U.S. Severe Weather Forecast (Convective Outlook)

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swody1 
Storm Prediction Center ac 240530 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1230 am CDT Fri Mar 24 2017 


Valid 241200z - 251200z 


..there is a slight risk of severe thunderstorms this afternoon and 
evening across parts of the southeastern plains into the Ozark 
Plateau and lower Mississippi Valley... 


..there is a marginal risk of severe thunderstorms across 
surrounding areas of the central and Southern Plains and Mississippi 
Valley... 


... 
Severe thunderstorms are possible today across portions of the 
southeastern plains into the lower Mississippi Valley. Strongest 
activity may impact portions of The Ark-la-tex late this afternoon 
and evening, accompanied by some risk for tornadoes. 


... 
The mid/upper flow regime appears likely to remain progressive, with 
models indicating troughing, within a couple of belts of westerlies 
emanating from the mid-latitude Pacific, advancing inland across the 
Canadian and U.S. Pacific coast during this period. As this occurs, 
an increasingly vertical stacked downstream southern branch 
lower/mid tropospheric cyclone is forecast to continue east of the 
central/southern High Plains, toward the mid/lower Mississippi 
Valley. The manner in which this occurs, and the rate of eastward 
motion, remain points of at least some variability/spread within the 
model output. 


At least some weakening/filling of the cyclone appears probable, but 
lower/mid tropospheric wind fields above the surface warm sector may 
still remain on the order of 50-70 kt. However, mid-level cooling 
to the south and east of the cyclone center appears likely to cut 
off the plume of elevated mixed-layer air emanating from the 
southern rockies/Mexican plateau region. And, given the state of 
the air mass over the Gulf of Mexico, a deep moist return flow off 
the Gulf appears unlikely. Models also suggest that attempts at 
low-level moistening may continue to be hampered by downward mixing 
of dry lower/mid tropospheric air, particularly near/east of the 
lower Mississippi Valley today through tonight. All of this 
contributes to uncertainty concerning the extent of the severe 
weather potential, but scattered thunderstorm activity may impact 
much of the lower central and Southern Plains into the lower half of 
the Mississippi Valley and southern portions of the Great Lakes 
region during this period. 


..plains/Mississippi Valley... 
A band of remnant cloud cover, from initial convection along the 
leading edge of mid-level cooling associated with the cyclone, may 
prevent or slow substantive pre-frontal dryline sharpening across 
the southeastern plains today. This adds to aforementioned 
uncertainties, but low-level moistening within an axis of stronger 
surface pressure falls forecast across parts of northeast Texas, 
northwestern Louisiana and western Arkansas by around 23-00z this 
evening seems to provide the best opportunity/focus for vigorous 
convective development. Destabilization probably will be at least 
marginally sufficient for severe storms, in the presence of strong 
deep layer wind fields and vertical shear which may include sizable 
clockwise curved low-level hodographs by early evening. The 
environment may become conducive to organized convection, including 
supercells with at least some risk for tornadoes, in addition to 
severe hail and locally strong surface gusts, before activity wanes 
across the lower Mississippi Valley overnight. 


Other strong storm development may not be out of the question in 
closer proximity to the mid-level cold core across parts of 
central/eastern Kansas and eastern Oklahoma late this afternoon and 
evening, with marginally severe hail and surface gusts possible. 


.Kerr.. 03/24/2017 


$$ 

Mesoscale Discussion


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Storm Prediction Center mesoscale discussion 240231 
okz000-txz000-ksz000-coz000-240330- 


Mesoscale discussion 0316 
National Weather Service Storm Prediction Center Norman OK 
0931 PM CDT Thu Mar 23 2017 


Areas affected...Texas and Oklahoma panhandles and southwest Kansas 


Concerning...Severe Thunderstorm Watch 78... 


Valid 240231z - 240330z 


The severe weather threat for Severe Thunderstorm Watch 78 
continues. 


Summary...an evolving line of thunderstorms will continue to move 
east into the overnight. Although an isolated large hail or damaging 
wind gust will be possible, the overall severe weather threat should 
diminish with time. 


Discussion...a surface cold front will continue to accelerate east, 
overtaking a dryline across the Texas and Oklahoma panhandles. The 
result will be a brief increase in thunderstorm intensity and 
coverage as low-level convergence increases, especially across the 
Texas and Oklahoma panhandles. However, with time, weakening 
instability, increasing convective inhibition, and decreasing 
surface moisture to the east should result in an overall weakening 
thunderstorm trend. As such, the Severe Thunderstorm Watch will be 
allowed to expire. 


.Marsh/Thompson.. 03/24/2017 


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


Attention...WFO...oun...ddc...gld...lub...Ama...maf...pub... 


Latitude...Lon 33620279 35750296 38120264 39140159 38980020 37049976 
35359971 34129983 33420005 32810096 32950241 33620279