Pomona, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

851
FXUS66 KLOX 151728
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1028 AM PDT Tue Apr 15 2025

.SYNOPSIS...15/849 AM.

Strong onshore flow and a deep marine layer will bring plenty of
night through morning low clouds and fog this week. There will
also be a chance of drizzle each morning. Partly to mostly cloudy
skies will occur Thursday and Friday with a chance of showers and
a slight chance of a thunderstorm with the best chance over the
mountains and far interior. Dry and warmer conditions are
expected for the weekend into early next week.

&&

.SHORT TERM (TDY-THU)...15/859 AM.

***UPDATE***

A 3000 foot marine layer combined with an onshore flow as high as
9mb to the desert will make for a cool, and occasionally damp
weather pattern this week. Hi res models are indicating almost
complete clearing by this afternoon but given the strong inversion
this may be overly optimistic. Regardless, temperatures will be at
least 4-8 degrees below normal and possibly as much as 15 degrees
below normal Wed-Fri as an upper low approaches and chances for
legitimate light rain increase, especially on Thursday.

***From Previous Discussion***

The upper low will move a little closer to the coast on
Wednesday. Moderate onshore flow will remain in place and the
additional lift from the low will keep the marine layer clouds in
place longer. Cooler air will also move into the interior. Look
for 4 to 8 degrees of cooling across the board with max temps for
the csts/vlys only in the 60s or 5 to 10 locally 12 degrees blo
normal.

The 564 dam upper low will move over Srn Ca on Thursday. The
marine layer will be at its deepest. There is a good chance the
cooler air form the upper low will wreak havoc with the marine
inversion. There will likely be a hodge-podge of clouds and in the
afternoon a strata cu layer will likely cook up. Probably the best
way to describe the day is partly to mostly cloudy. There is a
10 percent chc of a mtn shower due to the cool air aloft. The big
news will be the max temps which will cool further. Max temps will
be mostly in the lower to mid 60s (which would actually be below
normal in January!)

A 2 to 30 percent chc of showers with a smaller chc of a TSTM will
develop Thursday evening and overnight as mdls shows an uptick in
instability and dynamics from the upper low.

.LONG TERM (FRI-MON)...15/318 AM.

Friday could be an interesting day. A very cold (550 dam) upper
low will retrograde out of the interior and into NV. This will put
it in a good position to advect plenty of PVA into the area from
the north. There will be a chance of showers and a slight chc of
TSTMs starting in the morning peaking in the afternoon and then
diminishing in the evening. Due to the N to NE flow into the area
the mtns and interior portions will have the best chance of
convective activity but the northerly flow could easily push any
cell out of the mtns and into the vlys or even csts.

Rainfall will be highly variable due to the showery nature of the
system, but a quarter inch seems like a good bet for the high end
total. Snow levels will be in the 6000 to 7000 feet range (locally
lower under convective bursts). The northerly flow pattern will
also provide enough upper level wind support for some advisory
level winds in the mtns. Max temps will rise 2 to 4 degrees as
there will be a little more sunshine but will still end up many
degrees blo normal.

Clearing skies and cold airmass will team up to lower min temps
into the upper 30s and lower 40s for the interior and mid 40s to
lower 50s for the csts/vlys.

Dry NW flow with rising hgts will move in Saturday and persist
into Monday. All of the cold air will have wiped out the marine
inversion so the low clouds will be at a minimum or even non
existent. Sunnier skies and 570 dam hgts will team up to bring
three days of warming (greatest on Saturday) with most max temps
across the csts/vlys in the upper 60s to mid 70s degree range.

&&

.AVIATION...15/1728Z.

At 1652Z at KLAX, the marine layer was 3000 ft deep, with an
inversion top at 4100 ft and a maximum temperature of 12 C.

Moderate to high confidence in TAFs. Timing of cig clearing to
VFR may be off +/- 3 hours, and may not clear at at for some
sites. Cigs may be one category lower than forecast at times.

KLAX...Moderate to high confidence in TAF. There is a 40 percent
chance of cigs scattering out from 20Z Tue to 04Z Wed. No east
wind component is expected.

KBUR...Moderate to high confidence in TAF. There is a 30 percent
chance of no clearing of through today. Cigs may be one category
lower than forecast at times.

&&

.MARINE...15/649 AM.

Overall, high confidence in current forecast as conditions are
expected to remain below Small Craft Advisory (SCA) levels today
through Saturday. There is a 20% chance of SCA level winds around
Point Conception Thursday through Saturday in the afternoon and
evening hours.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...MW/Rorke
AVIATION...Schoenfeld
MARINE...RAT
SYNOPSIS...MW

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox