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Area forecast discussion...updated 
National Weather Service Little Rock Arkansas 
642 PM CDT Thursday Aug 7 2008 


Aviation... 
scattered showers over the west will move east this evening...but 
will begin dissipating after sunset. Front over west central into 
southern Arkansas...with much of the rainfall remaining near the 
boundary. Models are trying to hint at mesoscale convective system development tonight over 
the southwest...and have included vcsh in the southern tafs. 
&& 


Previous discussion... /issued 215 PM CDT Thursday Aug 7 2008/ 


Discussion... 
main concerns this forecast cycle are first period convection. 
Then the precipitation trend as the front sags south. Then chances of 
rain on Sunday into next week...with a continued northwest upper flow. 


Have seen convection continue to develop this afternoon...with a 
few storms becoming strong...and still cant rule out an isolated 
marginal severe storm...especially over south Arkansas where 
differential heating has raised instability. The boundary 
continues to sag south...along a line from south of kfsm...to 
south of khot...to near kpbf...to near kmem. Focus of convection 
has been along it...and in Theta-E rich air south of boundary. 
This will continue into the evening hours and overnight. Some 
drier air is being seen over NE Arkansas to southeast MO. As stated 
earlier...short wave energy over Kansas this morning has moved southeast over 
Arkansas and along the boundary...help convection. Some heavy 
rain...small hail..gusts to around 30 miles per hour main threats. 
Precipitation water values are around 1.5 to 2 inches. High temperatures are 
only reaching the middle to upper 70s to lower 80s in the rain and 
clouds areas...while outside...upper 80s to lower 90s. 


Short term...tonight through Sunday night 
first period convection trends will driver forecast initially. 
Will start with likely over the south...chance elsewhere in the 
evening period. Frontal boundary will be the main focus south with 
some energy...while northern convection mainly shortwave driven. 
After sunset...overall convection will settle down through 
midnight...especially behind the front. Pop trends show this. 
Models take the boundary to far south Arkansas to northern la by 12z 
Friday. Forecast does have some low pop in central to southern 
areas Friday morning...then ending central to south into the 
afternoon. Dry weather Friday night and Saturday. Pop back in the 
forecast Saturday night...starting in the SW...as the boundary 
lifts back northeast as a warm front. The chances over the state 
Sunday. Some upper energy is depicted by GFS...but amount looks 
over done. Slight chance continue into Sunday night with possible 
weak boundary and impulses in the northwest upper flow. 


Long term...Monday through Thursday 
models are now in pretty good agreement at the start of the long 
term. Both agree that boundary will make its way over the forecast area...with 
the GFS moving it a little faster. Went with a blend...and kept at 
least slight probability of precipitation in through Tuesday. 


Major discrepancies between models begin by midweek...with European 
stalling this system just south of the state as the GFS has the 
boundary way to the south. Went with more of a GFS solution...with 
just below slight criteria for Wednesday. This will need to be 
adjusted as needed. 


Ridge axis over Texas will begin to build towards the end of the 
period and allow for Gulf moisture to re enter the state. European 
keeps the forecast area dry with moisture way to the south through the end of 
the extended. Went with a blend...but kept probability of precipitation out of the slight 
category. 


Temperatures will be close to normal...to slightly below on account 
of the cloud cover and rain. High temperatures will be in the upper 
80s to lower 90s. Lows will range from the upper 60s to lower 70s 
through the midweek. 
&& 


Lzk watches/warnings/advisories...none. 
&& 


$$ 


Aviation...58