04/949 PM.
Mostly clear skies, dry conditions, a general warming trend with periods of offshore winds are likely through the week. The warmest and windiest conditions are likely on Friday and Sunday.
(tdy-Sat), 05/808 AM.
***UPDATE***
Overall, a quiet morning across the forecast district. Latest satellite and surface observations indicate mostly clear to partly cloudy skies as some cirrus clouds drift overhead. Northeasterly winds, gusting 25-35 MPH, across the mountains and valleys this morning.
Forecast-wise for the immediate short term, no significant weather is expected. The northeasterly winds will likely increase a bit this morning, but should remain below advisory levels, before diminishing later this afternoon. Under mostly clear skies this afternoon, temperatures will be noticeably warmer with the offshore pressure gradients. Morning TEMP STUDY data indicates boundary layer 3-5 degrees Celsius warmer than Wednesday morning along with stronger offshore gradients. So, afternoon highs in the mid 70s to lower 80s look very much on track.
Current forecast looks good for the immediate short term. So, no significant updates are expected.
***From Previous Discussion***
Very benign weather on tap for today. Dry NW flow will be over the area. There is about 5 mb of offshore flow from the north and a weak 2 mb offshore push from the east. There will be some gusty sub advisory north winds through the passes and canyons this morning. Max temps will be the bigger talking point. The offshore flow and 578 dam hgts will combine with copious sunshine to raise temps 3 to 6 locally 8 degrees. This will bring max temps up into the upper 70s and lower 80s for most of the csts/vlys.
Not much change to the sfc grads on Friday. But a ridge will nose into the northern portion of the state and begin to switch the direction of the upper flow to the NE. This transition happens a little after the morning diurnal pressure max so while the winds will be a little stronger (and more northeasterly) than today the gusts for the most part will be under advisory levels. Max temps will jump another 2 to 4 degrees and will end up 4 to 8 degrees over normal.
The best upper level and sfc gradient conditions for offshore flow occur on Saturday morning. These conditions should be strong enough to bring low end advisory gusts to portions of the Santa Ana Wind Corridor (roughly 7 miles either side of a line from Santa Clarita to Pt Mugu). Sunny skies and continued offshore flow will add another 1 or 2 degrees to the max temps which will end up in the 80s across the csts/vlys.
Given the gusty offshore winds, warming temperatures and dry conditions, there will be elevated to locally critical fire weather conditions across the area by Friday and Saturday. Recent rainfall has helped mitigate the fire threat a bit, but live fuel moistures are still in the 65-80% range which means the area is not "out of the woods" with respect to the fire threat. There is a 30% chance of "targeted" Red Flag Warnings on Friday and Saturday.
(Sun-Wed), 05/1215 AM.
Not much happening in the days 4 to 7 time frame. On Sunday the ridge will remain overhead with 583 dam hgts but the offshore flow will decrease. There will still be some offshore winds but they will fall short of advisory levels. This will allow an earlier sea breeze and most cst vly locations will cool a few degrees.
The ridge and offshore flow will continue to weaken on Monday and this will lead to 2 to 4 degrees of cooling with no wind issues. Max temps across the csts/vlys will mostly be in the upper 70s to mid 80s. Despite the cooling max temps will still be 4 to 8 degrees above normal.
Weak westerly flow moves in overhead on Tuesday. The offshore flow from the east will be weaker still and will actually turn onshore in the afternoon. It will be an unremarkable day 2 or 3 degrees cooler than Monday, but still above normal.
Change is afoot on Wed - though there is not the best mdl agreement. A large storm system will begin to approach the west coast. There will either be a weak ridge or weak SW flow overhead. The weather actually will not be that different as the system will still be fairly far off. Perhaps a little cloudy and likely a few more degrees cooling.
All mdls deterministic, AI and ensemble have differing ideas on the exact details of the forecast for the Thu to Sun (12th to 15th) time period. But all mdls agree that it will be wet sometime in that period. Right now it looks like about a half inch of rain fall with a 30 percent chc of it being a 1 inch storm. Peering even further out it looks like the rain window may stay open into the week of the 16th to 20th. This forecast will be refined more and more as time draws nearer.
05/1608z.
At 1545Z at KLAX, there was a surface-based inversion. The top of the inversion was 2000 feet with a temperature of 19 degrees Celsius.
For 18Z TAF package, high confidence in CAVU conditions for all sites.
KLAX, High confidence in 18Z TAF as CAVU conditions are expected through the period. No significant easterly wind component is expected.
KBUR, High confidence in 18Z TAF as CAVU conditions are expected through the period.
05/808 AM.
For the Outer Waters, high confidence in current forecast. Through Friday, a combination of Small Craft Advisory (SCA) level winds and seas will prevail. For Saturday, SCA level seas are expected to continue with winds dropping below SCA levels. For Sunday and Monday, winds will increase once again to SCA levels with seas remaining at SCA levels.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Friday, there is a 30-40% chance of SCA level winds in the afternoon and evening hours. For Saturday and Sunday, high confidence in winds and seas remaining below SCA levels. On Monday, there is a 50-60% chance of a combination of SCA level winds and seas.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. High confidence in winds and seas remaining below SCA levels today, except for a 30% chance of SCA level winds across the western Santa Barbara Channel late this afternoon and evening. For Friday and Saturday, there is a 30-40% chance of SCA level northeast winds from Ventura south to Santa Monica. On Sunday and Monday, winds and seas are expected to remain below SCA levels.
Through Friday, the gusty winds will likely result in choppy, short-period, seas.
Ca, NONE. PZ, Small Craft Advisory in effect until 3 AM PST Friday for zones 670-673-676. (See LAXMWWLOX).
