Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/31/23
Area Forecast Discussion
National Weather Service Indianapolis IN
1033 PM EDT Tue May 30 2023
.Forecast Update...
Issued at 1033 PM EDT Tue May 30 2023
Showers from this afternoon have now completely dispersed across
central Indiana with only a few clouds remaining. Only changes
needed to the forecast were to adjust hourly temperatures down
slightly to reflect current conditions but overnight low still looks
to be in the mid 60s. Quiet conditions with southeasterly flow are
in store overnight.
&&
.Short Term...(This evening through Wednesday)
Issued at 250 PM EDT Tue May 30 2023
Rest of Today.
Latest ACARs soundings are showing the PBL has deepened to around
3500ft with no cap above the mixing layer which is allowing for the
cu field to become more agitated. Will have to keep an eye on
vertical growth of the field for any potential showers and storms
into the later afternoon and evening hours. SB CAPE is now
approaching 1000 J/kg, but the LFC is pretty shallow with poor
lapse rates above 600mb. Current thoughts are that at least a few
showers by 4-5PM. Any shower will quickly dissipate after sunset
with the loss of diurnal heating.
Tonight.
Quiet conditions are expected during the overnight hours with the
diurnally driven cu field rapidly dissipating leaving only any
potential residual convective debris assuming showers and storms end
up developing. If conditions remain dry, skies will be clear. The
slightly stronger daytime winds will also weaken to near calm with
the loss of mixing. Dewpoints are running about 10 degrees higher
than yesterday which will keep conditions more mild through the
overnight hours with lows in the mid 60s expected.
Wednesday.
Wednesday will begin similar to today with a rapid warm up and a
quickly developing cu field. Shower and thunderstorm coverage is
expected to be slightly higher on Wednesday with weaker subsidence
above the PBL and slightly more favorable lapse rates in the mid
levels which will lead to better instability. Any residual outflow
boundaries from showers and storms today would also create localized
areas of increased lift and would be the focus points for initial
convection tomorrow. Highs should again rise into the mid to upper
80s with a few 90s likely in spots. Storm coverage will then lessen
towards sunset.
&&
.Long Term...(Wednesday night through Tuesday)
Issued at 250 PM EDT Tue May 30 2023
Wednesday Night Through Thursday...
Hot and mostly dry conditions are expected through much of the
period as upper ridging remains across the central and eastern
CONUS. Highs will generally be in the upper 80s to low 90s which is
around 10-15F above normal. Large-scale subsidence will keep most of
central Indiana dry, but remnant low-level moisture and daytime
heating may produce isolated showers and storms Thursday afternoon.
Forecast soundings show steep low-level lapse rates, modest
instability, and some low level moisture which supports the slight
chance for precipitation. Any convection that develops would be
short-lived/disorganized due to very weak deep-layer shear.
Thursday night Through Tuesday...
The upper ridge will begin to retrograde westward late in the week.
This will help advect a drier airmass into the area. Lower dewpoints
in the upper 40s to mid 50s should promote more efficient daytime
heating and limit the potential for diurnal convection. Expect highs
in the low 90s with a few spots potentially warming into the mid
90s. Flow aloft remains weak and with the stagnant airmass in place,
air quality concerns will continue into the weekend. Afternoon RH
values are expected to fall below 30 percent, but the fire threat
will be limited due to relatively weak winds.
Ensemble guidance suggest the upper ridge will continue to
retrograde, allowing a deepening trough across the northeast CONUS
to push a cold front towards central Indiana at the end of the
period. A lack of better moisture return ahead of the front will
limit precipitation, but a relief in temperatures is possible.
&&
.Aviation...(00Z TAF Issuance)
Issued at 751 PM EDT Tue May 30 2023
Impacts:
* Isolated showers continuing in the first hour of period and
possible again tomorrow afternoon
Discussion:
A diurnally driven cu field will diminish over the first few hours
of the period with isolated showers and potentially a stray
thunderstorm near BMG in the first hour. Tomorrow will be
essentially the same as today with afternoon showers and storms
possible, but chances and coverage is a little higher than was seen
today. Will likely need to introduce TSRA or VCTS in subsequent TAF
issuances, but confidence was not high enough to mention more than
afternoon VCSH for now. Winds will generally be southeasterly at 5-
10 kts with brief periods up to 15 kts tomorrow afternoon.
Conditions will remain VFR outside of any convection.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...KH
Short Term...White
Long Term...Melo
Aviation...KH
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
750 PM PDT Tue May 30 2023
.SYNOPSIS...30/621 PM.
A broad area of low pressure over the West Coast will maintain
strong onshore flow, along with a persistent and deep marine
layer through Thursday. Night through morning low clouds and fog
with limited afternoon clearing will continue through much of the
week. There will be areas of drizzle or light rain possible again
late tonight and Wednesday morning. Temperatures will be below
normal through Thursday then a warming trend is expected Friday
and Saturday.
&&
.SHORT TERM (TUE-FRI)...30/747 PM.
***UPDATE***
A closed upper low moving over Southwest to southern California
today helped to produce some showers over the mountains this
afternoon, with a large thunderstorm over the Ventura Mountains
near Lockwood Valley. A Flash Flood Warning was issued due to this
nearly stationary thunderstorm producing heavy rain over the area.
All storm activity has ended as of 700 pm.
Otherwise, a disorganized cloud pattern can be seen on satellite
imagery over the area. A very deep marine layer remains in place,
and is expected to persist overnight into Wednesday morning,
likely extending well inland across the coastal slopes. There is
a possibility of patchy drizzle over Ventura and LA Counties as
the layer is lifted over the terrain.
For Wednesday, only partial clearing is likely due to the deep
marine layer, especially near the coast. Highs will be in the 60s
to low 70s west of the mountains, and in the mid to upper 70s
further east. Shower chances are non-zero, but under 15 percent.
***From Previous Discussion***
A rather muddled cloud pattern exists across the region today as
a deep marine layer depth remains in place. The latest AMDAR
soundings indicate a marine layer depth near 5200 feet deep with a
weak marine inversion. The trough has done its job cooling the
top of the marine intrusion and mixing out the low clouds in some
areas. The weak inversion in place across the area will likely
make for some uncertainty overnight tonight and into Wednesday
morning as far as cloud formation.
There is some concern that light rain or showers could develop
late tonight into Wednesday morning. NAM BUFR time height sections
indicate measurable rain at many terminals across southern
California. PoPs have been nudged higher across the Southland as
multi-model high resolution ensemble members suggest higher
chances of rain across the South Bay and Los Angeles Harbor areas,
and up into the coastal slopes of the Los Angeles and Ventura
County mountains. EPS ensembles suggest a mix of members at KLGB
with higher chances of a few hundredths of drizzle or light rain
farther to the north. For now, mentions of drizzle have been added
to the forecast, but future shifts will need to take a closer
look at this.
A bit better clearing is possible across the area on Wednesday in
the wake of the trough, but ridging aloft nosing into central
California on Wednesday afternoon should start to tighten the
marine inversion again. As a result, a cooler and gloomy pattern
will resume again through Thursday. Clouds will likely to struggle
to clear on Thursday.
.LONG TERM (SAT-TUE)...30/304 PM.
The latest ensemble members suggest a steady warming trend for
late week and through next week. EPS ensemble solutions keep a
persistent marine layer depth in place in the cloud coverage
field, but the marine layer depth will thin, especially over the
weekend. Temperatures will get close to normal in most areas by
Saturday, and possibly warm above normal in the mountains and the
Antelope Valley.
Southwest flow aloft should develop early next week as an upper-
level low pressure will approach the West Coast. EPS ensemble
members suggest cooler weather developing with a deeper marine
layer. Night through morning low clouds will likely struggle to
clear away from the land mass each day for the early portion of
next week.
&&
.AVIATION...31/0119Z.
At 0016Z, the marine inversion at KLAX was based at 4800 feet.
The top of the inversion was 6300 feet with a temperature of 7
degrees Celsius.
Overall, moderate confidence in the 00Z TAF package. For the
overnight period, there is a 60 percent chance of high MVFR CIGs,
but there is a 40-50% chance that CIGs could remain at VFR levels
overnight. Earlier clearing is likely Wednesday afternoon,
especially along the coast.
KLAX...Moderate confidence in the 00Z TAF. There is a 40% chance
that CIGs will remain at VFR levels. No significant easterly wind
component is expected.
KBUR...Moderate confidence in the 00Z TAF. There is a 40% chance
that CIGs will remain at VFR levels.
&&
.MARINE...30/735 PM.
For the Outer Waters, moderate to high confidence in current
forecast. Tonight through Wednesday morning, high confidence in
winds and seas remaining below Small Craft Advisory (SCA) levels.
From Wednesday afternoon through Friday, there is a 60-80% chance
of SCA level winds and seas. For Saturday and Sunday, there is a
30-50% chance of SCA level winds.
For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Tonight through tonight, high
confidence in winds and seas remaining below SCA levels. For
Wednesday through Friday, there is a 50-70% chance of SCA level
winds in the afternoon and evening hours. For Saturday and Sunday,
high confidence in winds and seas remaining below SCA levels.
For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. Tonight through Sunday, high
confidence in winds and seas remaining below SCA levels for a
majority of the southern Inner Waters. The only exception will be
the western half of the Santa Barbara Channel, where there is a
40-50% chance of SCA level winds during the afternoon and evening
hours on Wednesday and Thursday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 3 PM Wednesday to 3 AM
PDT Thursday for zones 670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...Hall/Smith
AVIATION...Smith
MARINE...RAT/Lund
SYNOPSIS...Hall/Smith
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox