Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 310930

Area Forecast Discussion
National Weather Service Denver/Boulder CO
330 AM MDT TUE MAY 31 2016

.SHORT TERM...(Today and tonight)
Issued at 330 AM MDT Tue May 31 2016

Cold front has pushed across northeast Colorado and stratus is
developing pretty much as expected. There has been a bit of drying
noted to the north which is allowing from some breaks/lifting of
the stratus deck, but overall should see fairly widespread stratus
early this morning along with some fog in the foothills. Can`t
rule out a couple showers or patchy drizzle either.

For later this morning, the clouds are expected to break and
slowly lift with a light southerly component in the low level
winds fields developing. This should allow for better heating and
destabilization. Even with the cooler temperatures today, there
is still 400-800 J/kg of CAPE forecast for the I-25 corridor with
a T/Td of 66/46. If we get more warming then could see CAPES
upward of 1000 J/kg but best bet for those higher numbers would be
over the Palmer Divide, southern foothills, and Park County area
so a low severe threat there with hail the main threat. Isolated
tornado can`t be ruled out with weak surface boundary expected in
that region as well this afternoon. A weak short wave and Q-G lift
is noted for this afternoon and GFS indicates another easterly
push, so have increased PoPs for the late afternoon and early
evening hours. The bulk of this rainfall is expected from the
Front Range southeastward across the I-25 corridor and Palmer
Divide area.

Overnight, showers should gradually decrease with stabilization. A
low/mid level cloud deck may persist with generally light flow,
lowering the chance of fog development outside of the foothills
where clouds intersect the terrain.

.LONG TERM...(Wednesday through Monday)
Issued at 330 AM MDT Tue May 31 2016

Rising sfc pressure across Wyoming and Nebraska beneath sinking
northwest flow aloft should continue to produce a moist east-
northeasterly low-level upslope flow east of the Front Range
Wednesday morning. Model cross sections show a stratus cloud deck
extending east to the Nebraska/Kansas border early with bases
down to around 2000 ft agl along the foothills. However the in-
cloud environment favors little more than spotty drizzle or
sprinkles and mainly over and immediately near the foothills
prior to 15z. Areas of fog also possible in the lower foothills
during the same period. By late morning and early afternoon...low-
level flow on the plains is fcst to turn sely with the stg sfc
high in sern Wyoming trekking sewrd acrs n-cntrl Kansas by
00z/Thu. This will likely result in gradual warming and drying on
the plains but not sufficient to break the stg inversion layer up
around 700 mbs. Therefore the chance for showers/t-storms east of
the mtns will be quite low on Wednesday. Meanwhile light upslope
flow and destabilization at higher elevations should suffice to
product at least isolated showers and t-storms mainly along and
east of the Continental Divide by early to mid-afternoon. Gusty
and light rainfall main product of these short duration showers.
High temps on Wednesday generally 3-5 degs f warmer than those on

Rest of the week...upper ridge over the Desert SW and lower Great
Basin is projected to strengthen and expand eastward over Colorado
and northward up over the northern Great Basin on Friday. Should
see steady warming aloft with the 700mb temp rising to around 11
deg c over nern Colorado by Friday afternoon. Strong mixing
should give us max temps in the low to mid 80s on the plains,
potentially making it the warmest day of the fcst period.
Meanwhile odds of seeing any convection, i.e. precip, during this
two day period appears remote.

Over the weekend the upper ridge continues to build northward...
and as it does the flow aloft over Colorado assumes more of a
north-northwesterly trajectory. The shift in flow causes the very
warm air aloft to retreat westward leading to slightly cooler
temps across eastern Colorado. A majority of the models show a
weak...mostly dry cold front sliding swrd through nern Colorado
late on Saturday after a day of isolated t-storms and afternoon
temps in the upper 70s-lower 80s on the plains. Post-frontal nly
winds curving into the Front Range could enhance shower/t-storm
development during the evening hours. However precip should still
be light and spotty.

Sunday should be a tad (1-3 deg F) cooler on the plains with a
continuation of north-northwesterly flow aloft. However stg solar
heating should manage to produce isolated showers and t-storm
over the Front Range by mid to late afternoon. By Monday...models
show the upper ridge collapsing some which returns a west-
northwest flow aloft over the area leading to slightly warmer
temps. A slight chance of late day t-storms will remain in the
fcst mainly for the higher terrain.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 330 AM MDT Tue May 31 2016

MVFR ceilings will persist through 15Z, then should see a gradual
erosion and lifting of the lower ceilings with daytime heating and
mixing. Chance of showers and thunderstorms will increase across
the Front Range airports 20Z-21Z as airmass destabilizes. Chance
of a storm is around 30% with around 60% chance of showers between
21Z and 03Z. Lower visibility to around 5SM and ceilings down to
1000-2000 feet possible with heavier showers. After 03Z,
precipitation chances will decrease but an MVFR cloud deck may
affect the airports through the night. As long as the cloud deck
persists, any chance of fog late tonight would remain under 20%.


.BOU Watches/Warnings/Advisories...


SHORT TERM...Barjenbruch
AVIATION...Barjenbruch is the U.S. government's official web portal to all federal, state and local government web resources and services.