Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231654
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1054 AM MDT Sun Jul 23 2017

.UPDATE...
Issued at 1006 AM MDT Sun Jul 23 2017

No significant changes to the grids today. Weak cap could allow
for isolated storms to develop and drift into the Urban Corridor
late this afternoon so have carried isolated pops a little further
east into this evening.

&&

.SHORT TERM...(Today and tonight)
Issued at 355 AM MDT Sun Jul 23 2017

Broad high pressure ridge aloft continues to build over much of
the Great Basin resulting in a west to northwest flow aloft over
Colorado. This flow pattern continues to bring in drier air aloft.
Precipitable water trends from GPS continue to drop, now around a
third of an inch lower than 24 hours ago. Water vapor imagery
showing some weak ripple in the flow moving across northeast
Colorado now with even isolated showers over Morgan county. This
looks to be gone by sunrise. Forecast soundings today look to dry
for any storms on the plains with any activity confined to
mountains and higher terrain near the Palmer Divide. Temperatures
look to be very similar to Saturday`s readings. Any storms that do
develop this afternoon will diminish early this evening with lack
of any upper support.

.LONG TERM...(Monday through Saturday)
Issued at 355 AM MDT Sun Jul 23 2017

The upcoming week could end up being wetter and more unsettled than
earlier thought. Models continue to show a broad upper ridge over
the central CONUS during the first part of the week. On the west
side of this ridge waves of moist and unstable subtropical air
rotate northeastward over the Four Corners region, which should lead
to enhanced t-storm activity across the region, including much of
Colorado. Models show a couple of mid-level shortwave disturbances
embedded in this moist swly flow, the first one apparently reaching
the CWA late on Tuesday, and the other late on Wednesday. Because of
decent agreement in the models, will up PoPs acrs the fcst area
Tuesday and Wednesday, esply across the high country since swly flow
orographically favors west slope areas. Mid and high clouds may
continue to convection east of the mtns, however outflow from t-
storms over the Front Range may be all that`s needed to spark
isolated to scattered late day t-storms on the plains and Palmer
Divide. A relatively dry sub-cloud environment indicated by model
soundings could lead to more gusty winds than soaking rainfall.
Although cannot rule out a few slow moving t-storms producing heavy
rainfall esply with the passing shortwaves. See temperatures
remaining above average Monday and Tuesday with highs in the low/mid
90s at lower elevations. On Wednesday, 1.5-2 deg C cooling aloft and
greater cloud cover should give most areas a 3-6 deg f cool down.

During the latter half of the week, models show the upper ridge
weakening over he Great Plains and building over the Great
Basin/intermountain west. This appears to only slightly reduce the
chance of storms across the fcst area as the airmass over Colorado
appears to remain relatively moist and unstable. See little change
in temperature through the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1006 AM MDT Sun Jul 23 2017

Could see an isolated thunderstorm drift off the foothills and
potentially produce gusty outflow winds to 30 kts at the
terminals after 22z. May add vcts to KAPA in the upcoming TAFS
based off the latest HRRR solution but leave it out elsewhere for
now. east to southeast surface winds this afternoon then back to
drainage overnight.
&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...Cooper
SHORT TERM...Entrekin
LONG TERM...Baker
AVIATION...Cooper


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