Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 202053

Area Forecast Discussion
National Weather Service Pueblo CO
253 PM MDT Fri Oct 20 2017

.SHORT TERM...(This evening through Saturday)
Issued at 239 PM MDT Fri Oct 20 2017

...Quick Moving System will Bring Snow to the Continental Divide

A fast moving Pacific weather system will bring a brief period of
snow to the Continental Divide tonight.  Satellite shows the
disturbance moving through Utah at this time.  Disturbance should
move into western Colorado this evening with snowfall ramping up
along the Divide, mainly after 9 pm.  It then looks like it will
continue for about 6 hours before gradually winding down through 9
am tomorrow morning. Warm airmass initially but good cooling behind
the system so snow levels come down quickly as trough axis moves
through later in the evening. Model projections yield snow totals of
2-4 inches across the central mountains with locally higher amounts
possible.  Elsewhere in the mountains, projections range from more
localized 1-2 inch amounts. This appears to be mainly a terrain
driven event so little to no precipitation is expected over the
lower elevations.  A spotty shower around the time of trough passage
cannot be ruled out but the odds of seeing measurable precip at any
one spot are pretty slim.

Saturday morning, the cold front associated with this system will
spread south through the plains.  The cold front will deliver a much
cooler airmass to the region than in previous days.  Afternoon highs
will be at least 15-20 degrees cooler than today and about 5-10
degrees below average for this time of year.  Winds across the
plains will be brisk and from the north on Saturday with gusts to
around 30 mph possible at times.

.LONG TERM...(Saturday night through Friday)
Issued at 239 PM MDT Fri Oct 20 2017

...First taste of winter late next week...

Models in good agreement through the extended period and ensemble
spreads are generally small until late next week. The main
forecast impact will be a storm system that will bring the first
real taste of winter to the region.

Saturday night through Wednesday...the upper level pattern will
be amplified with troughing over the Ohio Valley and ridging along
the West Coast. This will put southern Colorado under broad
northwesterly flow aloft. Expect dry conditions to prevail through
this period with no precipitation across the region. Temperatures
Sunday and Monday will top out in the 70s over the lower
elevations. A weak cold front is forecast to arrive by Tuesday
morning with a northerly wind shift and cooler temperatures. Highs
Tuesday will only reach the 60s for highs across the Plains.
Temperatures will rebound on Wednesday back into the 70s.

Thursday and Friday...a quick moving upper trough is forecast to
drop south out of western Canada and across Colorado late in the
work week. Both the GFS and ECMWF are similar with this system,
with the ECMWF just a tad bit slower. Both models drop cold air
south into eastern Colorado behind a strong cold front by Thursday
evening. Both solutions also develop precipitation across the
region behind the cold front, Thursday afternoon through Friday
morning. The primary focus at this time appears to be the Eastern
Mountains and adjacent Plains. Temperatures throughout the
atmospheric profile would support snow for all locations by
Thursday evening. As for amounts, its still way to early to tell.
Temperatures by Friday morning will likely be in the upper teens
to lower 20s across the Plains. Expect precipitation to shift
south into New Mexico Friday morning with clearing conditions in
the afternoon. This storm is still a long ways out, and model
solutions can change. But start preparing for the first real shot
of winter late next week.  Mozley


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 239 PM MDT Fri Oct 20 2017

For tonight and Saturday, a quick moving Pacific disturbance will
track from west to east across the flight area. It will bring a
period of snow and blowing snow to the Continental Divide overnight
into early Saturday, particularly from the Monarch Pass area
northward.  Could even be an embedded thunderstorm during the
evening.  Widespread IFR/LIFR conditions are expected with this
activity.  A few showers could reach the eastern mountain areas
overnight into early Saturday but nothing too widespread is
expected. The plains should stay mostly dry with this disturbance.
The disturbance will continue to bring gusty winds to the flight
area. Gusts to around 30 mph will be possible across the lower
elevations with gusts to around 40 mph in the mountains. Winds will
start out from the west to southwest this evening, shift westerly
overnight and become northwest to northerly on Saturday. The KALS,
KCOS and KPUB terminals will continue to deal with gusty winds at
times through Saturday. Otherwise, VFR is expected at these sites.




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