Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 201047
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
447 AM MDT Wed Sep 20 2017

.SHORT TERM...(Today and tonight)
Issued at 436 AM MDT Wed Sep 20 2017

There were a few light snow showers early this morning
in the mtns near the WY border however these should end
by 6 am.  Otherwise dry WSW flow aloft will be over the area
today and tonight with no precipitation. At the sfc a Denver
Cyclone will be in place thru the day with gusty sly winds
occurring by midday across the plains which will continue into the
early evening hours. Gusts up to 40 mph will be possible over the
Palmer Divide. Over the higher terrain the flow aloft will not be
as stg as yesterday so winds gusts will mainly be in the 30-40
mph range. As for highs, temps will not be as wrm across nern CO
with readings mainly in the mid 70s to lower 80s.


.LONG TERM...(Thursday through Tuesday)
Issued at 436 AM MDT Wed Sep 20 2017

Southwesterly flow aloft will dominate the forecast area Thursday
through Friday night. Jet level speeds in the 40-60 knot range on
Thursday will increase slowly Thursday night and Friday. By
Friday night, a 100-115 knot south-southwesterly jet maximum will
be over the western half of the CWA. Upward synoptic scale energy
is progged on the QG Omega fields for the CWA from Thursday
afternoon into the extended period. The upward vertical motion is
pretty weak Thursday night, but becomes moderately strong Friday
afternoon and night. The boundary layer winds on Thursday are
downsloping southwesterly and a bit breezy. Normal drainage winds
are progged Thursday night. Friday is another day of breezy
southwesterly downsloping low level winds. Most of the models
bring a cold front into the CWA sometime Friday night. It is a
pretty decent cool down. Considering moisture, it looks pretty
dry, Precipitable water values are about 0.20 to 0.50 inch
Thursday and Thursday night. Moisture increases on Friday and
Friday night, with the precipitable water values doubling from
Thursday night. Will have no pops in into early Friday morning.
Will have "chance"s in the mountains Friday afternoon and night
and mainly "slight chance"s for the plains. There is no measurable
precipitation on the QPF fields Thursday into Friday morning,
then some minor amounts mainly in the mountains Friday afternoon
and night, with a bit over the eastern border overnight Friday.
For temperatures, Thursday`s highs are 2-4 C warmer than this
afternoon`s. Friday`s highs are 1-3 C cooler than Thursday. For
the later days, Saturday through Tuesday, models keep strong
south-southwesterly flow aloft for the CWA Saturday into Monday.
The speeds decrease a bit later Monday into Tuesday with models
not even showing the upper trough axis to get into western
Colorado until Tuesday night. Models show pretty much all low
level upslope flow Saturday into Tuesday. Temperatures will be
below seasonal normals all four days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 436 AM MDT Wed Sep 20 2017

VFR today thru tonight.  Sely winds early this morning will become
more sly by 15z.  For this aftn should see a Denver Cyclone
to the west or sw of DIA. Currently the HRRR and RAP keep gusty
south winds mainly to the south and east of DIA however they will
probably affect the airport by 20z or 21z into the evening hours.
Overnight winds will become more ssw by midnight.

&&

.FIRE WEATHER...
Issued at 436 AM MDT Wed Sep 20 2017

Humidity levels will be slightly higher today with winds not as
strong in most areas.  However, areas over the Palmer Divide towards
Limon will still have elevated Fire Danger due to gusty south winds
this afternoon. Fire Danger will decrease this evening in those
areas as winds decrease and humidity levels increase.

The fire danger will increase by late morning on Thursday with
above normal temperatures, a pretty dry airmass in place and
decent south-southwesterly winds. The areas most susceptible to
the critical fire danger will be over the southeast forecast area
Thursday afternoon.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Thursday afternoon through Thursday
evening for COZ241-245>247-249.

&&

$$

SHORT TERM...RPK
LONG TERM...RJK
AVIATION...RPK
FIRE WEATHER...RPK/RJK



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