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

Area Forecast Discussion

National Weather Service Denver/Boulder CO

 908 PM MDT Wed Jul 6 2022

.UPDATE...
Issued at 859 PM MDT Wed Jul 6 2022

We have allowed the rest of the Severe Thunderstorm Watch to
expire at 9 pm. Scattered thunderstorms will continue across the
northeast plains this evening, but will gradually decrease in
coverage and intensity overnight. Some of the models suggested
some low stratus or fog developing north and northeast of Denver
late tonight into Thursday morning, so added patchy fog to those
areas from 3 am to 9 am Thursday morning.

UPDATE Issued at 642 PM MDT Wed Jul 6 2022

The severe thunderstorm watch continues for Morgan, Lincoln,
Logan, Sedgwick, Phillips and Washington counties until 9 pm, but
it has been canceled for the remainder of the watch area including
the urban corridor. Showers and thunderstorms however will still
be possible over the urban corridor this evening, with gusty winds
to 35 mph, locally heavy rainfall and frequent cloud to ground
lightning with the stronger storms.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 217 PM MDT Wed Jul 6 2022

Moisture moving around the periphery of the upper ridge brought
increased precipitable water (PWAT) values of over an inch to the
region. Dry air intrusion earlier today helped to decouple the
atmosphere over the higher terrain lowering MLCIN and increasing
CAPE values across the CWA from 1,000 to 2,000 j/kg. Steering flow
is rather weak causing slow storm motions that will aid in possible
flooding scenarios over the metro area and across the eastern
plains. Continued surface NE flow will help to maintain an upslope
component over the foothills and Palmer Divide that will aid in the
formation of storms. Mid-level flow although weak will carry storms
over the metro area and urban corridor after 2 pm and will continue
into the evening. Although storms are currently struggling to stay
together off the foothills initially there is confidence that storms
will still form and drop heavy rain across the metro with current
ACARs soundings showing lapse rates over 8.1 c/km and no capping
inversion in place. Current visible satellite shows decent shear
with northeast flow near the surface and southwest flow in the mid
and upper levels. Hires models continue to show bulk shear values in
the 30-40 kt range which is enough for strong to severe storms
mainly east of I-25. These storms could produce quarter size hail or
copious amounts of small hail with strong wet microbursts with
damaging winds into the evening hours. Also can`t rule out training
storms or an MCS over the eastern plains with weak corfidi vectors
and more unidirectional flow present. Current CAMs show storms
pushing east and diminishing after midnight.

For Thursday, PWAT values will decrease slightly but will still be
over an inch projected for the eastern plains. Models are showing a
weak disturbance in the upper ridge that will aid in the formation
of convection by the afternoon with slightly less coverage than
today. Storms will be moving only slightly faster than today so will
maintain a limited risk of flooding for the burn scars. More info
can be found in the hydro section below. Temperatures will continue
to be closer to seasonal normals with highs in the upper 80s over
the plains and 60s to 70s for the high country.

.LONG TERM...(Thursday night through Wednesday)
Issued at 217 PM MDT Wed Jul 6 2022

Isolated to scattered showers and storms are expected to continue
across the forecast area Thursday night, most numerous east of
the mountains. The best moisture and instability will be over the
plains east of Denver where one or two stronger storms with brief
heavy rain and small hail will be possible.

Warmer and drier weather is expected Friday through the weekend as
upper level high pressure builds over the Southern Rockies. There
may be enough lingering moisture combined with daytime heating to
produce a few afternoon and evening showers and storms, mainly
over the higher terrain south of I-70. Saturday and Sunday look
to be quite hot across the plains with forecasted max temperatures
ranging between 95 and 103 degrees.

Early next week, the models are suggesting that the upper high will
retrograde westward as an upper level shortwave rides over the ridge
into the Upper Midwest. This pattern would put Colorado under the
influence of a northwesterly flow aloft which may open the door
to occasional cold fronts moving across Northeastern Colorado. If
this verifies, the weather could become more active with cooler
temperatures and a better chance for precipitation, especially
east of the mountains. However, many of the ensemble members keep
the high further to the east which would limit precipitation
chances and keep temperatures warmer. Time will tell.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 642 PM MDT Wed Jul 6 2022

Thunderstorms continue in and around the terminal locations so
will keep showers/thunderstorms in the forecast until 01-02z, then
the focus should shift east of Denver. North/northwest winds this
evening should transition to southwest by late this evening.
Similar conditions expected on Thursday, with another round of
thunderstorms expected in or near the terminal after 20z. The main
impacts from the convection will be gusty and erratic winds with
speeds up to 35kts and locally heavy rainfall, if a storm passes
directly overhead.


&&

.HYDROLOGY...
Issued at 217 PM MDT Wed Jul 6 2022

Showers and thunderstorms capable of producing heavy rain will be
possible over the burn scars today and Thursday. Storm motion will
be slower so will maintain a limited threat over the burn areas.
Storms will be capable of dropping up to 0.5 inches in a short
period of time.

An upper level ridge of high pressure building over the the
Southern Rockies will bring warmer and drier conditions to the
area Friday through the weekend. As a result, the flash flood
threat will be very low. By early next week, the flash flood
threat across the burn scars may increase to limited as monsoonal
moisture increases somewhat.

&&

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

$$

UPDATE...Cooper
SHORT TERM...Bowen
LONG TERM...Kalina
AVIATION...Cooper
HYDROLOGY...Bowen/Kalina



Area Forecast Discussion...CORRECTED

National Weather Service Phoenix AZ

 453 PM MST Wed Jul 6 2022

.UPDATE...Updated Aviation discussion.

&&

.SYNOPSIS...
Much drier air surging into the region will almost completely
eliminate thunderstorm chances the remainder of the week.
Correspondingly, temperatures will rebound into an above normal
range with highs across lower elevation communities returning to
levels in excess of 110 degrees by Friday and persisting into next
week. Isolated higher terrain showers and storms could return
over the weekend and early next week as moisture seeps back into
the area.

&&

.DISCUSSION...
Very quiet convectively across the region this afternoon, with
the only notable storms well north and east of our forecast area.
Morning RAOBs and midday ACARS soundings show boundary layer
mixing ratio values of 5-6 g/kg, resulting in surface dew points
generally in the lower 30s to lower 40s F across our AZ zones and
lower 50s to lower 60s in the Imperial Valley. This very dry
pattern will likely remain in place through Friday as deep
southwesterly flow continues, with PoPs across our CWA remaining
at or below 10 percent. Temperatures today are likely to top out
still a few degrees below normal, this will be the last day in the
forecast period for below normal readings as near normal values
return by tomorrow. By Friday, the probability for 110F+ high
temperatures quickly jumps to 30-70% for lower desert communities.

This weekend, an upper level low over the Pacific Northwest will
weaken, allowing the mid-level anticyclone over the Southern
Plains to shift west and increase in intensity/coverage. Low
levels of boundary layer moisture (~8-10 g/kg) will flow back into
eastern Arizona under this scenario beginning Saturday, allowing
for low probability of afternoon/evening mountain convection. That
gradual westward expansion of moisture will slowly continue into
the middle of next week, keeping daily mountain convection
possible. The lower deserts will likely remain hostile towards
additional storm development for the time being, with moisture
being marginal and instability further limited by warming mid-
level temperatures. TS chances for Phoenix will creep to around
10% by early next week and remain there for the following days.
The more likely impact will be a return of gusty and dust
outflows.

As mentioned, the airmass will be warming up with the large high
coming in. Though H5 heights will be reaching toward the 99th
percentile (per EPS mean), lower level temperatures are not
showing a corresponding increasing trend and peaking more around the
90th percentile. This may be a reflection of the very dry airmass
in place. Still, temperatures will be quite hot and approaching
Excessive Heat Warning criteria (especially Sat-Mon). Future
forecasts that trend up could result in an EH.A/EH.W. Temperatures
will reduce slightly toward the middle of next week, but that is
highly dependent on convective activity - values could continue to
run hot through next week.

&&

.AVIATION...Updated at 2350Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns expected through the period as a
very dry airmass in place will inhibit thunderstorm formation with
mostly clear skies. Westerly winds below 10 kts will continue
into the overnight with a switch to easterly between 10-12z
Thursday morning. A switch back to westerly winds can be expected
by late morning into the early afternoon Thursday with speeds
mostly remaining aob 10 kts, however, some afternoon gusts near 20
kts cannot be ruled out at times.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns expected through Thursday. Winds will
generally retain a southerly component at both KIPL and KBLH.
Otherwise, gusts up to 20 kt will be possible once again Thursday
afternoon at KBLH.

&&

.FIRE WEATHER...
Isolated thunderstorm coverage will gradually return to far
eastern districts this weekend, but will remain dry until then.
Even as storms return, wetting rainfall potential remains somewhat
limited. With drier air spreading across the region, minimum
afternoon humidity levels will fall into the teens. Higher terrain
of eastern districts should see humidity values closer to a
20-30% range next week as moisture starts to return. Overnight
recovery will be mostly poor to fair in a 20-50% range. Some
enhanced upslope afternoon breeziness will be common, but gusts
should generally not exceed 20-30 mph.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Iniguez
AVIATION...Lojero/Frieders
FIRE WEATHER...Iniguez/18