30/523 PM.
Santa Ana winds will continue tonight and Wednesday under mostly cloudy skies. A storm system will move into the area from the south Wednesday with periods of rain through at least Saturday, heaviest Wednesday night into New Years Day.
(tdy-Fri), 30/125 PM.
Overall, 12Z models in good synoptic agreement through the short term period. At upper levels, low well southwest of Point Conception will move northeast towards the coast, moving inland across the Central Coast on Thursday then eastward on Friday. Near the surface, offshore flow will weak through Wednesday with southeasterly flow developing Thursday/Friday. With this pattern, a wet New Years Eve and New Years Day remains in the cards for Southwestern California.
RAIN: Light rain will gradually increase across the area tonight and Wednesday. The peak of the rainfall in the short term will be Wednesday night through Thursday afternoon with a lingering shower threat Thursday night and Friday.
Totals through New Years Day will generally range from 0.75 to 2.50 inches across coastal and valley areas with 2.00-5.50 inches across the foothills and mountains. An additional 0.10-0.50 is likely on Friday with the lingering shower threat.
Rainfall rates, generally, are expected to be in the 0.25 to 0.50 inch per hour range. However, there will be localized higher rates, in the 0.50-1.00 inch per hour range, Wednesday night and Thursday associated with heavier pockets of rain and potential thunderstorms.
SNOW: Snow levels through New Years Day are expected to remain above 8500 feet then drop to around 7500 feet on Friday. So, do not anticipated any significant winter weather issues through Friday.
THUNDERSTORMS: As the heaviest rain moves across the area Wednesday night and Thursday, there will be some enhanced instability. So, have included a chance of thunderstorms into the forecast Wednesday night through Thursday afternoon. At this time, the threat of any severe thunderstorms looks to be minimal. Will continue to monitor the situation closely.
WIND: Santa Ana winds have peaked this morning and have begun to diminish early this afternoon. Tonight through Wednesday, high resolution models decrease the gradient by about half from the peak this morning and decrease the upper level support. So, any advisory-level winds are likely to remain localized. So, will most likely allow the WIND ADVISORIES to expire at 300 PM this afternoon.
For Wednesday night and Thursday, there will be some gusty southeasterly winds is association with the systems. However at this time, any advisory-level winds look to remain localized.
IMPACTS: Given the expected rainfall totals and rainfall rates, there is concern for significant hydrologic issues from southern Santa Barbara county southward. Therefore, a FLOOD WATCH is in effect from 1000 PM Wednesday through 1000 PM Thursday (see LAXFFALOX for details).
There will be an enhanced risk of rockslides and mudslides across canyon roadways. Widespread urban flooding is likely along with debris flows in and around the recent burn scars. Strong flows will be likely in local waterways.
(Sat-Tue), 30/125 PM.
For the extended, 12Z models continue to exhibit decent synoptic agreement. The overall message will be a continued wet pattern across the area through Tuesday.
Models differ somewhat in the timing of things, but a series of impulses will move across the area through the extended period. At this time, the two best shots of rain will be on Saturday then again on Tuesday, but rain will be possible through the entire period. With either system, light to moderate amounts of additional rainfall are likely. Snow levels on Saturday will be above 7500 feet, but will drop into the 6000-7000 foot range Sunday through Tuesday. So, some accumulating snowfall will be likely at the higher elevations into early next week.
31/0121z.
At 2315Z at KLAX, there was a shallow surface inversion to 600 feet. The top of the inversion was near 1500 feet with a temperature of 22 degrees C.
Moderate confidence in TAFs. N to NE winds will continue to impact KOXR and KCMA through the period. Then expecting SE winds to develop at the terminals near/north of KSBA after 31/21Z to 01/00Z. VFR CIGs expected through 31/18Z, then lower confidence in forecast of IFR conds between 31/18Z-01/00Z
Isolated -SHRA are possible tonight, then rain chances increase after 31/12Z. The most intense rain will fall sometime between 01/06Z and 03Z/00Z, heaviest south of Point Conception. Slight chance for -TSRA after 01/06Z, especially south of Pt. Conception.
Light to moderate turbulence and LLWS is likely over and near mountainous terrain, especially across Los Angeles and Ventura counties through the forecast period. More widespread turbulence and LLWS likely after 31/18Z.
KLAX, Moderate confidence in the 00Z TAF. -SHRA possible at times tonight, but increasing chances of measurable rain after 31/15Z. Slight chance of -TSRA as early as 01/06Z. High confidence in winds remaining NE to E through 01/00Z, with east wind component up to 10 knots during the afternoon hours. SE winds expected to develop during the overnight period 01/00Z-01/15Z with east wind component potentially remaining near 10 knots. Lower confidence in CIGs/VSBY after 31/18Z.
KBUR, Moderate confidence in the 00Z TAF. -SHRA possible today, but chances for measurable rain increase after 31/16Z Wed. Lower confidence in CIGs/VSBY after 31/18Z.
30/156 PM.
Small Craft Advisory (SCA) level Santa Ana winds from the northeast will continue to impact portions of the inner waters south of Point Conception through the remainder of the day, including nearshore areas from Ventura south through Malibu. Localized Gale Force gusts to 35 knots may occur, with best chances over the next couple of hours.
SCA level Santa Anas may continue into Wednesday morning across typical areas, but confidence is higher in widespread SCA level winds from the east to southeast impacting the region (including harbors) as early as Wed afternoon and continuing through at least late Wed night as another storm makes its presence felt across the region. There is a 30% chance for Gale Force Winds during this period, highest chances across the Santa Barbara Channel and near Point Conception. A relative lull is possible Thursday afternoon and evening, but a return of SCA level south to southwest wind is likely Friday into Saturday, especially north and west of Point Conception as a cold front moves through the area.
A steep and choppy southerly wind swell will accompany the winds, peaking Wednesday night into Thursday. By Friday, a west to northwest swell will accompany the secondary storm coming through. This swell will be larger and a longer period.
Rain will likely be heaviest Wednesday (New Year's Eve) night through Thursday (New Year's Day). There is a chance of thunderstorms (mainly south of Point Conception) during this period, but confidence is low in timing. Waterspouts, gusty and erratic winds, frequent lightning, and brief heavy rain are all possible with any thunderstorm.
30/142 PM.
Abnormally large tides between 6.8 and 7.5 feet MLLW will occur during the morning hours, roughly between 4am and noon Wednesday through Sunday. Surf heights remain relatively small through Friday, although moderate south-southeast winds and a wind swell from the south-southeast will add a little bit to the water levels. There may be a risk for some minor tidal overflows through Friday, with best chances Thursday and Friday. There is a moderate chance for a Beach Hazards Statement to be issued for Thursday and Friday for a majority of the beaches.
Saturday and Sunday pose more of a threat for moderate coastal flooding as a larger swell from the west-northwest enters the region. While there exists some uncertainty in timing of the highest surf, this would be the best chance for impacts such as shallow flooding of parking lots and roadways, some inundation of harbor walkways, and more significant beach erosion. There is a moderate chance for a Coastal Flood Advisory to be issued for Saturday and Sunday, highest for west facing beaches.
Ca, Flood Watch in effect from Wednesday evening through Thursday evening for zones 88-349>358-362-366>382-548. (See LAXFFALOX). PZ, Small Craft Advisory in effect until 9 PM PST this evening for zones 650-655. (See LAXMWWLOX).
