Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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879
FXUS65 KBOU 232056
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
256 PM MDT Sun Jul 23 2017

.SHORT TERM...(This evening through Monday)
Issued at 146 PM MDT Sun Jul 23 2017

There is a nearly stationary flow this afternoon and evening with
the upper ridge centered over the Great Basin and central Rockies.
Storms south eventually drift to the east/southeast. Visible
satellite showing a cumulus field over the northeast plains this
aftn and outflow could help initiate additional thunderstorms. For
now will keep the mention of thunderstorms to areas through this
evening in and near the Front Range Foothills, Palmer Divide and
Urban Corridor. Overall coverage will be isolated. Locally heavy
rain the main issue. On Monday the upper ridge will be centered
over New Mexico and west Texas, with weak west to southwesterly
flow aloft over the cwa. Subtropical moisture advecting into the
area from the southwest will allow for scattered thunderstorms in
the mountains in the aftn, with isold coverage over the northeast
plains late in the day. Low level theta-e ridge is progged to set
up there toward 00z Tuesday. Main issue will continue to be
locally heavy rain, wind gusts to 40 mph and frequent cloud to
ground lightning with the stronger storms.


.LONG TERM...(Monday night through Sunday)
Issued at 146 PM MDT Sun Jul 23 2017

Weak west/southwest flow aloft will further increase the mid and
upper level moisture Monday evening. The increase in mid level
moisture, in combination of a northerly surge of low level
moisture on the plains as shown in the theta-e fields, could allow
some convection to develop on the plains through the early
evening hours. Have added some low thunderstorm chances on the
plains for that. Overnight lows will be several degrees above
normal as we should see some mid/high clouds linger through the
night.

Tuesday will start off quite warm and dry, and highs should again
reach the mid 90s over most of the plains. However, by late
afternoon and evening, models continue to indicate a weak
embedded short wave approaching the state. This should bring an
uptick in convective coverage, with a few storms with gusty winds
and brief heavy rain spilling onto the plains. Highest storm
coverage will still be confined to the mountains.

Wednesday is trending toward a cooler and potentially wetter day.
The mid level moisture plume is advertised to hold over the
forecast area, while at the same time a real cold front is
expected to push across the plains. At this time, the front is
stronger than anything we saw last week, and thus we should see a
better potential for storms with locally heavy rainfall in/near
the Front Range and I-25 Corridor. Farther east on the plains it
may stay too stable for much storm development so will continue to
watch this over the next few days. A similar setup may hold into
Thursday, so will maintain the slightly cooler and unsettled
weather then.

By Friday into next weekend, a slightly drier west/northwest flow
aloft is still expected to develop. There will still be daily
chances of thunderstorms, but overall less coverage expected.
Temperatures should also return to near normal levels for this
period.


&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 146 PM MDT Sun Jul 23 2017

Isolated thunderstorms near the terminals until 01z with outflow
winds to 30 kts lingering until possibly 02z. VCTS at most
expected in the terminals at this time. Overall VFR with no
restrictions. southeast surface winds until late this afternoon.
with potential west/southwest outflow possible with dissipating
convection off the foothills in the 22-24z window. Winds will
eventually settle back to drainage overnight.


&&

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

$$

SHORT TERM...DB/Cooper
LONG TERM...DB
AVIATION...Cooper



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