Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 160349

Area Forecast Discussion
National Weather Service Denver/Boulder CO
949 PM MDT Wed Mar 15 2017

Issued at 934 PM MDT Wed Mar 15 2017

Satellite showing increased moisture upstream with upper level
flow turning more zonal on Thursday. The upper jet will drop a
finger into northern Colorado increasing winds over portions of
the northern mountains and counties bordering Wyoming. These
increased winds combined with continued dry conditions and low RH
values has created another day of high fire danger. More specifics
can be found in the fire weather section below. Elsewhere, some
mid level moisture from the west will move over the mountains and
encounter a weak stable layer near mountain top that will help to
create a mountain wave. From cross sections the stability layer
looks weak but could be enough to bring clouds to the front range
and wind gust to 40 mph by the afternoon. This will help to keep
RH values up and possibly prevent enough mixing to hinder stronger
wind gusts over the urban corridor of Denver. Further east and
south the RH values will drop into the teens with winds decreasing
the further south you go. Even without meeting wind or RH
criteria still expect conditions to be ripe for fire growth so
maintained the Fire Weather Watch for these areas.


.SHORT TERM...(This evening through Thursday)
Issued at 150 PM MDT Wed Mar 15 2017

A ridge of high pressure will remain over the region through
Thursday. It will be dry and stable with decreasing mid and
upper level cloudiness this evening. NAM12 spatial cross-sections
show a weak mountain wave overnight, so the foothills will remain
gusty late tonight into Thursday morning. Very warm and dry again
on Thursday with gusty winds. The fire danger will be very high
across the foothills and the northeast plains late Thursday
morning into early evening. Strongest winds will be in the
northern front range foothills and the norther tier counties of
the plains, see the fire weather discussion below. The record for
Denver on the 16th is 79. Temperatures are expected to fall just
short of the record, we`ll see.

.LONG TERM...(Thursday night through Wednesday)
Issued at 150 PM MDT Wed Mar 15 2017

A cold front associated with an upper level trough moving across
the northern part of the country will drop south across eastern
Colorado Thursday night. Easterly upslope winds around a surface
high will bring cooler temperatures Friday with highs in the 60s.
Depending on cloud cover, parts of the northeast plains may
struggle to reach 60 degrees. This cooler air will only last a
day. The upper level ridge will rebuild over region this weekend.
Highs will rebound back into the 70s Saturday. On Sunday,
downslope winds will help warm the airmass more pushing some
locations into the lower 80s. Airmass will remain dry and will
lead to elevated fire danger, especially Sunday when winds pick

Some uncertainty in regards to Monday. The GFS shows a weak wave
embedded in the flow aloft and a cold front pushing through.
Meanwhile, the ECMWF does not have the wave and only brings in
slightly cooler air. Will warm temperatures a little for Monday,
but keep them a little lower than Sunday`s highs. The GEM also
supports the warmer and drier weather.

Flow aloft becomes southwest as an upper level low approaches the
California coast Tuesday. The ECMWF and GEM show a frontal
passage Monday night with cooler temperatures for Tuesday. The GFS
keeps the cooler air over the area, so confidence in a cool down
is higher for Tuesday. Moisture eventually increases Wednesday and
may bring a chance for precipitation to the mountains. The GFS is
much more amplified and quicker with the Pacific system than the
ECMWF and GEM. This doesn`t make much sense, so will trend the
forecast towards the ECMWF and GEM with some moisture reaching
the mountains Wednesday. Temperatures are expected to cool a
little Wednesday but still remain above normal.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 934 PM MDT Wed Mar 15 2017

VFR conditions are expected through Thursday night with weaker
winds out of the SE that will veer around to drainage by 05z. Wind
direction will turn more westerly by 18z as lee trough builds and
winds will increase with gusts to 30 mph with increased stability
over the mountains and a possible mountain wave. Expect some mid
level moisture to bring a ceiling by 18z but conditions will
remain VFR.


Issued at 934 PM MDT Wed Mar 15 2017

Models continue to show influence of upper jet bringing increased
winds to zones 242, 244, 248-251 with RH values dropping into the
lower teens by Thursday afternoon. Elsewhere along the foothills
winds will gust up to 40 mph...however increased moisture will
help to keep RH values higher. Further south winds will be
lighter but RH values will drop into the lower teens. Kept the
Fire Weather Watch active for all other foothill and plains
counties for tomorrow afternoon given current dry conditions and
heightened fire weather concerns.


Red Flag Warning from 11 AM to 7 PM MDT Thursday for COZ242-244-

Fire Weather Watch from Thursday morning through Thursday
evening for COZ215-216-238>241-243-245>247.



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