Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 240318
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
918 PM MDT TUE AUG 23 2016

.UPDATE...
Issued at 915 PM MDT Tue Aug 23 2016

At 9:15 PM the upper level trough was spinning over NW New
Mexico. Convection that had developed over the Central Rockies and
the San Juan Mountains in southwest Colorado has weakened.
Lightning activity has diminished with the loss of heating, and a
few lingering showers remain over the higher terrain west and
southwest of the urban corridor. Skies will remain mostly cloudy
overnight. The forecast for tomorrow is on track with
thunderstorms expected over the mountains and a few making it east
into the urban corridor by late afternoon.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 230 PM MDT Tue Aug 23 2016

The upper level trough will make its way east through the state
through Wednesday. Energy associated with this feature will allow
for continued propagation of the circulation over the four corners
region to bring showers and thunderstorms to the mountains and
Park county through the evening and into Wednesday. A cold frontal
boundary that pushed in from the NW earlier today brought
increasing stable conditions onto the plains along with gusty
winds. This will help to keep storms at bay for this afternoon and
evening. Models show persistent QG lift and increasing specific
humidity and PW values over the SW portions of the state reaching
into the higher elevations of the CWA and Park county. Expect
upwards of 1 inch of precipitation possible over a few hours under
the stronger storms. Overnight wet bulb zero levels will drop
enough to possibly produce a dusting of snow above timberline. For
Wednesday temperatures will be cooler with highs only reaching
into the mid 70s. CAPE values increase over the plains with just a
slight chance of afternoon storms with increasing mid level
moisture from a surface low that will push north during the day.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 230 PM MDT Tue Aug 23 2016

Scattered showers will be continuing over the high terrain
Wednesday evening...with some able to produce brief heavy rain.
There will be a slight chance over the urban corridor and nearby
plains with upslope flow. Forecast soundings look too stable
further out east.

Southwest flow aloft will continue Thursday with surface flow
turning more south-southeasterly. Look for high temperatures to
warm a few degrees. Again, storms should confine themselves
mostly to the high terrain and urban corridor in the afternoon,
then the chance of precipitation will push out over the eastern
plains that evening as the upper trough with cooler air aloft
sinks further south toward the area and a jet streak positions us
in the right entrance. Instability will increase over the eastern
plains through the evening and overnight, so will keep a slight
chance going across the area.

The upper trough over the northern Rockies will push into Colorado
late Friday bringing warmer temperatures. Southerly surface flow
will bring up increased moisture over the eastern plains as a
surface low forms over the CO/NE state borders. CAPE values of
600-1000 J/kg over the plains will result in higher POP values
overall with a focus over the far northeast plains. As the trough
pushes over Colorado overnight, it will send drier air in on its
heals.

On Saturday and Sunday, flow aloft will stay southwesterly as
another weak upper trough over the Great Basin moves slowly into
the state. Less shower/storm coverage is expected and should
remain mostly over the high terrain. High temperatures should be
back toward seasonal norms. Upper ridging for Monday and Tuesday
will keep the seasonal temperatures around and slight chance of
afternoon and evening showers/storms, mainly over the high
terrain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 915 PM MDT Tue Aug 23 2016

Overcast skies expected for the terminals overnight and into the
day Wednesday. Winds should be generally out of the west and 10
kts or less overnight. By 18Z expect the surface winds to back to
ESE at all terminals in response to surface high pressure across
the Nebraska panhandle. HRRR and Hi-res NAM both generate
convection over the mountains early afternoon, and push the
convection over the terminals by 20-21Z. Chances are still pretty
low but any storms that form will likely generate gust fronts with
strong and gusty winds.

&&

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

$$

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


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