Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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274
FXUS65 KBOU 261648
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1048 AM MDT FRI AUG 26 2016

.UPDATE...
Issued at 1040 AM MDT Fri Aug 26 2016

Satellite imagery shows band of moisture over the eastern plains
as subsidence moves into northwestern portions of the state. The
elongated upper level trough remains over the region with the main
branch of energy over southern Idaho. Western flow will dominate
with subsidence aloft that most short-term models are picking up
on and leaving the central portions of the CWA dry. Looking
upstream and with dominate western flow this afternoon I will
lower pops over the urban corridor. Most of the precip will be
over the higher terrain and over the eastern plains as a majority
of the moisture will be over these areas. With forcing over the
east combined with PW values near 1 inch the main threats this
afternoon will be moderate rain and lightning. CAPE profiles are
not impressive for hail growth and with the deeply saturated lower
layer winds may gust to 25 or 30 mph.

&&

.SHORT TERM...(Today and tonight)
Issued at 330 AM MDT Fri Aug 26 2016

An upper level trough over northeast Utah will move east across
Colorado this morning. Lift ahead of the trough is producing
widespread clouds along with scattered to isolated showers. The
showers are expected to shift east across the state this morning.
So far, rain has been spotty and light. Given the cooler
temperatures expect light snow has fallen above 11000-12000 feet.

For the rest of this morning, forecast is unclear. General
consensus among the models is that scattered showers will drift
east early this morning. Then a band of rain will form over the
northeast corner of the state. Models vary on the amount of rain
that will fall under this band. The ECMWF shows around an inch of
rain over Washington county while the GFS has a few tenths. The
HRRR has a bullseye over Logan county with almost nothing over
Washington county. So far models, have over predicted rainfall.
Will have likely pops over the northeast corner with scattered
pops elsewhere.

Expect some partial clearing late this morning and early
afternoon along the Front Range. This should allow temperatures
to climb into the lower 70s. Airmass becomes slightly unstable
over the mountains and Front Range. Expect scattered to isolated
storms this afternoon, with the best chance being over the higher
terrain. The airmass dries tonight and expect precipitation to
end by mid evening if not sooner.

.LONG TERM...(Saturday through Thursday)
Issued at 330 AM MDT Fri Aug 26 2016

On Saturday a weak southwesterly flow aloft will be over Colorado.
The mdls show a weak trough over the desert southwest Saturday
aftn...this feature then shifts even further south on Sunday as an
upper level ridge builds into NV. As a result...the mdls shift the
plume of subtropical moisture more to the south and east over the
weekend...which will allow the airmass to become drier and warmer.
Will hold onto sct pops in the mountains on Saturday...then go
with isolated coverage on Sunday.

By early next week a ridge of high pressure will be over the
west. Some subtropical moisture will be around...but the best
chance of thunderstorms each aftn and evening will be over the
mountains of CO. The latest GFS/ECMWF maintains a weak
southwesterly flow over the state which could allow for a better
influx of moisture over cwa by the middle of next week. The ridge
at that time is progged to set up over the southeastern u.s. For
now will keep the pops each aftn/evng primarily in the mountains
...but could see pcpn coverage start to increase a bit by late
next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1040 AM MDT Fri Aug 26 2016

VFR conditions are expected through the period. Winds will be
light and variable then turn NE around 09z. Have removed the
threat of thunder this afternoon but there will be some
development over the foothills and eastern plains. Ceilings will
stay over the region but BKN will be around 100 to 150 through the
period. Winds will move to drainage overnight.

&&

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

$$

UPDATE...Bowen
SHORT TERM...Meier
LONG TERM...Cooper
AVIATION...Bowen



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