Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 142132
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
332 PM MDT Mon Aug 14 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 308 PM MDT Mon Aug 14 2017

This aftn the lower levels of the atmosphere have dried out with
dewpoints dropping into the 30s at KDEN. The max at DIA has hit 90
before the clouds moved in, the last one since 92 on the 4th. Still
enough mid level moisture around to support a few thunderstorms
this evening. Best CAPE values however will be further east,
ranging from 500-1000 j/kg. Strong storms possible there with
heavy rain and wind gusts in the 50-60 mph range, but weaker
storms elsewhere with less moisture and limited CAPE. Will keep
scattered weaker storms in the high country early this evening,
more isolated over the urban corridor, then scattered further east
where better moisture will be. The flow aloft will be
southwesterly, with a weak upper trough to the northwest of CO,
stretching from western MT into northern NV late around 00z. On
Tuesday it will be cooler and wetter. The trough axis will stretch
from western WY into central NV at 12z. There may be some light
showers in the mountains in the morning especially north of
Interstate 70. By the afternoon, scattered showers and
thunderstorms will spread to the south and east, with the best
pops over along the northern tier counties. Overall, the NAM and
GFS both show weak mid level QG ascent over the region on Tuesday
morning will get more consolidated and shift more into east
central/southeast CO on Tuesday with cooler air moving in from.
the north. This allow weak northeast winds to advect the the
boundary layer theta-e max along the eastern border westward
toward the Urban Corridor in the aftn. Better instability with SPC
placing most of northeast CO in the marginal risk of severe, with
the slight risk along the eastern CO border. NAM12 forecast
soundings for Tuesday range from around 1000 j/kg for the Urban
Corridor to over 2000 j/kg over the northeast plains, with
precipitable water values back over one inch.

.LONG TERM...(Tuesday night through Monday)
Issued at 325 PM MDT Mon Aug 14 2017

The upper level pattern across the western United States will be
undergoing some changes through this week, but the resulting
weather over Colorado will be little changed. A lack of ridging
across the western United States is going to allow mid level
moisture to continue moving across the Rocky Mountain West which
will feed afternoon thunderstorm activity each day. Early in the
forecast period, an upper trough which is over eastern Nevada this
afternoon will be shearing out and moving across northern Colorado
Wednesday morning. A surge of cool temperatures at low levels will
also move into the region that morning. Dynamic forcing associated
with the passing upper disturbance may extend Tuesday evening
showers over the mountains through most of the night. Temperatures
on Wednesday will also be cooler because of the presence of the weak
cold front. Through the latter half of the week, the GFS and ECMWF
show weak upper ridging developing over the southwestern United
States, but the weak mid level flow will also allow a resurgence
of monsoonal flow into the Four Corners region. This will bring
more moisture over Colorado, feeding additional shower development
over the mountains each day. Temperatures will warm back up to
seasonal normals, but the unsettled pattern of afternoon showers
will also prevail. This pattern looks to continue until either a
much stronger ridge builds over the southwest, or a potent upper
trough develops and sweeps down out of Canada or the Pacific
Northwest.


&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 308 PM MDT Mon Aug 14 2017

VFR will prevail over the next 24 hrs. Isolated thunderstorms are
expected to impact the area until around 01z. Still think vcts
will suffice for the terminals this evening with variable outflow
wind gusts to 30 kts. Sfc winds will go to drainage until closer
to 12z when a northwest to northeast winds will develop as a weak
front pushes to the south on Wednesday. Better moisture around on
Wednesday with a better chance of thunderstorms in the aftn.

&&

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

$$

SHORT TERM...Cooper
LONG TERM...Dankers
AVIATION...Cooper


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