Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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416
FXUS65 KBOU 171020
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
420 AM MDT SUN JUL 17 2016

.SHORT TERM...(Today and tonight)
Issued at 410 AM MDT Sun Jul 17 2016

Weak cold front is pushing across northeast Colorado early this
morning, but the cooler and more moist airmass appears to be
rather shallow. As a result, daytime heating will likely result in
mixed layer CAPES of 500 J/kg or less along the Front Range by
afternoon. Farther east around Sterling and Julesburg CAPES will
be closer to 2000-2500 J/kg, but some CIN noted there so it will
likely take some convection moving east/southeast from Wyoming/NE
panhandle to break the cap. Potential for an isolated severe
storm over the northeast corner late this afternoon and evening.
Closer to the Front Range any storms will likely produce gusty
winds but only light rainfall for the most part.

Despite the morning cold front, temperatures should reach 90F or
higher as any reinforcing cool air looks quite shallow. Mountain
temperatures will be similar to those observed yesterday.

For later tonight, partly cloudy skies should prevail. There is
some mid/high level streaming up this way from the southwest but
not enough to produce any showers at this point.

.LONG TERM...(Monday through Saturday)
Issued at 252 AM MDT Sun Jul 17 2016

By Monday...models continue to show a plume of subtropical moisture
advecting northward around the western edge of a large dome of high
pressure over the southern Great Plains. The leading edge of this
moisture, mainly at mid and high-levels is fcst to reach southern
Colorado early on Monday and then eventually spread northeastward
over the remainder of the state through the day. A weather disturbance
embedded within this flow is progged to pass over central Colorado
by around midday and over northeast Colorado by late afternoon.
Model sfc and boundary layer wind fields indicate the presence of
a Denver cyclone at the same time which would provide adequate
upslope lift and shear to enhance t-storm formation along the
Front Range from the Palmer Divide northward. The increase of
moisture both aloft and at the sfc with mean layer precipitable
water values exceeding 1.1 inches could produce scattered t-storms
capable of heavy rainfall which could lead to localized flash
flash flooding. This setup does not look like a widespread heavy
rain event since storm motions will be relatively fast. As for
temperatures on Monday...an earlier start to cloud formation of
cloud cover on Monday...daytime temperatures are expected to run a
few degrees cooler than the day before.

FYI...based on the past 50 years of climate data...the average start
date for the summer enhanced thunderstorm season associated with the
southwest monsoon for northeast Colorado is July 8th for the Front
Range mountains and foothills...and July 10th for the adjacent high
plains communities including Denver. Therefore the Monday arrival of
the monsoon will be slightly more than a week late.

The monsoon plume of moisture is forecast to remain draped over
Colorado for most of the week...but with thinning during the
latter half of the week with southern Great Plains upper high showing
signs of migrating westward which would evidently cut off the
northward flow of subtropical moisture from western Mexico.
Should this happen the chance of the t-storms and wetting
rainfall would drop off and with less cloud cover a return
temperatures several degrees above average. However...by Friday...
models show the upper ridge moving far enough west to place the
forecast area under northwest flow aloft which appears to drive a
cold front through the area during the day. This would produce cooler
temperatures and a slightly greater chance for t-storms esply over
and along the higher terrain.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday night)
Issued at 410 AM MDT Sun Jul 17 2016

VFR conditions will prevail. There is about a 20 percent chance of
thunderstorms affecting the Front Range airports including KDEN in
the 22Z-04Z time frame. Weak cold front moving through early this
morning with north to northeast winds around 10 knots behind
it, then turning more easterly around 10-15 knots toward 18Z and
holding there through most of this evening. Don`t see enough
moisture for any stratus deck this morning, but could develop one
around 1000-2000 feet AGL toward 12Z Monday morning.

&&

.FIRE WEATHER...
Issued at 410 AM MDT Sun Jul 17 2016

Fire danger will still be elevated over the mountains and high
valleys today with very warm temperatures and low humidities.
However, winds will be a little lighter and shy of Red Flag
criteria.

&&

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

$$

SHORT TERM...Barjenbruch
LONG TERM...Baker
AVIATION...Barjenbruch
FIRE WEATHER...Barjenbruch



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