Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 262105
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
305 PM MDT Sat May 26 2018

.SHORT TERM...(This evening through Sunday)
Issued at 304 PM MDT Sat May 26 2018

A pretty decent Cirrus shield is covering most of the CWA this
afternoon. Temperatures are in the lower to mid 90s F for most of
the plains. The highest reading so far at DIA has been 94 F. Dew
points are mostly in the 40s F over the eastern plains and down
into the 20s F over the western plains. There are 10 to 20 knot
southerly winds over the far eastern plains, with weak flow over
the rest of the plains. Models have south and southwesterly flow
aloft for the CWA overnight, then southwesterly flow on Sunday. By
12Z Sunday morning, there is an upper closed low over central
Utah. By 00Z late Sunday afternoon it is over the northwestern
Utah. There is weak upward vertical velocity noted over the CWA
tonight and Sunday on the QG Omega fields. Models keep pretty
strong south-southeasterly winds going over the eastern half of
the plains tonight and Sunday. More normal drainage winds
patterns are expected for the western plains and mountains. There
looks to be a pretty decent Denver cyclone set up for Sunday
afternoon. For moisture, models keep the upper cloudiness around
much of tonight, especially over the eastern half. On Sunday, more
moisture is around in the mid, even the lower levels. Models show
the dew points in the 50s F over most of the plains by Sunday
afternoon. Both the GFS and NAM show significant CAPE over the
northeast on Sunday afternoon. Both show values well above 2000
J/kg. There is a favorable shear profile on the soundings for
severe weather, mostly over the northeast corner. The QPF fields
have a tad a measurable rainfall over the plains Sunday morning,
with higher amounts over the northeast during the afternoon. For
pops, the highest will be over the northeast corner and over the
north central mountains on Sunday afternoon. Will mention some
severe possible over the corner as well. For temperatures,
Sunday`s highs will be 1-2.5 C cooler than this afternoon`s
readings.

.LONG TERM...(Sunday night through Saturday)
Issued at 104 PM MDT Sat May 26 2018

Sunday night, the closed upper low will be over eastern NV/western
UT, with weak mid level QG ascent over the area. Slight risk of
severe will linger over the northeast plains through early
evening. Monday and Monday night, the closed low will shift into
central UT with weak to moderate QG ascent over eastern CO as the
trough opens up and shifts slowly to the northeast. Sfc based
computed CAPES from 1800 to 2800 j/kg in the afternoon.
Interactive forecast soundings suggest increasing speed and
directional shear as well. Low level east/sely winds with
increasing southwesterly winds aloft associated with the
approaching trough. Large hail, damaging winds and possible
tornadoes as well. Threat of severe storms along and east of the
I-25 corridor as low level moisture advects westward into the
Front Range. Temperatures will be cooler with highs near 80.
Tuesday and Tuesday night, the mid level trough axis will pass to
the north of CO through the day. CAPEs around 500 j/kg along the
I-25 corridor, with values from 1000 to 1500 j/kg along the
eastern border. The best chance of pcpn around the cwa will occur
Sunday night through Tuesday afternoon. For Wednesday and Thursday,
an upper level ridge will build back over the region. This will
result in the trend of warmer and drier weather, especially for
Thursday. Thunderstorm coverage will be more isolated in the
afternoon and evening at that time. Next system may impact the
region late Friday into Saturday, could at least see a better
chance of thunderstorms over the high country by that time. There
could be a brief period of strong post-frontal winds as well for Friday
night into Saturday morning. Will need to keep any eye out for
bora wind potential at that time when a strong pocket of moderate
to strong subsidence could pass across the cwa.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 304 PM MDT Sat May 26 2018

Currently winds at DIA are generally east-southeasterly at this
time. Models show normal drainage wind patterns by 03Z this
evening, then continuing the rest of the night. On Sunday, winds
will become southeasterly after 18Z. There will be no ceiling
issues overnight and Sunday.

&&

.FIRE WEATHER...
Issued at 304 PM MDT Sat May 26 2018

Will keep the Red Flag Warning going for Park County into this
evening and again Sunday afternoon and evening. The current airmass
in Park County is very dry with many of the observation showing
relative humidities below 10% The same is expected for Sunday
afternoon/evening. Winds are marginal currently for a Red Flag
Warning but they are expected to be high on Sunday. The fuels are
very dry in Park County as well.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for COZ214.

Red Flag Warning from noon to 9 PM MDT Sunday for COZ214.

&&

$$

SHORT TERM.....Koop
LONG TERM......Coop
AVIATION.......Koop
FIRE WEATHER...Koop



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