Scientific Forecaster Discussion
fxus66 klox 191121
Area forecast discussion
National Weather Service Los Angeles/Oxnard California
321 am PST sun Nov 19 2017
surface high pressure over the central rockies will continue to
supply a cool and dry air mass to the region with another round of
frost and freeze conditions for cooler interior areas through
Sunday morning. A ridge of high pressure building into the region
early next week will bring significant warming with widespread
record heat possible mid-week, including Thanksgiving day.
The main story of the the weather is the heat...but oddly have to
start out talking about freezing weather. Clear skies and cool
airmass have allowed for a nice temp drop this morning and the
interior vlys...desert...and the Ojai and Santa Ynez valleys will
all dawn with temps below or at freezing.
A ridge will build in today and hgts will rise to 582 dm these
hgts...sunshine and the offshore flow will all combine to produce
Max temps 4 to 8 degrees above normal. The offshore flow may
produce a few sub advisory gusts between 15 and 25 mph this
morning as well.
The ridge grows on Monday. Flow is still offshore but it is about
a mb weaker in both directions. There are a grip of clouds
currently at 140w and while most of them will be deflected to the
north of the area by the ridge enough mid and high levels clouds
will slip through to create partly cloudy skies, sba and esp slo
counties may have an hour or two of mostly cloudy skies. Max temps
will jump a few more degrees. The biggest jumps in Max temps will
be across the interior where the cool air from saturday's
offshore push will modify and the central coast where there will
be better easterly flow.
On Tuesday the ridge spikes up and hgts soar to 591 dm or 13 dm
above normal. Offshore flow will continue and Max temps will soar
5 to 10 degrees. Almost all of the coasts and the vlys will have
Max temps in the 80s or 10 to 20 degrees above normal.
The ridge grows to 594 dm and offshore flow increases. There will
be some north winds in places like the I-5 corridor. Under sunny
skies Max temps will rise several more degrees and Max temps will
be in the 80s and lower 90s across all of the coasts and vlys
except maybe for the central coast north of the city of slo.
Hgts fall a few dm on Thanksgiving as the ridge tilts to the east.
Offshore flow weakens a touch also. Max temps should fall a degree
or two. The all time record Max temp for Thanksgiving is 90 and
right now it looks like that record will stand but its still not
out of the question. Skies will be clear and there will not be
much of any wind.
The ridge flattens out as a large upper low moves out of the Gulf
of Alaska. Gradients will reverse to onshore and there will be
cooling both Friday and Saturday. Max temps...however...will still
be a few degrees above normal.
At 090z, there was a surface based inversion at klax. The top of
the inversion was at 1300 ft with a temperature of 21 deg c.
Clear skies and VFR conds expected across the region thru the pd.
There will be locally gusty NE winds thru and below passes and
canyons in the mtns and valleys of l.A./Vtu counties through
mid to late morning with local low level wind shear and moderate uddf.
Klax...high confidence in the 12z taf. VFR conds thru the pd.
Kbur...high confidence in the 12z taf. VFR conds thru the pd.
Moderate confidence in the forecast. There is a 30-40% chance that
a Small Craft Advisory will be needed across the outer waters this afternoon and
evening, and across the southern two outer waters zones Mon
afternoon and evening. Otherwise, Small Craft Advisory conds are not expected
through Wed morning. Small Craft Advisory level winds are likely across the
southern two thirds of the outer waters late Wed through Thu, and
possible across the northern outer waters.
California...frost advisory in effect until 9 am PST this morning for
zones 36-38-44. (See laxnpwlox).
Freeze warning in effect until 9 am PST this morning for zone
37. (See laxnpwlox).
Hard freeze warning in effect until 9 am PST this morning for
zone 59. (See laxnpwlox).
Hazard potential outlook...(tue-sat)
no significant hazards expected.