U.S. Severe Weather Forecast (Previsión convectiva)

Hoy
Mañana
día tres

000 
acus01 kwns 231245 
swody1 
Storm Prediction Center ac 231243 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0643 am CST Sat Feb 23 2019 


Valid 231300z - 241200z 


..there is a moderate risk of severe thunderstorms this 
afternoon/evening for northern MS...northwestern Alabama...and southern 
parts of western and middle Tennessee... 


... 
A few strong tornadoes, as well as damaging winds and isolated large 
hail, will be possible this afternoon and evening primarily across 
parts of Mississippi, Alabama, and Tennessee. 


..MS/al/TN area today into early tonight... 
A surface cyclone across the northern Texas Panhandle will translate 
quickly northeastward to the mid MS valley by this evening and the 
upper Great Lakes overnight. The cyclone will deepen rapidly in 
conjunction with an ejecting midlevel shortwave trough and the 
left-exit region of a strengthening (100+ kt) mid-upper jet streak. 
The deepening cyclone will draw the moist warm sector northward from 
la/MS/al this morning to the Tennessee Valley later this afternoon/evening 
to the east of a weak cold front/pseudo-dryline, as a 50-60 kt 
low-level jet develops within the northern part of the warm sector. 
Marginally severe hail could occur with the stronger elevated storms 
across the mid MS valley, but the primary severe threat is expected 
farther to the south in the surface warm sector. 


Convection will increase in coverage/intensity beginning this 
morning across East Texas as large-scale ascent encounters the west 
edge of the moist sector, and storms will subsequently spread 
northeastward to The Ark-la-miss and mid south through early 
afternoon. Isolated large hail will be the main threat with the 
storms this morning. Farther east, surface heating in cloud breaks 
will result in destabilization within the open warm sector across MS 
by early afternoon. Surface temperatures in the mid-upper 70s with 
boundary-layer dewpoints of 68-70 f will support afternoon MLCAPE of 
1000-1500 j/kg, with only weak convective inhibition. Semi-discrete 
storms are expected within the lingering band of morning convection, 
and in the open warm sector, given strong deep-layer shear and 
substantial cross-boundary shear vectors. The tornado threat will 
be greatest from about 20-03z from central/northern MS into 
western/northern Alabama and southern middle Tennessee. Strong tornadoes will 
be possible given 0-1 km/effective srh of 300-500 m2/s2 and 
effective bulk shear near 60 kt in a moist environment. Thereafter, 
storms should weaken by 03-06z, though isolated tornado/damaging 
wind potential could persist a little longer into northeast 
Alabama/northwest Georgia where storms will encounter a remnant wedge front. 


.Thompson/Jewell.. 02/23/2019 


$$ 

Mesoscale Discussion


000 
acus11 kwns 231257 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 231257 
laz000-arz000-txz000-231500- 


Mesoscale discussion 0123 
National Weather Service Storm Prediction Center Norman OK 
0657 am CST Sat Feb 23 2019 


Areas affected...eastern Texas...western and northern 
Louisiana...southern Arkansas 


Concerning...severe potential...watch possible 


Valid 231257z - 231500z 


Probability of watch issuance...60 percent 


Summary...storms are expected to gradually develop over East Texas into 
la and southern Arkansas this morning. A few storms could become severe, 
and trends will be monitored for a possible watch. 


Discussion...as of 13z, a warm front extends from och Texas across 
northern la and into north-central MS, with a moist air mass to the 
south (upper 60s to near 70 f dewpoints). Morning soundings from the 
region indicate steep midlevel lapse rates in place, with a capping 
inversion just below 700 mb. As such, minor convective inhibition 
exists even for areas in the warm sector, such as lch where around 
50 j/kg mlcin was noted on the 12z sounding. 


Radar trends show increasing elevated thunderstorms over northeast 
TX, north of the warm front and closer to the upper vort Max track 
where cooling aloft will take place. However, a cold front is 
approaching the area from the west, and will eventually enhance lift 
both along the intersecting warm front and southward across the warm 
sector. During this time, the low-level jet will also strengthen to 
around 50 kt. 


Increasing lift of a moist air mass is expected to erode cin through 
late morning, with an eventual line of thunderstorms along the wind 
shift, some possibly supercells. Ample low-level effective srh would 
support a tornado threat along and south of the warm front, while 
hail is possible to the north. Thus, while the primary severe risk 
today will be along and east of the MS river, a watch is possible 
earlier today for western areas. 


.Jewell/Thompson.. 02/23/2019 


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


Attention...WFO...Jan...lzk...lch...shv...hgx... 


Latitude...Lon 30869552 31779510 32539486 33039447 33539379 33869314 
33879243 33659208 33189200 32699213 31669249 30829285 
30319397 30189457 30289519 30549538 30869552