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Area forecast discussion...updated 
National Weather Service Pueblo Colorado 
641 am MST Thursday Nov 20 2008 


Update... 


A quick update on the fog and freezing drizzle potential. 
11u-3.9(fog) satellite imagery data showed stratus now covers a 
good "chunk" of southeast Colorado to the sangre Delaware cristo mountains and 
through Chaffee County. Web cams around sunrise showed fog...dense 
at times...at Rye...Canon City...Cripple Creek...Widefield...and 
Monument towards the County line. Also...noted radar very light echo 
returns picking up some of the fog/drizzle around Fort Carson to 
Canon City to Rye and trying to expand towards Colorado Springs. 
Cloud ceiling having a tough time reaching the ground in Colorado 
Springs thanks to slightly lower dew points and a northeast wind 
at 10-15 miles per hour creating downslope drying off the Palmer Divide. 
There are some relatively higher dew points...middle to upper 
20s...around Denver into northeastern Colorado. This could still move 
into El Paso County just as the surface wind veers to the 
southeast-south by later this morning and through the afternoon. 
This fact makes ME a little hesitant in dropping the Winter 
Weather Advisory for areas of dense fog and freezing drizzle 
across El Paso County. The 13km RUC model still wants to veer the 
surface winds to the east- southeast now between 15z-18z/20 and 
southerly around 12z/20. Very tough call and terrain dictates 
everything around Colorado Springs. Metze 


&& 


Previous discussion... /issued 347 am MST Thursday Nov 20 2008/ 


Short term... 
(today and tonight) 


.Areas of freezing drizzle/dense fog across El Paso County today... 
.much colder across southeastern Colorado today... 


Currently...hand surface analysis at 07z/20 showed the frontal 
boundary well past southeastern Colorado and up against the eastern Colorado 
mountains. The well advertised 1040-1045mb surface high was about to 
enter Montana/ND early this morning. Stratus has expanded across much of 
the eastern 1/2 of Colorado. Satellite 11u-3.9u(fog) imagery revealed the 
low clouds making it into Fremont County...eastern slopes of the 
sangre Delaware cristo mountains...lower elevations of Teller County with 
Pikes Peak still clear per live web cam...and of course all of 
southeastern Colorado. As of 09z/20...the fog level was around the 6.5k-9k 
feet mean sea level layer. Ceilings are still MVFR-low VFR for elevations below 
6k feet mean sea level across the southeastern Colorado plains. Live web cams across 
Monument show dense fog. A call to the El Paso County sheriff 
indicated only dense fog in Monument and no freezing drizzle yet. 
Rye doesn't look too foggy yet per live web cam. The kmnh AWOS 
sensor just north of El Paso County has 1/4sm fzfg and 25f. 
Temperatures across northern El Paso County are in the middle/upper 
20s with Lower/Middle 30s across southern El Paso County. The 
northeast wind(downslope off the southern Palmer divide) at cos is 
keeping the ceiling still low VFR...but that could change 
considering bullseye AWOS is 300 foot and 3 miles mist at 09z/20. 


Today...well advertised 20-35 degree colder temperatures across 
southeast Colorado still look on track. Diurnal temperature ranges across 
our southeastern Colorado mountains and adjacent plains may only be 5-10 
degrees from early morning temperatures. Greatest impact weather 
will be the fog and possible drizzle/freezing drizzle across 
portions of the I-25 corridor and westward towards the mountains. It 
appears the highest probability for areas of dense fog/freezing 
drizzle will be across El Paso County through today and probably 
around the Raton and La Veta passes. Local heights are already near the 
surface. Fog/stratus will continue to fill in across much of 
southeastern Colorado. Surface winds should veer from the 
northeast(downslope off the southern Palmer divide) to the 
southeast-south across El Paso County today. The 08z/20 13km RUC 
model has the east-southeast winds across El Paso County between 
13z-16z/20 this morning. The combination of weak upslope 
flow...trapped cold low-level moisture...an inversion aloft...and 
relatively drier aloft aloft...should keep the LIFR-IFR ceilings/visible 
across much of El Paso County and a narrow ribbon between 6k-9k feet 
mean sea level along the eastern slopes of the Wet Mountains...Wet Mountain 
Valley...and southern sangre Delaware cristo mountains. Considering its 
the first event of the season and morning/afternoon rush hours...will 
go with a Winter Weather Advisory for areas of dense fog and 
freezing drizzle across El Paso County. Still think there could be 
some very light snow or flurries considering the -3c to -10c layer 
2d frontogenetical forcing comes into the I-25 corridor with a 
second surge of cold moist low level air. Meanwhile...around the 
Continental Divide and the San Luis valley...it should be mostly 
sunny and relatively warmer. This could be one of those events where 
Leadville is slightly warmer than Colorado Springs. 


Tonight...low level cp air mass begins to recede eastern Colorado with 
west-northwesterly flow aloft. Middle-level warm air advection kicks-in 
tonight with 700mb temperatures increasing to +2c to +3c across the 
I-25 corridor. Low level flow becomes more southerly and should help 
to start diminishing the low clouds across southeastern Colorado...except 
the southern Palmer Divide/cos where it's still upslope flow. As 
typical with these scenarios....the stratus/fog may hang on across 
El Paso County until the southwest-westerly flow can develop late 
tonight or Friday morning. May need to extend the Winter Weather 
Advisory in time across El Paso County through night...but will let 
the day shift handle this if needed. 17 


Long term... 
(friday through wednesday) 


.Dry weather pattern to continue across southeast Colorado... 


Quiet and stable weather pattern is expected to continue through 
at least early next week as The Rockies remain on the east side 
of a longwave ridge with axis over the intermtn region and western 
Canada. Temperatures will continue to run about 5-10 degrees above 
average...with no measurable precipitation expected for the next six days. 


Residual clouds should clear by Friday morning...as a Lee trough 
re-establishes...and srly flow strengthens in advance of another 
shortwave moving through South Dakota and eastern NE. No real weather change is 
expected with this system...as the colder air and any real 
moisture remain well to the NE of our County Warning Area. A shortwave ridge will 
follow on Saturday...then another weak trough will follow a 
similar track through the Dakotas on sun. Once again...this system will 
not bring much moisture to the area...maybe just an increase of 
clouds to the northern zones. 


The upper ridge will build Monday through Wednesday...and dry conditions will 
likely continue with generally sunny skies and temperatures over the 
plains staying in the 60s. The pattern finally breaks down in time 
for Thanksgiving...as a very complex scenario sets up involving 
two branches of the polar jet. Far to early to say how this pattern 
change will affect the area...but there is at least the chance for some 
much needed mountain snows by the latter part of next week. 44 


Aviation... 


Er short term discussion...LIFR-IFR ceilings and visibilities in 
freezing fog/drizzle drizzle should affect the kcos terminal much of 
the day and through the night where temperatures will remain in the 
upper 20s to lower 30s. IFR-MVFR ceilings will continue at the kpub 
terminal with areas of fog for today...and then ceilings and 
visibilities should improve tonight. VFR clear below 12k feet mean sea level 
conditions will prevail at the kals terminal through tonight. 
Mountains will be obscured in clouds and fog just west of the I-25 
corridor. 17 


&& 


Pub watches/warnings/advisories... 


Winter Weather Advisory until 5 PM MST this afternoon for coz084- 
085. 


&& 


$$ 


17/17 

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