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
709 FXUS66 KLOX 241700 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 1000 AM PDT Mon Jun 24 2024 .SYNOPSIS...24/224 AM. Dangerously hot weather will continue away from the coast especially over the Antelope Valley. Elsewhere, there will be a gradual cooling trend through the week. There is a slight chance of thunderstorms today over the mountains and SLO county. && .SHORT TERM (TDY-WED)...24/959 AM. ***UPDATE*** We continued to track showers and isolated thunderstorms near the Central Coast, which should move northeast towards interior areas this afternoon to early evening. Main potential impacts are expected to be cloud-to-ground lightning including potential fire starts (dry lightning) and potentially damaging wind gusts of 50+ mph with any stronger thunderstorms. Storms will be moving slow, with any stalled storms potentially leading to flood concerns, focused across the mountains. Challenging temperature forecast today as mid level clouds continue to interrupt the typical marine influence across the region and especially coastal areas. High temperatures should be cooler most areas, especially coastal areas of Ventura and Los Angeles Counties where moderate onshore trends should support an earlier and stronger sea breeze. The cloud cover led to warm overnight lows nearing 80 in some high deserts, which increases heat impacts for those areas, and warrants the continuation of heat products away from the coast, despite slightly cooler daytime highs. With the afternoon forecast package we will continue to watch convective chances over the next day or so and examine the need for heat products over th next couple of days. ***From Previous Discussion*** A lobe of PVA currently south of the Channel Islands is moving from S to N. It has a few embedded showers in it and will bring a slight chc (15 percent) of a shower or TSTM to the Channel Islands, The Santa Barbara Channel and SBA county this morning. Otherwise skies will be partly cloudy as debris clouds float overhead. Only very minimal marine layer clouds today as the clouds and humidity aloft have greatly disrupted the stratus formation. The onshore flow this afternoon will be about 3 mb strong than ydy and this will bring noticeable cooling to the coasts and vlys. 591 dam hgts however will continue to bring the heat to the interior. The vlys will not be warm enough for heat advisories and these were cancelled. A heat warning was added for the Western Antelope Foothills where triple digit heat will occur. One more day of heat advisories for the interior of SLO and SBA counties as there will be little or no change in temps from ydy`s readings. Mid level moisture will combine with afternoon solar induced instability over the mtns to bring a slight chc (20 percent) of TSTMs to the higher peaks of the LA/VTA mtns. This morning`s vort lobe will be over SLO county this afternoon and will also generate the same slight chc of TSTMs. The strong onshore push will likely generate more coastal low clouds tonight but given how disorganized the marine layer is now it will likely take much longer for the clouds to develop. The upper high will shift a little to the SW and this will bring dry SW flow over the area and squash the risk of convection. Most cst/vly locations away from the beaches will cool 2 to 5 degrees and will end up 3 to 6 degrees above normal. The Antelope Vly will continue to sizzle under 593 dam hgts and the heat warning will persist there. An upper will will move through the PAC NW on Wednesday. Weak troffing will move over CA and hgts will drop to 588 dam. Onshore flow will remain strong and there will be more and earlier arriving marine layer stratus. The beaches will see slower clearing. Most areas will cool 2 to 4 degrees which may be enough over the Antelope Vly to end the Heat Warning early. The csts/vlys will cool to near normal while the inland areas will end up 4 to 6 degrees above normal. .LONG TERM (THU-SUN)...24/322 AM. Both the EC and GFS as well as most of their respective ensembles have trended away from their rather dire heat predictions they both had earlier. Now the xtnd fcst looks pretty static. The upper high will migrate to the east while a fairly stationary troffing pattern sits over the west coast. This will keep dry SW flow over the area and eliminate any convective threat. The marine layer will be very shallow and may behave as it has lately with hardly any inland penetration. Max temps will slowly fall through Saturday as hgts fall. By Saturday max temps will be 2 to 4 degrees blo normal. Onshore flow will weaken some on Sunday and this will bring a few degrees of warming to the area. && .AVIATION...24/1646Z. At 16Z over KLAX, the marine layer was 600 feet deep. The top of the inversion was 3500 ft and 24 degrees Celsius. There is a chance of -TSRA today: 20% chance at KSBP 16-19Z, KPRB 17-22Z, KWJF KPMD 20-02Z...10% chance KSBP KPRB 00-04Z. All other sites have a low (5%) but non zero chance. Any thunderstorm will likely produce brief gusty winds and little if any rain. There is a chance of IFR/LIFR conditions tonight into Tuesday: 40% chance at KSMX, 20% chance at KSBP KSBA, 10% chance at KOXR KSMO KLAX KLGB. Otherwise, high confidence in VFR conditions into Tuesday. KLAX...There is a 10% chance of IFR/LIFR conditions after 08Z tonight. There is a 5% chance of -TSRA through early Tuesday, with higher chances over the nearby mountains and deserts. Otherwise, high confidence in VFR conditions. High confidence that any southeast winds will remain under 8 knots. KBUR...There is a 5% chance of -TSRA through early Tuesday, with higher chances over the nearby mountains and deserts. Otherwise, high confidence in VFR conditions. && .MARINE...24/946 AM. The threat of isolated thunderstorms will remain today, and possibly through Tuesday as moisture from the remnants of Tropical Storm Alberto linger over the region. With dry air near the surface, any storm can product brief but very gusty winds. Dense fog with visibilities under one mile will remain a concern, and while the coverage and shrunk a lot, expect some random patches tonight into Tuesday. There is a 30 percent chance of Small Craft Advisory (SCA) level wind gusts tonight and Tuesday Night for the Outer Waters (offshore waters of the Central Coast to San Nicolas Island). Otherwise, high confidence in weaker than usual winds for this time of the year. Northwest winds will increase Wednesday afternoon through Thursday night. High confidence in SCA level winds and steep seas for the Outer Waters. 50 percent chance for SCA winds and seas for the nearshore Central Coast waters, and a 20 percent chance for the western Santa Barbara Channel. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory remains in effect until 8 PM PDT this evening for zones 38-344-345-348-353-379. (See LAXNPWLOX). Excessive Heat Warning in effect until 8 PM PDT this evening for zone 381. (See LAXNPWLOX). Excessive Heat Warning remains in effect until 8 PM PDT Thursday for zones 382-383. (See LAXNPWLOX). PZ...NONE. && $$ PUBLIC...Rorke/RM AVIATION...Kittell MARINE...RK SYNOPSIS...30 weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox