Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 200159
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
659 PM MST Thu Jan 19 2017

.UPDATE...
Issued at 645 PM MST Thu Jan 19 2017

Satellite shows fog moving westward from Kansas into the far
eastern plains at this time. The RAP and HRRR continue to show
this trend overnight, with the fog primarily impacting eastern
sections of Sedgwick, Phillips and Washington Counties. This fog
then gets flushed east late tonight and Friday morning.  Have
included areas of fog in these zones tonight and also increased
the cloud cover there. In the mountains, we increased the pops,
but no adjustments to the snow amounts as the overall totals still
appear to be on the light side.

&&

.SHORT TERM...(This evening through Friday)
Issued at 308 PM MST Thu Jan 19 2017

Models show southerly flow aloft overnight into Friday morning.  The
flow weakens and becomes southwesterly by afternoon.  There is a
weak upper trough that moves across the CWA from 09Z to 21Z on
Friday.  The QG Omega fields show some moderately strong upward
synoptic scale energy for the CWA tonight and much of Friday.  The
low level wind fields have southeasterlies this evening, then weak
normal drainage winds overnight. Winds are weak and downsloping
for the most part on Friday. Models have moisture on the increase
tonight from west to east. By 12Z Friday morning, moisture is
deep over the mountains and that continues through Friday. There
is plenty of moisture over the plains, but not in the lower levels
on the GFS or the ECMWF. The QPF fields have limited measurable
in the mountains tonight and Friday. There is a tad of measurable
precipitation over the plains on Friday. For pops, will go with
50-80%s in the mountains from about 06Z tonight through Friday.
Orographic enhancement is not the greatest, but there is moisture
and some synoptic scale energy. Snowfall amounts do not warrant
highlight criteria amounts. For the plains, will go with mostly
"chance"s late tonight into Friday afternoon. For temperatures,
Friday`s highs are 3-6 C cooler than this afternoon`s.

.LONG TERM...(Friday night through Thursday)
Issued at 308 PM MST Thu Jan 19 2017

A series of weakly organized weather systems will move across
Colorado over the weekend, and then a bit stronger system will
move over the state during the first half of next week. Each
system will bring a little light snow to the mountains, but not
necessarily affect the plains. The system that sets up over the
state for the Monday through Wednesday time period will have more
of a region-wide impact. The first trough, on Saturday will be
diving southeastward as it produces the bulk of snowfall over the
western slope and San Juan mountains. The north central mountains
will see scattered afternoon snow showers. Upper ridging will
build over the state Sunday with dry weather across the forecast
area.

Monday will be transitional as an upper trough carves out over
the entire western United States. By Monday evening snow should be
moving into the mountains. Then on Tuesday the ECMWF shows an
upper low developing over over northeast Colorado which will lead
to unsettled weather across the mountains and plains. A strong
upper level jet will accompany this trough which may add to the
strength of the developing system. The GFS shows a very similar
solution, so we will have to watch how much moisture this system
brings with it. Unsettled weather and cooler temperatures are the
main story for now.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 645 PM MST Thu Jan 19 2017

The southeasterlies should move towards normal drainage
directions, south/southwest after 03Z this evening. MVFR ceilings
020-030 after 10Z Friday morning with a chance of snow showers.
Ceilings should climb back above 060 by 18Z Friday, with VFR
conditions in the afternoon.

&&

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

$$

UPDATE...Cooper/Meier
SHORT TERM...RJK
LONG TERM...Dankers
AVIATION...Cooper



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