Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 251733

Area Forecast Discussion
National Weather Service Pueblo CO
1133 AM MDT Tue Apr 25 2017

.SHORT TERM...(Today and tonight)
Issued at 343 AM MDT Tue Apr 25 2017

...Wet weather expected this afternoon and tonight...

Currently...there are a couple of upper level disturbances across
the area, one sitting over Central Wyoming which has sparked showers
and isolated thunderstorms over northeast Colorado early this
morning, while a secondary shortwave is gathering strength over
Utah.  This disturbance has led to light snowfall along the
Continental Divide this morning, especially over the Central
Mountains.  Increasing westerly flow aloft has kept the atmosphere
well mixed across the Plains with temperatures in the upper 40s to
mid 50s.  A cold front has reached near Highway 50 as of 3 am, and
winds have switched northerly behind the front with gusts to 25 mph
possible through the early morning.

Today...expect generally dry conditions across much of the region
this morning before precipitation spreads across the region this
afternoon.  Models in good agreement with the cold front across the
Plains clearing to the south by midday, and low level flow turning
northeasterly upslope this afternoon.  Aloft, the disturbance over
Utah is forecast to track southeast into northern New Mexico by this
afternoon.  Continued showers are expected along the Continental
Divide this morning, spreading east into the Eastern Mountains by
early afternoon.  As the upper system approaches, good diffluence
aloft and weak instability will combine with the moist low level
upslope flow to produce showers and isolated thunderstorms.  Initial
develop over the Eastern Mountains by early afternoon will spread
east into the I-25 corridor by late afternoon and blossom heading
into the evening hours.  Moderate to heavy rainfall is expected
generally south of Highway 50, with the primary focus over the
southern I-25 corridor.  We will need to monitor area burn scars if
heavier rainfall develops over them, and with initial snow levels
being above 9 kft through the afternoon.

Tonight...the time period between early evening and midnight will of
primary concern across the region.  The upper disturbance will
continue to the southeast into the Texas Panhandle by morning.  As
it does so, the evening period should see the most favorable
conditions for heavy precipitation.  A secondary cold front will
back west across the Plains this evening with an enhancement of the
low level upslope.  Wind flow around the upper disturbance will
maximize northeasterly upslope flow at this time as well.  Colder
air behind the secondary cold front should allow for snow levels to
drop to near 6 kft.  As the night progresses and the upper
disturbance moves away from the area, models in good agreement with
precipitation coming to an end from north to south, with areas along
the New Mexico border having light precipitation by morning.
Temperatures will be cool tonight with lower to mid 30s across the
region.  As far as snowfall totals, higher elevations of the Sangre
de Cristo and Wet Mountains will generally see 6 to 10 inches, with
locally higher amounts over the Wet Range.  Locations over the
southern I-25 corridor may see up to 3 inches, especially west of
Trinidad.  Mozley

.LONG TERM...(Wednesday through Monday)
Issued at 343 AM MDT Tue Apr 25 2017

...Unsettled period through the extended...

Cool northwest flow will persist through much of the extended with
precipitation ending pretty quickly Wednesday morning across
southern CO as the upper trof moves east of the area.  Residual
moisture/instability and weak shortwave energy will be sufficient to
trigger another round of isolated afternoon showers over and near
the mountains but precipitation amounts will remain light.

Another stronger system drops in for Wednesday night/Thursday
bringing another uptick in showers and higher elevation snows to the
mountains Wednesday night...and rain to the plains on Thursday as
another front drops through. Although there isn`t a lot of
CAPE...there will still be sufficient instability for an isolated
embedded thunderstorms Thursday afternoon. Precipitation decreases
late Thursday night and depending on the amount of clearing we
could be flirting with freezing temperatures across the plains by
early Friday morning.

A broad trof carves out across the central U.S. Rockies for
Friday night and Saturday. GFS is farther south with the upper low
position vs the GFS. Both models bring a front in with fairly
widespread precipitation developing across southern CO Friday
night and Saturday. GFS`s farther south solution puts the heavier
QPF in NM while EC puts it across southern CO. Both models suggest
colder air will come in with this system with the potential for a
sloppy rain snow mix across the southeast plains Saturday
morning. Of course model solutions are bound to go through some
more changes over the next several days. Overall blended POP
grids weren`t too bad with likely pops across southeast CO during
this period. Southeast mountains may need another highlight if
system pans out close to the ECMWF solution. Drier weather
returns for Saturday night and Sunday as system exits to the east.
Saturday night could end up another potential freeze night for
the plains depending on how quickly skies clear out.

A brief reprieve is expected for early next week however another
system looms for Tues/Wed with another front and another round of
precipitation possible. Timing in extended models is quite a bit
different with Tuesday either being dry warm and windy ahead of
the system according to GFS, or cool and wet according to the
faster ECMWF. Lots of uncertainty that far out so will allow
grids to trend towards climo. -KT


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1128 AM MDT Tue Apr 25 2017

Upper trough of low pressure swinging across the Rockies will
produce a wet and cloudy afternoon and evening for much of the
state and forecast area, including the three TAF sites of KCOS,
KPUB and KALS. VFR conditions currently are expected to drop to
IFR for most locations between 20-22z this afternoon, and last due
to lowering clouds and a rain/snow mix through this evening until
08-10z. VFR conditions then expected to develop between 10-12z,
though there is an outside chance for fog developing at KALS
through the early morning hours. Chances are too low at this time
to include in the TAF.

Pcpn and clouds will then slide to the southeast corner of
the state before exiting overnight.


Winter Weather Advisory until 9 PM MDT this evening for COZ058-

Winter Weather Advisory until 6 AM MDT Wednesday for COZ073-075-



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