790 
fxus65 kpub 052127 
afdpub 


Area forecast discussion 
National Weather Service Pueblo Colorado 
327 PM MDT Sat Jul 5 2008 


Short term... 
(tonight and sunday) 


Currently...upturn in convection underway as weak upper trough moves 
out of the Great Basin toward Colorado. Best coverage of thunderstorms and rain so far 
this afternoon has been over western zones...where upward motion is 
slightly stronger closer to the upper trough. Low and middle level 
moisture is also more plentiful farther west...where a few pockets 
of near 40f dewpoints have held on through the afternoon. Over the 
plains...prefrontal surface trough stretches from kcos northeastward 
to near klic...with a few thunderstorms and rain going up on the boundary as of 2030z. 
Certainly appears we have the instability and upward motion for 
fairly widespread thunderstorms and rain today over the plains...but the lacking 
ingredient is low level moisture...as surface dewpoints have mixed 
out into the 30s most areas along and east of I-25. Resulting 60-70f 
temperature/dewpoint spread is not very conducive for precipitation reaching the 
ground...thus most storms this afternoon are very short-lived and 
outflow dominated. Backed off the severe mention in the severe weather potential statement for 
today...though suppose a 60 miles per hour downburst is possible. 


Tonight...best chances for thunderstorms and rain will remain over the 
mountains...especially central zones where storms could last much of 
the night as upper trough approaches. Isolated mainly dry convection 
should end quickly over the I-25 corridor and plains this 
evening...as models and latest surface data suggest little in the 
way of low level moisture working back westward toward the mountains 
overnight. In the grids...precipitation chances were increased over the 
western zones...decreased over the east. Removed probability of precipitation from the 
plains for the after 06z time frame and also lowered dewpoints over 
most lower elevation zones. 


Sunday...main frontal boundary...over northeast Colorado early in 
the day...sweeps south across the plains...reaching the Arkansas 
River by 00z. Most convection should be along and north of the 
boundary...as low level moisture surges back westward. Will continue 
to see plentiful convection over the mountains as upper jet streak 
lifts into northwest Colorado by evening. Both NAM and usually dry GFS 
crank out significant precipitation much of the area...and while the 
suspicion is both models are too wet...did nudge probability of precipitation upward 
slightly and lowered maximum temperatures a degree or two. 


Long term... 
(sunday night through saturday) 


Sunday night-Monday night...fairly active weather pattern setting up 
across the region as models continue to indicate a series of short 
waves moving through the moderate to weak westerly flow aloft across 
the northern tier of states into The Rockies. Latest models 
indicating frontal boundary moving across the eastern plains Sunday 
afternoon stalling out along or just south of the Highway 50 
corridor Sunday evening and then lifting back across northeast 
Colorado and northwest Kansas Sunday night as surface low pressure 
develops across the far eastern plains in advance of wave moving 
across the northern rockies. Wave continues across the region Monday 
with frontal boundary moving across southeast Colorado Monday 
afternoon and into northeastern New Mexico and western Texas Monday 
night. Models indicating good level moisture pooling along and 
behind boundary with convective available potential energy between 1000-2000 j/kg across the eastern 
plains. Generally weak shear is prognosticated across the area Sunday 
night...though increases across the area Monday with passing 
wave...with strong to severe storms a possibility. Main change to 
current forecast was to increase probability of precipitation to scattered across the area 
Sunday evening and Monday...along with keeping precipitation mentioned 
through the overnight hours with some upward vertical velocity across the region. 


Tuesday-Wednesday...weak northwest flow aloft is prognosticated across the 
region with surface front south of the area keeping weak low level 
upslope flow in place across eastern Colorado. Minor disturbances 
embedded within the flow will help initiate convection...and have 
stayed close to previous forecast of best probability of precipitation across the eastern 
mts and adjacent plains...with temperatures at or slightly cooler 
than seasonal averages. 


Thursday-Saturday...models continue to indicate possible monsoonal 
tap developing into the late weekend...with a deep trough developing 
across the West Coast allowing for the high pressure ridge to slide 
east across the southern High Plains Saturday. Will wait and see how 
pattern evolves and will keep current forecast as is with temperatures at 
or above seasonal averages along with isolated diurnal convection. -Mw 


&& 


Aviation...isolated thunderstorms and rain at all taf sites will produce erratic and 
gusty winds through 03z this evening...though large temperature/dewpoint 
spreads cloud bases will remain very high and little rainfall will 
reach the ground. Isolated storms are expected to persist over the western 
mts overnight. For Sunday...increasing moisture should lead to 
more widespread thunderstorms and rain areawide...with potential for brief MVFR 
conditions under some of the stronger storms. 




&& 


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


$$ 


10/23