Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 312220
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
320 PM PDT Thu Jul 31 2014

.Synopsis...
Hot temperatures with a cooling trend beginning Sunday. A return
to Sierra showers and thunderstorms possible again early/mid week
next week.

&&

.Discussion...

A very hot afternoon across NorCal with temperatures above 100
degrees at valley locations. These type of readings are about 10
degrees above normal. Afternoon high temperatures should remain a
few degrees under record values. Increasing southwest flow is
keeping thunderstorms near the crest with motion east and
northeast toward Nevada. Not much relief overnight without a delta
breeze.

Drier air will filter into the area Tomorrow with the increased
southwest flow as weak trough develops over the eastern Pacific.
Isolated thunderstorms will be confined to the Lassen area...dry
over the rest of the Sierra. Temperatures will remain hot as
valley readings rise to from 100-105 degrees.

Slightly cooler Saturday then a few more degrees of cooling Sunday
as delta breeze/onshore flow develops. Moisture will remain east
of the area keeping thunderstorms over Nevada.

&&

.Extended Discussion (Monday through Thursday)

Medium range models showing diverging solutions through the
extended period leading to uncertainties in forecast. Guidance
similar in gradually building upper ridging through the period
but differ with depth and track of offshore upper low. NAEFS mean
precipitable water ensembles and GFS/ECMWF-HiRes RH progs show a
trend upward in moisture through the extended period. GFS elevated
instability also show increasing mid level CAPE and Total totals
over the mountains through midweek. Forecast thus advertising
threat over the higher terrain of the Sierra Nevada, Plumas, and
Shasta mountains Tuesday, expanding over Shasta into the Coastal
Range Wed into Thu. High temperatures expected to be near to
slightly above normal Mon through Thu.


&&

.Aviation...

SWly flow alf with upr trof ofshr and upr rdg axis ovr Grt Basin.
Isold tstms poss ovr hyr mtn trrn of Shasta, Plumas, and Siernev
thru 05z Fri otrw VFR conds ovr Intr NorCal nxt 24 hrs. Isold SWly
sfc wnd gsts to arnd 25 kts poss ovr hyr mtn trnn and thru Delta
aftns into eves.


&&

.STO Watches/Warnings/Advisories...
None.
&&

$$







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