Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 041701
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
901 AM PST Tue Mar 4 2014
Some lingering showers will be possible across the interior of
northern California today. Another weather system will affect
parts of northern California late tonight into Thursday. Dry
conditions are expected for Friday and Saturday with another low
pressure system possible on Sunday.
Satellite imagery shows a weak area of high pressure currently
moving over California. The moisture plume from yesterday remains
over Northern and Central California, but subsidence over the
region is inhibiting widespread precipitation. Interestingly
enough, the subsidence and residual low-level moisture combined to
bring areas of drizzle to parts of the Central Valley this
morning. A wide range of precipitation totals were observed from
last night`s system, with less than a quarter of an inch in the
greater Sacramento area, less than an inch elsewhere in the
Valley, but well over an inch in Redding and over the mountains.
Snow reports have been relatively impressive, with 4 to 8 inches
being reported over trans-Sierra passes, and upwards of a foot
over the highest peaks.
Expect mostly benign weather today under the influence of the weak
upper ridge. Drizzle has largely stopped, but low level clouds of
the forecast area through late morning or early afternoon.
Temperatures today should be a bit warmer than the last few days,
but cloud cover may keep them below their maximum potential. Have
updated the forecast to tweak today`s forecast a bit.
The next low pressure system is evident on satellite imagery near
140W, and the first precipitation bands are expected to arrive
over far NorCal late tonight. Precipitation is generally expected
to remain north of Interstate 80 on Wednesday before spreading
southward Wednesday evening and Thursday morning. Compared to
yesterday`s system, this next one appears to have a more vigorous
associated surface front, and comparable moisture tap. Given the
track record of recent weather systems, we may include mention of
a slight chance of thunderstorms with the passing of the front
The upper trough shifts over the area Thursday continuing a
chance of showers with snow levels lowering to 5500 to 6500 feet,
then a more amplified ridge builds in for Friday and Saturday
leading to a return of dry and milder weather.
.Extended Discussion (Saturday through Tuesday)
Dry and unseasonably mild conditions continue into Saturday with
Valley highs reaching into the lower to mid 70s. Improving agreement
with extended models showing a shortwave moving through on Sunday.
Some of the moisture from Tropical Storm Faxai, currently located
east of Guam looks like it will be transported across the Pacific
into California. The 06Z GFS shows PW levels around 1.20 inches
extending inland during the day Sunday. Although dynamics look
limited, this could bring a decent amount of moisture into the
mountains. Mild temperatures with this tropical airmass should
mean high snow levels (around 8000 feet), though, so addition to the
snowpack would be limited. Monday looks less certain, with
potentially another wave bringing some more precipitation, if the
ECMWF is correct. The GFS is slower, and brings this wave in on
Widespread MVFR with areas of IFR and local LIFR from low cigs
and BR/-RA/-DZ this morning...improving to MVFR cigs after 20z and
VFR conditions high OVC late afternoon and evening. Freezing level
8000 ft MSL. RA returns later tonight spreading into the coastal
mountains after 06z...and into the nrn Sac vly by 12z Wed...and
into the I-80 corridor of the Sierra around 00z Thu.