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247
FXUS65 KBOU 190906
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
306 AM MDT Sun Aug 19 2018

.SHORT TERM...(Today and tonight)
Issued at 306 AM MDT Sun Aug 19 2018

Autumn like conditions will prevail today. Upper level low will
drift east across Nebraska leaving Colorado under a north-
northwest flow aloft. Cloudy skies and scattered showers over
Wyoming at this time will drop south into Colorado. A strong
pressure gradient will bring windy conditions to the eastern
plains where gusts to 40 mph are expected. Best chance for showers
today will be closer to the low over far northeast Colorado.
Elsewhere, showers will be more spotty and generally light. CAPE
reaches up to 500 J/kg over the eastern plains, so can`t rule out
a few thunderstorms. Temperatures will be chilly for August with
highs in the upper 60s to lower 70s. Airmass dries and stabilizes
early this evening bringing the showers to an end. Skies will
clear out and expect a chilly night with temperatures falling into
the upper 40s to lower 50s over northeast Colorado. Some mountain
valleys may drop below freezing.


.LONG TERM...(Monday through Saturday)
Issued at 306 AM MDT Sun Aug 19 2018

Monday and Monday night, the flow aloft will remain northwesterly
with the upper level ridge axis over western CO. The airmass will
be dry and stable through the day, but by the evening there will
be enough mid level moisture in the high country for some isolated
shower activity. Temperatures will continue to run on the cool
side with highs in the upper 70s. Tuesday and Tuesday night, the
flow aloft will be more westerly with a ridge centered over New MX
and TX, with an upper level trough stretching from MT into
northern CA. There will be a gradual increase in subtropical
moisture over western and northern CO by the afternoon, with a
more noticeable increase Tuesday night as a weak disturbance
embedded in the flow aloft slips across the cwa. Consequently,
should see an increase in showers and thunderstorms Tuesday night.
Temperatures on Tuesday will increase another degree or two, but
still be running below normal. At the surface, low level
east/southeasterly winds expected with high pressure over the
northern and central Great Plains. A weak front will briefly back
into the northeast plains Tuesday night, then it washes out to the
southeast. On Wednesday, the upper ridge will shift more to the
southeast of CO with the upper trough extending from central Mt
into southern ID. This will open up northern and western CO a
better intrusion of subtropical moisture and a better chance of
thunderstorms in the mountains on Wednesday. On Thursday the
trough axis is expected to move across the state, with the axis
along the eastern border by 00z Friday. Best chance of
thunderstorms Thursday will be in the high country, with isolated
thunderstorms across the plains ahead of the trough axis. Friday
and Saturday, it will be closer to normal with a dry westerly flow
aloft over CO and the upper ridge over the southeastern U.S.


&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 306 AM MDT Sun Aug 19 2018

Mid level clouds will move into Colorado this morning. Ceilings
are expected to fall to 4000 to 6000 feet and then slowly rise
during the day. Scattered to isolated showers are expected. There
is a slight chance for weak short-lived thunderstorms during the
afternoon. Skies will begin to clear after 00Z. Gusty northerly
winds to 30 knots are expected to develop by 18Z.

&&

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

$$

SHORT TERM...Meier
LONG TERM...Cooper
AVIATION...Meier