Area forecast discussion
National Weather Service Sacramento California
1006 am PDT Tuesday may 21 2013
Short term discussion...
Upper low is just off the Oregon/Washington coast this morning.
The system is relatively dry with only isolated showers possible
over the mountains of Shasta County today. Winds are gusting to 30
miles per hour at Travis AFB and expect gusts to 35 miles per hour through the Delta
during the afternoon. This will hold temperatures in the 70's over
the Delta...but flow should not make it into the valleys with
temperatures warming into the low 80's over the southern SAC valley. Cold air
advection is already in progress over the northern SAC valley where
redding's temperatures are holding in the upper 60's and readings will
only warm into the low and middle 70's over the northern SAC valley.
Current forecast is on track and no morning update will be needed.
Previous discussion...
Cold upper low presently off the coast of Washington will continue
to shift southeastward today and will be over Oregon by tonight.
Cold front out ahead of the upper system is moving into northwest California at this time
and will shift southward through norcal today. The low is forecast
to remain nearly stationary over the pacnw into Friday as several
disturbances rotate about its periphery. A weaker trough is
forecast to linger over the region through the weekend and into
early next week.
Appears the main impact from this system for interior norcal will
be much cooler temperatures expected for the remainder of the week
after the warm start to the work week on Monday along with breezy
conditions. Highs today are expected to be around 10 to 15 degrees
cooler than Monday as the cold front passes. Further cooling of 5
to 10 degrees is forecast for Wednesday.
Appears showers will be limited to stronger forcing and
instability closer to the upper low...so the northern mountains
will see the best chance for a few showers today and Wednesday. A
stronger shortwave forecast to move around the base of the low may
bring shower chances a little further south into the northern
Sierra Nevada on Thursday.
Weakening trough lingers across the region through the upcoming
Memorial Holiday weekend. The northern mountains may see a few
afternoon/evening showers...but temperatures are forecast to
moderate back to near or slightly below normal levels.
&&
Extended discussion (saturday through tuesday)
Eakening trough lingers across the region through the upcoming
Memorial Holiday weekend. The northern mountains may see a few
afternoon/evening showers...but temperatures are forecast to
moderate back to near or slightly below normal levels.
&&
Aviation...
low pressure system moving into the pacnw today. VFR conds persist
for norcal. Due to the low pressure cell...Delta breeze is picking up
this morning and the SAC valley will have southerly winds ranging 5-15 kts
this morning. Near 18z and through the evening...stronger southerly winds
will impact the southern and cntl SAC valley with sustained winds 10-20
kts and gusts around 25+ kts. Meanwhile...the northern SAC valley will
transition to MDT-strong northerly flow near or after 00z ranging 10-18
kts with gusts around 25 kts. MDT to strong westerly/northwesterly winds over
ridgetops today into Wednesday morning. Jbb
&&
Sto watches/warnings/advisories...
none.
&&
$$
