Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 261629
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1029 AM MDT SUN JUN 26 2016

.UPDATE...
Issued at 1025 AM MDT Sun Jun 26 2016

Today`s forecast remains on track. New model guidance continues to
support a later start to convection in the mtns and on the plains,
and less activity in the high country with drying at mid-levels.
Temps at this hour in the mtns and along the I-25 corridor are
running near to slightly behind those yestereday at this time...
while from 2 to 8 deg f ahead farther out on the plains. Ample
sunshine and a sly low-level flow will have little problem raising
the mercury into the upper 80s/lower 90s at lower elevations and
into the 70s/lower 80s in the high country.

It`s late this afternoon and evening when models show strengthening
s-sely bndry layer flow on the plains causing a steady increase in
moisture within the sfc-650mb layer. By 00z NAM indicates BL CAPES
in the 1500-1900 j/kg range over the Palmer Dvd and up around
2500 j/kg across the nern corner of the state. Increasing deep
layer shear and low-level speed convergence early this evening
will contribute to t-storm formation in these areas with and
isolated severe t-storms a threat acrs the northeast corner where
SPC indicates a marginal risk for severe. Large hail and damaging
winds main threats out there...but can`t rule out a stray storm
approaching severe on the Palmer Dvd. Storms should end in all
but the far northeast corner by midnight.

&&

.SHORT TERM...(Today and tonight)
Issued at 330 AM MDT Sun Jun 26 2016

The most significant change today is the amount of drying that is
moved into the Western 2/3 of Colorado. Water vapor imagery shows
this nicely and Integrated Precipitable Water trends from GPS
concurs as GJT only showing about a 1/3 of inch of PW. The
moderate Westerly flow aloft will continue to nudge the deeper
moisture into far Eastern Colorado. Also don`t see any upper level
disturbances that will move across the state through this evening
as QG fields are rather neutral.

Temperatures will be warmer today as 700mb temperatures expected
to climb to around +15c which will result in surface temperatures
4-6 degrees warmer than Saturday. For storm development
today...looks too dry in most mountain locations....especially
West of the Divide and North of Interstate 70. As for the
Northeast plains...models keep surface dewpoints up in the 50s
across the plains under increasing Southeast flow but expect some
of this to mix out into the lower 40s...especially over the Urban
corridor. Forecast soundings mainly inverted V so main threat will
be gusty winds. Deeper moisture out on the plains will result in
stronger storms as surface based capes ranging from
1000-1800j/kg and decent shear profile. Main threats would be
Large Hail up to 1 inch in diameter and damaging winds.

Expect initial storms to develop over the higher terrain of the
Palmer Divide and CYS ridge with surface convergence in these
locales and then move onto the plains. Overall coverage will be
rather isolated through this evening due to the dry mid/upper
levels and lack of any upper support noted.

.LONG TERM...(Monday through Saturday)
Issued at 330 AM MDT Sun Jun 26 2016

Weakening of the upper level ridge will bring multiple
disturbances across Colorado keeping storms and lower temperatures
in the extended.

For Monday the upper level ridge will start to degrade over the
southwest bringing flow aloft more NW. A cold front will move
onto the NE plains by 00z Tuesday bringing increased moisture and
cooler temperatures. This front will move against the foothills
and provide the trigger to help set off afternoon and evening
convection on the plains. CAPE values will be 1500-2000 j/kg with
decent mid level shear values in the 40s. Storms could fire off
along the boundary through the afternoon before the easterly flow
moves into the foothills and continues convection over the higher
terrain into the evening hours. The main threats will be heavy
rain, gusty winds and isolated hail up to one inch in
diameter...mostly over the eastern plains. Subsidence behind the
front will help to stabilize the atm early Tuesday before another
round of storms Tuesday afternoon. These will mainly be over the
higher terrain with a few that could make their way off the
foothills during afternoon hours bringing rain, gusty winds and
small hail. Temperatures for Monday and Tuesday will hover around
seasonal normals with highs in the upper 80s to lower 90s.

For Wednesday through Friday the upper level ridge continues to
move south bringing increased NW flow aloft over the state. This
will deliver a round of disturbances on Wednesday and Friday. For
Wednesday a shortwave will clip the NE corner of the state. A
deep lee surface low will keep the brunt of the moisture over NE
and KS with some storms possibly making their way onto NE corner
counties with heavy rain and winds early wednesday. Diurnal
afternoon storms will be possible for Wednesday and Thursday
afternoon with temperatures in the mid to upper 80s.

On Friday morning another disturbance will move over the state
bringing cooler temperatures and increasing moisture. Models are
showing more of a stratiform rain set-up with increasing
stability. Highs on Friday will be on the lower to mid 80s. For
Saturday and Sunday more rain is in store...however models diverge
slightly on timing and placement of upper level features so will
have to monitor.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1025 AM MDT Sun Jun 26 2016

Light and variable winds at this hour across the Denver metro
area should become predominatly east-southeasterly after the noon
hour...with speeds on the order of 7-14kts. T-storm development
in the Denver area will be minimal at best and not until late this
afternoon when low-level moisture feeds up from the southeast.
However...the bulk of the storm activity should remain south-
southeast of the metro area along the Palmer Dvd and across the
northeast corner of the state where it could linger late into the
evening. Spotty convection on the Palmer Divide could produce
gusty outflow winds early this evening on the order of 20-25kts.
Speeds should then relax once convection dissipates and the typical
drainage wind pattern sets up.

&&

.BOU Watches/Warnings/Advisories...
None.
&&

$$

UPDATE...Baker
SHORT TERM...Entrekin
LONG TERM...Bowen
AVIATION...Baker



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