FXUS66 KHNX 171120
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
320 AM PST Sun Dec 17 2017
High pressure will build in over the Great Basin over the next
several days with offshore flow and dry conditions over Central
California. Continued above normal afternoon highs and cool
mornings through Tuesday. A strong cold front will push across the
region on Wednesday with gusty winds. Cold temperatures and
continued dry conditions are expected Thursday through next
The passage of a dry cold front through the region allowed for a
change of air-mass over Central California. Winds will continue to
be the main focus this morning as good mixing of the atmosphere
has allowed for better overnight visibility reports from across
the San Joaquin Valley. Currently, the location of the upper low
near the northern end of the Gulf of Baja California may not allow
for very strong winds near Yosemite overnight. Yet, a chance
still exist of having breezy over the Sierra Nevada Crest in the
short term. Therefore, while the threat of a Mono Wind Event is
not likely, breezy conditions are still possible over the higher
terrain as observed on upper air data.
While the cold frontal passage was dry, the change in wind
direction toward a more northerly flow has lowered the fire
threat due to low humidity values. The increase in overnight
humidity recovery is only slight as the lack of precipitation will
allow for some lowering of values in the coming days. Short range
models progging the continuation of the northerly to almost
northeasterly flow aloft that will keep humidity hovering on the
drier side. Yet, the dominating ridge pattern offshore is prog to
weaken as a significant storm drops from the Gulf of Alaska toward
the middle of the week.
By Tuesday morning, models show a good westerly flow developing
that could introduce a fetch of moisture into the region. While
models do shift moisture westward by the middle part of the week,
moisture transport progs show the amount diminishing as it shifts
toward Central California. Therefore, will not expect significant
precipitation during the passage of the next cold front. Yet,
humidity is expected to rise as the fire danger lowers across the
district. However, as with the current cold frontal passage, cold
overnight temperatures could be observed around the sunrise hours.
While the current atmosphere may allow for the development of
early morning frost, temperature progs are still indicating a
possible hard freeze by Thursday and Friday mornings. Based on the
trend of little to no precipitation, will favor a minimal
rain/snow event solution. In addition, the lack of significant
precipitation during the next cold frontal passage will increase
the confidence toward a hard freeze solution in the extended
Strong northeast winds of 35 knots or greater will continue along
the Sierra crest through 00z Monday. Otherwise, VFR conditions will
prevail across the central California interior during the next 24
.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.