Area forecast discussion
National Weather Service Sacramento California
435 am PDT Tuesday may 21 2013
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.
&&
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.
&&
$$
