30/1216 AM.
The Santa Ana winds will continue today under mostly cloudy skies. High temperatures will end up in lower 70s for most of the coasts and valleys. A new storm 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-Thu), 30/307 AM.
A fairly unusual day with a moderate Santa Ana and mostly cloudy skies. This morning there will about a 7mb offshore push from the east and about 4mb from the north. The upper support is weaker than ydy but still there will be enough to produce advisory level gusts in the wind prone areas through early afternoon. Temperatures this morning across the windy areas are still in the mid 60s while the wind sheltered areas have much lower temps since the dry air cools so quickly. For example Van Nuys is currently 63 degrees and Burbank, only a few miles away, is 54 degrees. At the same time a large layer of cirrus clouds is spinning off an upper low to the SW of LA. These clouds will make the day a mostly cloudy one. The current forecast calls for some coastal cooling due to slightly weaker offshore flow and warming across the interior due to much less cool air advection. The clouds could throw a monkey wrench into the temp fcst however if they come in thicker than fcst - the warming would be much less or even turn cooler.
Wednesday will be an interesting day. The offshore flow will continue albeit only half a strong as it is today. The aforementioned upper low will move northward and spin a large lobe of PVA over the area. A slight chance of rain will develop in the predawn hours. In the morning rain will become likely across the Central Coast (~70 percent chc) with a 30 to 40 percent chc south of Point Conception. The vort lobe will cover the entire forecast area during the afternoon and all areas should see some rain. The really juicy air will still be south of the area so rainfall totals and rates will not be that high. Also the downsloping drying offshore flow will also diminish the rainfall. Rainfall totals for the day should come in between a quarter inch and three quarters of an inch. Max temps will fall with the thicker clouds and reduced offshore flow. Max temps across the csts/vlys will fall 3 to 6 degrees and maybe more if the rain arrives earlier.
PWATs rise quickly to about 1.25" Wednesday night and as high as 1.5" New Years Day. At the same time the upper pivots to the east and moves across SBA/VTA/LA counties through the day. This track will bring plenty of south winds to help with the orographic rainfall. The heaviest rain will occur from midnight to noon across areas south of Point Conception. From midnight to dawn cst/vlys will likely recieve .50"-.75" inches of rain while the mtns and foothills see .75"-1.25". From dawn to noon about an additional half inch will fall on southern SBA and VTA counties. The csts/vlys of LA county will likely another .50"-.75" inches of rain while the mtns and foothills see .75"-1.25". The Central coast will see much less rain likely between .50 and .75 for the entire day. Rain will be much lighter in the afternoon with only a quarter to a third of an inch of rain fcst. In total from Midnight to late evening rainfall should be 1.25" to 1.75" locally 2" for the csts and vlys and 2 to 4 inches for the foothill and mtns. Rain rates should peak at around 0.5" per hour, with isolated rates up to 0.75" per hour. The higher rates will be south of Pt Conception and across the upslope areas. Due to the large amount of rain that fell last week, there will be much more runoff than usual and flood watches will be strongly considered over the next 24 hours, particularly in light of the slight risk of excessive rainfall from WPC.
There is a near 100 percent chc of a wet New Years Parade as well as the overnight hours leading up to it (which will affect people camping out before the parade). The last wet New Year's parade was in 2006.
There is quite a bit of lightning with the core of the storm now and the chc of TSTMs will have to be monitored as the low approaches. Right now the chc of a TSTM is about 10 percent but this could rise if the upper low keeps churning out lightning. Winds will not be as strong with gusts only to 40 mph expected at the storms peak. Since this storm moisture south and flow is from the south, snow levels will be over 9000 feet.
(Fri-Mon), 30/1214 AM.
Moist SW flow will set up over the area on Friday. There will likely be plenty of clouds. Some energy will move down the coast and will trigger a 60 percent chc of rain across the Central Coast and around a 30 percent chc south of Pt Conception in the morning. Rain is almost a certainty for the Central Coast in the afternoon and a 50 to 60 percent chc or rain will develop south of Pt Conception. Rainfall amounts will not be too great under a half inch and likely under a quarter inch south of Pt Conception. Max temps will end up in the lower to mid 60s for most of the csts/vlys.
A cold front will work its way from the northwest to the NE Friday night and Saturday morning. Steady rain is likely for most of the area as the front sweeps across. The steady rain will end in the afternoon and turn to scattered showers in the wake of the front. Snow levels will start out around 7500 ft and will lower to 6500 feet in the afternoon. This system is not very moist or dynamic and rainfall amounts should not be too concerning. Right now it is forecast to drop a quarter to a half inch across the csts/vlys and a half inch to an inch across the coastal slopes and foothills. Max temps, again, will end up in the lower to mid 60s for most of the csts/vlys.
Moist SW flow continues Sun and Mon. There are a multitude of mdl solutions that have rain developing at various different time. Because of this there is a chc of rain all through the period. This is mostly representative of the blended mdl smearing effect rather a forecast of 60 hours of rain. So it is very likely that it will rain a times during the period but there will also be dry periods. Another quarter to a third of an inch of rain is possible over the two and a half day period. Little change in temps on Sunday and perhaps a couple degrees of warming on Monday.
30/1139z.
At 0915Z at KLAX, there was no inversion and no marine layer.
Overall, moderate to high confidence in 12Z TAF Package.
Strong offshore winds will generate light to occasionally moderate turbulence and LLWS over and near mountainous terrain across LA and VTA counties through the forecast period. Most impactful for sites: KCMA, KOXR, KBUR, and KVNY.
-SHRA chances move into the region from the south after 06Z Wednesday.
KLAX, Moderate confidence in TAF. Moderate confidence that the east wind component will remain under 7 knots, with a 25% chance of exceeding 10 kts through 17Z Tuesday. 15-30% chance of -SHRA after 06Z Wednesday, increasing to 60% chance after 15Z Wednesday.
KBUR, High confidence in TAF. 10% chc of -SHRA after 09Z Wed.
29/1139 PM.
For the Outer Waters, moderate to high confidence in current forecast. Small Craft Advisory (SCA) level NE winds are expected across the waters around and to the south of the Channel Islands through Tuesday. Elsewhere conditions are expected to remain below SCA levels. A storm system approaching from the south will bring a 60-80% chance of SCA level SE winds with a 20% chc of GALE force winds. Moderate chance SCA winds continue north of Pt Conception on Saturday. Also, seas will approach SCA levels during this time.
For the Inner Waters north of Point Sal, moderate confidence in current forecast. SCA level NE winds are likely through Tuesday morning with the strongest winds nearshore from Point Estero to Morro Bay and Irish hills to Oceano Beach. There is a 30-40% chc of SCA level SE winds on Wednesday, increasing to 60-80% chc on Thursday and Friday. These hazardous winds to small craft could linger into early Saturday depending on timing.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. High confidence in SCA level winds impacting typical Santa Ana wind prone waters thru tonight, with potential for lasting into Tuesday night. This excludes San Pedro Channel. Localized GALE force gusts are possible nearshore along the Ventura coastline through early Tuesday morning (25% chance). A storm system from the south will likely continue SCA level winds especially across the Santa Barbara Channel & northern/western portions of PZZ655 Wednesday possibly into Thursday (SE winds). High confidence in winds and seas remaining below SCA levels Friday into Saturday.
Ca, Wind Advisory now in effect until 3 PM PST this afternoon for zones 88-354-355-358-362-369>376-378>380. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 9 AM PST this morning for zones 645-676. (See LAXMWWLOX). Small Craft Advisory in effect until 3 PM PST this afternoon for zones 650-655. (See LAXMWWLOX).
