Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 252148
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
348 PM MDT WED MAY 25 2016

.SHORT TERM...(This evening through Thursday)
Issued at 348 PM MDT Wed May 25 2016

...Quiet through tonight then severe weather possible Thursday...

Dry southwest flow across southern Colorado this afternoon with
temperatures near average for this time of year.  A bit breezy in
spots and the humidities are low so not really a good day for
burning.  However, meteorological conditions are just marginally
critical and fuels are generally in greenup so no fire weather
highlights.  Regardless, caution is advised to avoid activities that
could spark an unwanted fire.  Dry weather and seasonal temperatures
should continue through tonight.

On Thursday, the weather will get busier.  A spring storm system
visible in satellite pictures over southern California this
afternoon has Colorado in it`s crosshairs.  This storm will track
across Arizona tonight and then east across northern New Mexico,
just south of the 4 corners on Thursday.  As this storm nears the 4
corners region Thursday morning, surface low pressure will deepen on
the southeast Colorado plains and a cold front boundary will start
to take shape somewhere along or a little north of the US Highway 50
corridor across the plains.  During the afternoon, frontogenesis
will occur and a strong cold front will emerge over the Pikes Peak
Region and push its way rapidly south through the I25 corridor. Over
the plains east of the corridor, warm, dry southerly breezes will
continue through the day Thursday.

As the front organizes and pushes south on Thursday, a number of
weather hazards will present themselves.  First, there will be the
severe weather threat.  Based on the latest model projections of
frontal timing and position, the Storm Prediction Center has pushed
the Slight Risk of severe weather down across most of El Paso and
part of northern Pueblo Counties Thursday.  This looks good based on
the latest positioning and timing of things in the models. However,
if things shift north or south just a little, the severe weather
threat will likewise shift north or south.  The primary severe
weather concerns at this point are large hail an inch or more in
diameter and possibly even a brief tornado.  The window for a
tornado will probably be fairly brief as once the cold front plunges
south and the cold air deepens behind, we loose the low level shear
and instability, diminishing the prospects for low level circulation.
However, there will be a window of opportunity along and near the
frontal boundary when coupled with the better elevated shear and
instability above the frontal boundary.

Another thing we will have the watch tomorrow afternoon is the flash
flood threat on the Waldo Canyon Burn Scar.  The initial burst of
convection during the afternoon could deliver high enough
precipitation rates to cause some runoff concerns.  If the scar
takes a direct hit, from the wrong cell, for too long a time, we may
see some problems.  Then, I think, later in the day into the
evening, precipitation will become more stratiform in nature as
colder air moves in and cold rain processes take over, reducing the
threat for intense rainfall rates and flash flooding.

Additionally, with the colder air moving in, snow levels will be
dropping late in the day.  They may be nearing 9,500 feet by 6 pm
allowing any high elevation rain to change over to snow above this
level.  At least a few inches of heavy wet snow should have
accumulated on top of Pikes Peak by this time.  While this is not
quite down to the top of the Waldo burn scar yet, snow levels
promise to drop even lower Thursday night, which should turn rain
over to snow across the higher reaches of the burn scar.  This, in
itself, will help to diminish the flash flood threat Thursday
evening.

.LONG TERM...(Thursday night through Wednesday)
Issued at 348 PM MDT Wed May 25 2016

...Rain and Higher Elevation Snow Thursday night and Friday...

Thursday night-Friday night...Latest models in good agreement and
continue to indicate an upper level low across the Four Corners area
Thursday afternoon slowly lifting north and east into southeast
Colorado Friday morning, which then continues to slowly weaken as it
moves into north central Kansas through Friday night.

The severe weather threat across northern portions of the Eastern
Plains diminishes through the early Thursday evening, with the focus
becoming snow levels and snow amounts across the higher terrain.
Latest models continue to bring best QPF over the Pikes Peak region
with UVV associated with upper level deformation, along with mid
level north to northeast flow Thursday night through mid day Friday.
Cooling aloft under the passing low, with H7 temperatures progged
between 0C and 4C across the area Thursday night, supports snow
levels down to between 8K and 9K feet into Friday morning before
lifting back up to around 10K feet with scattered showers and
thunderstorms expected area wide Friday afternoon. Current grids are
indicating snow accumulations of over a foot on top of Pikes Peak
with 2 to 6 inches across the rest of Teller county, the higher
elevations of the Sawatch and Mosquito Ranges, and the Sangre de
Cristo and Wet Mountains. Have kept current Winter Storm Watch
intact for the Summit of Pikes Peak, with later shifts likely
upgrading and possibly adding advisories for the other higher
mountain zones for Thursday night and Friday. Passing system sends
cold front across the Eastern Plains Thursday night, with breezy
north winds and temps below seasonal averages expected across the
area on Friday.

Saturday-Sunday...Drier westerly flow aloft across the area Saturday
gives way to increasing southwest flow through the day on Sunday
ahead of an embedded disturbance translating across the southern
Rockies through Sunday night. There will be enough residual moisture
to support isolated to scattered showers and storms across the area
Saturday afternoon and evening, with the best coverage over and near
the higher terrain. A better chance of showers and storms expected
across the area Sunday afternoon and evening, with stronger storms
possible across the far SE Plains with retrograding dry line across
western Kansas. Temperatures look to be at or slightly below
seasonal averages through the weekend.

Monday-Wednesday...A relatively cool and unsettled weather pattern
remains in the offing into early next week, as another embedded
disturbance translates across the northern and central Rockies
Monday and Tuesday. This will keep isolated to scattered afternoon
and evening showers and storms possible through the period, with
temperatures remaining at or below seasonal averages.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 348 PM MDT Wed May 25 2016

Generally VFR across flight area next 24 hours. There could be some
spotty convection around during through the evening hours, mainly
over the mountains and Palmer Divide but most areas should remain
dry. Lightning and erratic wind gusts to around 50 mph would be the
primary threats from any storms that might develop today.

Weather pattern starts to turn more active late tomorrow morning,
after about 15Z, when showers and storms should start to develop
over the mountains west of I-25 in advance of an incoming system.
Areas of MVFR, IFR and LIFR conditions will begin to develop over
the mountains.  After 18Z, these conditions will intensify and
spread east across the I-25 corridor onto the plains.

For the KCOS, KPUB and KALS TAF sites, conditions should remain VFR
through 18Z Thursday. However, MVFR, IFR and LIFR conditions will
begin to spread east to KCOS after 18Z and reach KPUB by around 21z.
For KALS, precipitation will be more scattered, focused more on the
areas nearer the mountains around the site.  However, the terminal
may take a hit from a storm at some point.  For the time being, this
will likely be handled with VCSH in the next forecast issuance.

&&

.PUB Watches/Warnings/Advisories...
Winter Storm Watch from Thursday afternoon through Friday
afternoon for COZ082.

&&

$$

SHORT TERM...LW
LONG TERM...MW
AVIATION...LW


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