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Area forecast discussion 
National Weather Service Norman OK 
948 PM CDT Tuesday Aug 19 2008 


Update... 
the upper low over western North Texas is expected to drift 
generally to the east-southeast overnight. With the upper low located farther 
south than last night... and so far showing little indication 
that it will track northeast... believe the heavy rain threat will 
be mainly across parts of southern Oklahoma and western North 
Texas. Although we believe the threat of heavy rain will be lower 
over the northern half of Oklahoma... we will maintain the Flash 
Flood Watch for central Oklahoma...at least for a little while 
longer... due to the saturated conditions in some areas from last 
nights rainfall. Similar saturated conditions also exist in the 
watch area of southwest Oklahoma and western North Texas... except 
that showers are ongoing over that area. Special Weather Statement picked up a quick 
half inch or so from showers that recently moved through. 
Meanwhile... rain is expected to increase in coverage over parts 
of south central and southeast Oklahoma later tonight as the upper 
low drifts in a more or less easterly direction. 


&& 


Previous discussion... /issued 321 PM CDT Tuesday Aug 19 2008/ 


Discussion... 
upper low continue to meander across southwest into central OK tonight 
into Wednesday before gradually opening up and shifting northeast through 
late Thursday. Some significant differences between 12z NAM and GFS with respect to 
precipitation amounts and location tonight into first part of Wednesday. NAM 
develops storms later this afternoon across SC/southeast OK and then rotates 
this area back north and northwest toward the I-35 corridor around 
the northeast side of upper low... while the GFS takes this initial 
development from southeast OK more northerly across eastern part of OK. 
Yesterdays NAM did a better job with the precipitation event earlier today 
and will give a little more weight toward its forecast for probability of precipitation/quantitative precipitation forecast 
for first two periods. Also with afternoon trend in satellite showing 
upper low slowly retrograding to the west and as parts of southwest 
OK into western North Texas do not need much rain to cause 
additional flooding problems. Will therefore extend watch farther 
west to include the Lawton and Wichita Falls areas through 12z Wednesday 
morning. 


Heavier rain should push east of the area by tomorrow afternoon and then 
end across the area Thursday night... although middle level trough continue to 
hang on across southeast OK into the weekend. By this time a northern 
stream wave moves east across southern Canada bringing a surface front 
at least into northern OK with some chance for additional rain 
across north. Will also see warmer temperatures ahead of surface boundary by 
the weekend as will likely see more sun. 


&& 


Preliminary point temps/pops... 
Oklahoma City OK 63 77 64 88 / 60 60 30 20 
Hobart OK 62 79 65 91 / 40 30 20 10 
Wichita Falls Texas 65 81 65 91 / 60 30 20 10 
gage OK 55 79 60 87 / 20 20 10 10 
Ponca City OK 63 75 64 85 / 40 50 40 30 
Durant OK 67 78 68 87 / 80 70 50 30 


&& 


Oun watches/warnings/advisories... 
OK...Flash Flood Watch until 7 am CDT Wednesday for okz023>025- 
027>032-038>048-050>052. 


Texas...Flash Flood Watch until 7 am CDT Wednesday for txz086-089-090. 


&& 


$$ 


32/03