Flint, California Weather Forecast Discussion

329
FXUS66 KLOX 211817
AFDLOX
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1117 AM PDT Sun Sep 21 2025
UPDATED AVIATION AND MARINE SECTIONS
.SYNOPSIS...21/831 AM.
Monsoonal moisture will begin to move north again today. There is
a slight chance of thunderstorms over the coastal waters near
Catalina Island this morning and in the mountains this afternoon.
The chance of showers and thunderstorms will expand to all areas
Monday night into Tuesday when the monsoon reaches its peak. This
may continue into Wednesday before the monsoon weakens.
&&
.SHORT TERM (TDY-TUE)...21/846 AM.
***UPDATE***
A narrow line of convection has developed along the northern
periphery of a band of moisture coming up from south of the
border. The line is currently headed straight for Catalina Island
and should arrive around 10am give or take. The CAMs are
indicating a significant weakening in the line as it approaches
the mainland between LAX and Long Beach and this is common for
morning convective over the coastal waters to weaken by afternoon
so for now the forecast for southern LA County is just for some
virga or light showers.
The rest of the forecast is on track. There is a slight chance of
a shower or storm over the LA/Ventura Mountains this afternoon,
otherwise little change in temperatures from yesterday which were
more or less near normal for this time of year.
***From Previous Discussion***
There will be a little break in the convective chances on Monday
as today`s moisture exits the area and Tuesday`s remains too far
offshore. There is a small chance of an isolated shower or TSTM
over the northern VTA county mtns in the afternoon. Otherwise the
day will start off with some coastal low clouds in the morning but
will otherwise be sunny. Max temps will cool some as hgts fall
from an approaching low.
There is good mdl agreement that an upper low will slide southward
and end up to the SW of Pt Conception. The Central Coast will be
under increase difluent flow and just enough moisture advection to
create a slight chc of nocturnal TSTMs. The low will also usher
in enough clouds to make it a mostly cloudy night.
The upper low will bring enough clouds to the area Tuesday to make
it a mostly cloudy one. And while not as moist as last week`s
system it will still raise PWs to about 1.25 inches. There is no
real focus to the system so there will be just moisture and weak
instability. This equates to a 20 to 30 percent chc of a shower or
TSTM just about anywhere across the area. At this time it does not
look like there is that much of chance for high rainfall totals or
rates. All of the cloud cover should lower max temps by 2 or 3
degrees.
.LONG TERM (WED-SAT)...21/306 AM.
Mdls are in decent agreement that the upper low will swing to the
NE and will approach Pt Conception. Tuesday night and Wednesday
look like they will have the best chc of rain as the best
moisture, lift and instability move over the area. Still there is
not that much moisture to work with so the threat of heavy rain is
limited. The clouds and lower hgts will bring 2 to 4 degrees of
cooling to the area.
The upper low is fcst to wonder around Srn CA, western AZ and nrn
Mexico through the rest of the period. At this point it does not
look like it will have much effect on the weather. There will be a
slight chc of an isolated mtn TSTM on Thursday afternoon. Max
temps will not change much and will remain blo normal.
&&
.AVIATION...21/1758Z.
At 1732Z at KLAX, the marine layer was 1200 ft deep. The top of
the inversion was at 3200 feet with a temperature of 21 C.
High confidence in VFR TAFs for KPRB, KPMD, & KWJF.
Moderate confidence in TAFs for KSBP, KSMX, KBUR, and KVNY.
Timing of arrival of cigs at KSBP and KSMX may be off +/- 2 hours
and minimum flight cats may be off by one. For KBUR and KVNY,
there is a 15% chance for LIFR to IFR conds between 10Z and 17Z.
Low confidence in remaining coastal TAFs. There is a 20-40% chance
for no low clouds, highest at KSBA. Otherwise, timing of arrival
may be off +/- 3 hours and minimum flight cat may be off by one
cat. There is a 30% chance for -SHRA at through at least 02Z at
KSMO, KLAX, and KLGB, with latest chances for KLGB. There is also
a 10-20% chance for -TSRA during this time frame, highest at KLGB.
KLAX...Low confidence in TAF. There is a 15% chance for -TSRA 19Z
through 01Z. Timing of flight category changes could be +/- 3
hours and minimum cig height could be off +/- 200 feet. No
significant east wind component is expected.
KBUR...Moderate confidence in TAF. 15% chance for LIFR to IFR
conds between 10Z and 17Z.
&&
.MARINE...21/1116 AM.
Moderate confidence in conditions remaining below Small Craft
Advisory (SCA) levels across the coastal waters through Thursday,
with localized NW gusts of 20-25 knots each afternoon and evening
across typically windier portions of the Outer Waters, including
far northwestern portions and from Point Conception to San
Nicolas Island. Localized NW to W wind gusts 20-25 knots across
portions of the Southern California Bight are possible Wednesday
and Thursday in the afternoons. Conditions are expected to remain
relatively benign along the Central Coast through Thursday.
Moisture streaming in from the south will bring the potential for
thunderstorms to the coastal waters from San Nicolas Island to
Point Dume and south through the coastal waters adjacent to Los
Angeles and Orange Counties through this evening. Any thunderstorm
that forms will be capable of producing locally gale force winds
and rough seas, dangerous lightning, heavy rainfall with reduced
visibility, and waterspouts. More widespread coverage of showers
and thunderstorms is expected Monday night into Wednesday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until noon PDT today for zone
      676. (See LAXMWWLOX).
&&
$$
PUBLIC...MW/Rorke
AVIATION...Lewis
MARINE...Lewis
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox

NWS LOX Office Area Forecast Discussion