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fxus65 kbou 172101 

Area forecast discussion
National Weather Service Denver/Boulder Colorado
301 PM MDT sun may 17 2020

Short term...(this evening through monday)
issued at 300 PM MDT sun may 17 2020

There is some weak convective cloudiness over the the mountains,
foothills and Palmer Ridge. There is a also a batch of cirrus
moving across in the upper ridge. Models have the upper ridge move
across the County Warning Area overnight through Monday. At 00z Monday late day,
the upper ridge axis is over eastern Colorado. The qg Omega fields
have benign synoptic scale energy for the forecast area tonight
and Monday. The low level winds and pressure fields show normal
drainage surface wind patterns tonight. East and southeasterlies
will prevail by late morning Onward. There should be a Denver
cyclone. Moisture is quite limited overnight, just some upper
level clouds, but not much. Monday looks pretty dry too. There is
decent cape this evening, especially over the south central County Warning Area.
Will leave the 10-20 percent pops there this evening. There is
pretty decent cape over the plains on Monday with some low level
moisture, but there is a cap in place. No pops on Monday at this
time. For temperatures, monday's highs are 3-6 c warmer than
today's highs.

Long term...(monday night through sunday)
issued at 300 PM MDT sun may 17 2020

Upper level ridge axis shift eastward Monday night and Tuesday,
putting the forecast are in stronger south/southwest flow. This
will bring gusty winds to much of the forecast area, with gusts of
25 to 35 mph over most of the plains by late in the day. The
strongest winds will occur over the Palmer Divide, while locations
around Boulder to Fort Collins may be sheltered as typical in
deeper south/southwest flow. Temperatures will be Summer-
like, with highs near 90f across the I-25 corridor and adjacent
plains, but slightly cooler temps over the far eastern plains in
the more moist environment (some stratus late Monday night into
Tuesday morning). There is a narrow ribbon of high cape of
1600-2400 j/kg, but that's in the capped off environment over the
eastern plains. There is a small chance we could pop a brief
strong/severe storm along a narrow band between the drier but
fully mixed airmass along the I-25 corridor, and the more
moist/cape rich airmass to the east.

A similar setup occurs Wednesday, but there will be a higher
chance of severe storms over portions of the plains. That threat
will increase due to an ejecting short wave out of the deep
southwest U.S. Trough that opens up and lifts northeast. Model qg
solutions shows a pretty healthy shot of lift arriving by
afternoon. Also, a mid level cold pool arrives by 00z, steepening
mid level lapse rates and allowing the cap to break. There will
be uncertainty in how far west the low level moisture and severe
threat will be, but anywhere along and east of the dryline will be
prone to the severe storm threat, with large hail and damaging
winds. Right now, that most likely stays just east of the I-25
corridor. Tornado threat will depend on evolution of low level
wind fields, so something to watch closely over the next few days.
Southerly winds will be quite gusty, with speeds of 35 to 45 mph
possible across much of the plains and Palmer Divide by late

Thursday and Friday will feature southwest flow across the
forecast area, with the mean trough still holding to our west. The
airmass should become slightly unstable each day, so can't rule
out a few showers and thunderstorms. Temperatures will return
closer to normal levels.

Another wave may approach by Saturday, but confidence in the
forecast begins to decrease next weekend as model divergence
becomes quite pronounced.


Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 300 PM MDT sun may 17 2020

Pretty normal diurnal wind patterns should be the rule tonight
and Monday at dia. There should not be any ceiling issues.


Fire weather...
issued at 300 PM MDT sun may 17 2020

Concerning monday's Fire Weather Watch in South Park, winds are
still somewhat weak to warrant a red flag warning, so will leave
the watch going. Also, north and middle Parks both show elevated
fire weather conditions for Monday afternoon.

Winds will be increasing Tuesday across the area, with gusts to 30
to 40 mph over the plains. Humidities may be slightly higher in
some areas, but South Park into the Palmer Divide will still be at
critical levels it appears. Fuels are greening up over the Palmer
Divide, however, per latest observations.

Wednesday may be of bigger concern as drier and windier
conditions are expected ahead of a cold front late afternoon/early
evening. Highlights may be needed again where fuels are driest.


Bou watches/warnings/advisories...
Fire Weather Watch from Monday afternoon through Monday evening
for coz214.



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