U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 180545 
Storm Prediction Center ac 180544 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1144 PM CST Tue Jan 17 2017 

Valid 181200z - 191200z 

..there is a marginal risk of severe thunderstorms across portions 
of southwestern Louisiana and southeastern Texas... 

Isolated damaging wind gusts cannot be ruled out with thunderstorms 
tonight across portions of southwestern Louisiana and southeastern 

An area of midlevel cyclonic flow, and a jet streak along its 
eastern flank, are forecast to track eastward across portions of the 
south-central states. As this occurs, a weak wave is forecast to 
develop northeastward along a surface front draped from south Texas 
to the lower MS valley region. 

..portions of southwestern Louisiana and southeastern Texas... 
Despite the very modest low-level mass response to the approaching 
jet streak, onshore flow ahead of the wave will maintain a moist 
boundary layer across portions of the western/central Gulf Coast 
vicinity. Tuesday evening soundings at Lake Charles and Corpus 
Christi indicate mean mixing ratios around 13-15 g/kg, and similar 
moisture will support marginal buoyancy on the warm side of the 
front through the period. 

Areas of showers and thunderstorms will likely be continuing into 
the day across portions of eastern Texas and western la, in response to 
initial warm advection. Thereafter, a renewed potential for 
thunderstorm activity will likely accompany low-level ascent related 
to the progressive frontal wave tonight, after additional inland 
moistening occurs. Sufficient deep shear will exist around the jet 
streak to support weakly organized convective clusters, perhaps 
supporting localized damaging wind gusts. 

However, the presence of weak low-level flow and poor midlevel lapse 
rates will marginalize the severe risk. The marginal area has been 
confined to areas of anticipated greatest inland moistening amid the 
enhanced vertical shear, though areal reductions or removal of the 
marginal area may become necessary in subsequent outlooks. 

.Cohen/Dean.. 01/18/2017 


Mesoscale Discussion

acus11 kwns 180749 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 180749 

Mesoscale discussion 0068 
National Weather Service Storm Prediction Center Norman OK 
0149 am CST Wed Jan 18 2017 

Areas affected...Texas Gulf Coast 

Concerning...severe potential...watch unlikely 

Valid 180749z - 180915z 

Probability of watch issuance...5 percent 

Summary...isolated strong storms are possible early this morning 
along portions of the Texas Gulf Coast. While a brief tornado or 
damaging gust cannot be ruled out, a watch is not anticipated. 

Discussion...a cluster of strong thunderstorms is currently 
affecting portions of Wharton, Fort Bend, and Harris counties Texas. 
These storms appear to be along a well-defined quasi-stationary 
surface boundary. South of the boundary, moist and marginally 
unstable surface conditions are present with dewpoints near 70f. 
Modifying forecast soundings for these parameters would indicate an 
environment minimally favorable for rotating storms capable of gusty 
winds or a brief tornado. Recent trends in surface observations 
suggest there may be a weak mesolow to the southwest of these 
storms, which would potentially enhance the low level shear and lift 
for the next few hours. While severe weather is possible, the risk 
appears rather low and a watch is not currently anticipated. 

.Hart/Peters.. 01/18/2017 

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


Latitude...Lon 29819663 30699579 30799531 30569481 30099471 29259592 
29029643 29369676 29819663