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Area forecast discussion 
National Weather Service Pueblo Colorado 
340 am MST Friday Nov 21 2008 


Short term... 
(today and tonight) 


..some early morning dense fog northern El Paso County... 
..A little warmer temperatures and sunshine southeast Colorado today... 


Currently...west-northwesterly flow increasing aloft over the central 
rockies. High terrain AWOS Mountain Pass sensors reporting 15-29kts 
with gusts 30-35kts. Pikes Peak is sustained 40 miles per hour with a peak wind 
of 57 miles per hour. In response to the midlevel warm air advection...Lee side 
trough beginning to develop across eastern Colorado with brisk southerly 
winds across much of the far eastern Colorado plains and the southern 
Palmer Divide. Pueblo-La Junta has weak easterly flow in the lower 
Arkansas River valley. IFR-MVFR stratus breaking up across portions of 
southeastern Colorado due to relatively drier air aloft entraining into 
the low level moisture. However...as usual...stratus and fog holding 
tight across El Paso County with the southerly moist orographic 
flow. Very dense freezing fog across northern El Paso per live web 
cams since we came into the office at midnight. Four out of the 
five northern El Paso County I-25 corridor web cams had zero 
visibilities. Already issued the dense fog advisory around 1245 
am...so that still looks on target. Patchy dense fog...also...noted 
in downtown Colorado Springs now. 


Today...rather vigorous midlevel shortwave trough and associated jet 
streak to push just north of Colorado today. A little stronger midlevel 
winds...along with drier air aloft...as this system brushes Colorado. 
Model soundings suggest the dense freezing fog/stratus should break 
up across El Paso County between 500 am and 800 am this 
morning...so will maintain the dense fog advisory due to morning 
rush hour to start between 400-500 am. After the stratus 
dissipates this morning...just looking for mainly high clouds and 
a possible scattered-broken thin cirrus/cs mountain wave cloud along the Front 
Range later this morning and afternoon. Temperatures will be 
tricky and most locations should be warmer than yesterday given 
northwest flow Chinook. The biggest challenge will be from Pueblo 
to La Junta in the lower Arkansas River valley. The high resolution 
model data...RUC and NAM-WRF...suggest surface winds could stay 
easterly much of the day. This could limit the potential warming 
in these areas given the lighter winds...lower sun angle...and any 
high clouds...however... 700mb winds are prognosticated to be 30-40kts by 
the RUC yet the NAM-WRF only has 15-20kts. If the winds don't pick 
up then highs 45-50f at Pueblo...if they pick up then highs 
55-60f. 


Tonight...northwest flow continues and weakens. With a nearly clear 
sky...strong radiational cooling will occur in valleys with the 
banana-belt warmer temperatures likely generally along I-25 corridor 
and westwards towards the mountains from 6k-9k feet mean sea level...and near the 
mountains in the upper Arkansas River valley and San Luis valley. Metze 


Long term... 
(saturday through thanksgiving) 


..dry pattern to continue through early next week... 
..Unsettled weather to return by Thanksgiving... 


This weekend and early next week continue to look dry with 
above average temperatures for most of the County Warning Area. A short wave ridge 
will move through on Saturday and temperatures should rise to near 
60 degrees over the plains in the afternoon. Overnight temperatures will be 
in the 20s as skies remain generally clear. Will see the usual belt 
of higher temperatures over the eastern foothills and higher terrain. 


A shortwave will move through the Dakotas and upper miss valley on 
sun...but models are quite consistent in showing little sensible 
impact from this particular system. Have left slightly cooler weather 
intact for the northestern zones. Skies will continue to be mostly clear 
through Monday as the upper ridge rebuilds and the atmos remains very 
dry. 


All signs continue to point to a change in this persistent pattern 
by Wednesday of next week. Ensemble spaghetti plots are in remarkably good 
agreement through about 200 h. 700 mb zero line will move through southeastern Colorado on 
Wednesday...and the next 3-4 days Promise to be cool and unsettled. A lead 
shortwave trough will move into the southwestern mts late Wednesday or Thursday...and 
hopefully this will bring some needed moisture to the dvd. Could 
even see some precipitation over the plains by the end of the week. The 
scenario becomes more complex by next weekend as the main global 
models have been persistent in amplifying the West Coast trough and 
cutting off an upper low over Southern California over the desert SW...possibly 
even northern Mexico/baja. This could return the area to a stagnant weather 
pattern by the latter half of the weekend. Will have to wait to see 
how this develops over the next few days. Rose 




&& 


Aviation... 
per short term discussion...LIFR ceilings and IFR-LIFR visible should 
dissipate around the kcos terminal between 13z-15z/21. 
Otherwise...VFR clear below 12k should be the rule for kcos... 
kpub...and kals terminal points rest of today and tonight. Metze 


&& 


Pub watches/warnings/advisories... 
dense fog advisory until 8 am MST this morning for coz084. 


&& 


$$ 


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