321 
fxus64 kmeg 082020 
afdmeg 


Area forecast discussion 
National Weather Service Memphis Tennessee 
320 PM CDT Friday Aug 8 2008 


Discussion... 


Surface high pressure has settled over the middle south this 
afternoon and has resulted in cooler and less humid weather. Dry 
and pleasant weather will continue through tomorrow as the surface 
high slowly moves to the east. 


An unseasonably deep upper level trough now exists over the 
eastern U.S. With ridging over the intermountain west. This has 
placed the middle south under northwesterly flow aloft. This upper 
air pattern will persist through the forecast period and should 
become increasingly more active. The first in a series of middle level 
shortwaves will approach the region from the northwest on Sunday. 
In advance of this feature...deeper moisture will attempt to 
overrun the stable airmass in place as a strengthening low level 
jet sets up over the Southern Plains into the arklatex region. The 
big question that still exists is whether the atmosphere can 
moisten sufficiently on Sunday to result in precipitation. At this 
time...have included chance probability of precipitation across the western two-thirds of 
the area with the greatest chances west decreasing to slight 
chances east. Initially...the low level airmass will be relatively 
dry before slowly saturating as an unseasonable overrunning 
pattern sets up. If precipitation can break out...expect 
temperatures to remain several degrees below average on Sunday. 
Currently have the lowest highs colocated with the best rain 
chances in the west with higher temperatures east where rain 
chances will be lower. Although overall instability appears 
minimal...cannot completely rule out some elevated thunderstorms 
as the low level jet strengthens. Any thunderstorms that can 
develop will remain below severe limits as elevated instability 
is expected to remain rather limited. 


The first middle level shortwave will move to the southeast by Monday 
morning. Another shortwave embedded within the northwesterly flow 
aloft will drop southeast out of the middle Mississippi Valley and 
into the middle south by Tuesday. Low level flow ahead of this 
feature should allow a warm front to lift northeast into our area 
late Monday night into Tuesday. Expect additional chances for 
showers and thunderstorms with this approaching boundary Monday 
afternoon and night over southern areas and areawide on Tuesday as 
the shortwave aloft moves through. Stronger instability should be 
present across portions of the area on Tuesday and may support a 
few strong thunderstorms. 


Weak high pressure will briefly build over the middle south for 
Wednesday and Wednesday night with dry weather and near normal 
temperatures. Additional middle level shortwaves will move across the 
area in northwest flow aloft for the end of next week into next 
weekend with additional chances for showers and thunderstorms. The 
airmass should be more unstable during this period with some 
potential for strong storms. Temperatures will remain near average 
for the end of the extended forecast period. 


&& 


Preliminary point temps/pops... 
mem 66 89 69 83 / 0 0 20 40 
mkl 57 85 64 85 / 0 0 10 30 
jbr 60 87 66 83 / 0 0 30 50 
tup 58 88 64 85 / 0 0 10 30 


&& 


Meg watches/warnings/advisories... 
Arkansas...none. 
MO...none. 
MS...none. 
Tennessee...none. 
&& 


$$ 


Jlh