Weather

385 
fxus64 kmeg 061538 
afdmeg 


Area forecast discussion 
National Weather Service Memphis Tennessee 
1038 am CDT Monday Oct 6 2008 


Update... 


High pressure will hang on for one more day across the middle south 
before the weather turns wet. Sunny skies prevail across the middle 
south this morning and temperatures have quickly warmed into the 70s. 
Areas west of the Mississippi River may see a few high clouds this 
afternoon from the approaching system otherwise expect plenty of 
sunshine. Highs will reach into the middle 80s across the region. 
Forecast on track with no changes planned. 


&& 


Previous discussion... /issued 428 am CDT Monday Oct 6 2008/ 


An active weather pattern...especially for October...is shaping 
up for the first half of this week. However...for today...we will 
squeeze out another nice day weatherwise with above normal 
temperatures. 


An upper level ridge had shifted just to the east of the middle-south 
early this morning as a deep upper level trough pushed through The 
Rockies. Thunderstorms extended from western OK southward into 
Texas ahead of the trough. Across our area...skies remained clear. 
Surface high pressure along the East Coast was providing a light 
southeast wind flow across the middle-south with low level moisture 
slowly increasing. 


Mostly followed the GFS in the forecast of the upper level trough 
across our area. The European model (ecmwf) does slow the upper level trough and 
associated cold front more than the GFS about Wednesday...thus 
kept probability of precipitation for Wednesday higher than indicated by mav probability of precipitation. 


After todays good weather...conditions will begin to change 
tonight. Clouds will quickly stream into the area overnight as 
strengthening low level flow shifts more to the south and taps 
into Gulf moisture. Elevated instability along with a warm front 
will push into the middle-south from the southwest and west with 
increasing diffluence aloft as the upper level trough pushes into 
the plains. An associated cold front is forecast to extend from 
eastern Kansas through eastern OK into eastern Texas by sunrise Tuesday. 
Scattered to numerous showers and thunderstorms are expected to 
spread into the middle-south from the west ahead of this system 
after midnight. 


Wet weather is forecast for Tuesday into Wednesday sometimes 
stormy with locally heavy rainfall possible. The upper level 
trough will push toward the region with the GFS indicating that a 
closed upper level low will evolve over southern MO by Wednesday 
morning. The associated surface cold front is forecast by late 
Tuesday afternoon to extend from eastern MO through eastern Arkansas 
into eastern la...moving eastward through the remainder of our 
forecast area Tuesday night. Although model timing differences do 
exist with the European model (ecmwf) slower. Think a few strong thunderstorms are 
possible ahead of the cold front across all of the middle-south Tuesday 
and Tuesday night...but the best chance for strong thunderstorms 
appears to be from east-central Arkansas into north MS. Impressive upper 
level dynamics are forecast with this upper level trough 
considering that it is early October. Upper level diffluence will 
increase over the area and instability will become surface based 
as a warm front pushes northward. The GFS shows lifted indices 
decreasing to minus three and convective available potential energy climbing to near 1000 j/kg from 
east-central Arkansas into north MS with surface dewpoints climbing into 
the 60s...think this will be the area to have the best chance for 
strong thunderstorms. But can not rule out a few strong 
thunderstorms elsewhere in association with the upper level low. 
Small hail and wind gusts to 45 miles per hour would be possible with any 
strong thunderstorms that do develop. At this time...think 
instability will be a limiting factor due to abundant clouds for 
the formation of severe thunderstorms...but this will be monitored 
in later forecasts. Locally heavy rainfall is also possible as 
precipitable water values climb to between 1 1/2 and 2 inches. 


The upper level low is forecast to move to our east Thursday with 
upper level ridging spreading over the area from the west and 
continuing over the area Friday. As a result...dry weather is 
forecast to return by the latter half of the week. Significant 
model differences exist for the weekend. The GFS shows the 
approach of an upper level trough and surface cold front by Sunday 
while the European model (ecmwf) maintains a strong upper level ridge over the 
area. For now...added a 20 percent chance of showers and 
thunderstorms for Sunday to be in line with surrounding offices. 


&& 


Preliminary point temps/pops... 
mem 86 67 77 63 / 0 40 80 80 
mkl 87 59 78 63 / 0 20 70 80 
jbr 85 62 73 59 / 0 60 90 70 
tup 85 59 80 65 / 0 10 60 80 


&& 


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


$$ 


Sjm/jcl