Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 07/29/22

Area Forecast Discussion

National Weather Service Denver/Boulder CO

 950 PM MDT Thu Jul 28 2022

.UPDATE...
Issued at 949 PM MDT Thu Jul 28 2022

The last of the Flash Flood Watch was cancelled as the storm
moving south from Wyoming weakened considerably. There will still
be a chance of showers and storms with locally heavy rainfall
overnight, as a weak short waves moves across southern Wyoming.
However, the main flash flood threat has ended.

UPDATE Issued at 813 PM MDT Thu Jul 28 2022

Latest ACARS data shows a small stable layer now around 650 mb and
becoming more pronounced, and so far that has capped off lower
elevation convection and the flash flood threat.  Meanwhile,
there`s a strong/severe storm heading straight south from Wyoming,
and that will likely reach the border by 830 pm. That storm may
produce flash flooding in the Mullen and western portions of the
Cameron Peak burn area, so we kept the Flash Flood Watch in effect
there. The chances of flash flooding was decreasing along the
Front Range. However, just in the last 10-15 minutes there`s been
some shallow cumulus development here. We`ll still have to watch
this carefully since this airmass has not yet been overturned this
afternoon or evening. If convection did develop, we would have to
reissue/expand a Flash Flood Watch since it through the midnight
hour.

UPDATE Issued at 647 PM MDT Thu Jul 28 2022

These days with clouds are always tricky with regard to convective
development, and this one is no different. Days like this can be
little or nothing, or we`ve also seen them unfold into the worst
of flooding situations. The first round of convection did produce
heavy rain in some of the burn areas, but very little on the
adjacent plains noted so far. The aircraft soundings showed a hint
of a stable layer near 700 mb, even though we reached what would
appear to be the convective temperature (near 80 over the
south/east parts of Denver metro). A look at radar and outside the
window shows things are quite stable in/near the Front Range, but
stronger convection in southern Wyoming and we haven`t even
overturned the Front Range/I-25 Corridor airmass.  Also, some
convective initiation over the Palmer Divide area, and still
can`t rule out something popping through the cap near the best
surface convergence/cyclone center near DIA. We`ll keep the Flash
Flood Watch in place since any weak disturbance/boundary could
kick something off, but PoPs have been reduced. We`ll keep
monitoring the latest trends to see if Watch is still warranted
late this evening, but odds of significant flash flooding are
decreasing in/near the Front Range.

&&

.SHORT TERM...(This evening through Friday)
Issued at 152 PM MDT Thu Jul 28 2022

Moisture levels continue to be elevated with PW values well above
average for this time of year at over an inch on this mornings GJT
sounding. This is aided by the continued high pressure system over
TX helping to pull that moisture into the state. The morning MCS
brought rainfall and cloud cover that kept conditions fairly stable
over the I-25 corridor into the afternoon. Convection has been able
to initiate over the higher terrain, especially over Jackson and
Grand counties where clouds scattered out early on. These storms
will continue to form and push ESE into the evening hours.
Temperatures overall have rebounded slightly with mainly 70s across
the plains and 60s south of I-70 and the Palmer Divide area where
cloud cover has lingered longer. There is higher confidence that
storms will be able to move off the higher terrain and across the
northern plains along and west of I-25 where a Flood Watch is in
place. These areas have seen higher precipitation amounts and
therefore have more saturated soils where some heavy rain could
cause flooding. The latest Denver ACARS soundings show decent lower
level lapse rates with weak shear where a storm could produce heavy
rain and small hail along with strong gusty winds if it is able to
survive off the higher terrain. Overall, CAMs show storms coming to
an end after 10 pm with a mid-level cloud deck sticking around
overnight bringing more mild overnight low temperatures.

For Friday there will be continued ample moisture over the eastern
plains with over an inch along and east of I-25 with a slight drop
over the mountains with 0.5 to 0.8 inches. With the additional hours
of heating there will be MLCAPE values of 1000 to 1200 j/kg by the
afternoon and decent lapse rates. Latest CAMs show storms forming
over the higher terrain and pushing ESE over the I-25 corridor.
Coverage is expected to be less than today but with slower storm
motions will go with a limited threat of burn scar flash flooding.
More information can be found in the hydro section. Temperatures
will rebound slightly with upper 70s to lower 80s expected.

.LONG TERM...(Friday night through Thursday)
Issued at 152 PM MDT Thu Jul 28 2022

Airmass dries out some this weekend with precipitable water
values falling to 0.75 to 1.00 (in) across northeast Colorado. For
the higher terrain precipitable water values drop to 0.5 to 0.75
(in). These values are very near to slightly above normal. Expect
late day showers and storms to form over the higher terrain and
spread eastward. Threat for heavy rain rain will be lower, but the
burn areas will still see a low threat for flash flooding. Upper
level high that has been parked over the western states will
slowly shift eastward through the weekend. This will bring a
warming trend with temperatures topping 90 degrees across
northeast Colorado by Sunday.

Upper level high will track east across the Central and Southern
Rockies Monday and end up southeast of Colorado by Tuesday. Dry
and warm air will accompany the ridge. Other than a few weak
showers/storms over the higher terrain, dry conditions are
expected for Monday. Highs will climb well into the 90s across
northeast Colorado. Southwesterly flow around the high will bring
monsoonal moisture back to the area Tuesday. Best moisture should
be across western and central Colorado. Some models showing a
short wave trough for Tuesday as well, so will have scattered PoPs
for areas along and west of I-25. It should be another very warm
day with highs in the 90s across northeast Colorado. The upper
level high remains to the southeast of Colorado for Wednesday and
Thursday. This will keep a southwesterly flow aloft and monsoonal
moisture over Colorado. Expect daily afternoon and evening storms
to continue with temperatures topping out in the lower to mid 90s
across northeast Colorado.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 647 PM MDT Thu Jul 28 2022

Chances of storms have decreased considerably, but still a low
threat this evening with weak Denver Convergence Zone in the
vicinity. Main concern is the winds over the next couple hours
since DIA basically under the weak Denver Cyclone, so variable
winds quite likely at least til about 02Z-03Z. Otherwise VFR
conditions should prevail overnight, but a slight (20%) chance of
low clouds below 2000 feet AGL and some fog after 11Z. Storm
chances will increase, especially at KDEN and KAPA on Friday
afternoon, so opted for TEMPO there after 21Z.


&&

.HYDROLOGY...
Issued at 949 PM MDT Thu Jul 28 2022

The main threat of flash flooding has ended, and thus the rest of
the Flash Flood Watch was cancelled. Atmospheric moisture remains
quite high, but a shallow layer of stability really held back
convective development in lower elevations. That said, isolated to
scattered showers and storms and locally heavy rain will still be
possible overnight, as a weak shortwave moves east across
southern Wyoming.

Another round of convection combined with continued high
levels of precipitable water will bring a limited threat of flash
flooding to area burn scars Friday afternoon and evening.
Thunderstorms are expected to form over the higher terrain and
move ESE over the I-25 corridor into the late afternoon and
evening. Although storm coverage is expected to be less than today
storms could still produce up to an inch of rain in less than a
hour.

Airmass dries some for this weekend. However, enough will be
around for scattered afternoon and evening thunderstorms. Flash
flood threat will be confined to the burn areas where the threat
will be limited both Saturday and Sunday. Upper level high will
bring warm and mostly dry conditions for Monday. Other than a few
weak storms, dry conditions will prevail. Moisture begins to
return to the area Tuesday with daily showers and storms expected
Tuesday through the rest of the week.

&&

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

$$

UPDATE...Barjenbruch
SHORT TERM...Bowen
LONG TERM...Meier
AVIATION...Barjenbruch
HYDROLOGY...Barjenbruch/Bowen/Meier