Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/16/22
Area Forecast Discussion
National Weather Service Denver/Boulder CO
735 PM MDT Mon Aug 15 2022
.UPDATE...
Issued at 735 PM MDT Mon Aug 15 2022
Rain cooled air has spread across the area this evening, helping
to stabilize the airmass. Even though the airmass remains moist,
the threat for heavy rain has ended and the Flood Watch has been
canceled. Rain showers and isolated weak thunderstorms will
remain possible through the evening hours over most of the
forecast area. Adjusted PoPs and temperatures to line up with
current conditions. The airmass will stay moist through the night
and into Tuesday. Models differ quite a bit if rain showers will
persist overnight and into Tuesday morning. Not seeing an obvious
source of lift to produce this rain. Will keep a chance for rain
in the forecast with all the moisture in place and model
uncertainty.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 330 PM MDT Mon Aug 15 2022
Showers and thunderstorms are continuing to develop in the
mountains and foothills at this time. Surface dew points have
mixed down a bit from this morning with 50s F over much of the
CWA. The far northeast still has some 60s F. The Acars soundings
show the upslope up to about 700 mb.
Proggs continue to show ubiquitous precipitable water values,
0.80 to 1.50 inches well past midnight. The QPF fields are loaded
as well. The high resolution models all still show significant
rainfall for the southern 2/3rds of the CWA later this afternoon
and tonight. Will stay the course with heavy rains and flash
flooding during this first period.
For Tuesday, models show a significant decrease in moisture, with
the precipitable water values progged in the 0.4 to 1.00 range
for the CWA. The QPF fields show the measurable rainfall
relegated to the southern half of the CWA and current pops in the
GFE grids show similar. Will stay that course as well.
For temperatures, Tuesday`s highs are are 0-2 C warmer than
today`s highs. Hopefully we can stay away from the 90 degree beast
for another day in Denver.
.LONG TERM...(Tuesday night through Monday)
Issued at 245 PM MDT Mon Aug 15 2022
There will still be some moisture from southeast Colorado into the
central mountains Tuesday evening, so there may still be a few
storms in those areas early in the evening. For Wednesday and
Thursday the plains should be fairly quiet with an inversion
around 600 mb capping convection. We`ll also be relatively dry on
the plains for a while. There will likely still be enough
heat/moisture over the mountains for at least isolated diurnal
convection. For Friday into the weekend there will likely be at
least a gradual increase in moisture and instability. We`ll still
be under the ridge axis, and there are disagreements about the
subtle movement of moisture during this period that would affect
the eastward progress and amount of convection from day to day.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1105 AM MDT Mon Aug 15 2022
Models continue to show the upslope winds at DIA. Will keep a
northeasterly and/or easterly component to the winds into the
early/mid evening hours, before drainage wind patterns kick in
around 06Z. Will leave the TEMPO group in for thunderstorms, and
the heavy rains are possible. Ceilings could be BKN030-045 from
22Z-05Z with the precipitation.
&&
.HYDROLOGY...
Issued at 330 PM MDT Mon Aug 15 2022
There will be a continued threat of flash flooding through this
evening into the overnight hours for much of the forecast area
with ongoing convection and plenty of available atmospheric
moisture. On Tuesday it looks to be significantly drier and the
threat of flash flooding will be very low to non existent.
Just a low level of thunderstorm activity is expected over the
mountains through Thursday, with a very low flood threat. Some
increase in moisture is expected by the weekend.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Meier
SHORT TERM...RJK
LONG TERM....Gimmestad
AVIATION.....RJK
HYDROLOGY....RJK/Gimmestad
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
807 PM PDT Mon Aug 15 2022
.SYNOPSIS...15/210 PM.
Above normal temperatures will continue through most of the
week, peaking Tuesday and Wednesday before slowly cooling the rest
of the week. Skies will be mostly clear except for night through
morning low clouds and fog along the coast, mostly northern areas.
&&
.SHORT TERM (MON-THU)...15/806 PM.
***UPDATE***
Overall, a quiet early evening across the forecast district.
Latest satellite and surface observations indicate clear skies
across the area except for stratus/fog across the immediate
Central Coast. Current AMDAR sounding data indicates marine
inversion 500-700 feet deep. Some lingering onshore breezes, gusts
20-25 MPH, still occurring across interior sections.
For the immediate short term, main challenge will be the marine
layer stratus. For the Central Coast, expect current stratus/fog
to push inland, impacting a good chunk of the coastal plain with
some patchy dense fog (due to the shallow inversion). South of
Point Conception, the potential for stratus/fog decreases
dramatically. The HREF indicates, at "best," a 30-35% chance of
stratus development. So, will anticipate most areas south of Point
Conception to remain stratus-free. However, would not be shocked
to see some stratus/fog impact the Long Beach area late tonight.
Other than the potential stratus issues, conditions will be very
benign overnight.
Current forecast has very good handle on the immediate short term.
So, no significant updates are anticipated at this time.
***From Previous Discussion***
Temperatures continue to run a couple degrees cooler than
yesterday in many areas. The one exception is across interior SLO
County and the Cuyama Valley where temps are up 1-4 degrees. Highs
in that area have been close to heat advisory the last couple days
and with the increase today and not much change Tue/Wed (perhaps
slight cooling Wed), and with warming overnight temps, will go
ahead and issue a heat advisory there for those days. Elsewhere,
above normal temps will continue but mostly be below heat advisory
levels. The warmer western end of the San Fernando Valley gets the
closest but with lows in the low to mid 60s that provides enough
overnight relief to hold off issuing an advisory for now. Cooling
temperatures are expected by Thursday as onshore flow increases
but still above normal.
Thunderstorm chances remain low through the period so the forecast
remains dry. We should still see some cumulus clouds in the
afternoon over the mountains but the better instability and
moisture remains well east of LA County.
Marine layer stratus is starting to make a return south of Pt
Conception and some beaches there may see some patchy low clouds
and fog the next few mornings. The Central Coast will continue to
see periods of dense fog overnight and through the morning, and
lingering into the afternoon at some beaches.
.LONG TERM (FRI-MON)...15/208 PM.
Increasing onshore flow and a slight weakening of the high
pressure aloft are expected to bring a slow cooling trend to the
area by the end of the week with temperatures actually falling
slightly below normal in most areas by Saturday. The only areas
that will still be above normal will the Antelope Valley and parts
of interior SLO County but only by a couple degrees. Otherwise a
fairly quiet pattern. Thunderstorm chances have been removed from
all days except Saturday and even then it`s very marginal as most
of the moisture and instability remains to the east.
&&
.AVIATION...16/0018Z.
At 18Z at KLAX, the marine layer was about 750 ft deep. The top
of the inversion was at 2300 ft with a temperature of 28 deg C.
Moderate confidence in the 00Z Central Coast TAFs due to
uncertainty in low cigs/vsbys. High confidence low cigs/vsbys will
return to KSMX and moderate confidence for KSBP, and timing of low
cigs arrival could differ by +/- 2 hours.
Low confidence the other 00Z coastal TAFs, due to uncertainties
the potential for in low cloud cover overnight. For KOXR and KCMA
there is a 40% chance that no cigs occur, and that VSBY remains
MVFR or higher. For the LA County coastal sites, there is a 30
percent chance cigs occur overnight.
High confidence in VFR conditions for the valley and desert sites.
KLAX...Low to moderate confidence in the 00Z TAF. There is a
30-40 percent chance of IFR cigs between 09Z and 16Z. Any east
wind component will be 5 kt or less.
KBUR...High confidence in CAVU 00Z TAF.
&&
.MARINE...15/741 PM.
Small Craft Advisory (SCA) conditions will continue across the
outer waters through late tonight with gusts to 30 knots common,
and local gusts to 35 knots possible near Point Conception. SCA
conditions are likely (60-80 percent chance) for the outer waters
Thursday and Friday.
For the nearshore waters, SCA conditions may (20-40 percent
chance) impact portions of the inner waters Thursday and Friday,
mainly during the late afternoon through evening hours.
Areas of dense fog are likely to develop north and west of the
Channel Islands tonight into Tuesday morning.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 11 AM Tuesday to 8 PM PDT
Wednesday for zones 344-345. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Tuesday for
zones 670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...MW/Thompson
AVIATION...Smith
MARINE...Smith
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
Area Forecast Discussion
National Weather Service Phoenix AZ
410 PM MST Mon Aug 15 2022
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
The first part of this week will see temperatures climb back to or
even slightly above normal, while daily showers and thunderstorms
become fairly isolated. Starting Thursday, ample monsoonal moisture
will return to the region leading to much better chances for showers
and thunderstorms, persisting through next weekend. Temperatures are
also forecast to cool to below normal with highs across the lower
deserts falling into the nineties.
&&
.DISCUSSION...
Latest water vapor imagery reveals a trough lifting northward
through northern Arizona. In its wake, drier air aloft continues to
overspread the lower deserts. However, conditions remain moist at
the surface with dewpoints widespread in the mid 60s.
Latest ACARS soundings indicate weak mid-level lapse rates near KPHX
associated with the overturning from last night’s convection. This
is depicted well in the HREF, which suggests the higher values of
CAPE will be situated further west in southeastern California.
Convection will be most favored in these areas as well as across
portions of southern Gila County, where natural convergence remains
prevalent across the higher terrain. However, given the subsidence
behind the trough, only isolated activity is anticipated.
Latest HREF suggests low probabilities of strong winds and any
storms that develop are generally not expected to be severe. ACARS
soundings also indicate weak, southerly steering flow, which may
lend itself to slow moving cells and the potential for localized
flash flooding with the strongest storms. CAMs remain in good
agreement little change is expected for Tuesday, where the 1000-500
mb layer dries out further and isolated convection will generally
remain relegated to eastern Arizona.
&&
.PREVIOUS DISCUSSION...
For the latter half of the week into the weekend, forecast attention
then turns toward a tropical disturbance currently situated across
far southern Texas. Both the GEFS and EPS show this disturbance
slowly tracking west northwest across northern Mexico over the next
couple days, likely becoming an inverted trough over southern
Arizona as early as late Wednesday. NBM PoPs have also increased to
around 50% across southeast and south- central Arizona Wednesday
evening into Wednesday night as a moisture surges northwestward into
southern Arizona. Overall potential impacts for late Wednesday look
fairly minor as the activity is likely to be elevated, but some
heavy rainfall and localized flooding could be possible.
For Thursday through the upcoming weekend, there is a decent amount
of spread within ensemble guidance, but there is at least some
potential for significant impacts. Ensembles agree there will be a
strong influx of tropical moisture Thursday into Friday across
southern Arizona and southeast California with PWATs likely
exceeding 2", with the disturbance very likely stalling out across
Sonora Mexico. Additionally, models show an upper level trough
developing off the California coast over the next couple days before
slowly moving into the Great Basin region later this week. This
trough will likely provide stronger westerly winds aloft later this
week and larger scale forced ascent over much of our region. The
potential scenario of having plentiful moisture and a much more
favorable wind profile (upper level westerly winds and northeasterly
mid level winds) could give rise to multiple days of fairly
widespread showers and thunderstorms later this week.
As of now, the NBM is favoring Friday and Saturday as having the
highest potential of widespread showers and thunderstorms, focused
more across southeast and south-central Arizona. WPC QPF is also
quite impressive with a large area of 1-2" over the aforementioned
areas from Thursday evening through Saturday night. Looking at the
00Z Euro ensemble Extreme Forecast Index (EFI), it is pointing
toward the potential for a significant rainfall event late Friday
and Saturday. Given this is several days out, uncertainty in
potential rainfall amounts and timing is still fairly high, but
forecast confidence is increasing that some areas will see heavy
rainfall and likely some form of flooding. The threat for strong to
damaging winds could also be present at some point later this week
as models are at least showing some potential for stronger mid level
easterly winds which in the past have led to organized MCSs coming
off the high terrain into the lower deserts. Be prepared for a
potentially active weather period later this week.
&&
.AVIATION...Updated 2310Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Very little chance of weather impacts will exist through Tuesday
evening as thunderstorm activity remains far removed from terminal
locations. Even distant traveling outflow boundaries are unlikely
today and tomorrow with probabilities under 20-30%. Confidence is
only moderate in exact timing of diurnal wind shifts, and periods of
variability may be common. Overall, wind speeds should remain under
10kt.
Southeast California/Southwest Arizona including KIPL and KBLH:
No weather impacts should occur through Tuesday evening with just a
few passing mid/high clouds. Light SE winds will be favored through
the period though extended periods of variable directions are
possible during early morning hours.
&&
.FIRE WEATHER...
There will be an overall decrease in shower and thunderstorm
activity through at least Tuesday, but minimal chances will persist
and humidities will remain fairly elevated. Overall, the fire danger
threat will remain low this week. Afternoon minimum RH values will
dip slightly to 25-30% for Tuesday and Wednesday, but then climb
back upward later this week as even higher moisture levels return
and temperatures cool off. Chances for wetting rains through
Wednesday will mostly be lower than 10%, but climb dramatically late
this week as shower and thunderstorm chances climb to above 50% over
much of the area from an anticipated weather disturbance. Winds for
the most part will remain light, with the exception of any
thunderstorm outflows generating stronger gusts.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman