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Area forecast discussion
National Weather Service Denver/Boulder Colorado
308 am MDT Fri Sep 20 2019

Short term...(today and tonight)
issued at 306 am MDT Fri Sep 20 2019

Strong upper level trough will move east across the northern
rockies today and tonight. This will produce a strong southwest
flow aloft across Colorado. A surface low will form near the
Colorado, Wyoming, Nebraska border. Southwest winds will increase
this morning across the much of the area. Drier air shifting east
across the area will result in a dry line. Appears the dry sets up
over far eastern Colorado. This is where the best chance for
storms will be. Could be a severe storm over far northeast
Colorado, but the best chance will be over Nebraska. Temperatures
will cool a few degrees today with high in the mid 80s for
northeast Colorado. Airmass mixes to at least 600mb today. This
will help produce gusty southwest winds. Gusts to 40 mph will be
possible. The dry airmass and gusty winds will result in elevated
fire danger.

A cold front tracks southeast across the area this evening. Could
be enough moisture and instability behind it for a few showers
and storms over far northern Colorado during the evening. The
airmass will continue to dry overnight with mostly clear skies
expected after midnight. Dry air and clear skies will lead to good
radiational cooling where winds are light. Temperatures should
fall into the 40s for most of northeast Colorado late tonight. The
mountain valleys will be chilly with temperatures falling into
the 20s.

Long term...(saturday through thursday)
issued at 306 am MDT Fri Sep 20 2019

For Saturday, the upper low will be over southwest Montana with the
trailing shortwave moving into northwest Colorado. The upper trough
will push east-southeast through the day with increasing upward qg
by the afternoon and evening hours. In the Post-frontal environment
there will be mostly northeast to easterly winds across the eastern
plains. However, at this time, moisture is looking more on the
weaker side with precipitable water values less than half an inch and higher-based
cloud decks. Cannot rule out a slight chance of showers and storms,
but they will be more isolated in nature. The cooler airmass will
allow for a drop in temperatures from the previous few days with
highs reaching into the mid-70s across lower elevations.

By Sunday, the trough will continue its eastward progression with
upper level ridging increasing from the west by the afternoon hours.
Qg subsidence will help to keep showers and storms at Bay with highs
in the 50s and 60s for the mountains and 70s on the plains. This dry
and warming period will stretch through Monday with high
temperatures reaching back into the lower 80s for the start of the

On Tuesday, the upper trough that moved onshore over the Pacific northwest
will deepen and transition to the southeast, reaching the Desert
Southwest by Tuesday morning. There is some minor disagreement with
the placement of the low center with the GFS being the more eastward
and faster solution and the ec and Canadian lagging behind in
Southern California and nm. Conditions in the region will remain dry with
temperatures still hovering the upper 70s to lower 80s. The question
of when moisture will return to the region is hard to determine at
this point as models become more dispersed with their solutions
starting Wednesday. Will keep highs hovering around seasonal normals
through the week, which at this time is in the mid 70s.


Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 306 am MDT Fri Sep 20 2019

A dry airmass over the area will result in VFR conditions through
tonight. Any clouds will be above 10,000 feet. Gusty south winds
will turn southwesterly around 15z. Gusts to 35 knots will be
possible after 18z through 00z. A cold front will push through
this evening causing winds to turn to the northwest around 03z.


Fire weather...
issued at 306 am MDT Fri Sep 20 2019

Gusty southwest winds will spread across Colorado with gusts up
to 40 mph. Relative humidity is expected to bottom out in the mid
to upper teens. The dry conditions and gusty winds will help to
increase fire weather concerns. Relative humidity may fall to or
below 15 percent in a few areas. However, widespread relative
humidity values are not expected to fall below 15 percent for
three or more hours required for a red flag warning, so no warning
is planned at this time. Will highlight the gusty winds and low
relative humidities in the fire weather forecast, hazardous
weather outlook and social media.


Bou watches/warnings/advisories...


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