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Area forecast discussion
National Weather Service Denver/Boulder Colorado
843 PM MDT Mon may 29 2017

Update...
issued at 843 PM MDT Mon may 29 2017

Th elast of the evening showers are moving oout of eastern Larimer
County and on the decrease as the airmass cools and stabilizes.
Other convection earlier this evening over the Palmer Divide has
also moved eastward into western Kansas. Forecast updates this
evening included removing the mention of showers this evening and
overnight. Also changed the wording for tomorrow's shower activity
to not include the mention of snow.

Synoptically, northern Colorado will remain under moderate
northwesterly flow aloft with an embedded short wave possibly
moving across during the afternoon hours. The availability of
moisture will be marginal with very modest amounts of instability.
This should keep most of tomorrow's shower activity over the
mountians and adjacent plains. Primary threat from storms should
be brief rain and small hail.

&&

Short term...(this evening through tuesday)
issued at 236 PM MDT Mon may 29 2017

Enough moisture and modest instability for a continuation of
scattered showers/storms this afternoon/evening. Most of the
showers will be done by midnight with gradual clearing skies
overnight.

High pressure ridge aloft nudges a bit closer to Colorado on
Tuesday with a bit weaker northwest flow aloft over the mountains.
With the ridge approaching, temperatures will be a few degrees
warmer on the plains and slightly drier. Still expecting scattered
showers and storms over the mountains Tuesday afternoon with
enough moisture and marginal instability for thunderstorms.
Surface based convective available potential energy 500-1000j/kg over mountains and higher
terrain of the Palmer Divide with brief heavy rain/small hail with
the stronger storms. A few of the showers may drift over the
adjacent plains late in the day/evening hours. No storms expected
on the far plains with drier and more stable airmass in place.

Long term...(tuesday night through monday)
issued at 236 PM MDT Mon may 29 2017

Scattered showers and thunderstorms over the higher terrain and
adjacent plains will be decreasing Tuesday evening, likely never
reaching the far eastern plains due to stable conditions expected.

Temperatures will be warming Wednesday and Thursday as an upper
ridge passes overhead on Wednesday then southwesterly flow aloft
produces warm advection Thursday. Expecting moisture to move up in
southeasterly flow for a chance for stronger storms over the
eastern plains. However, viewing forecast soundings show moisture
decreasing slightly on Thursday along with lighter winds aloft as
a weak trough aloft pushes overhead. More of an inverted-v type
sounding, so more gusty winds than even precipitation.

Confidence in the forecast for Friday through the weekend is lower
as the models have quite different solutions with timing and
position of their surface and upper features. A shortwave trough
is expected to push over the area Friday from the Great Basin,
though the GFS is further south and stronger with this feature.
Then a couple of shortwaves dropping on the backside of a low over
the Great Lakes area is expected to push in cooler air with a
surface high setting up over the Great Plains. The GFS is stronger
with this high, producing stronger upslope flow. Will have at
least chance pops for Friday with the stronger shortwave from the
northwest, then just keep slight chance pops for the weekend. If
the GFS verifies, will need to increase these values. Overall,
expect cooler temperatures for the weekend with at least more
cloud cover.

&&

Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 843 PM MDT Mon may 29 2017

Very few aviation impacts through the next 24 hours or so. Skies
will be clearing out over the next couple hours and remaining that
way overnight. Winds should be out of the south all night.

Light west to northwest winds Tuesday morning should switch around
to east and northeasterly early in the afternoon. A few showers
and thunderstorms are expected over the Front Range foothills in
the early afternoon, and one or two these may move over the
Denver area airports later in the afternoon. Gusty winds, small
hail and brief rains will be possible.

&&

Bou watches/warnings/advisories...
none.
&&

$$

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