U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 292002 
Storm Prediction Center ac 292000 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0300 PM CDT Wed Mar 29 2017 

Valid 292000z - 301200z 

..there is an enhanced risk of severe thunderstorms for the 
Missouri and Arkansas Ozarks... 

..there is an enhanced risk of severe thunderstorms for southeast 
Texas northeast into the lower Mississippi Valley... 

..there is a slight risk of severe thunderstorms for East Texas and 
lower Mississippi Valley and Ozark Plateau... 

..there is a marginal risk of severe thunderstorms surrounding the 
slight risk... 

Severe thunderstorms are expected this afternoon into tonight from 
parts of East Texas, eastern Oklahoma, and southeast Kansas into the 
lower and middle Mississippi Valley. Large hail, tornadoes, and 
damaging winds will be possible especially later this afternoon and 

The biggest substantial changes have been dictated in part to 
upper-air raob data from lzk (19z raob) and short-term model trends 
(time-lagged hrrr model). Have confined the 10-percent tornado to 
the Ozarks and in a corridor from the lower Sabine valley 
northeastward into northeastern la and far west-central MS. Have 
removed the significant tornado delineation based on instability 
concerns and prior convective overturning earlier today and recent 
surface analysis displaying a slower-than-expected recovery. 

.Smith.. 03/29/2017 

Previous discussion... /issued 1147 am CDT Wed Mar 29 2017/ 

..Ozarks/lower MO valley to arklatex/lower MS River Valley... 
The closed upper trough currently over the south-Central Plains at 
late morning will continue a slow-general-northeastward advance 
toward the lower MO River Valley through late tonight and early 
Thursday. Ahead of this system, 12z regional observed soundings 
reflected considerable lapse-rate-related impacts from the 
overnight/early morning squall line that continues to move generally 
east-northeastward and decay across the Ozarks and Ark-la-tex 
vicinity. This may have ramifications on the 
extensiveness/likelihood of significant hail potential, for 
instance, although the air mass will recover/gradually moisten and 
destabilize to the south of a northward-moving warm front across the 
Ozarks/lower MO valley, and ahead (east) of a slow-eastward-moving 
cold front. 

Latest thinking is that surface-based storms will develop as early 
as mid-afternoon near the eastern Kansas surface low southward along the 
front, including far eastern portions of Kansas/OK into western portions 
of MO/AR. Moderate low-level hodograph curvature (beneath strong but 
somewhat backed mid-level southwesterly winds) and resultant strong 
low-level shear/srh will support a tornado risk aside from large 
hail and evolving damaging wind risk into this evening. 

Farther south, storms may diurnally be a bit more isolated across 
the remainder of the arklatex vicinity, although an ongoing 
quasi-linear cluster across near-coastal southeast Texas may persist 
east-northeastward into la as it favors a zone of outflow-related 
weak boundary/zone of differential heating. This cluster and other 
peripheral development may pose a damaging wind/tornado risk through 
the afternoon and evening hours. 

Later tonight, storms should increase in coverage/intensity 
initially across portions of Arkansas/la as forcing for ascent/DPVA 
increases related to an east/northeastward-ejecting vorticity maxima 
within the base of the larger-scale trough. Related mass response 
should result in increasingly strong low-level winds/confluence. A 
mixed Mode of storms should be prevalent, with hail initially 
possible prior to a more common damaging wind/embedded tornado risk 
as storms toward/across the MS river late tonight. 


Mesoscale Discussion

acus11 kwns 300034 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 300034 

Mesoscale discussion 0372 
National Weather Service Storm Prediction Center Norman OK 
0734 PM CDT Wed Mar 29 2017 

Areas affected...portions of far northeast Texas...western/central 
Arkansas...and far southeast Oklahoma 

Concerning...Tornado Watch 100... 

Valid 300034z - 300200z 

The severe weather threat for Tornado Watch 100 continues. 

Summary...some potential for occasional damaging winds and a tornado 
or two continues across eastern portions of the watch. Farther 
southwest near the arklatex, thunderstorms may increase in coverage 
through the evening, with a conditional threat for a few damaging 
wind gusts and perhaps a tornado. 

Discussion...the ongoing threat for damaging winds and a couple 
tornadoes is focused over northeastern portions of Tornado Watch 100 
this evening. Several cells in this area have exhibited supercell 
structures, with occasional mid/low-level rotation noted on regional 
radars. The 00z lzk sounding as well as recent vwp data indicate 
sufficient veering of low-level flow with height, supportive of 
occasional rotation as these cells interact with a corridor of upper 
50s/lower 60s dew points. This zone of favorably backed surface flow 
ahead of ongoing convection should continuing shifting northeast 
towards Missouri over the next few hours, with the resultant spatial 
maximum in tornado/damaging-wind potential also gradually lifting 
into Missouri later this evening. 

Farther southwest, sustained convection has struggled to organize 
near the arklatex, likely due to some subsidence aloft in the wake 
of prior ascent. However, as another wave of ascent rotates around 
the main trough and reaches the region late this evening, 
moistening/cooling aloft may sustain more organized convection, with 
an attendant threat for a few damaging wind gusts and perhaps a 

.Picca.. 03/30/2017 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 33059495 34389466 36549305 36489158 35099238 33389343 
32939423 33059495