Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
330 am PDT Thu may 28 2015
daytime temperatures 10 to 15 degrees above normal over the next
few days as high pressure slides across the West Coast. Cooler
early next week with a slight chance of showers and thunderstorms
over the northern Sacramento Valley and surrounding mountains as
the tail end of a Pacific trough brushes through.
high pressure moving in over the West Coast bringing fair skies
over the forecast area this morning. Delta breeze just slightly
weaker than 24 hours ago but marine layer much more shallow as
upper ridge develops so not expecting a significant intrusion of
coastal stratus into the valley again this morning although parts
of the western Delta will see some stratus. With subsidence under
the ridge...mountain shower or thunderstorm development is not
expected today and this is expected to remain the case over the
next few days. Overall airmass warms under the ridge with daytime
highs today forecast to run about 10 to 15 degrees above normal.
Friday looks to be the warmest day as upper ridge axis centers
over the West Coast. On Saturday...daytime highs drop down just a
bit as the upper ridge axis shifts east of the state in response
to an eastern Pacific trough forecast to approach the coast. This
system is forecast to move onto the coast by Sunday afternoon or
evening bringing a threat of showers to the Coast Range...the
northern mountains and possibly the northern Sacramento Valley.
Stability proggs show possibly enough instability over the Coast
Range for thunderstorms but conditions are more stable farther
east so removed afternoon/evening thunderstorm threat there. Most
locations Sunday will just see some increased high cloud
cover...increased southwest winds and about a 5 to 10 degree drop
in daytime temperatures.
Extended discussion (monday through thursday)
Models continue to forecast several short wave troughs through
northern portions of California Monday into Tuesday. Dynamics and
moisture look limited with main impact being synoptic cooling
with increased onshore flow. Locally gusty southwest to west winds
expected through the Delta and over higher mountain terrain. A
slight chance of showers and afternoon thunderstorms are possible
mainly over the mountains north of I-80 through this period.
Weak ridging moves through Wednesday followed by weak upper
troughing Thursday. Slight warming of the air mass depicted through
midweek by models with mid to upper 80s for highs in the central
and mainly 60s to around 80 for the mountains and foothills.
Upr rdg blds ovr the fcst area nxt 24 hrs. Mnly VFR conds for intr
norcal exc LCL MVFR/IFR cigs poss vcnty Delta in St til 18z Thu. LCL
swly sfc wnd gsts to arnd 25 kts poss thru Delta.