Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

877
FXUS65 KBOU 221309
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
709 AM MDT Thu Sep 22 2016

.SHORT TERM...(Today and tonight)
Issued at 337 AM MDT Thu Sep 22 2016

Surface low pressure is over Southeast Colorado early this morning
while weak surge is moving through Northeast Colorado with light
North to Northeast winds and higher moisture levels behind it. Satellite
imagery showing stratus and fog developing over the Northeast
plains and advecting South and Southwest. Latest indication is
that the stratus and fog will make it as far West as Denver,
especially Northern and Eastern sections of the metro area. The
low level flow will increase from the Southeast this afternoon
which will scour out the stratus over the Front Range by later
this morning. This low level flow will result in a Denver Cyclone
which may allow enough convergence to spark isolated showers and
thunderstorms by later in the day.

Temperatures will be a bit tricky today but looks like the coolest
temperatures will be North of Denver and stretching out over the
Northeast plains with lingering stratus and reduced sunlight. Best
chance for showers will be over the mountains, closer proximity to
the deeper moisture and qg ascent.

.LONG TERM...(Friday through Wednesday)
Issued at 337 AM MDT Thu Sep 22 2016

At 12z Friday morning, an upper trough and closed low is over
Utah. There is strong southerly flow aloft for the CWA on Friday
and Friday night. In fact, models show a 90 to 115 knot jet over
the CWA into Saturday morning. The upper trough axis doesn`t get
over the CWA until Saturday evening and night. There is pretty
strong QG ascent over the CWA on Friday, but downward energy is
over the forecast area by late Friday evening. The boundary layer
flow shows south and southwesterly winds Friday, with normal
drainage patterns Friday night. There is downsloping flow on
Saturday, then northerly upslope winds Saturday night into
Sunday. For moisture, there is little Friday morning, but it
increases during the afternoon. Is is only fair Friday night.
Moisture increases again in the afternoon Saturday afternoon. It
increases Saturday night and lowers somewhat too. Precipitable
water values range from 0.25 inch over the western CWA to 1.00
over the far eastern CWA on Friday. They dry out a tad Friday
night. On Saturday and Saturday night, values are in the 0.25 to
0.50 inch range. There is a bit of CAPE over the far eastern
quarter of the CWA late day Friday, then no CAPE is progged
through the forecast period. There is some measurable
precipitation on the QPF fields Friday and Friday night, but it
is mostly over the high country. There is a tad of measurable
precipitation for mainly just the mountains Saturday and Saturday
night. The plains are pretty dry. For pops will go "chance"s over
the mountains and foothills friday into Saturday night. Lower
pops for the plains during that time. Concerning fire danger,
there are pretty decent winds on Friday, but relative humidities
look to be to high to warrant watch/warning criteria at this
time. For temperatures, Friday`s highs are 2-4 C cool than today`s.
There is pretty decent cold front that comes through Friday night
associated with the upper trough. Saturday`s highs are 4-9 C cooler
than Friday`s. For the later days, Sunday through Wednesday, models
are still trying to get the upper trough axis east of the CWA
Sunday morning. By later Sunday, the GFS has strong northerly
flow for the CWA, the ECMWF`s upper level wind speeds are much
lower. The flow aloft remains north and northeasterly Sunday
night through Wednesday. There is enough moisture for some pops
on Sunday, then next week is dry. Temperatures are below normal
through Tuesday,then near normal on Wednesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 701 AM MDT Thu Sep 22 2016

Fog with visibility under 1/4SM has pushed back to KDEN.
Potential for this thicker fog to hold til 1430Z-1500Z. Looking at
cams the fog is very thin and some breaks are noted, so potential
it could lift sooner but we also have a weak advection component
from the north. This adds complexity to the situation and there is
also a thicker stratus deck to the north so some fog and stratus
could linger til 17Z or so. The stratus could last a bit longer
toward KFNL and KGXY. At KBJC should see mostly stratus versus fog
while KAPA on the edge of stratus deck this AM. Shower or
thunderstorm still possible after 22Z but coverage should be
isolated.

&&

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

$$

SHORT TERM...Entrekin
LONG TERM...RJK
AVIATION...Barjenbruch



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