Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 202029
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
229 PM MDT SAT AUG 20 2016

.SHORT TERM...(This evening through Sunday)
Issued at 225 PM MDT Sat Aug 20 2016

Upper level ridge centered over California will shift east into
Nevada Sunday. This will keep a northwest flow aloft over
Colorado. Enough moisture and instability will be over the higher
terrain south of Interstate 70 for isolated storms through early
evening. The best chance will over Park county. High pressure
remain over the region tonight. Clear skies and dry air will lead
to another cool night, but not as chilly as last night.

Airmass warms 4-7C on Sunday. This will result in highs climbing
into the mid to upper 80s across northeast Colorado. Moisture and
instability will be limited again with most of the showers and
storms expected to be over the higher terrain south of Interstate
70.

.LONG TERM...(Sunday night through Saturday)
Issued at 225 PM MDT Sat Aug 20 2016

broad nearly zonal upper flow pattern over Colorado and central
U.S. on Monday. Shortwave energy was off the northwest California
coast and over the Desert Southwest. Models in reasonably good
agreement as they show these upstream features consolidating over
the Four Corners Monday night into Tuesday. This increasingly
organized shortwave energy appears to entrain more moisture up
from New Mexico as it tracks across Colorado. The NAM is prone to
overdoing the moisture and that may be the case again as the other
models do not appear as wet...particularly east of the Front
Range. NAM also attempts to close off this shortwave trough over
the state Monday night...while other models pass a weaker open
wave over the area. At any rate...do not see much in the way of
upslope flow east of the mtns with this first wave...and models
indicate the bulk of the precip over the high country. This
initial wave lifts out over Nebraska Tuesday morning where it
quickly weakens. In its wake... models show a weak surge of cool
air slipping south across northeast Colorado on Tuesday causing a
few deg drop in max temps.

Then a second batch of mid-level shortwave energy moving onshore
over central/southern California Monday quickly makes its way to
Colorado by late on Tuesday. Prior to its arrival...models show a
stronger cold front with gusty northerly winds spreading south
across northeast Colorado during the afternoon hours along with a
reinforcing surge of even cooler air Tuesday night. Should see
precip chances increasing along and east of the Front Range during
this 12-hour period...although the boundary layer doesn`t look all
that moist on the plains during the daylight hours. So perhaps more
wind than rain for the plains. However overnight slightly higher
dewpoints...falling temps and a northeast/upslope wind should
increase precip chances esply along the foothills and over the
Palmer Divide during the evening hours as the main shortwave energy
swings out over the plains.

By Wednesday...models still show the trough hanging around as well
as quite a bit of moisture in the form of clouds and spotty light
showers to start the day. Could see another weak push of cool air
from sern Wyoming during the day resulting in daytime temperatures
some 12-16 deg f lower than those the day before. Will hang onto low
pops on Wednesday with showery precip more likely than t-storms.

Thursday through Saturday...period remains fairly unsettled...
starting out on Thursday dry and warmer with zonal flow aloft and a
southerly wind on the plains. Thereafter...could see a series of
weak mid-level disturbances passing over the CWA about every 18-24
hours. This will require at least low pops each day. And, with the
flow aloft turning southwesterly should see gradual warming each
day...although readings are progged to remain below average through
the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 225 PM MDT Sat Aug 20 2016

Isolated thunderstorms will be possible southwest of Denver this
afternoon and evening and again Sunday. These will stay well
southwest of the Denver area but could affect the southwest
approach gate. Easterly winds will shift to the southeast to south
02z-07z. Winds speeds will remain light, mainly less than 10
knots.

&&

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

$$

SHORT TERM...Meier
LONG TERM...Baker
AVIATION...Meier



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