Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000 FXUS66 KLOX 101813 AFDLOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 1013 AM PST Sat Dec 10 2016 Updated Aviation Discussion .SYNOPSIS... A chance of light rain will continue through Sunday morning, with the best chance of rain on the Central Coast. Dry weather is expected Sunday afternoon and Monday. Rain could return to the Central Coast by Tuesday, then possibly the entire area late next week as a stronger low pressure system develops. Near or slightly below normal temperatures are expected through next week. && .SHORT TERM...(TDY-MON) Low clouds and fog with patchy dense fog was noted over the coast and vlys of swrn CA this morning. These low clouds are forecast to gradually dissipate thru the morning hours. Otherwise, partly to mostly cloudy skies will prevail across the forecast area thru the afternoon as some moisture at lower to mid levels continues to stream in from the w. A slight chance to chance of showers can also be expected over SLO/SBA Counties thru the day, altho the best chance of showers will be toward the Monterey County border. Some gusty nw winds can be expected over higher terrain and in the Antelope Valley today as well. Temps across the region are expected to be several degrees below normal for the coast and vlys, and several degrees above normal for the mtns and deserts. Highs should reach only into the mid to upper 60s in the warmest vlys and coastal areas this afternoon. A flat upper level ridge will linger over srn CA today. A weak impulse will lower 500 mb heights tonight from around 580 dm to 575 dm or so, with little change expected Sun thru Mon as a broad wnw flow aloft persists. A weak surface cold front is forecast to sag south from central CA into SLO/SBA Counties tonight then dissipate as it moves further s on Sun. This front will bring cloudiness and widespread light rain to SLO/SBA Counties tonight then taper off to scattered showers by Sun morning. There will also be a chance of rain mainly on the n mtn slopes of VTU/L.A. Counties during the period. This front will be accompanied with nw flow thru the lower levels which should limit the rain from moving s of the mtns over VTU/L.A. Counties, altho there should still be a slight chance of pcpn for the coast and vlys later tonight into Sun morning. Rainfall will be light over the region tonight thru Sun morning, with about 0.05 to 0.15 inch expected for SLO/SBA Counties and the n mtn slopes of VTU/L.A. Counties, except up to 0.25 inch cannot be ruled out in far nwrn SLO County. Elsewhere over VTU/L.A. Counties, 0.05 inch or less can be expected, with many locations probably not receiving any pcpn at all. Lingering moisture at mid and upper levels will continue to move in from the w Sun afternoon thru Mon which should keep partly cloudy skies as a whole over the area. However, the 12Z NAM was indicating plenty of moisture below 2000 ft with a weak eddy Sun night into Mon morning s of Point Conception, with low clouds and fog possible for the coast and vlys of VTU/L.A. Counties. Temps on Sun are forecast to remain several degrees below normal for the coast and vlys and a few degrees above normal for the mtns and Antelope Vly. Temps should warm slightly overall on Mon, with highs near normal to slightly below normal for the coast and vlys, and 4 to 8 deg above normal in the mtns and deserts. Highs in the warmest vlys and coastal areas should reach the mid to upper 60s on Sun, and mid 60s to around 70 for Mon. ***FROM PREVIOUS DISCUSSION*** .LONG TERM...(TUE-FRI) Overall, 00Z models continue to exhibit decent synoptic agreement through the period. At upper levels, near zonal flow will continue through Wednesday, then a trough will move across the area Thursday and Friday. Near the surface, weak onshore flow will prevail through Wednesday with stronger flow developing on Thursday and Friday. Forecast-wise, Tuesday and Wednesday will be partly to mostly cloudy days. There will br the threat of some light rain north of Point Conception as the tail end of a northern California system clips the area. Rainfall amounts, if any, will be light. On Thursday and Friday, a more significant system is forecast to impact the area. The models exhibit some differences in timing (ECMWF faster than GFS), but there is a good chance of decent rainfall sometime Thursday through Friday. && .AVIATION...10/1800Z. At 11Z at KLAX, the marine layer was 1700 ft deep (base temp of 11C) with an inversion to 5000 feet (temp of 15C). Moderate confidence of 015-25 CIGS common 20-03Z at most coastal airports (except KSBA)...with high clouds VFR elsewhere. Moderate confidence of CIGS 005-015 common at all airports (except KPMD KWJF) after 06Z tonight. Low confidence on timing of CIG arrivals. High confidence of periods of -RA/RA after 00Z at KPRB KSBP KSMX, with a 30 percent chance of occasional LIFR. 30 percent chance of occasional -RA and briefly lowered CIG/VIS elsewhere after 03Z. Periods of -DZ more likely. KLAX...60 percent chance of occasional SCT decks 20-02Z, but low confidence in timing. Moderate confidence in CIGS around 012 arriving by 02-05Z tonight, with a 30 percent chance for CIGS under 010 after 06Z. 30 percent chance of -RA/-DZ after 09Z. KBUR...Moderate confidence in VFR conditions and high clouds through 03Z. Moderate confidence in CIGS around 008 arriving by 02-06Z tonight, with a 30 percent chance for CIGS under 005 after 06Z. 30 percent chance of -RA/-DZ after 09Z. && .MARINE...10/800 AM. Moderate to high confidence that gusty w to nw winds (around 25 KT) and/or short period steep seas (4-6 feet at 6-8 seconds) will reach the lower end of Small Craft Advisory (SCA) levels across the southern two thirds of the outer waters, and at least western portions of the southern inner waters (Santa Barbara Channel and Santa Monica Basin) later today through tonight. Winds should decrease some late tonight, but SCA NW winds are likely across the outer waters Sunday afternoon and night. Winds could get close to advisory levels nearshore on the Central Coast as well, and over the western portions of the SBA channel. Choppy short-period seas will likely continue everywhere through at least Monday, but should be smaller than tonight. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PST Sunday for zones 650-676. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PST Sunday for zones 655-673. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK...(MON-FRI) There is the potential for widespread rains and gusty winds later next week. Still considerable uncertainty in timing and amounts from this storm, but most likely impacting the area sometime between Thursday and Friday. There is the potential for a cold and unsettled pattern lingering into next weekend, with a threat of rain showers and mountain snow. && $$ PUBLIC...Sirard/RAT AVIATION...Kittell MARINE...DB/Kittell SYNOPSIS...Sukup weather.gov/losangeles

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