Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
855 PM PDT Monday Aug 29 2016
dry weather with below normal temperatures this week. Locally
breezy over higher terrain in the afternoons and through the Delta
nights into early mornings.
large upper low off the b.C. Coast with lower latitude mesolow
approaching norcal. Some mid to high level moisture in southwest
flow aloft is streaming over the area with more seen upstream on
satellite. 00z soundings showing that this moisture is mainly
around 500 mb and above. Mesolow progged to weaken to trough and
track across norcal Tuesday. High resolution models however only
showing weak instability and no precip with high based moisture.
Thus have removed mention of possible deep moist convection over
the coastal range Tuesday morning.
Ksac-ksfo surface pressure gradient is over 3 mb and appears to
be trending up. Expect Delta breeze will also increase tonight, as
supported by MOS guidance at ksuu, and provide some low level cold air advection
into the Central Valley. Marine layer is only about 1200 ft on the
ft. Ord profiler at this time and coastal stratus field has mixed
Behind mesolow, larger scale upper low mentioned earlier is progged
to deepen along the West Coast as it slowly digs south through
the week. Result will be dry weather with below normal temperatures
and decent onshore flow.
Extended discussion (friday through monday)
Norcal will be under the influence of a longwave trough through the
weekend. This will continue below normal temperatures. No
precipitation expected. By the end of the weekend into early next
week, ridging may gradually build in, bringing a warming trend in
temperatures and more northerly flow. Ceo
Incrsg swly flow Alf ovrngt into Tue mrng as upr trof movs thru.
VFR conds ovr intr norcal nxt 24 hrs with some sct-bkn clds at or above
fl150 poss til abt 20z Tue. LCL swly sfc wnd gsts up to 30 kts
poss thru Delta til arnd 13z Tue.