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fxus65 kbou 232108 
afdbou 


Area forecast discussion 
National Weather Service Denver Colorado 
308 PM MDT Wednesday Jul 23 2008 


Short term...scattered thunderstorms occurring across mountains... 
foothills and along the urban corridor into Weld County as shown by 
latest radar. No storms yet across rest of plains...but things are 
trending toward a better chance for storms. Radar showing outflow 
boundaries from the foothill convection and the cells over northern 
Weld County. Laps surface analysis and acars soundings indicate cape 
has been eroded. So...combination of weak ascent in area of upper 
level divergence and boundaries should be sufficient to sustain the 
storms as they move across the plains. In addition... radar showing 
boundary extending from eastern Elbert County into norther Lincoln 
and southern Washington counties. Satellite showing cumulus along 
this boundary...so could see some storms develop as the afternoon 
progresses. Will increase the probability of precipitation across all of the plains for this 
evening. Latest integrated precipitable water values around 1.25 
inches...so storms should produce heavy rain which may create 
localized flooding problems. Surface dewpoints currently in the middle 
to upper 50s along and east of the above mentioned boundary with 
convective available potential energy of 1000-1500 j/kg. Still a threat of a few severe storms 
producing large hail east of this boundary. Most convection to end 
by midnight...though some storm could linger beyond midnight over 
the far northeast corner. Upstream satellite showing quite a bit of 
cloud...enough to keep mostly cloudy overnight. On Thursday...models 
show upper level trough moving into the Pacific northwest. Though 
ridge axis remains across Colorado...Theta-E axis prognosticated to shift 
southeast of the County Warning Area. Cross sections indicate flow aloft becomes a 
bit more westerly...with bulk of the moisture plume south and east 
of the area. This could lead to a lower chance of precipitation. Qg 
vertical velocity forecasts indicate all of the ascent remains south and 
west of the County Warning Area. Still...should see storms develop over the higher 
terrain during the afternoon as the airmass destabilizes. Across 
plains...models show northerly surge moving across area. There may 
be enough cin hanging around during the afternoon to hinder storm 
development...but will leave the low probability of precipitation due to the potential of 
any boundaries for foothill convection. As for highs...temperature 
and thickness forecasts show little change from today. Guidance showing 
highs in the 90s across the plains. Will continue with current 
temperature grids which fall in line with guidance. 


Long term...upper level ridge over the southwestern U.S. Will 
continue to dominate the weather pattern through the weekend and 
early next week. It will remain very warm during the extended 
forecast. Highs should be able to climb above 90 degrees each day 
over the plains. Enough moisture should be present for at least 
scattered thunderstorms to form over the mountains and foothills. 
The plains will see at least a slight chance of thunderstorms each 
day. Models show a brief increase in moisture Friday so bumped probability of precipitation 
up into the 30-50 percent range for Friday afternoon and evening. 
Both the GFS and European model (ecmwf) show the remnants of Hurricane Dolly rotating 
from Arizona northeast into Colorado some time Sunday or Monday. 
Will keep probability of precipitation in the 20-30 percent range for this because of the 
uncertainty in timing and also because the models keep most of the 
moisture south of the forecast area. 


&& 


Aviation...scattered thunderstorms will continue across the area 
through 05z. Potential for heavy rain and gusty outflow winds to 
40ks affecting area airports. Ceilings and visibility could briefly 
become MVFR in the heavier showers...otherwise VFR conditions to 
prevail. On Thursday...most of the moisture will shift south of the 
area...with only a slight chance of afternoon storms. Gusty outflow 
winds could affect area airports. Surface winds to shift to the 
north after 18z as a weak front moves across the area. 


Bou watches/warnings/advisories...none. 


&& 
D-l/meier