Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231555
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
955 AM MDT TUE AUG 23 2016

.UPDATE...
Issued at 939 AM MDT Tue Aug 23 2016

The frontal boundary has made it into Central Wyoming bringing
increased gusting and drier condition behind it. Areas in Wyoming
are gusting up to 31 kts with frontal passage. PW and specific
humidity values continue to increase over the mountains and Park
county through the day so have maintained high pop and QPF values
for those areas. For the plains the frontal passage is creating
more stable conditions behind it so will keep mention of thunder
out for the time being. Some storms may form along the foothills
with increased easterly upslope but with light mid level winds do
not expect storms to move onto the plains. Made minor adjustments
to temperatures and winds.

&&

.SHORT TERM...(Today and tonight)
Issued at 325 AM MDT Tue Aug 23 2016

Latest analysis shows mostly clear skies over the forecast area.
Precipitable water values were just slightly higher than those
observed 24 hours ago, but a more significant increase had
occurred over western Colorado in advance of the next short wave.
Meanwhile, a surge of drier and slightly cooler air was advancing
southward behind a cold front moving through eastern Wyoming.

This front will arrive across northeast Colorado later this
morning and will have a tendency to dry the airmass even further.
The majority of this drying will occur on the plains and
therefore convective development in the lower elevations will
likely be hindered. In the mountains, moisture should actually
begin to increase this afternoon into the evening with potential
for numerous showers and storms ahead of the short wave. There is
persistent lift and increasing specific humidities and
precipitable water. Could see some locally heavy rainfall develop
but right now the heaviest seems to favor southwestern Colorado as
would be typical in these scenarios.

By tonight, there should be a little better chance of showers and
storms reaching the plains as airmass gradually moistens again
with persistent Q-G lift noted. Will keep generally low PoPs in
place across the plains through the course of the night. In the
mountains, wet bulb zero levels drop sufficiently with passage of
cold pocket aloft to bring potential of an inch or two of snow to
the higher peaks above 12000-12500 feet.

.LONG TERM...(Wednesday through Monday)
Issued at 254 AM MDT Tue Aug 23 2016

There is still an upper trough around the CWA Wednesday into
Thursday. It never pushes through and east of the CWA however.
The flow aloft remains southwesterly through Thursday night. The
synoptic scale energy on the QG Omega fields is benign through the
four periods. For the low level winds, east and southeasterlies
prevail Wednesday mid day through Thursday. There is drainage flow
on Thursday night. A cooler airmass is certainly in place on
Wednesday. Models continue to show pretty decent moisture for the
CWA through Thursday night. The precipitable water values are in
the 0.50 to 0.80 inch range all four periods. The low level
moisture is not very good Wednesday into Thursday with dew points
in the 30s to lower 40s F. They come a bit by later Thursday with
40s to lower 50s F. There is a bit of CAPE over the mountains late
day Wednesday. Values a bit higher late day Thursday with the CAPE
over the mountains, foothills and immediate plains. Won`t change
pops much, 30-50%s in the high county look okay for late day
Wednesday and late day Thursday. Will go with 10-20%s for the
plains at those times. Temperatures will be 4-9 C cooler Wednesday
afternoon from this afternoon`s highs. Thursday readings will be
close to Wednesday`s. For the later days, Friday through Monday,
models have southwesterly flow aloft for the forecast area into
Sunday, then a weak upper trough axis pushes through. There is
zonal flow on Monday. There is decent moisture around Friday, then
it gradually dries out through Monday. Temperatures are near or a
tad below seasonal normals.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 939 AM MDT Tue Aug 23 2016

For APA and DIA have kept thunder to VCTS for the time being. With
increased stable conditions behind frontal passage as seen on
short term and upper air model sounding do not expect thunder to
make it on station. However...winds will be possible with frontal
passage later this afternoon. Have the mention of increased
ceilings after 23z with moisture increasing in the mid levels.
Still expect VFR conditions through the period. BJC could see some
thunder as storms may be able to impact closer to the foothills.
Will maintain -TSRA for the time being with increased gusting.

&&

.FIRE WEATHER...
Issued at 939 AM MDT Tue Aug 23 2016

Frontal passage will bring increased gusting with obs in WY
registering up to 31 kts. These gusting winds combined with
decreased RH values to 7% by later this afternoon will cause
increased possibility for rapid fire spread. Included in the RFW
will be zones 238...242...and 248 with more critical values closer
to the Wyoming border. Conditions for other portions of the plainseast
of I-25 will be elevated with lowered RH values and gusty winds
but do not meet RFW criteria at this time. Will continue to
monitor conditions through the day.

&&

.BOU Watches/Warnings/Advisories...
Red Flag Warning until 6 PM MDT this evening for COZ238-242-248.

&&

$$

UPDATE...Bowen
SHORT TERM...Barjenbruch
LONG TERM...RJK
AVIATION...Bowen
FIRE WEATHER...Bowen



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