Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 190915
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
315 AM MDT Wed Jul 19 2017

.SHORT TERM...(Today and tonight)
Issued at 315 AM MDT Wed Jul 19 2017

Little change in the weather pattern since yesterday. West-
southwest flow aloft will prevail around an upper level high over
Oklahoma. This will keep monsoon moisture over the area.
Precipitable water values may increase a little today, around an
inch across the lower elevations. Heavy rainfall will be possible
with some of the storms due to the moisture and slow storm
movement. With a large temperature/dew point spread, gusty winds
will likely accompany the convection. Best chance for storms will
be over the higher terrain where scattered thunderstorms are
expected. Convergence along outflow boundaries may trigger
isolated storms over the plains late this afternoon and evening.
Otherwise, there does not appear to be anything to kick off
storms, like convergence along a boundary yesterday.

It will be another warm day with mid to upper 90s across northeast
Colorado. There is a good amount of mid and high cloud over and west
of the area. If more cloud cover prevails than expected, highs may
fall short of the mid 90s. Though expect enough sun to push
temperatures into the mid 90s at least.

.LONG TERM...(Thursday through Tuesday)
Issued at 315 AM MDT Wed Jul 19 2017

Thursday through Friday, the models to show the center of the
upper ridge moving into the central plains states. This will allow
for the plume of monsoonal moisture to move more directly across
the cwa. The forecast soundings show the precipitable water
values approaching an inch by late Thursday afternoon, then around
1.10 inches on Friday. The storm motions will be slow as well so
locally heavy rainfall will be the primary concern. Models vary
quite a bit regarding the CAPES each afternoon, but 500-1500 j/kg
would appear to be a mean value. Over the weekend, the ridge
flattens and stretches across the entire southern half of the U.S.
The flow aloft over Colorado will be a little drier and more
westerly. The best chance of thunderstorms at that time would
appear to be over southern and eastern Colorado, impacting areas
primarily east of I-25 and south of I-76, with lesser coverage to
the north and west. A weak front will push across the area by
the weekend, and likely settle along the Palmer Divide. This
would also help as a focusing mechanism for tstms there. By early
next week, a ridge tries to re-establish itself over the Desert
Southwest. The flow aloft will remain weak and more southwesterly,
allowing for the plume of monsoonal moisture to advect back into
western Colorado. The best pops at that time will be in the
mountains, with more isolated coverage across the northeast
plains. Overall temperatures will be at to slightly above normal
for Thursday and Friday, which is 90 for Denver. High temperatures
will not be as hot the rest of the period, generally be in the
mid to upper 80s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 315 AM MDT Wed Jul 19 2017

VFR conditions are expected through tonight. Scattered
thunderstorms will form over the higher terrain west and south of
Denver after 18Z. Outflow from these storms is expected to produce
a wind shift from the southwest between 22Z and 01Z. There is a
slight chance for thunderstorms over the Denver airports today
with KAPA having the best chance at seeing a thunderstorm. If a
storm passes over an airport, brief heavy rain and wind gusts to
45 knots will be possible. The threat for thunderstorms is
expected to end around 03Z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Meier
LONG TERM...Cooper
AVIATION...Meier



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