Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 180330
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
930 PM MDT Thu Oct 17 2019

.UPDATE...
Issued at 925 PM MDT Thu Oct 17 2019

Only minor changes at this time to try to time the cloud cover and
for slightly cooler lows tonight. Weak lead wave has pushed the
clouds onto the plains with a clear slot ahead of the main
shortwave. These clouds will push into the mountains overnight
with the main shower band in the late night/morning hours for the
mountains and midday for the plains. It still doesn`t look like
much in the observations although there are some mid level clouds
and a few showers around Salt Lake City now, so the front is
developing a bit. Left the light snow showers for the mountains
with low PoPs elsewhere for now, but it may be too dry east of the
mountains for anything. One other change was to bump up the winds
a bit behind the front, models are stronger with the wind all day
on the plains and this looks good.

&&

.SHORT TERM...(This evening through Friday)
Issued at 311 PM MDT Thu Oct 17 2019

High level moisture has been moving over the state today, helping
to filter the sunshine and shave a couple degrees off of the
expected high temperatures. This helped to limit mixing in the
high mountain valleys, keeping winds below the 25 MPH threshold at
most locations. Dew points have been very low, causing afternoon
relative humidity values to drop below 10 percent. Benign weather
conditions are expected to continue through the evening and
overnight as high clouds continue moving overhead.

Looking further to the west, deeper moisture is evident over Utah
and northeast Nevada which will be working its way toward Colorado
tonight. After midnight, the chance of rain and/or snow in the
northern mountains will begin to increase. Light precipitation
is expected over the northern mountains through tomorrow. Up to a
couple inches of snow will be possible over the higher peaks.
Lesser amounts are expected below 10,000 feet. The plains are
expected to remain dry through the morning, but will see a cold
front move down between sunrise and noon. Winds may gust up to 25
MPH or so behind the front. Later in the afternoon, a few rain
showers may drift away from the mountains, but amounts will be
light.

.LONG TERM...(Friday night through Thursday)
Issued at 311 PM MDT Thu Oct 17 2019

...PROGRESSIVE WEATHER PATTERN WITH BOUTS OF MOUNTAIN SNOW AND
WIND...

There is excellent agreement in the large scale pattern over the
next several days, with passing shortwaves in strong
west/northwest flow aloft. While the first wave passes into the
Central Plains tomorrow evening, another stronger one moves across
the state Saturday night and Sunday, and then possibly another by
late Wednesday or Thursday.

For Friday night, clearing skies and diminishing winds should
allow for strong radiational cooling, and temperatures falling to
or below freezing in most areas. Saturday will feature warmer
temperatures with flat upper level ridging and warm advection in
advance of the next short wave. Fire danger will increase Saturday
in areas that don`t receive precipitation, with warmer
temperatures and lower humidity, but winds may not reach criteria
(similar to today).

The next stronger shortwave moves into the mountains Saturday
night with increasing Q-G lift and moisture. This system will have
more moisture and stronger orographics, and the result should be
several inches of snow for most of the high country above 9000
feet. Stronger winds will also bring blowing snow, and colder
temperatures will be enough to create snow covered roads and
slick/hazardous travel conditions late Saturday night through at
least Sunday morning. Conditions may improve Sunday afternoon/
evening as we do expect gradual drying in the storm system`s wake.
On the plains, can`t rule out a few rain/snow showers with the
trough passage.

Orographic snow showers in the mountains may increase again
Monday with perhaps another wave of moisture in cold northwest
flow aloft. Again, a few light showers possibly spilling onto the
plains.

Tuesday and most of Wednesday should be dry and relatively mild,
but then there`s reasonable agreement in the ensemble data showing
another trough, colder temperatures, and chance of snow arriving
by Wednesday night or Thursday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 925 PM MDT Thu Oct 17 2019

VFR through Friday. A cold front is expected to pass through
Denver around 15z with north winds gusting in the 20 to 30 knot
range through the day, diminishing after 23z. There is a slight
chance of light showers around 18z, but they are not expected to
impact terminal operations.

&&

.FIRE WEATHER...
Issued at 311 PM MDT Thu Oct 17 2019

Fire danger will increase again on Saturday, mainly in the
foothills, South Park, and Palmer Divide area where gusty
southwest winds, low humidity, and little if any precipitation is
expected.

&&

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

$$

UPDATE...Gimmestad
SHORT TERM...Dankers
LONG TERM...Barjenbruch
AVIATION...Gimmestad
FIRE WEATHER...Barjenbruch


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