Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 041025
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
325 AM PDT FRI SEP 4 2015
A low pressure system over the Pacific Northwest will bring a
chance of showers or thunderstorms to the northern mountains with
partly cloudy skies and well below normal temperatures elsewhere.
Lassen peak may see a dusting of snow. Breezy north winds over
the weekend warming to near normal by Sunday. A little warmer
than normal next week under upper level high pressure.
.Discussion (TODAY THROUGH MONDAY)... Northern California under
fair skies this morning between a weak disturbance now moving into
the Great Basin and an upper low dropping southward down the
Pacific northwest coast. Onshore flow and a cooler airmass will
bring cooler temperatures today down to 7 to 14 degrees below
normal. The upper low will drop southward just far enough to bring
a threat of showers to the northern mountains this afternoon with
enough instability indicated for a chance of thunderstorms. The
upper low is then projected to swing quickly eastward into the
Great Basin with a few lingering showers possible over the
southern Cascade crest during the late morning hours Saturday.
Then...Northerly flow and more stable conditions take over. A
northerly surface gradient developing behind the departing low
will bring breezy north winds to much of the forecast area over
the weekend. Surface gradient from MFR to SAC reaches about 6 mb
Sunday morning but upper support out of the west northwest so
breezier winds will likely be somewhat spotty. Arms warms over
the weekend with daytime highs reaching right around normal by
Sunday. Heights continue to rise on Monday for a little more
warming and lighter north winds.
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
Upper ridging over the EPAC will gradually build over Interior
Northern California through the extended forecast period. Dry
weather will result with above normal temperatures. Highs
temperatures in the Central Valley are expected from the mid 90s
to around 100 degrees in the north, with mostly 80s to low 90s
for the mountains and foothills.
UPR LOW DIGS S ALG W CST WITH SWLY FLOW. VFR CONDS OVR INTR
NORCAL NXT 24 HRS EXC LCL MVFR CIGS POSS IN SHWRS OVR SHASTA MTNS
AND ISOLD -TSRA POSS OVR NRN MTNS BTWN 21Z-03Z. LCL SWLY SFC WND
GSTS TO 30 KTS OVR HYR TRRN THIS AFTN INTO EVE.