Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 252116

Area Forecast Discussion
National Weather Service Denver/Boulder CO
316 PM MDT Thu May 25 2017

.SHORT TERM...(This evening through Friday)
Issued at 240 PM MDT Thu May 25 2017

Scattered showers and thunderstorms are expected to continue into
the evening hours. Best moisture and instability are located over
the eastern plains. Threat for severe thunderstorms is expected to
end late by early evening over the plains. Strong thunderstorms will
remain possible with gusty winds, small hail, and brief heavy rain.
Lift from a nearby jet is helping to trigger the thunderstorms.
Additional showers and isolated storms will be possible overnight
because of this lift.

A weak cold front will bring northerly winds late tonight. On Friday
the winds will turn southeasterly and increase low level moisture.
Dew points are expected to be in the mid 40s to lower 50s. This will
help produce surface based CAPE of 700 to 1500 J/kg. Shear will be
good enough to support supercell development. The best chance for
severe thunderstorms is expected to be east of I-25.

.LONG TERM...(Friday night through Thursday)
Issued at 316 PM MDT Thu May 25 2017

West-southwesterly flow aloft is over the CWA Friday night and
Saturday. An upper trough moves in Saturday afternoon into Sunday
morning. Weak flow aloft moves in with an upper ridge to the west
by Sunday night. There is some weak upward energy progged in the
synoptic scale on the QG Omega fields Friday night through
Saturday night, then benign forcing is progged. The low level wind
fields have upslope flow for the plains and foothills Friday
night and Saturday. Normal drainage patterns look good for
Saturday night, then downsloping for Sunday and Sunday night.
Moisture increases over the CWA Friday night, with quite a bit of
moisture progged Saturday into the evening. Moisture decreases
Sunday and Sunday night. There is some CAPE over the plains and
foothills Friday evening, with the highest values over the
foothills. There is more CAPE around Saturday afternoon and early
evening, mainly over the mountains, foothills and western plains.
There is pretty decent CAPE over the mountains only late day
Sunday. The QPF fields have measurable rainfall over much of the
CWA Friday night, then again late day Saturday over all areas but
the eastern plains. By late day Sunday, there are minimal amount
of precipitation progged over the high mountains only. For pops,
will go mostly with "chance"s Friday night and Saturday. There
will be a few areas with "likely"s. Saturday night through Sunday
night are much drier, with only a few "chance"s in the mountain
only. For temperatures, Saturday`s highs are 4-9 C cooler than
Friday`s highs. Sunday`s highs are 3-6 C warmer than Saturday`s.
For the later days, Monday through Thursday, there is an upper
ridge to Colroado`s immediate west Monday and Tuesday. The upper
ridge weakens somewhat on Wednesday and Thursday, and is right
over the state. The moisture for late day storms is mainly
confined to the mountains and foothills.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 240 PM MDT Thu May 25 2017

Scattered thunderstorms will remain possible through about 03Z. Main
threat with the storms will be gusty outflow winds to 40 knots,
brief heavy rain, and small hail. Wind direction through 03Z will
primarily be determined by outflow boundaries pushing through.
Eventually northerly winds are expected to prevail behind a weak
cold front after 06Z. On Friday, southeast winds will usher moisture
into the area. Low clouds will be possible with ceilings of 2000 to
4000 feet possible. Stronger thunderstorms are expected after 18Z
Friday with wind gusts to 50 knots and large hail possible with the
stronger storms.




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