would like to see a bit more confidence on some drying aloft ahead of the pre-frontal surface trough (perhaps with some cloud breaks to increase instability a bit more) and also some more confidence in at least southerly surface winds ahead of the same feature. I also have concerns about the degree of warming aloft, as 500 mb and 300 mb temps are not particularly cold.

The 12z CIPS run for the SE domain showed a rather impressive list of analogs including at least 7 that resulted in at least one F/EF3 tornado in the region, which is quite a few for a winter setup given the typical uncertainty with thermodynamics. Listed below...

#2: 2/24/01 - deadly Pontotoc, MS F3 and several other strong tornadoes
#4: 3/1/07 - outbreak with Enterprise and Millers Ferry, AL EF4s and Americus, GA EF3
#6 2/17/08 - Prattville, AL EF3
#8: 1/10/08 - Caledonia, MS EF3 and several other strong tornadoes
#10: 1/20/88 - F4 in MS and a long tracked F3 starting east of Memphis
#12: 1/17/99 - Bemis/Jackson, TN F4 and several other strong tornadoes
#13: 1/24/97 - Murfreesboro, TN F4 and Tuscaloosa, AL F2
 

Timhsv

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There are a lot of pieces on the board for a fairly significant event here. BL moisture quality is one of them, most guidance agrees on getting mid-upper 60s dewpoints over a rather expansive piece of real estate from the Arklamiss and Mid South eastward into the TN Valley on Saturday afternoon. The timing of the trough is another, with it kicking negatively tilted and ejecting ENE right during peak heating on Saturday. The wind fields are obviously strong given time of year and intensity of the shortwave. Shear vectors are well aligned with the pre-frontal trough to encourage semi-discrete/discrete storm modes assuming initiation.

I would like to see a bit more confidence on some drying aloft ahead of the pre-frontal surface trough (perhaps with some cloud breaks to increase instability a bit more) and also some more confidence in at least southerly surface winds ahead of the same feature. I also have concerns about the degree of warming aloft, as 500 mb and 300 mb temps are not particularly cold.

The 12z CIPS run for the SE domain showed a rather impressive list of analogs including at least 7 that resulted in at least one F/EF3 tornado in the region, which is quite a few for a winter setup given the typical uncertainty with thermodynamics. Listed below...

#2: 2/24/01 - deadly Pontotoc, MS F3 and several other strong tornadoes
#4: 3/1/07 - outbreak with Enterprise and Millers Ferry, AL EF4s and Americus, GA EF3
#6 2/17/08 - Prattville, AL EF3
#8: 1/10/08 - Caledonia, MS EF3 and several other strong tornadoes
#10: 1/20/88 - F4 in MS and a long tracked F3 starting east of Memphis
#12: 1/17/99 - Bemis/Jackson, TN F4 and several other strong tornadoes
#13: 1/24/97 - Murfreesboro, TN F4 and Tuscaloosa, AL F2

Andy, Are you in school out there?
 
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334
Location
Madison, WI
Honestly not impressed by CAPE values at this point. First sniff of the NAM came in even less than the GFS. Think a forced squall line with damaging winds, maybe a few embedded tornadoes in the most likely outcome.
 
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Don’t forget Cape values do not have to be very high at all this time of year! Cold season events do not require that
Exactly ... there some pretty nasty analogs in cips ... Andy eluded to... most those events were not cape either.... cape is something a lot time are under done on global models .... that could change even.... still early ....
 

Kory

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Both the GFS and Euro have CAPE values in excess of 1,000 J/KG come Saturday...bullseye being Mississippi. As far as the NAM, it appears it keeps the warm sector socked in clouds...which looking at the dry punch at 700mb, doesn't quite make sense to me. I'd expect at least SOME breaks in the clouds with that dry air intrusion in the mid levels (thus, higher instability values).
 

Taylor Campbell

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Point soundings off the 06z, and 12z NAM near the bootheel of Missouri show:

* SBCAPE of 250-500 joules.
* Mid level lapse rates in excess of 7.
* SRH at the low, mid, and effective layers of 500 m2/s2.
* 110knt + upper level jet overtop a 70knt + low level jet.
 
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