Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 051051
Area Forecast Discussion
National Weather Service Sacramento CA
351 AM PDT THU MAY 5 2016
An upper level disturbance will keep chances for showers and
thunderstorms across our region through the rest of this week.
.Short Term Discussion...
Between now and the weekend, interior NorCal weather will be
dominated by a closed low that gradually moves from the West Coast
into the Great Basin region before weakening and pushing farther
eastward early next week.
Today and Friday will probably be two of the more active weather
days this week as the center of the low tracks just south of our
CWA border. Current radar (3:30 am) is pretty quiet right now for
our region. However, the HRRR and HRRRX models both indicate that
shower/thunderstorm development will become more active as the day
progresses. The HRRR initially has shower activity over the
Coastal Range and Sierra this morning before moving into the
valley by afternoon. The HRRRX (experimental HRRR) shows some
shower activity this morning across the northern Sacramento Valley
and surrounding terrain before spreading across other areas in our
CWA. The regular HRRR model seems to have a better handle on the
pattern development for today since it shows no activity now which
is verified by current radar while the HRRRX shows that showers
should be in the valley right now.
As for impacts the next few days, residents should be aware that
periods of moderate to heavy rain could occur in showers along
with thunderstorms that could produce small hail and gusty winds.
If driving, slow down immeadiately in showers to avoid spinouts.
If you hear thunder, take shelter to stay safe in thunderstorms.
As for higher terrain, a couple of inches of snow may occur over
the pass along Highway 88 this evening but the other major passes
should be OK for travel from snow.
.Previous Discussion...On Friday the center of the low will move
into Southern California with wrap around moisture continuing
showers over the northern part of the state. At this time it looks
like a shortwave will rotate around the top of the low westward
and into the Sacramento valley. Friday still looks unstable enough
for thunderstorm activity. Temperatures will cool into the low to
mid 70s in the valley and mainly in the 50s for the mountains
Thursday and Friday.
Saturday the center of the low looks to be near the southern
Nevada area and will continue to bring more wrap around moisture
into the area. Little change in daytime high temperatures is
expected for Saturday.
By Sunday, the low will be well east of our CWA and most of the
shower activity will be across the western Sierra slopes and
daytime highs will start a warming trend. JBB/RB
.EXTENDED DISCUSSION (Monday THROUGH Thursday)
Forecast models are in good agreement to the overall upper level
flow pattern in the long term period with a shortwave trough feature
depicted to push southward out of the Pacific northwest through
portions of NorCal. This upper level disturbance will bring some
chances for showers and storms, mainly for the mountains, for Monday
and Tuesday. Models are hinting at some instability in the
atmospheric profile, so a rumble of thunder cannot be ruled out.
However, decided to not include thunder at this time due to
scattered nature of instability between the forecast models.
An upper level ridge will build into California from the eastern
Pacific by Wednesday. As a result of more stable conditions, warm
and dry weather will return to the forecast area. High temperatures
will return to above normal values in the mid to upper 80s to low
90s across the valley, and the mid 50s to lower 60s for the higher
VFR conditions are expected at the terminals for the next 24 hours.
A large upper level storm system will continue to bring overcast
conditions and chances for showers and thunderstorms to the
terminals during the current TAF period. Wind shifts could be
erratic in thunderstorms near the airports, but generally surface
winds should remain in the southerly direction.