Area Forecast Discussion
Issued by NWS Sacramento, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
277
FXUS66 KSTO 042104
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
204 PM PDT WED MAY 4 2016

.Synopsis...

An upper level disturbance will continue to bring chances for
showers and thunderstorms this afternoon, mainly for the foothills
and the Sierra.  Chances for showers and thunderstorms should
increase in coverage across Northern California on tonight through
Thursday. The storm system will linger through the weekend, which
will cause more chances for showers and storms.

.Short Term Discussion (Today through Saturday Night)...

Water vapor analysis and upper level model guidance indicated the
trough of low pressure moving across the eastern Pacific just to the
west of the California coastline.  An increased amount of moisture
was streaming through California, which was bringing overcast skies,
showers, and isolated thunderstorms to portions of NorCal.

High resolution short term model output shows chances for
thunderstorms (mainly over the foothills and the Sierras) this
evening through Thursday afternoon.  Storms that may develop could
bring brief heavy downpours and small hail.  As the upper level
trough pushes eastward Friday night, showers and storms could linger
over the forecast area as moisture and instability continue to be
present through the weekend.  Small hail and brief heavy downpours
are possible in stronger developing storms.  High temperatures will
remain cooler in the low to mid 70s in the valley, 60s in the
foothills, and in the upper 40s to low 50s at higher elevations
through Saturday.

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)

Warmer and drier weather pattern will be developing over Norcal
during the EFP. Lingering cyclonic flow from closed 5H low over
the 4-Corners will keep unsettled wx over Norcal on Sun...especially
over the Sierra...followed by high pressure building into Norcal for
the rest of the extended forecast period.

At times...the models indicate some instability or light precip
developing over a small portion of the Nrn portion of our CWA
spilling over or developing within the amplifying ridge. This activity
should be diurnal in nature as a result of differential heating and
topographic forcing...and will continue the low PoPs over the higher
mtns for now. Some large-scale ascent is possible as a trof...
moving through the Pac NW and Nrn Rockys...brushes Norcal early
next week especially if the ECMWF verifies.

Temps will gradually warm through the period. Maxes will start out
just a little below normal (up to 5 degrees or so most areas) on Sun
before warming to 5-10 degrees above normal on Tue/Wed. Forecast
highs mostly in the 70s in the Central Vly on Sun warm into the
80s for the rest of the period.    JHM
&&

.AVIATION...

Sly flow alf with upr low off the CA cst. VFR conds ovr Intr NorCal
nxt 24 hrs exc isold MVFR poss in shwrs or tstms...mnly ovr fthls
and mtns. Sfc wnds genly blo 15 kts exc gsty nr tstms.

&&

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

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.