Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 172200

Area Forecast Discussion
National Weather Service Denver/Boulder CO
400 PM MDT Thu Aug 17 2017

.SHORT TERM...(This evening through Friday)
Issued at 350 PM MDT Thu Aug 17 2017

Current radars are showing less than 10% coverage of showers and
storms over the CWA right now. Best coverage is over the northern
border counties of the CWA. There is a decent boundary stretching
from southeastern Douglas county into east central Washington
County. Models have west-northwesterly flow aloft for the CWA
tonight and Friday. The QG-Omega fields have weak downward
synoptic scale energy for the CWA both tonight and Friday. The
boundary layer winds should go to normal drainage patterns by 04z
with maybe a little westerly downsloping mixed in. Friday`s winds
look to adhere to normal diurnal patterns. Moisture-wise, it has
dried out somewhat today and should again on Friday. Precipitable
water value progs show 0.50 to 0.75 inch tonight and Friday in
the mountains. Over the plains, tonight`s number range from 0.75
to 1.00 inch, then they decrease to 0.50 to 0.75 inch of Friday.
For CAPE this evening, the best numbers are over the mountains,
Palmer Ridge and far eastern border. CAPE decreases on Friday
according to the models, with some over the mountains, foothills
and Palmer ridge. For pops, will go with 10-20%s this evening for
much of the CWA. For Friday afternoon, will go with 10-20%s for
the southwestern corner of the CWA only, mainly Park County. For
Temperatures, Friday highs are 0- 2 C warmer than this

.LONG TERM...(Friday night through Thursday)
Issued at 150 PM MDT Thu Aug 17 2017

The upper ridge over the South will move North into southern
Colorado Friday night and into the weekend. This will turn flow
aloft more westerly with subtropical moisture increasing into

For Friday night into Saturday moisture will be high enough to
produce some storms over the higher terrain and Palmer Divide
given the need of orographic lift. These storms will be isolated
in coverage and end before the evening hours.

For the weekend waves embedded waves in the flow combined with
increasing subtropical moisture from the South will bring
isolated storms over the higher terrain by the afternoon.
Temperatures will continue to be warm with the ridge still in
place with westerly flow. Highs are forecasted to be in the lower
90s through Sunday.

Monday will see continued WSW flow aloft with the ridge building
over the state. Subtropical moisture will move north under the
ridge and increase PW values slightly over the region. A lee side
trough will set up over eastern CO increasing westerly flow off
the Foothills and keeping conditions more stable closer to the
foothills. A convergence could set up on the place east of
Sterling with the trough and bring scattered storms by the late
afternoon. Sky conditions continue to look partly cloudy around
Eclipse time and increasing through the late afternoon and early
evening with convection building. For the rest of the week
models show the continued building of the ridge with waves
embedded in the flow bringing continued chances of afternoon
storms. Temperatures through the week will continue to be around
seasonal normals or slightly above.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 350 PM MDT Thu Aug 17 2017

There should be no ceiling issues tonight of Friday. By 03Z
drainage winds should kick in and they may have a tad more of a
westerly component to them then the normal 200-210 degrees. Will
continue to keep thunder out of the TAF for the next 24-30 hours.
There will be ceiling issues.




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