24/817 PM.
Weak northeast winds this weekend will continue to bring drier conditions and warmer temperatures through the first half of this coming week. Cooler conditions will follow, with a growing potential for a storm system towards the end of the week and into next weekend.
(Sat-Tue), 24/725 PM.
Overall, latest models in good synoptic agreement through the short term period. At upper levels, weak ridge will move across the area tonight/Sunday with broad cyclonic flow developing on Monday and Tuesday. At the surface, a general weak diurnal flow will prevail through Monday with weak onshore flow on Tuesday.
Forecast-wise, relatively benign weather is expected through the short term period. With the gradual return of onshore pressure gradients, the marine layer should start to become more established from night-to-night across the coastal plain. Otherwise, skies are expected to remain mostly clear through the period.
With respect to winds, the weakening of the offshore flow the last couple of days will keep any offshore winds rather weak and localized tonight through Monday. On Tuesday, more widespread onshore winds will return to the area, but speeds will remain well below advisory levels.
Finally as for temperatures, there will be minor day-to-day changes through Monday, mainly at the whims of the onshore flow and marine influence. On Tuesday, will expect some slight cooling for most areas with the uptick in onshore flow.
(Wed-Sat), 24/725 PM.
For the extended, latest models continue to exhibit a rather broad synoptic agreement, but differ in the details. At upper levels, a low will develop over the Pacific Northwest on Wednesday/Thursday. On Friday and Saturday, the GFS continues to drop the low south along the coast while the ECMWF keeps over the Pacific Northwest (resulting in a sharp trough sweeping across the area).
Overall, either solution indicates a wet and unsettled Halloween weekend for Southern California. At this time, there is high confidence in measurable rainfall for most, if not all, of the area Friday through the weekend. However, confidence in timing of rainfall and totals remain very low. The latest 12Z/18Z runs have backed off on totals just a bit with even the run total QPF on the ensembles decreasing. Previous estimates of totals from 0.50 to 2.00 inches are still in play, but totals, in the end, could be more or less than that range.
The uncertainty in this pattern will be a challenge over the coming days. So, the forecast will likely change from one day to the next. However, residents should expect Halloween activities to be impacted by rainfall to some level. Stay tuned for the latest details about this upcoming storm.
24/2230z.
At 2215Z over KLAX, there was no marine layer and no inversion.
For 00Z TAF package, high confidence in CAVU conditions for all sites through the period.
KLAX, High confidence in 00Z TAF as CAVU conditions are expected through the period. No significant easterly wind component is expected.
KBUR, High confidence in 00Z TAF as CAVU conditions are expected through the period.
24/752 PM.
High confidence in quiet conditions through this weekend. Northwest winds will increase early this coming week. SCA conditions are likely Monday and Tuesday for the outer waters from near Point Sal through San Nicolas Island.
Ca, Coastal Flood Advisory in effect from 5 AM Sunday to 1 PM PDT Thursday for zones 340-346-349-350-354-362-366. (See LAXCFWLOX). PZ, NONE.
