U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 191957 
Storm Prediction Center ac 191956 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0156 PM CST Tue Feb 19 2019 

Valid 192000z - 201200z 

..there is a marginal risk of severe thunderstorms across parts of 
East Texas into the lower MS valley... 

Isolated, marginally severe storms are possible today from East 
Texas to southern Arkansas and central Mississippi, and overnight in 
the southern/eastern Louisiana and southwestern/central Mississippi 

..20z update... 
Several adjustments have been made to the general thunderstorm area 
to account for current convective trends. Otherwise, no changes have 
been made to the marginal risk extending from parts of East Texas into 
the lower MS valley. There still appears to be some potential for 
near-surface-based thunderstorm development late in the period 
(mainly from 08-12z early Wednesday morning) across parts of 
southern la into southern/central MS as surface dewpoints increase 
into generally the low to mid 60s. For now, the wind/tornado threat 
still appears too isolated/marginal to include a slight risk across 
this region, mainly due to the weak instability expected. 

.Gleason.. 02/19/2019 

Previous discussion... /issued 1030 am CST Tue Feb 19 2019/ 

..East Texas/arklatex to lower Mississippi Valley... 
Very isolated marginally severe hail is a possibility through the 
afternoon and early evening primarily across far East Texas toward the 
arklamiss vicinity. Elevated buoyancy and strong shear through the 
cloud-bearing layer could support hail growth, although the modest 
nature of the elevated buoyancy and the commonality of updraft 
interference will curb the overall hail potential. 

Later tonight, as the upper trough glancingly influences the region 
and weak height falls begin to occur, steady boundary-layer 
moistening and destabilization are expected in conjunction with weak 
surface cyclogenesis (~1010 mb) across the lower Mississippi Valley. 
Although the more consequential forcing for ascent will be focused 
to the north, thermodynamic profiles should trend more conducive for 
near-surface based convection late tonight coincident with 60s f 

That said, relatively weak lapse rates progged by various forecast 
soundings suggest the bulk of the convection may be subtly rooted 
atop shallow near-surface stability. 12z-based convection-allowing 
models imply only limited storm intensity/organizational character 
through the period, and if anything, indicate a slight downward 
intensity trend from prior 00z runs. Regardless, given strong 
deep-layer/low-level shear, at least a conditional risk for damaging 
wind and/or some tornado potential will exist after 06z/midnight 
local time through the early morning hours of Wednesday. 


Mesoscale Discussion

acus11 kwns 191807 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 191807 

Mesoscale discussion 0109 
National Weather Service Storm Prediction Center Norman OK 
1207 PM CST Tue Feb 19 2019 

Areas affected...portions of central Oklahoma and vicinity 

Concerning...winter mixed precipitation 

Valid 191807z - 192200z 

Summary...an area of precipitation lifting northward from the Red 
River will encounter colder air to the north. Both freezing rain and 
sleet will be possible within the I-44 corridor, including the okc 
Metro area. Farther northwest, snow will be more likely. Heaviest 
precipitation should occur between 2-4 PM CST. 

Discussion...current radar mosaic shows an area of precipitation 
moving northward out of North Texas and crossing the Red River. 
Temperatures in the I-44 corridor have risen slightly since this 
morning to the low 30s with upper 20s to the northwest. A 
complicating factor in where the highest freezing rain potential 
will exist is the warmer surface temperatures in northeast Oklahoma 
leading to modest warm air advection into the discussion area. 
Dewpoints remain in the low 20s in that region, however, and some 
decrease in temperature due to precipitation-cooled air is possible 
as drier air continues to advect in. The 18 UTC oun sounding shows a 
pronounced, saturated warm nose of +3-4c centered around 825 mb. 
This would indicate that freezing rain will be the predominant 
precipitation in this area, though some sleet is possible within 
heavier/convective elements. Farther to the northwest, generally 
colder 850 mb temperatures should keep more of the precipitation as 
snow. Expect the heaviest precipitation to occur from 2-4 PM CST. 

.Wendt.. 02/19/2019 

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


Latitude...Lon 35329988 36349820 36769713 36599657 36299623 36039618 
35589617 35379612 34839690 34289775 34209850 34529929 
34599970 35329988