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
117 FXUS66 KLOX 131818 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 1118 AM PDT Mon May 13 2024 .SYNOPSIS...12/837 PM. Quiet weather will continue the next several days with near to slightly below normal temperatures. Widespread night and morning low clouds are expected across coast and valleys as onshore flow increases. Temperatures will cool slightly through Wednesday, then warm slightly the end of the week. Gusty winds are likely across the mountains and Antelope Valley each afternoon. && .SHORT TERM (TDY-WED)...13/808 AM. ***UPDATE*** Latest satellite and surface observations indicate widespread stratus west of the mountains (and the Salinas River Valley) and clear skies elsewhere. Morning sounding data indicates marine inversion ranging in depth from 1400 feet north of Point Conception to around 2400 feet south of Point Conception. Forecast-wise for the immediate short term, classic "May Gray" will be the story. With moderate onshore gradients forecast through the day, stratus will gradually clear to the immediate coastal plain this afternoon with a quick return this evening. Otherwise, skies should be mostly sunny with just some scattered high clouds. The onshore gradients will produce some gusty winds this afternoon across interior sections, including the Antelope Valley, but speeds will remain below advisory levels. As for temperatures, morning TEMP STUDY data indicates today should be a few degrees cooler all areas with cooler boundary layer and greater marine influence. Current forecast has good handle on the immediate short term. So, no significant updates are anticipated. For the afternoon forecast suite, focus will be on a continuation of the "May Gray" theme for the area. ***From Previous Discussion*** A high hgt (574 dam) upper low will slowly transit over the area from the NW to SW over the next three days. There will be strong onshore flow from the west and moderate onshore flow from the south. The spectral mdls (GFS and EC) show an increasing trend in the onshore push to the east but now the NAM show little day to day change. So the May Grey will continue through the short term (sneak peak - through the long term too) Look for early to arrive and late to leave low clouds every day. Just like the last few days some coastal areas will see no clearing at all (esp from Malibu and points north) Max temps will not change much from day to day. Look for mid 60s to lower 70s across the coasts and 70s through the vly. The inland areas will be much warmer with max temps in the 80s. (A switch to SE flow will make Paso Robles the temp outlier with a 10 degree drop likely today). As it has been for the last few day the csts/vly will be 3 to 6 degrees blo normal and the inland areas will wind up 3 to 6 degrees above normals. Like ydy there will be some mtn cloud build ups in the afternoon but only a 5 to 10 percent chc of an TSTM developing as the upper low nears the area. There 8 mb onshore push in the afternoon will bring stronger than normal seabreezes and gusty winds (30 to 40 mph gusts) across the interior, especially the Antelope Valley. If the 10 mb onshore push advertised by the GFS pans out there will be advisory level (45 mph) gusts across the western Antelope vly and foothills Wednesday afternoon. .LONG TERM (THU-SUN)...13/308 AM. Deterministic mdls are in good agreement with the ensemble means and have good confidence in the xtnd forecast. Look for a week ridge to move in on Thu and Fri. The ridge will push to the east Saturday and an upper low will encroach on the area. Mdl agreement falls off on Sunday but there will likely be some sort of low pressure near the area. The night through morning low cloud pattern will continue unabated through the period. There maybe slightly better clearing on Thu and Fri and then slower to no clearing on Saturday. The troffing on Sunday may provide enough lift for some drizzle in the morning. Higher pressure and better clearing on Thu/Fri may lead to a few degrees of warming while the weekend will likely end up a few degrees cooler. && .AVIATION...13/1813Z. At 1737Z at KLAX, the marine layer was 2200 feet deep. The top of the inversion was around 3200 feet with a max temp of 17 C. High confidence in desert TAFs. Moderate confidence in all other TAFs. Flight cat change timing could be off by +/- 2 hours and cig hgt could be off by +/- 200 ft. KLAX...Moderate confidence in TAF. There is a 25 percent chc of BKN025 conds 20Z-01Z. Good confidence that any east wind component will be under 5kt. KBUR...Moderate confidence in TAF. Cigs will likely clearing between 19-21Z. Cigs will have a 70% chance of returning between 04 and 06Z tonight. && .MARINE...13/744 AM. Moderate to high confidence in the current forecast. For southern outer waters, there is a 50% chance of Small Craft Advisory (SCA) winds developing this afternoon or evening and lasting into tonight, and a 30-50% chance of returning again late Tuesday and Wednesday. There is a 10-20 percent chance of SCA conditions for the western third of the Santa Barbara Channel during this time. There is a 10-20 percent chance of SCA conditions across the southern inner waters including nearshore LA and Ventura County Wednesday afternoon and evening. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Tuesday for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...Rorke AVIATION...Schoenfeld MARINE...Munroe/Schoenfeld SYNOPSIS...MW weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox