817 
fxus64 kshv 101000 
afdshv 


Area forecast discussion 
National Weather Service Shreveport la 
400 am CST Wednesday Mar 10 2010 


Discussion... 
a well defined warm frontal boundary...evident by dewpoint 
gradient and low cloud cover south of boundary...moving very 
slowly north...currently near Interstate 20. Very isolated overnight 
convection has fired along the boundary. Vigorous upper low seen 
on water vapor racing across New Mexico. Some energy from 
preexisting upper low over NE/IA...become absorbed in this low 
as it moves across the Texas Panhandle into northern OK later today. 
As this energy will not come into play until afternoon hours to 
coincide with diurnal heating...keeping probability of precipitation low during morning hours. 
A good combination of decent low level dynamics...upper level 
diffluence...and steep lapse rates will bring convection to the 
area. The absence of upper level clouds...which have been an 
inhibiting factor in past several events...will aid 
instability...and thus enhance severe potential with some storms. 
Overall moisture is lacking...a limiting factor in storm coverage. 
Have lowered probability of precipitation to chance category...and could even be close to 
isolated in coverage. Dicrete supercell storms and or a narrow squall 
line possible in this scenario. However..do believe low level veering 
a little weak for tornadic outbreak. Dry slotting should affect 
East Texas late in the day...keeping probability of precipitation isolated across western County Warning Area by 
evening. Dry line boundary will slow down across la...so could see 
some convection eastern sections beyond midnight. Debated on 
patchy fog south of boundary this morning...apparently south winds 
have kept fog light thus far so decided not to include in zones. 


Low pressure to reform over upper Midwest...short waves around 
this large circulation should clip at least northern County Warning Area as low 
drops southeast into MO...and finally move as close as Memphis area. 
Enough northerly flow to bring temperatures back to near seasonal 
values...and bring low probability of precipitation showers across at least SW Arkansas. 
Models differ on evolution of next closed upper low first part of 
next week. GFS very agressive closing low off in south Texas on Monday... 
prefer a little slower and closer to European model (ecmwf)./Vii/ 


&& 


Aviation... 
the dry line has begun to shift back north this morning...extending 
roughly from a crs...to north of a jso...to ggg...to S of a pbf line as 
of 09z. IFR/LIFR ceilings with some reduced visibilities are widespread S of 
this boundary...and should encompass much of the area S of the Red 
River of NE Texas/SW Arkansas by 12z. Ceilings will be slow to improve this 
morning...eventually becoming MVFR by late morning/early afternoon. 
These ceilings should become VFR and scatter out during the afternoon as 
drier air aloft mixes downward. However...a well-defined closed low 
over central nm this morning will rapidly traverse east across the Red 
River valley of North Texas into eastern OK by afternoon...with scattered strong/severe 
convection developing after 19z over NE Texas/southeast OK...rapidly 
progressing NE into SW Arkansas/north la after 22z. Large hail will be the 
primary threat...with isolated damage wind gusts possible as well. This 
convection should be exiting the eld/mlu terminals around/shortly 
after 06z Thursday...with the dryline once again mixing east during the 
evening/overnight hours...resulting in sky clear conditions following the 
boundary passage. MVFR ceilings may redevelop over north central la/scntrl Arkansas 
ahead of the dryline this evening...but ceilings should rapidly improve 
after 06z. S winds 10-15kts today will become SW this afternoon over 
East Texas...with gusts to 20kts possible. Winds will veer west-southwest below 10kts 
areawide after 00z. /15/ 


&& 




Preliminary point temps/pops... 
shv 74 51 70 44 63 / 50 40 10 20 10 
mlu 74 55 73 46 65 / 40 50 10 20 10 
deq 73 44 65 41 59 / 40 40 10 30 20 
txk 74 48 65 42 60 / 40 40 10 20 20 
eld 73 51 69 43 62 / 50 50 10 20 20 
tyr 72 45 67 41 60 / 30 20 10 10 10 
ggg 72 47 68 43 62 / 30 20 10 20 10 
lfk 73 48 72 42 66 / 40 20 10 10 10 


&& 


Shv watches/warnings/advisories... 
Arkansas...none. 
La...none. 
OK...none. 
Texas...none. 
&& 


$$