Interesting next few days in SoCal…
A strong mid-level trough will be present over the western CONUS at
the start of the period on Thursday. An area of strong high pressure
will move into Interior West during the day Thursday and remain
through Friday. This will lead to strong offshore flow in southern
California with a strong Santa Ana event likely.
…Day 3/4 - Thu/Fri - Portions of southern California…
A strong Santa Ana event is setting up for Thursday and Friday in
southern California. The worst conditions are expected in the
typical Santa Ana prone areas including Los Angeles and Ventura
counties.
The strong offshore winds are expected to begin early Thursday
morning and strengthen gradually through the day. By the
afternoon/evening, sustained winds are expected to be around 25 to
30 mph in the lower elevations with sustained winds around 35 to 45
mph in the higher terrain. Wind gusts of 50 to 70 mph are also
expected in the Los Angeles and Ventura County mountains. Relative
humidity is expected to be less than 10 percent across the entire
area with some areas of less than 5 percent relative humidity as
well. Overnight recoveries are expected to be poor Thursday night,
especially in the higher elevation. The very windy and dry
conditions will support extremely critical fire weather conditions
in a large portion of the higher terrain in Los Angeles and Ventura
counties and some locally extremely critical conditions in the lower
elevations. In addition, extremely critical conditions are likely in
much of the Mohave desert in southeast California, but given the
sparse fuels across the region, the threat of large fire spread is
lower, and thus only 40 percent probabilities have been maintained.
Strong winds are expected to persist overnight as the pressure
gradient continues to strengthen with the LAX-DGT gradient expected
to peak around 7-9 mb at 12Z Friday.
The gradient will start to relax through the day on Friday, but
critical-strength winds are expected to persist for most of the day.
Therefore, a 70 percent critical probability has been extended into
Friday for the same areas as D3/Thursday.
“Less than 5% RH in some areas” … I’ll leave that there.