Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 09/03/22
Area Forecast Discussion
National Weather Service Denver/Boulder CO
724 PM MDT Fri Sep 2 2022
.UPDATE...
Issued at 710 PM MDT Fri Sep 2 2022
A small area of thunderstorms is making its way out of the
foothills of Larimer County, moving southeast around 20 mph.
Locally heavy rainfall, from 0.20 to 0.40 inches in less than 30
minutes, will be possible with the stronger storms. I increased
the pops, generally around 20 percent for those areas south and
east of the storms, which could impact northern/eastern Denver by
8 or 9 pm. Storms may persist along and west of a boundary
pushing in from the northeast this evening.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 149 PM MDT Fri Sep 2 2022
Northeast surface winds behind a weak frontal push have increased on
the plains bringing isolated convection to the higher terrain. Flow
will push any storms that form SSE and will mainly bring weak
showers, gusty winds, and some lightning. Current ACARs soundings
show an eroded stable layer at the surface with decent mid-level
lapse rates. If storms make it off the foothills they will most
likely be more high-based with gusty winds and lightning being the
main hazards. A convergent boundary has set up across portions of
Lincoln and Washington counties that will support some isolated
convection into the late afternoon hours. CAMs show some persistent
activity across the Denver metro area after 8 pm as well with weak
showers and gusty winds possible. Overnight conditions will be
mostly clear with lows in the 50s on the plains and mainly 40s in
the high country with mountain valleys dipping into the 30s.
For Saturday, the upper level ridge will begin its shift westward
and over Colorado bringing mostly dry conditions and another above
average day for high temperatures. There may be some lingering
moisture that could support isolated storms over the higher terrain
mainly south of I-70 by the afternoon. Highs will only be a few
degrees cooler than Friday with lower 90s expected on the plains,
70s in the high country and 80s in the foothills and high mountain
valleys.
.LONG TERM...(Saturday night through Friday)
Issued at 149 PM MDT Fri Sep 2 2022
An upper level high will be centered from Utah into western CO
from Sun into the middle part of next week. This will lead to a
dry pattern with temperatures remaining well above normal. Highs
across nern CO will remain in the 90s with some potential for a
few records.
For late next week, the GFS maintains an upper level high across the
region while the ECMWF weakens it. The ECMWF begins to show some
influx of subtropical moisture with a slight chc of convection.
Meanwhile the GFS keeps it dry with well above normal temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 710 PM MDT Fri Sep 2 2022
VFR conditions are expected through the TAF period. Winds will be
from east/northeast for area terminals with gusty winds up to 20
kts possible through 06z. Some variable winds with storm activity
will be possible through this time. Storms later in the evening
could also produce outflow boundaries 02z-05z, with gusts up to
30kts that could impact mainly DEN through 06z. Can`t rule out a
brief ILS restriction with a heavier shower, but that still looks
like a low probability at this time. Normal drainage patterns
expected overnight.
&&
.FIRE WEATHER...
Issued at 149 PM MDT Fri Sep 2 2022
Elevated fire weather conditions will be possible this afternoon
with some areas gusting up to 20 mph and RH values in the teens.
Saturday will see slightly higher humidity values but with
continued warmer than average temperatures.
Elevated fire danger will be in place from the foothills across
the plains Sunday through the middle part of next week. However,
winds will be relatively light through the period.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Cooper
SHORT TERM...Bowen
LONG TERM...RPK
AVIATION...Cooper
FIRE WEATHER...RPK
Area Forecast Discussion
National Weather Service Phoenix AZ
454 PM MST Fri Sep 2 2022
.UPDATE...00Z Aviation Discussion...
.SYNOPSIS...
Thunderstorms late this afternoon and tonight are expected to
produce large swaths of strong winds and blowing dust,
especially east of the Lower Colorado River Valley. However,
rainfall coverage will tend to be modest with most areas seeing
little if any rain. Over the weekend, storm activity trends down
as drier air filters in from the northeast. Heat will be more of
a concern and an Excessive Heat Warning remains in place for large
portions of the lower deserts including the Phoenix area.
Temperatures trend down during the latter half of next week but
humidity trends up again.
&&
.DISCUSSION...
The forecast remains on track for a strong convective wind
scenario later today/tonight over a large portion of our forecast
area. Looking at the flow pattern, there is large area of mid-
tropospheric high pressure centered over the southern Great Basin
and and to the south is a relatively small upper low/inverted
trough centered over central Baja. This will lead to fairly strong
east/northeasterly steering flow to help advect higher terrain
storms from Gila and Yavapai Counties to the lower elevations of
Maricopa/Pinal/La Paz. Additionally, storms from far northern
Sonora may also reach Yuma County. The steering flow is expected
to be strong enough that it will help keep new storm development
from being outrun by the outflow boundaries. Another factor that
may come into play to help storm development over the higher
terrain is a very positively tilted short wave in the upper
troposphere that is sagging south through northeast AZ and New
Mexico.
But, precipitable water values are modest over south-central AZ
at 1 - 1.5 inches (better over SW AZ and SE CA at 1.5- 2 inches).
If SBCAPE values could be fully realized, there would be
exceptional instability but that is more of a hypothetical because
the richer moisture is primarily in the lower levels (near and
below 850mb per latest PHX ACARS soundings). With drier air above,
even the MLCAPE values may be a bit optimistic in terms of what a
fully mixed layer will look like. Even taking that into
consideration there will still be healthy CAPE. However, the
latest ACARS soundings also so considerable CIN yet to overcome
over the Phoenix area. The CAMs are in pretty good agreement that
the rain footprint over the lower elevations will be pretty
modest. In spots that have colliding boundaries, locally heavy
rain will be possible - especially over southwest AZ. The main
concern though is the strong wind potential. The 12Z HREF has a
large area of 50-90% probability of gusts exceeding 30kts (70-90%
Phoenix area) and even a large area of 10-30% chance of exceeding
50kts. So, we expect a much broader swath of strong winds and
blowing dust compared to rainfall. The blowing dust potential is
also why a long fused Blowing Dust Advisory was issued for the
lower elevations along and east of the Lower Colorado River Valley
for later this afternoon and evening. There could very well be
blowing dust west of there but new storm development looks to
struggle over southeast CA.
Over the weekend, drier air from the northeast decreases storm
activity. Tropical Storm Javier, currently southwest of Cabo San
Lucas, will track northwestward before taking a due west track
beginning Sunday. So, it will not be a factor. Excessive heat will
be the main concern. Though HeatRisk values are not overly
impressive, temperatures will be at least a few degrees above
normal during a holiday weekend (even more than that over our
western areas on Monday).
The global ensembles show high pressure remaining centered over
the southern Great Basin Tuesday before weakening Wednesday as a
trough in the Westerlies moves through western Canada and the
northwest CONUS. Another factor that may come into play during
the latter part of next week is a tropical disturbance currently
far southeast of Cabo San Lucas. The global ensemble means
indicate that it will track over Baja and Sinaloa/Sonora and
weaken a lot in the process. This is supported by a majority of
the ensemble model track guidance. This makes sense given the
presence of an upper trough to the north. Increased cloudiness
and humidity can be expected and PoPs increase as well because of
increased moisture availability. Not enough to go on at this point
to be too concerned about something remaining at tropical storm
strength north of the Mexico a week or so from now.
&&
.AVIATION...Updated 2354z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Current t-storm activity that has been attempting to move into the
Phoenix area have been rapidly weakening over the last hour or so
due to a more stable airmass over the lower deserts. However,
outflows from these storms have (or will shortly) switched winds to
an easterly direction. Wind gusts as high as 30 kts are possible
over next 1-2 hrs, but blowing dust/direct impacts from t-storms now
appear unlikely. Lighter easterly winds are anticipated thru the
mid/late evening hours with periods of light/variable winds likely
overnight. Winds on Saturday are expected to remain easterly all day
with even some increase in wind speeds during the afternoon. Chances
for -SHRA/TS activity moving into the Phoenix area from the east,
but confidence is too low at this point to include anything more
than VCSH in the TAFs at this point.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds will be the primary weather issue through Saturday morning
under mostly clear skies. KBLH will favor south winds while KIPL
directions tend to be more southeast. Occasional gusts near 20kt may
be possible, but should not be prevalent for extended periods.
Approaching TS and outflow winds may impact KBLH during the mid-
evening hours, thus have included a TEMPO -TSRA and elevated winds
in the TAF.
&&
.FIRE WEATHER...
Above normal temperatures will continue the next several days as
high pressure predominates across the Desert Southwest. Showers
and thunderstorms are expected to form this afternoon along the
Mogollon Rim before moving into the lower deserts this evening. Any
storms that develop will be capable of producing frequent
lightning and strong wind gusts. Otherwise, winds will generally
remain light and diurnal. Warmer and drier conditions are likely
Saturday, but the threat of isolated storms will continue across
the higher terrain north and east of Phoenix. Showers and
thunderstorms are generally not anticipated Sunday through the
middle of next week. Thereafter, the forecast becomes more
uncertain though a switch to a cooler and wetter pattern is
looking more likely.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Tuesday for AZZ530.
Excessive Heat Warning from 10 AM Saturday to 8 PM MST Monday
for AZZ537-540>544-546-548>551.
Blowing Dust Advisory until 10 PM MST this evening for AZZ530-
533-534-537>540-542>544-546-548-550-551-553>555-559.
Blowing Dust Advisory from 6 PM this evening to midnight MST
tonight for AZZ531-532-535-536.
CA...Excessive Heat Warning until 8 PM MST Tuesday for CAZ560>570.
Blowing Dust Advisory until 10 PM MST this evening for CAZ569.
&&
$$
DISCUSSION...AJ
AVIATION...Heil/18
FIRE WEATHER...Hirsch
Area Forecast Discussion
National Weather Service Reno NV
219 PM PDT Fri Sep 2 2022
.SYNOPSIS...
Hot temperatures with some record highs will continue through
early next week, peaking through the Labor Day weekend. There is
a risk of daytime heat health impacts for much of the population
with this prolonged heat wave. Gusty winds will bring areas of
critical fire weather conditions along with choppy lakes Saturday.
Some cooling may arrive later next week.
&&
.SHORT TERM...through Saturday night...
The forecast updates made earlier today will remain in place.
A fast moving shortwave across Oregon will kick up winds first in
higher elevations tonight, then mixing down to lower elevations
Saturday morning, with pressure gradients keeping sustained winds
going through Saturday afternoon with choppy conditions
sufficient for a Lake Wind Advisory on Pyramid Lake. The dust will
be flying around the Black Rock Desert through much of Saturday.
See the fire weather section for more details on wind speeds and
impacts.
Behind this shortwave passage it looks like the heat will edge
downward by a few degrees for areas north of Susanville to near
the Oregon border on Saturday. Otherwise we`ll keep rolling with
triple digit heat for most lower elevations, especially for west
central NV which will experience full mixing without any
modification of the current hot air mass. MJD
.LONG TERM (Sunday onward)...
As has been previously messaged, a dome of stronger high pressure
centered over much of the Great Basin and central Intermountain
West continues to “Turn-Up-The-Heat” across much of the the
western US. Those who like in hot, please enjoy! Those waiting
patiently for some sign of fall, your time is coming. But for now,
near record hot temperatures hovering around the 100’s, dry
conditions, and elevated fire concerns will be the headline items
going into mid-week. It is still advised to hydrate often, and
continue to check on vulnerable populations as well as those who
are heat sensitive. Always look for children and pets in vehicles
before you lock it up.
Recent ensemble guidance adds confidence to the notion that the
current “Heat-Wave” and period summer-like temperatures will break
during the latter half of next week. An upper short wave lifting
into the Pacific Northwest overnight Tuesday into Wednesday will
press into, and encourage the shift east of the central High into
the central Rockies. The shift of the ridge axis east will allow
a southerly upper wind to increase and draw northward a more
modest flow of monsoonal moisture over the eastern Sierra east of
US-95. Continued hot temperatures, coupled with steeper afternoon
lapse rates and increased mid-level moisture could fire-up an
isolated thunderstorm or two over southern areas of the eastern
Sierra that will move off across Mineral County. Another
subsequent upper level disturbance that lifts northeast into OR/WA
will further flatten and nudge the now southwest-northeast
orientated upper ridge axis over western-central NV, thus
depriving the region of moisture for the time being.
The increased west-east zonal upper flow should allow upper short
waves to deepen and sag further south over northern CA/NV with a
follow-up of cooler temperatures into the region. Blended guidance
showing temps in the latter half of the week in the low 90s for
western NV valleys and widespread highs mostly in the high 70s to
low 80s for Sierra locations lends some confidence for this
notion. But large variances in current simulations still inject
uncertainty this far out in the forecast period. -Amanda
&&
.AVIATION...
* Expect VFR conditions for regional terminals with typical late
afternoon/evening breezes today with gusts 15-25 kt. An upper
level trough lifting over the Sierra and western NV later
tonight into Saturday will bring enhanced winds and gusty
conditions to main terminals KCXP-KTVL-KTRK, and northward to
the Oregon border.
* Highest gusts will top into the 25-35 kt range later Saturday
morning through the afternoon before gradually dissipating to less
than 10 kt later that evening. Ridge wind gusts around the Tahoe
Basin will approach 50+ kts late this afternoon and evening with
periods of turbulence below FL150 for Sierra and far western
terminals. General aviation and commercial jet aircraft
climbing/descending into the Reno-Carson City area will see bumpy
conditions through this evening into Saturday morning.
* Smoke and haze from wildfires in the vicinity of Yosemite NP could
bring occasional periods of IFR conditions in VIS/CIG to KMMH
through this forecast period. Conditions could change quickly and
are contingent upon local effects and fire activity. Also expect
some slant-range visibility concerns in haze from same fires
during the morning hours for the eastern Sierra and areas south of
highway 50. Hotter daytime forecast temperatures will top near and
at 100 degrees for lower valleys that may contribute to density
altitude concerns for western NV terminals through the holiday
weekend. -Amanda
&&
.FIRE WEATHER...
The Red Flag Warning remains in effect for much of Saturday in
parts of northeast CA and northwest-far western NV. Winds have
already ramped up across western Lassen County, although the main
push of winds arrives tonight into Saturday. 700 mb flow of 40-50
kt is well above typical values for early September, which will
support gusts greater than 50 mph at times for upper elevations
of northeast CA-northwest NV. Humidity recoveries are expected to
be quite poor overnight, with some thermal belts remaining below
20%. Some of these stronger ridge winds will mix down to lower
elevations Saturday morning with gusts 30-40 mph in the Red Flag
areas, and a sufficient gradient keeps sustained winds of 15-25
mph going through Saturday afternoon-early evening as humidities
drop into the single digits to around 10%. We continue to
anticipate between 5-9 hours of critical fire weather conditions
across the warning areas, where much vegetation has dried up
during the ongoing heat wave.
We have been very fortunate to avoid any large fires in eastern CA
or western NV so far this summer, but conditions are still
hazardous especially with the recent heat. Please be fire safe and
smart this weekend! MJD
&&
.REV WATCHES/WARNINGS/ADVISORIES...
NV...Heat Advisory until 9 PM PDT Tuesday for NVZ001-003>005.
Red Flag Warning from 8 AM to 8 PM PDT Saturday for NVZ420-423-
458.
Lake Wind Advisory from 10 AM to 8 PM PDT Saturday for NVZ004.
CA...Heat Advisory until 9 PM PDT Tuesday for CAZ070-071.
Red Flag Warning from 8 AM to 8 PM PDT Saturday for CAZ270-278.
&&
$$