Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/22/20

Area Forecast Discussion

National Weather Service Denver/Boulder CO

 849 PM MDT Sun Jun 21 2020

.UPDATE...
Issued at 849 PM MDT Sun Jun 21 2020

Evening convection is just about wrapped up, with just a couple
lingering showers. Those will be dissipating through late evening
(shortly after midnight in the northeast corner) as the jet core
shifts east, taking any support in the left exit region with it.
Some clouds may linger through most of the night so will adjust
those accordingly. A weak frontal push was moving through
southeast Wyoming, but will weaken further as it moves across
northeast Colorado tonight. That will usher in somewhat cooler
temperatures for Monday. The latest model data indicates a few
hundred joules of MLCAPE along the Front Range tomorrow afternoon,
higher PW, and lower LCLs. That would support storms with more
rainfall and less gusty winds than what we saw from today`s
convection.

&&

.SHORT TERM...(This evening through Monday)
Issued at 210 PM MDT Sun Jun 21 2020

The upper level jet is pushing into western Colorado with the left
exit region helping to bring increased convection across portions of
Wyoming and into northern Colorado. Most of this convection will be
isolated to the higher elevations of the mountain and foothills near
the border with some isolated storms pushing ESE into the evening
hours. ACARS soundings showing a slight stable layer over Denver
that is a byproduct of the persistent wave cloud that has kept
temperatures cooler and conditions more stable further south. These
isolated storms will be capable of gusty winds with model soundings
showing DCAPE values above 1000 j/kg with speeds of 35 to 45 mph
possible with the stronger storms. A surface cold push later this
evening will bring a cooler and more stable airmass that will help
to dissipate storm activity across the plains.

Monday will see another day of persistent cloud cover through the
afternoon hours and highs topping out around 80 degrees with
continued upslope northeasterly surface winds. This will keep
instability low with CAPE values between 100 to 250 j/kg. There is
better instability across the higher terrain so will maintain a
slight chance of storms over the mountains by the afternoon hours on
Monday. Main hazards will be gusty winds, lightning and light rain
showers.

.LONG TERM...(Monday night through Sunday)
Issued at 330 PM MDT Sun Jun 21 2020

A weak shortwave trough will pass through our forecast area Monday
night which may be able to provide enough lift for isolated
showers and storms to continue through the evening and into the
overnight hours. The best chance for showers and storms Monday
night will be over the mountains east of the Continental Divide,
foothills, and Palmer Divide.

Ridging will move closer to Colorado on Tuesday but continued
northwesterly flow aloft will allow for isolated showers and
storms to develop in the afternoon/evening. Instability will be
somewhat limited as mixed-layer CAPEs will be below 1,000 j/kg and
the lack of a shortwave will mean the coverage of these showers
and storms will be minimal.

The axis of the ridge will move over our forecast area on
Wednesday with increasing temperatures aloft. These warmer
temperatures will mix down to the surface across the plains
leading to highs around 90 degrees in Denver. Due to subsident
flow throughout much of the troposphere, only a few stray showers
and storms will form with most areas staying dry.

Global models begin to differ on Thursday in the timing and
strength of the trough that moves across the Pacific Northwest
towards Colorado. The ECMWF is the most progressive and weakest
with this trough while the Canadian is the deepest and slowest.
It`s hard to get a good read on which model will be right but I
tend to the think the trough may end up being closer to the
Canadian solution because troughs have been prone to being stronger
than forecast over the last month or so. If that`s the case,
isolated to scattered storms will form Thursday afternoon/evening
and then more widespread storms will form on Friday. With
sufficient instability and deep layer shear in place, some of the
storms on Friday may be strong to severe with damaging wind gusts
and large hail the primary threats.

After the trough moves east of our forecast area Friday night,
ridging will develop over Colorado next weekend. This will lead to
mostly dry conditions and hot temperatures.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 849 PM MDT Sun Jun 21 2020

Convection has ended for the evening. Winds are already settling
back to normal light south/southwest flow. However, a weak cold
front moving south from Wyoming may switch winds around to a
northerly component toward 06-07Z. There is a little low level
moisture behind the front, with a slight chance of a developing
stratus deck and ILS conditions. But, don`t think the upslope
would be sufficient so mainly VFR conditions will persist through
Monday. There will be scattered showers and storms again in the
afternoon, with potential for a little more rain and less wind
that from today`s activity.

&&

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

$$

UPDATE...Barjenbruch
SHORT TERM...Bowen
LONG TERM...Danielson
AVIATION...Barjenbruch