FXUS65 KPUB 260539

Area Forecast Discussion
National Weather Service Pueblo CO
1139 PM MDT Tue Sep 25 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 252 PM MDT Tue Sep 25 2018

Cold front has raced south into NM/TX today, and with main surface
pressure rises shifting into nwrn OK, gusty north winds were
gradually diminishing across the plains as of 21z. Still some
pockets of stronger west winds back over the mountains and interior
valleys, as upper level jet rotates eastward across the area. Some
weak convection has developed along and just north of the NM border
this afternoon, forced by some modest low level upslope flow and
weak lift under the departing upper jet. Will keep some low pops in
place for srn Sangres/Wets/srn I-25 corridor through 06z, with
mainly clouds/sprinkles lingering into Wed morning. Very dry air
mass spreading across the nrn half of the area will lead to cold min
temps over mtns/interior valleys where clouds clear, with well below
freezing conditions over mtn and highest valley zones. San Luis
Valley will see patchy 32f readings by early morning, though not
widespread enough for a freeze highlight at this point. On Wed,
still some weak instability and moisture over the srn mts, and with
secondary upper energy digging into the state, could still see some
isolated -tsra over the ern San Juans/srn Sangres/NM border region
through the day, though coverage/intensity will be sparse/weak. Max
temps area-wide will remain seasonably cool at most locations as
surface high pressure shifts south into TX by afternoon.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 252 PM MDT Tue Sep 25 2018

Operational models are in decent agreement through the weekend
with differences showing up early next week in how they want to
handle tropical storm Rosa. The ensemble mean tends to favor the
ECMWF so have trended that way for the early next week period.

Wednesday night through Sunday...an upper level shortwave is
forecast to be dropping southeast out of Colorado and into Texas
Wednesday evening. An isolated shower or thunderstorm may be
possible during the early evening hours over the southern Sangre
de Cristo range, with activity dissipating early.

Beyond Wednesday evening, expect dry conditions to prevail across
the area through Sunday afternoon. Warm conditions are expected on
Thursday afternoon with highs generally in the mid 80s. A cold
front will arrive Friday morning with much cooler air for Friday
afternoon. No precipitation is expected at this time with the
cold front. Temperatures are expected to only reach the lower to
mid 70s across the Plains. Northwest flow aloft will transition to
southwesterly flow aloft through the weekend. This will allow for
continued dry conditions across the area along with warming
conditions. Highs will once again climb into the mid to upper 80s
across the Eastern Plains. It should be noted that overnight lows
will be quite cool over the San Luis Valley by Thursday morning,
with mid 20s to lower 30s. Freeze watches may be necessary for
Thursday morning and this will continue to be monitored.

Monday into Tuesday...much early next week will depend on what
happens with tropical storm Rosa in the eastern Pacific. The GFS
has an upper system off the west coast, which traps the tropical
storm in southwesterly flow and lifts it across the area Monday
through Tuesday. This would bring a period of heavy rain to the
Continental Divide during this period, with locations over the San
Juan range seeing the greatest potential for heavier rainfall. The
ECMWF and most ensemble members bring the upper level trough on
shore, but slowly and tropical storm Rosa is not picked up by the
upper system. At most, the ECMWF and ensemble mean would bring a
period of isolated to scattered showers and thunderstorms to
mountain areas, and not the heavy precipitation as forecast by the
GFS. Mozley


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1129 PM MDT Tue Sep 25 2018

VFR conditions are forecast at all three TAF sites (KALS, KCOS,
KPUB) over the next 24 hours. While low clouds are possible over
the Palmer Divide and eastern slopes of the Sangre's early
Wednesday morning, expect only a low chance that KCOS experiences
restricting CIGS/VIS. Weak thunderstorms possible over the
southwest and southeast mountains during the afternoon on
Wednesday, away from the TAF sites.




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