U.S. Severe Weather Forecast (Convective Outlook)

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000 
acus01 kwns 280045 
swody1 
Storm Prediction Center ac 280043 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0643 PM CST Mon Feb 27 2017 


Valid 280100z - 281200z 


..there is a marginal risk of severe thunderstorms from eastern OK 
to southern MO... 


... 
Scattered thunderstorms are expected to develop this evening from 
eastern Oklahoma into the Missouri Ozark Plateau. Isolated large 
hail may be noted with the strongest updrafts. 


..eastern OK to southern MO... 


Convection that developed over northeastern Texas along an early-day 
outflow has mostly dissipated this evening. One remnant supercell 
over Camp County is weakening with loss of daytime heating and 
further development is becoming less likely. However, farther north 
across eastern OK/northwest AR, low-level warm advection is 
generating deep convection. Updrafts are now producing lightning 
and scattered thunderstorms should increase in areal coverage with 
movement expected toward the Ozark Plateau. Mid-level lapse rates 
are quite steep across this region with values on the order of 8 
c/km and 00z sounding from oun exhibits MUCAPE around 2000 j/kg. It 
appears hail could accompany the strongest storms as vertical shear 
supports organized rotating updrafts. 


... 


Remnants of central Gulf states mesoscale convective system have progressed into southeast 
Alabama/southwest Georgia. Eastward momentum should allow this activity to 
progress toward the Georgia/SC coast later this evening. While mid-level 
lapse rates are relatively steep across this region, marginal 
moisture and the lack of large-scale support suggest the severe 
threat will be limited. 


.Darrow.. 02/28/2017 


$$ 

Mesoscale Discussion


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acus11 kwns 271604 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 271603 
txz000-271730- 


Mesoscale discussion 0216 
National Weather Service Storm Prediction Center Norman OK 
1003 am CST Mon Feb 27 2017 


Areas affected...north central and northeast Texas 


Concerning...severe potential...watch possible 


Valid 271603z - 271730z 


Probability of watch issuance...40 percent 


Summary...potential exist for isolated supercells to develop over 
north central Texas by late morning and continue into a portion of 
northeast Texas this afternoon. Primary threat will be large hail 
though a brief tornado cannot be ruled out. 


Discussion...isolated storms are developing over north central Texas 
this morning within a weak warm advection regime. Objective analysis 
shows the atmosphere to be moderately unstable with around 1500 j/kg 
MUCAPE, but the storms are currently elevated. Widespread clouds 
will slow boundary-layer warming. However, unidirectional wind 
profiles with effective bulk shear of 40-45 kt and moderate 
instability is sufficient to support updraft rotation with these 
cells including potential for left splits which may augment the 
threat for large hail. With time, a gradual warming and moistening 
of the boundary layer may result in surface based activity. The 0-1 
km hodograph size is relatively small except in vicinity of warm 
front/outflow boundary over northeast Texas where the boundary layer is 
stable. A threat for a tornado will exist if low-level 
destabilization occurs in vicinity of this boundary during the 
afternoon as storms move east and interact with it. Subsidence 
drying aloft and warming due to eastward advection of elevated mixed 
layer plume will eventually cap the atmosphere from the west with 
time, suggesting a relatively small window for storms to organize 
and become severe in this region. 


.Dial/Hart.. 02/27/2017 


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


Attention...WFO...shv...fwd... 


Latitude...Lon 32319790 33199678 33149498 32669431 31929486 31649749 
32319790