Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 261632
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1032 AM MDT Mon Jun 26 2017

.UPDATE...
Issued at 1024 AM MDT Mon Jun 26 2017

Only minor changes to the forecast this morning. Shallow moisture
near the mountains will mix out this afternoon. Over the southern
part of the area this will be less true, so there is still a
slight chance of thunderstorms there. One question is the amount
of moisture that will be available over the eastern fringe of our
area over Washington, Sedgwick, and Phillips counties. Some of the
models are hinting as easterly flow developing and holding a
deeper moisture layer in this area. There should be a tendency
toward eastern surface winds, but the drier solutions seem more
reasonable. HRRR drops the dew points in this area into the mid
40s and has no convection. I did need to raise today`s highs in
Limon and Akron a couple of degrees, so the potential for
convection in Washington county bears watching. CAPEs should be
below 1000 J/kg so expecting fairly ordinary convection where it
does develop.

&&

.SHORT TERM...(Today and tonight)
Issued at 356 AM MDT Mon Jun 26 2017

An upper level ridge will shift east across the western states
today. By 00Z Tuesday, the axis will be along the Colorado-Utah
border. This will bring warmer and drier air to the area today.
Low clouds/patchy fog over Lincoln, Elbert, southern Douglas, and
Park counties will burn off by mid morning. Elsewhere, mostly
clear skies are expected through mid afternoon. Cumulus clouds
will form over the higher terrain during the afternoon. Soundings
show a cap around 600MB, so it will limit thunderstorms
development. Appears the only chance for storms will be along and
south of Interstate 70 where the least CIN and best instability
will be. If any storms form, they are expected to be high-based
and produce gusty winds to 40 mph and light to moderate rainfall.
With the warmer airmass moving in and less cloud cover, it will be
warmer today with highs in the lower to mid 80s across northeast
Colorado.

.LONG TERM...(Tuesday through Sunday)
Issued at 356 AM MDT Mon Jun 26 2017

On Tuesday...the upper ridge of high pressure shifts east into
the central plains states...with a moderate westerly flow aloft
over Colorado. Gusty winds to 30 mph combined with low relative
humidity and dry fuels will result in high fire danger across the
mountain valleys. Therefore...a Fire Weather Watch has been
issued for those areas from noon to 9 pm. In addition...a
downslope flow will produce hot and dry weather across the Front
Range Urban Corridor and adjacent Plains...with temperatures
climbing into the mid 90s. Further to the east...a moist south to
southeasterly flow ahead of a surface lee trough...combined with
an upper level disturbance...will result in widely scattered
afternoon and evening thunderstorms. Higher cape values of over
1500 J/KG combined with ample directional shear could result in
some of the storms becoming severe across the far northeastern
corner of the state.

On Wednesday...cooler temperatures are expected as a weak cold
front moves across northeastern Colorado. Moisture behind the
front seems somewhat limited. However...a 60KT+ jet sagging south
across the CWA may aid in some showers and thunderstorms during
the evening hours.

Thursday through Saturday...an upper level low pressure system
will move from Saskatchewan Canada into the northern plains
states. Colorado will remain under the influence of a northwest
flow aloft with occasional upper level disturbances and weak cold
fronts moving across the area. As a result...slightly below normal
temperatures along with isolated to scattered showers and
thunderstorms are expected both days...most numerous across the
far northeastern plains.

The GFS and ECMWF diverge somewhat by Sunday...with the GFS
showing a weak trough over the Great Basin...while the ECMWF tries
to build an upper level ridge over the Rocky Mountain Region. The
ECMWF solution brings warmer and drier weather to north central
and northeastern Colorado...while the GFS is cooler and wetter.
Since this is all the way out in day 7...have decided to keep the
near normal temperatures and slight chance of pop given by
Forecast Builder.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1024 AM MDT Mon Jun 26 2017

VFR through tonight.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Tuesday afternoon through Tuesday
evening for COZ211-213-214.

&&

$$

UPDATE...Gimmestad
SHORT TERM...Meier
LONG TERM...Kalina
AVIATION...Gimmestad


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