Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 191710

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1110 AM MDT Wed Oct 19 2016

Issued at 1051 AM MDT Wed Oct 19 2016

Water vapor pictures are showing subsidence moving into the CWA
behind the upper trough. Some of the northern plains have north-
northwesterly winds beginning. The wind field over most of the
plains is light and variable. Will make some sky grid changes in
GFE with real data in mind. Will leave some minor alpine pops in
this afternoon with dry over the rest of the CWA.


.SHORT TERM...(Today and tonight)
Issued at 300 AM MDT Wed Oct 19 2016

An upper trough currently over western Colorado will continue
pushing east this morning, to push into Kansas this afternoon. The
jet induced banded showers overnight brought 1-4 inches of snow to
the higher mountains as well as light rain showers to the plains
mainly north of I76. Expect these showers will be decreasing
through the rest of the morning as evidenced by the drier air
moving in from the west on water vapor imagery. A few showers
will still be possible however through the day, mainly along the
high peaks as flow aloft turns to a favorable northwesterly
direction, and along the northern plains as the trough transitions
across. A cooler airmass over the area today will result in highs
only in the 50s across the plains and in the 30s and 40s in the

As subsidence on the back of the trough pushes overhead tonight
and skies clear, minimum temperatures will be allowed to cool
quickly. Readings are expected to be near or below freezing over
most of the area. A shortwave will drop out of the north to push
in some stronger northwest winds overnight over the plains...which
may inhibit the temperatures from cooling as much as forecasted.
Therefore will issue a Freeze Watch for the plains. Lincoln county
and eastern Elbert will be left out as they have already seen subfreezing
temperatures this season. Left Phillips and Sedgwick counties out
as well since winds will likely keep temperatures above freezing.
Confidence is less for the urban corridor as a surface trough will
develop over the plains which will create slight downsloping
effects. Will monitor model trends today to see about what
highlights to issue where.

.LONG TERM...(Thursday through Tuesday)
Issued at 300 AM MDT Wed Oct 19 2016

For Thursday...a moderate northwesterly flow aloft will be over
the region ahead of an approaching upper level ridge from the
west. Sfc high pressure will start to shift eastward and a weak
lee side trough develops over eastern CO in the aftn. It will be
dry and stable with high pressure at the surface and mid level
subsidence aloft. Not much mixing through the day so cooler
temperatures should remain in place across much the northeast
plains. Thursday night and Friday...the upper level ridge axis
makes its way into CO with the flow aloft becoming more westerly.
Increasing mid level warm air advection and westerly downslope
winds along the Front Range will help daytime temperatures to
climb back into the 70s on Friday. Although the flow aloft will be
more zonal...not much in the way of mountain wave amplification
evident in the NAM12 spatial cross-sections so the strongest
winds for Thursday thru Friday should remain in the mountains and
higher foothills. Over the weekend...the flow aloft will
transition to west southwesterly with the upper ridge centered
over TX and NM. Dry and stable airmass with more warming as well.
Fire danger will start to creep back up by the weekend due to the
warmer temperatures but the wind across the region does not
appear to be very strong at the sfc or aloft. Monday into Tuesday
of next week...the southwesterly flow aloft over CO increases
ahead of a trough moving into the Pacific Northwest. The
combination of subtropical moisture advecting into the flow aloft
and an upper level jet max of 85kt moving fm eastern UT into
central WY is progged by the GFS/ECMWF to produce some pcpn over
western CO by Monday night...not much cold air with this initially
so a mix rain/snow showers for zones 31/33 at that time. Continued
dry and warm for the northeast plains of CO on Monday with just


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1051 AM MDT Wed Oct 19 2016

The north-northwest to north-northeast winds have already kicked
in at DIA. many of the models show this. They also have the normal
drainage patterns kicking in after 06Z. I will put them in before
that. The satellite pictures are showing some flat Cumulus or
Strata-cumulus developing in and around the airport. There may be
enough of this cloudiness for ceilings to develop by 20Z but they
won`t be overcast. Ceilings might be BKN060 or BKN70 after 21Z.
They won`t last past 03Z this evening. No precipitation.


Freeze Watch from late tonight through Thursday morning for



SHORT TERM...Kriederman
LONG TERM...Cooper
AVIATION...RJK is the U.S. government's official web portal to all federal, state and local government web resources and services.