848 
fxus65 kpub 051053 
afdpub 


Area forecast discussion 
National Weather Service Pueblo Colorado 
453 am MDT Sat Jul 5 2008 


Short term... 
(today and tonight) 




..increased chance of thunderstorms today... 


Frontal boundary is well defined in observation and Sat imagery...currently 
moving through central Utah and western Wyoming. Some light showers have been 
persisting over western Colorado...and could see some isolated showers or thunderstorms 
through the morning hours over the central and southwestern mts. Have 
added low probability of precipitation to these zones before 18z. Upper ridge will keep its 
grip on the southeastern plains through the afternoon...and with 700 mb temperatures rising 
another degree or two today...could see some low 100s show up over 
the lower Arkansas Valley. Convection will move with the frontal 
boundary...reaching the northern zones by late afternoon. 


Main question for later today is how widespread and robust to expect 
convection for later today and this evening. Instability and shear will 
be relatively modest...up to 1000 j/kg cape and 20-30 kts of 
environmental shear. Will have to watch the boundary for best chance 
of strong to possibly severe convection. By 03z...front looks to be 
located from just south of kpub...to north of klhx...to vcny kitr. 
Best probability of precipitation look to be along and north of this line...as well as along 
the Palmer dvd...ramparts...and wet mts. Convection will be less 
likely over the southeastern plains...although mesoscale convective system development could sustain 
some storms moving out into the plains by evening. This activity should 
die down later this evening. 00z runs all indicate the potential for 
some mesoscale convective system development over western Colorado overnight associated with a weak 
upper level disturbance...lasting through early Sun morning. Have added 
low probability of precipitation for the central and SW mts for the overnight period to 
account for this possibility. Rose 


Long term... 
(sunday through friday) 


Sunday...first in a series of shortwaves moves across the northern 
rockies as the upper ridge starts to retrograde towards the West 
Coast. NAM and GFS have the surface front in the vicinity of the 
County Warning Area. The NAM has the front being orientated from southwest to 
northeast across the Colorado plains. NAM and GFS have the best 
cape staying just to the north of the region. With the upper trough 
approaching the region...increased the probability of precipitation with scattered probability of precipitation over 
the mountains...decreasing to isolated near the Kansas border. Storm Prediction Center 
day 2 outlook has a --see text-- for northeast Colorado. Would not 
be too surprised to see stronger storms into the El Paso County 
region...if the surface front pushes south along the Interstate 25 
corridor as the NAM indicates. Did not change temperature grids 
much...and temperatures will be the warmest near the Kansas 
border...which stays south of the Colorado front. In the western 
mountains and high valleys...approaching trough would enhance 
convection and have scattered probability of precipitation. 


Monday..disturbance passes just tot he north of the region...with 
weak upslope flow possible on the plains. GFS has the surface front 
through the County Warning Area with convective available potential energy of 1000 j/kg or higher over much of the 
eastern plains...while the NAM keeps the front to the north with 
less cape. Am leaning toward the GFS solution which will put the 
front south of the County Warning Area. Increased probability of precipitation during the afternoon and 
evening on the plains and eastern mountains for better chances of 
thunderstorms. Shear currently looks to be weak...which would not 
favor much severe weather. In the western mountains and high 
valleys...northwest flow aloft will bring in drier air...and have 
isolated probability of precipitation for these region. 


Tuesday and Wednesday...there is northwest flow aloft with a 
surface front south of the County Warning Area. Tough to get specific about the 
amount and strength of convection. Strength of convection depends 
on the amount of low level moisture and heating as well as the 
amount of shear. Timing of weak shortwaves can also enhance or 
weaken convection. Grids have isolated afternoon and evening probability of precipitation 
with highest amounts over the eastern mountains. Cooled 
temperatures a couple of degrees to near seasonable values. 


Thursday and Friday...ec and GFS have a fairly strong trough moving 
into the Pacific northwest...and the southwest flow ahead of the 
system may bring some monsoon moisture northward. Ec is slower with 
the trough which brings more moisture northward. The GFS is more 
progressive with the trough...with hot and dry air aloft moving into 
Wyoming and brushing northern Colorado. Did not see any reason to 
make changes to the grids...and HPC guidance will be helpful to 
determine which solution is more likely. --Pgw-- 


&& 


Aviation... 
main concern will be the potential for widespread convection 
associated with a cold front moving through Colorado late this 
afternoon. The boundary and expected wind shift will reach the 
Palmer dvd from 21 to 23z...dropping southeastward to vicinity kpub by 00-03z. 
Locally heavy rainfall...gusty winds...and some gr will be possible 
with storms along and near the front. Isolated storms are expected to 
persist over the western mts overnight. 


&& 


Pub watches/warnings/advisories... 
none. 
&& 


$$ 


44/06