Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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374
FXUS65 KBOU 250304
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
904 PM MDT WED AUG 24 2016

.UPDATE...
Issued at 904 PM MDT Wed Aug 24 2016

Skies cleared late afternoon after the showers moved east,
resulting in thunderstorms forming over the mountains where
instability was highest. The High Plains continue to be stable
this evening and storms that moved east of the foothills weakened
quite a bit and were unable to generate much rain nor any gusty
winds. Latest model trends again initiate convection over the
mountains by 18Z and bring a chance of some of those showers
making it east and eventually across most of northeastern Colorado
overnight Thursday. Forecast grids have this well handled and no
updates needed.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 146 PM MDT Wed Aug 24 2016

Water vapor imagery continues to show corridor of increased
moisture streaming through central Colorado combining with
ongoing easterly upslope flow to produce prolonged showers over
the CWA. To the SE portions of Lincoln county and the higher
terrain could see some thunderstorm development by the late
afternoon as breaking in cloud cover has helped to increase
instability. Elsewhere heating has been hindered combined with
less than ideal 700 mb temperatures to not allow for good
instability and CAPE. Light rain showers will be possible this
evening over the urban corridor and out to DIA.

As the upper level trough continues to make its way eastward it
becomes disorganized with lack of upper level support and flow
turns more westerly. Weak QG vertical velocity continues Thursday
with less cloudy cover and increased CAPE on the plains. This will
help to fire off convection over the higher terrain by the
afternoon with increased SE flow at the surface. Moderate SSW
700mb flow will help to funnel moisture as well as help to push
some storms over the foothills possibly over the urban corridor by
early evening. Temperatures will be slightly warmer then today
with highs on the plains in the mid to upper 70s and 50s at higher
elevations.

.LONG TERM...(Thursday night through Wednesday)
Issued at 146 PM MDT Wed Aug 24 2016

As upslope low level wind continues Thursday evening, scattered
to numerous showers and thunderstorms over the high terrain and
urban corridor will move further east over the rest of the area
through the night as 700 mb flow turns west to southwesterly. This
will likely diminish convective activity along the urban corridor
by or just after midnight. Forcing and cooling aloft and upward
QG vertical velocities will help sustain CAPE, and sustain showers
and thunderstorms through most of the night over the rest of the plains.
As Friday morning rolls around, the far northeast plains will
likely continue to see convection.

The upper trough axis will swing over the state Friday to continue
the scattered showers and thunderstorms. Temperatures will be
slightly warmer at the surface, while temperatures will be cooling
aloft with the trough passage. This will bring higher CAPE values
to the area, 1000-1500 J/kg or more possible over the eastern
plains. Storms that direction may grow strong to severe Friday
afternoon and evening with hail and strong outflow winds.

As the main trough axis pushes east Saturday, higher heights will
be building over the area. However a weak trough on the backside
will push slowly across the area this weekend to keep some
diurnal convection possible but with less coverage. Temperatures
will be increasing back to near to slightly above normal readings
for this time of year.

Ridging aloft will continue Monday and Tuesday while high surface
pressure will be over the great plains. Just enough moisture under
the ridge should allow for isolated showers and thunderstorms for
the high country. Expecting warmer than normal temperatures.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 904 PM MDT Wed Aug 24 2016

VFR conditions will prevail overnight with light winds at the
surface, generally out of the south from 04-12Z at APA and DEN,
while at BJC expect westerly winds from 06-12Z. Mostly cloudy
slides this evening will give way to scattered mid/high clouds by
12Z. On Thursday there looks to be enough instability to warrant a
mention of thunderstorms in all the TAFS after 21Z.

&&

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

$$

UPDATE...Schlatter
SHORT TERM...Bowen
LONG TERM...Kriederman
AVIATION...Schlatter



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