Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
FXUS66 KHNX 291030
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
330 AM PDT Sat Apr 29 2017
Gusty downsloping winds are expected over parts of the Sierra and
foothills this early Saturday morning. Lighter winds, warming
temperatures and dry weather will then prevail this weekend into
early next week as high pressure strengthens over the region.
Strong winds lingering over the region this morning as Friday`s
disturbance continues to move eastward. Before pushing eastward,
the disturbance managed to produce wind gusts in excess of 40 mph
across the San Joaquin Valley Friday afternoon. At this point,
strong winds will be confined to higher elevations, mainly the
Sierra Nevada, during the early morning hours this Saturday. Short
range model upper-air analysis is showing 60-70 knot
northwesterly winds which will diminish to lower values during the
afternoon and evening hours. Therefore, support for this
morning`s winds are mainly surface based as surface pressure
gradients remain tight from Northern Nevada to South-Central
California. Yet, as the air-mass continues to modify, pressure
gradients will relax and allow for lighter winds tonight and the
rest of the weekend.
Beyond the current wind situation, the next major weather feature
to affect the region will be an East-Pac High. Initially,
temperatures will see a slow rise during the next few days. This
slow rise is due mainly to the upper level disturbances keeping
the ridge at bay. Models show the disturbances riding over the
ridge and through the Pacific-Northwest through at least Monday.
By Tuesday, the last weak disturbance pushes east and toward the
Northern Rockies as the ridge begins to amplify. At that point,
temperatures will begin a more significant rise to well above
climatology. Longer range models show the ridge pattern shifting
eastward during the week. By Wednesday, models prog the placement
of the ridge axis over the West Coast as warming peaks out.
Standardized Anomaly chart support this trend to well above
seasonal norms as they place the region under 2 positive standard
deviations during the mid-week period. Therefore, confidence is
high in raising temperatures some 10 to 15 deg-F above normal
before another disturbance approaches the region.
While models do agree on the development of a trof pattern latter
in the forecast periods, confidence in the timing is very low.
Will not introduce any mention of precipitation during the week
while uncertainty remains high. Currently, the ECMWF/Canadian and
Navy`s NOGAPS show the faster solutions while GFS lags behind.
Modified the weather forecast grids to reflect a more unsettled
pattern toward the end of the forecast cycle. At the moment, will
opt for the ECMWF solution of introducing the influence of the
disturbance during the day on Friday, with its passage during the
evening and into Saturday morning. Again, will wait for better
consensus of the longer range models before the any mention of
Surface wind gusts above 35KT are expected across the foothills
and higher elevations of the Sierra Nevada through 18Z Saturday.
Otherwise, VFR conditions and light winds will prevail across the
Central CA interior during the next 24 hours.
.AIR QUALITY ISSUES...
The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is medium.
Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.
Wind Advisory until 8 AM PDT this morning for the Mariposa,
Madera, and Fresno County Foothills along with the Sierra Nevada
from Yosemite to Kings Canyon /CAZ093-096/.