Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KBOU 151825
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1125 AM MST Fri Nov 15 2019

.UPDATE...
Issued at 1125 AM MST Fri Nov 15 2019

The impenetrable wave cloud(s) remains the story for today.
Latest GOES-16 imagery hasn`t indicated any significant thinning,
and regeneration looks likely most if not all of the afternoon.
High res models have a pretty good handle on the wave cloud,
keeping it in place until late evening. It is exceptionally warm
aloft for this time of year, and even with heavily filtered sun
surface obs have indicated 50s to low 60s across many lower
elevations. The exception is the South Platte River Valley from
Weld County northeast to Morgan and Logan Counties. It`s still
just in the 40s in many of those areas. Dropped the temps a degree
or two across those low areas with an inversion, otherwise kept
the warm temps intact. 70 not out of the question if thinning
occurs in the wave cloud. Rest of the forecast is on track with
light winds across the plains and increasing west wind in the
higher mountains. Dry everywhere.

&&

.SHORT TERM...(Today and tonight)
Issued at 247 AM MST Fri Nov 15 2019

Today and tonight will see rather quiet weather with minimal
forecast concerns. The axis of a 500 mb ridge will move over our
CWA today resulting in subsident westerly flow throughout the
troposphere. These conditions are a good combination for
temperatures to warm well above normal. Highs will reach the mid
to upper 60s across the urban corridor and eastern plains. The
one feature that may hold temperatures back from reaching the 70s
will be a strong and persistent mountain wave cloud. Water vapor
and IR satellite imagery show this mountain wave cloud is already
well developed this morning. Otherwise, dry conditions are
expected with light winds. The only area with moderate winds will
be the higher elevations in the mountains as gusts could reach 35
mph.

Tonight, downslope flow and cloud cover will keep temperatures 10
to 15 degrees above normal. Winds will increase over higher
elevations as a shortwave approaches from the northwest. Gusts
could reach 45 mph over the northern mountains.

.LONG TERM...(Saturday through Thursday)
Issued at 247 AM MST Fri Nov 15 2019

A fast moving short wave will drop southeast across the Northern
and Central Rockies on Saturday. This will push a cold front
across northeast Colorado in the afternoon with colder
temperatures, gusty northerly winds, and a chance of light
precipitation. QG forcing aloft is rather weak, but there appears
to be some shallow anticyclonic upslope to aid orographic forcing
along the Front Range and Palmer Divide.  Moisture is rather
meager, but 700-500 mb lapse rates increase to 7-8C/km as 500 mb
cold pool of -20C drops into the Front Range. As a result, we
expect to see mostly virga initially, and then sufficient
moistening with the shallow upslope for a few rain and snow
showers to reach the ground. At this point, we don`t see much
more than a dusting over the Palmer Divide and Foothills.
Meanwhile, the an inch or two is expected in the mountains with
better orographic forcing and less sub-cloud evaporation there.
Any precipitation should be pretty much over by midnight with
clearing skies from north to south through the late evening.

On Sunday and Monday, we`ll see moderate to strong northwest flow
aloft across the forecast area. Lee troughing will keep inversions
shallow and should bring a pretty decent warmup with high
temperature several degrees above normal Sunday, and close to 10
degrees above normal Monday. Tuesday has potential to see even
warmer temperatures with models now indicating potential for flat
ridging and further warm advection. No precipitation is expected
Sunday to Tuesday.

By Wednesday and Thursday, our focus will be shifting to the
pattern change. There is now reasonable consensus on the upper
low dropping off the southern California coast, leaving us in the
col between this storm and the northern branch of energy across
the Northern U.S. Plains. This northern branch, however, would
likely be strong enough to bring a cold front across northeast
Colorado by Wednesday, with colder temperatures settling in for
the latter half of next week. With regard to precipitation
chances, it may be difficult to generate much significant
precipitation over our forecast area given the col or weak ridging
over Colorado. That said, there is some agreement that the upper
low dropping off California will eventually pick up and kick out
remnants of what is now Tropical Depression Twenty-E in the
eastern Pacific. Even if that scenario unfolds, which is probable
at this time, the vast majority of the precipitation would be
wrung out over the southern Colorado mountains, leaving our
forecast area with only light showers for the most part. There`s
obviously much uncertainty with the details here, so we`ll go with
the cooler temperatures and a chance of snow showers for
Wednesday and Thursday of next week, and possible into Friday if
the upper low ever kicks out of the Desert.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1125 AM MST Fri Nov 15 2019

VFR through Saturday. Winds should go clockwise around the horn
at DIA this afternoon, going NW to NE during later afternoon, and
then east to southeast during the evening push. Normal SSW
drainage winds all night after 6 PM. In general, winds should
remain below 10 kts at all terminals today. On Saturday winds
should bot to west at the terminals and remain light until a cold
front approaches in the late afternoon hours, with an initial
shift to the NW. The cold air lags the initial shift by a few
hours, and then winds will shift to the northeast, likely after 6
PM. Expecting 20G30kt or so out of the northeast for several hours
Saturday evening.

&&

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

$$

UPDATE...Schlatter
SHORT TERM...Danielson
LONG TERM...Barjenbruch
AVIATION...Schlatter


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.