Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231019
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
419 AM MDT Tue May 23 2017

.SHORT TERM...(Today and tonight)
Issued at 419 AM MDT Tue May 23 2017

Current satellite imagery shows partly cloudy skies with scattered
to broken mid level cloud decks. Showers have ended for the most
part, with only a couple left in the mountains and a few up north
in eastern Wyoming.

Today will feature cool temps and breezy conditions in the post
trough environment. Low level lapse rates will steepen with
daytime heating, and should be enough to produce at least isolated
shower coverage over the plains. Most of these should stay east
of a Greeley to DIA line, as a sharp subsidence inversion will be
developing from west to east across the forecast area as upper
level ridge axis builds in.

Mostly clear skies and cool temperatures can be expected by this
evening as the upper ridge continues to build over the Central
Rockies.

.LONG TERM...(Wednesday through Monday)
Issued at 419 AM MDT Tue May 23 2017

Wednesday will be the warmest day of the week as medium range
models all show upper ridging over the southwestern U.S. with the
ridge axis centered over Colorado Wednesday afternoon. By that
time, warm air out of the desert southwest will have moved over
the state, delivering mostly sunny skies and afternoon
temperatures in the lower 80s. The warm spell will be short lived
though, as the ridge progresses eastward in advance of an upper
trough digging over the Pacific Northwest. An initial surge of
cooler air is expected to move in Thursday morning, holding
afternoon temperatures in the lower 70s. Dynamic forcing
associated with the approaching trough will generate afternoon
showers, mainly over the mountains. The effects of the upper
trough and then northwesterly flow aloft across Colorado are then
expected to persist into the holiday weekend. Cooler temperatures,
in the 60s, will last through Friday and Saturday along with
periods of afternoon and evening shower/storm activity. Friday
evening may have the highest chances of shower activity as the
ECMWF jet level charts show a sub-tropical jet over southern
Colorado and the northern jet over southern Wyoming. That will
make for lots of dynamic lift over the region.

The latter half of the holiday weekend will see moderation in
temperatures, but a continuation of the chance of afternoon and
evening showers. Northwesterly flow aloft will bring some warmer
air over the state, but any short wave impulses embedded in the
flow pattern will be able to support showers that initiate off the
higher terrain during the afternoon hours. The availability of
Gulf moisture is going to be limited by the progressive nature of
the weather pattern, so strong thunderstorms are not expected.

Mountain areas could see a mix of rain or snow showers at times,
but no significant snow accumulations are expected at any time.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 419 AM MDT Tue May 23 2017

VFR conditions will persist through today. There may be occasional
ILS approaches due to sct-bkn clouds in the 5000-6000 foot AGL
range this morning, but by 18Z would expect this layer to lift a
bit and closer to 7000-8000 feet. Skies should then clear rather
quickly 23Z-01Z as strong subsidence and drying build in. Isolated
showers possible east of KDEN for approaches through the northeast
and southeast approach gates til about 23Z. Westerly winds around
5-10 knots through 15Z will turn more northerly and increase to
around 10-15 knots with gusts to around 25 knots (strongest at
KDEN) 18Z-23Z. Then winds will weaken through 01Z and gradually
transition to normal south/southwest drainage winds 03Z-06Z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Dankers
AVIATION...Barjenbruch


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