Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Lake Charles la 
1247 PM CDT Wednesday may 22 2013 


Discussion... 
for 18z taf issuance. 


&& 


Aviation... 
local 88ds show lingering convection in associated with passing 
shortwave aloft and decaying frontal boundary over S-cntl 
la...thus included thunder at klft/kara through 20z to account. 
Expect this area of convection to eventually push eastward as the 
shortwave departs the region. Otherwise VFR conditions should 
eventually take over as drier air behind the front/shortwave takes 
hold. Low-level moisture trapped below the nocturnal inversion may 
be sufficient for some light fog/lower ceilings late tonight at 
the southern sites...otherwise VFR will continue through the period. 


25 


&& 


Previous discussion... /issued 942 am CDT Wednesday may 22 2013/ 


Discussion...a weakening frontal boundary has drifted into the 
area during this morning with scattered storms. The boundary is expected 
to become more diffuse and return north through the day, and with 
the boundary around more showers and storms can be expected, but 
mostly across the south and east half of the County Warning Area. 


The previous forecast remains on target and no major changes are 
needed at this time. 


Previous discussion... /issued 719 am CDT Wednesday may 22 2013/ 


Update... 
did a quick clean up to the pop and weather grids. Convective activity 
this morning is now confined to mainly south of I-10 and immediate 
coastal waters...as prefrontal trough and convective outflow 
boundary sags to the the south. Also...water vapor imagery showing 
drier and more stable air moving into the forecast area. Held on 
to slight to small chance probability of precipitation...as surface boundary will hang 
around the area...and may help focus daytime heating activity. 


Rua 


Previous discussion... /issued 652 am CDT Wednesday may 22 2013/ 


Discussion... 
22/12z taf issuance. 


Aviation... 
broken band of convection over southern portions of the area this 
morning...and expected to affect kbpt...klch...klft and kara for 
the next hour or two before pushing further south and diminishing. 
Periodic MVFR ceilings at these sites this morning will lift to VFR by 
midday. Otherwise...no precipitation expected at kaex with middle/high 
clouds decreasing through the day. Variable winds early this morning 
in the wake of convection will become more southerly late this morning 
into this afternoon. For tonight...light winds and moist ground could 
result in some patchy fog development after midnight. 24 


Previous discussion... /issued 411 am CDT Wednesday may 22 2013/ 


Discussion... 
an upper level trough from the Midwest down to East Texas will move 
eastward and help push a weak surface cool frontal boundary 
toward the forecast area today. Already showers and thunderstorms 
have formed...mainly north of the I-10...between the pre-frontal 
trough/convective outflow boundary and the surface front. Water 
vapor shows a jet streak moving across...helping to provide 
decent upper level divergence...which is giving a bit of an 
enhancement to the storms. There could be some isolated strong to 
marginal severe storms between now and dawn...with hail and 
straight line down burst winds the main severe aspects. 
Also...high moisture content and a bit of a training to the storms 
could provide some locally heavy rain with street flooding 
possible. And finally...frequent cloud to ground lightning will 
also occur with the storms. 


The upper level trough will gradually push east during the 
day...with a more stable and slightly drier air moving in behind 
it...with showers gradually decreasing from west to east by late 
morning to afternoon. 


Surface frontal system will linger across the forecast area on 
Thursday and Friday...that will combine with Gulf moisture and 
daytime heating to provide a slight chance of showers and 
thunderstorms each afternoon. 


Upper level ridging is then expected to build in over the Holiday 
weekend. This should end any rain chances. 


Rua 


Marine... 
a surface frontal boundary is expected to stall north of the 
coastal waters over the next couple of days. Meanwhile...high 
pressure is expected to ridge across the northern Gulf of Mexico 
from the east. The result should be mainly light onshore winds. 


Rua 


&& 


Preliminary point temps/pops... 
klch 86 71 87 71 89 / 30 10 20 10 20 
kbpt 87 72 87 71 88 / 50 10 20 10 20 
kaex 87 68 90 70 88 / 30 10 20 10 20 
klft 87 71 89 71 89 / 30 10 20 10 20 


&& 


Lch watches/warnings/advisories... 
la...none. 
Texas...none. 
GM...none. 
&& 


$$