Area Forecast Discussion
Issued by NWS Sacramento, CA

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043
FXUS66 KSTO 082337
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
337 PM PST MON FEB 8 2016

.SYNOPSIS...
Dry and mild weather over interior Norcal this week.

&&

.DISCUSSION...
NAEFS climate height percentiles and mean temp return intervals
indicate a 30(+) year max of values will prevail over/near the CWA
today and then shift mainly Ewd on Tue. This translated into record
(or ties) of max temps for 2/8 at several of our main climatological
sites...namely RDD (80 2006), RBL (79 2006), SAC (69 2006), DTS (72
2006), SCK (71 2006). Today`s final record numbers won`t be official
until after press time...so check back to the climate and RER reports
this evening. Enough Nly wind picked up today to allow for adiabatic
warming effects to boost max temps there into record territory
after a record warm start as the morning low was 63 at RDD with a
daily high minimum temp of 50. (The OFFICIAL calendar low will
likely occur around midnight which is still likely to be above the
record high min temp of 50.)

Today will likely be the last day of record warmth for the N
Valley while the Srn Sac Vly will flirt with record max temps
through Wed before cooling...albeit max temps will continue to be
above normal this week. This will include the foothill locations
where the data bases are more variable...and in some cases
unreliable due to missing years/data or movement of site
locations. An Omega Block/Strong high pressure along the W Coast
will shift inland as the deep cyclone over the Great Lakes/Ohio
Valley swings up to the NE. Energy from the Gulf of AK trof will
weaken as it encounters the blocking ridge so a dry and
unseasonably warm week of wx is ahead for Norcal. The chance of
rain earlier forecast for the end of the week looks less and less
promising for Norcal...perhaps brushing the Nrn mtns late Fri or
Sat. The NCEP 45 day Total QPF ensemble plume for SAC paints a dry
picture until the end of the month before there is an uptick in
precip again. Not too unusual for dry/drier periods during wet El
Nino years as March has sometimes been a wet month as in the
1982-83 (strong) and 1994-95 (moderate) El Nino years. It should
be mentioned that the 08/12z operational GFS did forecast a system
will break through the ridge around the 17th/18th.

This morning`s impressive 12 mbs Ely pressure gradient which resulted
in isolated strong gusty winds over the Siernev and Lake Co mtns is
weakening and the forecast for Tue morning is for less than half of
what it was this morning (5 mbs) with also weakening 925 mbs winds.
Winds should turn light/calm overnite and a strong surface based
inversion will form given the very warm aloft. Cooler min temps
are forecast over most of the area due to a lack of mixing wind
overnite even in the Siernev. Lighter winds will also allow some
patches of late night and early morning valley fog to develop as
the week unfolds and as Nly winds subside.   JHM

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)

A weakening trough temporarily breaks down the West Coast ridge of
high pressure Friday afternoon into Saturday. The model trend
continues to weaken this system, and now little to no
precipitation is expected across our forecast area. High pressure
rebuilds Sunday into early next week with continued warm and dry
conditions. Longer range models are hinting at a potentially more
dynamic frontal system impacting NorCal toward the middle of next
week.

Dang

&&

.AVIATION...

Generally VFR conditions for the 24 hours with clear skies and
light winds. The exception will be patchy fog near river valleys
which could briefly impact KSAC and KSMF early Tuesday morning.

&&

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

$$



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