


Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
894 FXUS66 KLOX 111622 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 922 AM PDT Tue Mar 11 2025 .SYNOPSIS...11/907 AM. A series of storms will bring periods of rain, mountain snow, winds and much colder temperatures through much of the week and possibly into the weekend. The strongest system will move into the area Wednesday night into Thursday morning. && .SHORT TERM (TDY-THU)...11/920 AM. ***UPDATE*** Everything still looking on track for both storms this week and not anticipating any big changes to the forecast. Mostly light showers today, especially south of Pt Conception with rain rates generally under 0.15" per hour, and in a lot of areas under 0.05/hr. As the upper low moves onshore near the US/MX border this afternoon showers will taper off across SB and Ventura Counties but showers will continue across LA County through the evening, then tapering off there by midnight. Storm 2 still on track as well light warm frontal rain Wednesday, followed by much heavier rain with the cold front Wednesday night into early Thursday morning. Peak rain rates of 0.5-0.75"/hr still look good, though some of the latest hi res models are showing very isolated rates as high as 0.85/hr in the foothills and mountains. ***From Previous Discussion*** Storm number 1 is here. The upper low is west of San Diego and is heading to the ESE. An occluded front wrapped well around the low is over SBA/VTA/LA counties and is producing very light rain. AS the low translates to the east it will spin a lobe of PVA up and into LA and VTA counties after dawn. By Afternoon the low will be far enough to the east that the only rain will occur across southern LA county - esp the San Gabriel Vly and the coastal slopes of the San Gabriel mtns. The rain will taper off late in the afternoon. Rainfall totals will be unimpressive for SLO county and western SBA county (less than a tenth or an inch), not much better for southern SBA county and VTA county (less than a quarter inch). LA county, however, will likely recieve between a third and two thirds of an inch of rain with local amounts nearing an inch along the coastal slopes of the San Gabriels. Snow levels will be around 6000 ft and the higher elevations of the San Gabriels could see local 6 inch amounts. Otherwise it will be a cloudy and cool day with max temps tumbling 6 to 12 degrees across VTA and LA counties. SLO and SBA counties will not see as much cooling due to less rain and less clouds since those counties are further from the upper low. Look for most cst/vly max temps to end up in the upper 50s to lower 60s. There will be a little break in the action tonight and most of Wednesday morning as a little pop up ridge separating the two systems moves into the state. Storm 2 will be much more powerful than storm 1. A warm front will develop over the area later in the morning and will continue through the afternoon. Warm frontal rain will concentrate on the coastal slopes and foothills where the extra oomph from the upslope flow will enhance the rainfall. Lighter rain will fall across the flatter csts/vlys and much less rain will fall across the interior. Snow levels will be around 6500 ft, but above these levels a decent amount of snow may fall and a Winter Storm Watch will start in the afternoon for the combination of snow and strong winds. A tightening sfc gradient ahead of the front could produce warning level gusts to 60 mph across the mtns and interior vly of SLO County and a High Wind Watch has been posted there. Max temps will end up near 60 degrees or 8 to 12 degrees blo normal. All eyes on the overnight period. As so often happens, the cold front will move through the area during the overnight hours. The front will bring periods of heavy rain, strong winds and a slight chc of TSTMS. Peak rainfall rates of 0.5 to 0.75 inches look likely just ahead of esp along the front. Isolated rates of 1 inch per hour are possible with any thunderstorms or the south facing coastal slopes. The rainfall total fcst has not changed with 1-2 inches of rain across the flat portions of the csts/vlys and 2-4 inches over the coastal slopes. The only uncertainly left is the strength of the low level jet running ahead of the front. Some solutions show a strong jet which would increase rainfall rates and totals on the coastal slopes and could slow the front progress which would increase the rain totals and really increase the flooding chc. A flash Flood Watch is in effect from Wednesday Evening to through Thursday afternoon. A Winter Storm Watch (4pm Wednesday through noon Friday) is now in effect for the major mountains and includes higher foothills of the Antelope Valley as well. One to two feet of snow is possible above 6500-7000 feet, 6-12 inches between 5500-7000 feet and lighter amounts as low as 3000 feet by Thursday as snow levels crash from 6000-7000 feet to as low as 2500-3500 feet Thursday and Friday mornings. The front will also bring winds of 30-50 mph to the area and many additional wind advisories are likely for non mtn areas. The rain will turn to showers Thursday morning in the wake of the front. Several impulses are forecast to move over the area all of which will trigger renewed shower activity as well as a slight chc of a TSTM. Rainfall rates under these TSTMs could also reach or exceed 1 inch per hour. Max temps will only be in the mid 50s or about 15 degrees blo normal and more of a January system. .LONG TERM (FRI-MON)...11/1217 AM. Confidence is not high for the extended forecast. Fast moving NW flow will bring in a variety of impulses. The ensembles all have differing opinions about the timing and intensity of the impulses. As a result there is some sort of chance of rain in every period of the fcst. The best chances for rain, however, look to be Friday and Monday when there are stronger better defined vort maxes. As usual with NW flow, the Central Coast will have the highest chc of rain. The models are trending drier with the weekend fcst and it is possible that those two days will be dry or at least mostly dry. None of the these systems look too impressive at this time and will likely only produce light rain. It is likely that there will be some warming Fri-Sun. Still, even with the warming, max temps will remain many degrees blo normals. Max temps Friday will continue in the 50s while the weekend temps will climb into the 60s. && .AVIATION...11/1049Z. Around 07Z, there was no marine layer depth at KLAX. Moderate confidence in the current forecast. Lower confidence in flight categories and timing. Ceilings at or below 6000 feet will likely continue through the period with a likely chance of MVFR conditions in rain at terminals south of Point Conception. There is a moderate chance in IFR conditions between 16Z and 23Z. Gusty south to east winds will prevail through much of the period, tapering off at northern sites first and persisting through the period at Ventura and LA County coastal and valley sites. KLAX...There is a 70 percent chance of ceilings at below 6000 feet through the period. Timing of the onset of rain and lower conditions may be off by up to 2 hours. There is a 60 percent chance of MVFR conditions and a 30 percent chance of IFR conditions between 16Z and 23Z. There is a 60 percent chance of easterly winds between 7 and 12 knots with a 30 percent chance of easterly winds between 12 and 18 knots. The highest chances for easterly winds will be 14Z and 20Z. KBUR...There is a 70 percent chance of ceilings at below 6000 feet through the period. Timing of the onset of rain and lower conditions may be off by up to 2 hours. There is a 60 percent chance of MVFR conditions and a 30 percent chance of IFR conditions between 16Z and 23Z. No wind impacts are expected at this time. && .MARINE...11/916 AM. Hazardous sea conditions through Friday. Stay in safe harbor. Wait for the weekend with improved conditions. Very confused seas will through Wednesday or Thursday, with a combo long period northwest to west swell, short period southwest swell, and south to east wind swell/wave. Small Craft Advisory (SCA) east winds common through the day today, focused south of Point Conception, with scattered light showers. Winds will weaken tonight, before ramping back up on Wednesday. A moderate to strong storm system will move through the area Wednesday and Wednesday Night. All areas will see at least a few hours of SCA level south winds on Wednesday. Low-end Gale Force winds possible (40-60% chance) for areas covered by the Gale Watch. Will convert that Watch to either a Gale Warning or SCA with the afternoon forecast release. Rain will be heavy at times, with a chance of thunderstorms and associated hazards like locally strong winds, lightning, and waterspouts. Post-frontal west to northwest winds will quickly form on Thursday, with a 40% chance of reaching Gale Force especially south of Point Conception (including nearshore). Another storm will move through the area on Friday, with another round of gusty south winds and post frontal west to northwest winds. Winds should be weaker than Wednesday/Thursday, but SCA-levels are likely over most waters. && .BEACHES...11/302 AM. There is a moderate to high (30-50 percent) chance of strong rip currents and elevated surf today at beaches south of Point Conception, otherwise no high surf is expected through Wednesday. There is a likely (60-80 percent) chance of high surf developing at all beaches between Wednesday night and Thursday night as a strong storm system originating out of the Gulf of Alaska moves over the region. There is a imminent to definite (80-100 percent) chance of strong rip currents and elevated surf during this period. Surf should diminish at southern beaches between Friday and Saturday, but there is a moderate chance that at least elevated surf could linger next weekend at Central Coast beaches. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Flood Watch in effect from Wednesday evening through Thursday afternoon for zones 87-88-349>352-354>358-362-366>375-378>380-548. (See LAXFFALOX). High Wind Watch in effect from Wednesday afternoon through late Wednesday night for zones 344-345. (See LAXNPWLOX). Winter Storm Watch in effect from Wednesday afternoon through Friday morning for zones 353-376>382. (See LAXWSWLOX). PZ...Gale Watch in effect from Wednesday morning through Wednesday evening for zones 645-670. (See LAXMWWLOX). Small Craft Advisory in effect until 5 PM PDT this afternoon for zones 650-655-673-676. (See LAXMWWLOX). Gale Watch in effect from Wednesday afternoon through Wednesday evening for zone 673. (See LAXMWWLOX). && $$ PUBLIC...MW/Rorke AVIATION...Hall MARINE...Kittell BEACHES...Hall SYNOPSIS...MW/Smith weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox