000
FXUS66 KSTO 052121
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
221 PM PDT Wed May 5 2021

.SYNOPSIS...
Warm and dry weather will continue today, then cooler Thursday
and Friday. Increased north winds and warmer into the weekend and
early next week with elevated fire weather concerns.

&&

.DISCUSSION...
We are sitting under the apex of a strong upper level ridge this
afternoon and that is bringing summer like temperatures to the
region. Right now we are generally 2-6 degrees warmer than
yesterday and we should see daytime highs a few degrees warmer
than yesterday. With the light north winds the Delta has seen
strong warming this afternoon but we should see a Delta Breeze
develop later this afternoon into the evening. This does make
their exact high temp a bit tricking, they should remain in the
mid 90s but if the Delta breeze is delayed they could see highs
near 100. The Delta breeze should bring some relief in the temps
to the Sacramento area around 2z/7pm.

Upper level ridge will push east tonight into tomorrow as a trough
digs out of the Gulf of Alaska. This will bring increased onshore
flow tomorrow and we could see some gusts up to 25 mph, stronger
in the Delta. The trough will also push a cold front into the
area and some cloud cover can be expected with that front but with
little to no moisture no precip is expected. There is some
instability that builds in east of the Sierra crest south of Tahoe
tomorrow afternoon and you may see some cumulus clouds if you
look east but the thunderstorm threat remains to our east. Onshore
flow will usher in much cooler temperatures and we should see
them 6-12 degrees lower than today, and as much as 15 degrees
lower in the Delta region.

Trough will be pushing to the east on Friday and that will help to
bring some north flow to northern parts of the Sacramento Valley
during the afternoon. Highs on Friday will continue to be closer
to seasonal averages. As we head into the weekend we will see
troughing develop over the northern Rockies and the Great Basin.
This will bring increased northerly flow to NorCal which will
lead to fire weather concerns. We will see very low humidity and
and the anomaly tables are having up to +4.5 wind anomalies.
Currently looking like gusts up to 35 mph but we may see these
gusts increase as higher res guidance starts to cover that time
frame. Highs will begin a warming trend and we should see them
near 90 in the Valley Saturday.

-CJM

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...
Troughing will be set up over the northern Rockies and Great
Basin for the start of the extended forecast. This is going to
bring gusty northerly winds, low humidity, and elevated fire
weather concerns. It will also continue to bring a warming trend
and we should see Valley highs push back above the 90 mark Monday.
There is very high confidence in long wave troughing over the
central US but ensembles diverge on how far east that long wave
troughing sets up. High confidence in north winds early next week
but the strength will be dependent on where the troughing sets up.
Highest confidence for gusty north winds will be this weekend but
if the trough favors the GEFS solution they will remain gusty
into early next week.

-CJM

&&

.AVIATION...
VFR conditions continue over interior NorCal next 24 hours.
Surface winds generally below 12 kts. Local southwest wind gusts
20 to 35 kts vicinity Delta this evening through Thursday. Local
marine stratus are possible over the western Delta 09z-15z.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$