Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 131545
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
845 AM PDT Sun Jul 13 2014
Warmer daytime temperatures will peak Monday followed by a slight
cooling trend into mid-week. A chance of Sierra crest thunderstorms
Monday through Thursday including the Coastal Range & Shasta County
mountains on Tues & Wed. Diminishing shower threat by the end of the
week as the upper level flow becomes more westerly.
Strong high pressure continues to build across the region today as a
weak closed low off the Oregon coast moves into the PacNW. Appears
that most thunderstorm activity will be further to our north today
as the ridge will cap things off around here.
Temperatures are getting off to a warmer start across much of the
region and it looks like several hot days ahead for interior NorCal.
Soundings show a decent amount of warming and it looks like much of
the Central Valley will be around the century mark today and warmer
Appears thunderstorm threat will return to the northern Sierra
Monday, spreading to the northern mountains through mid-week.
Current forecasts on track. No updates.
High pressure strengthens over NorCal today and tomorrow as a
warming trend continues through Monday. Hot temperatures will bring
widespread triple digit heat to much of the valley with Monday being
the peak of the heat this week.
850 MB temperatures aloft will range 25-28 degrees C which would
technically translate to surface valley highs ranging 103 to 109
degrees F. However, NorCal valley residents have the Delta Breeze
on their side which will knock that range down a bit as cooler
marine air tempers the heating. For today, daytime highs will
range in the upper 90s to 106 from Modesto up to Redding,
respectively. The Delta region will be a cooler range from the 80s
into the mid 90s. Mountains and foothills will generally range in
the 80s and 90s, respectively. For Monday highs, add another 2 to
5 degrees to the max temps. That will put us at 8 to 15 degrees
above normal for our region. On Tuesday, high pressure weakens
and shifts eastward which will allow for about 4-6 degrees of
cooling. Wednesday highs will be similar to Tuesday or a degree
or two cooler.
With today and Monday being hot days, please keep in mind
that the hottest part of the day will be between 2-7 pm. For those
planning to attend the CA State Fair, afternoon temperatures will
be peaking between 95 to 100 today and 100 to 104 on Monday in the
Sacramento Metro region.
Monday will not only be the peak heat day this week, but it also
marks the day that monsoonal moisture returns to the Sierra Crest.
Instability over the mountains plus that moisture could trigger some
thunderstorms Monday through Friday. On Tuesday & Wednesday, the
instability and monsoonal moisture will also impact the Coastal
Range and Shasta County mountains with possible thunderstorms.
Although there is only a slight chance to chance of thunderstorms
this week, please remember that it only takes one lightning strike
to start a fire, so stay alert if there are thunderstorms near you.
.Extended Discussion (Thursday through Sunday)...
Continued weakening of high pressure aloft towards the end of the
week means that daytime highs will be within a few degrees of normal
for Thursday into the weekend.
Conditions will generally be dry except for the possibility of
thunderstorms over higher terrain. Monsoonal moisture will linger
over interior NorCal. On Thursday, thunderstorms are possible along
the Sierra Crest and the crest of the Coastal mountains. By Friday
into Sunday, the wind pattern will become more westerly so that
thunderstorms should be limited to the Sierra and most cells that
develop would likely get pushed onto the eastern side of the Sierra.
Forecast for Fri, Sat, and Sun has mention of slight chance of
thunderstorms limited to the Sierra crest south of Tahoe region.
Mainly VFR conditions the next 24 hours across interior NorCal. IFR
stratus probably into around Cordelia this morning. Marine layer has
weakened since yesterday, so probably not any expansion beyond
Cordelia. SW surface winds 15-25 kt in western Delta today. JClapp