Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 230927
AFDBOU

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

.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 06Z TAFS through 06Z Tuesday night)
Issued at 325 AM MDT Tue Aug 23 2016

VFR conditions will prevail. Main challenge today is whether or
not showers and thunderstorms will be capable of spreading/
developing onto the plains again by late in the day. Right now it
looks as if drier air behind this mornings weak cold front will
try to win out. Will carry a Prob30 of -tsra for now starting
around 22Z-23Z late this afternoon into the evening. Main threat
would be gusty outflow winds to 35-40 knots again due to dry low
levels. Outside of convection...winds will transition to
northeasterly around 8-12 knots in the 15Z-18Z time frame behind
weak cold front. First wave of showers and storms over the
mountains this afternoon will then have potential to push a larger
west/northwest outflow boundary across the Front Range airports
with gusts to around 30 knots after 21Z-22Z.

&&

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

$$

SHORT TERM...Barjenbruch
LONG TERM...RJK
AVIATION...Barjenbruch



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