Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
FXUS66 KHNX 301100
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
400 AM PDT MON MAY 30 2016
.SYNOPSIS...A low pressure system moving east of the area today
will provide for isolated afternoon thunderstorms near the Sierra
Crest. Otherwise dry weather will prevail over the area through
Friday as a strong ridge of high pressure aloft builds over the
state. Temperatures will average well above normal Tuesday through
.DISCUSSION...WV imagery indicating the upper low that was
responsible for the mountain convection the previous two
afternoons is now moving east into Arizona this morning as large
dry upper ridge builds into the western CONUS. Offshore flow at
the mid levels around the departing low may provide for enough
mid level moisture for isolated showers and thunderstorms near
the Southern Sierra crest this afternoon where CAPE and
instability should be sufficient enough for convection. Once
again, some debris clouds from any convection over the Southern
Sierra Nevada could move over the foothills and eastern San
Joaquin Valley as the steering winds remain from the east.
SREF and the 06Z WRF indicating the large ridge will strengthen
over our area tonight and Tuesday resulting in our warmest
afternoon temperature readings across our area so far in 2016 as
a result of increasing heights and diurnal thicknesses in a dry
atmosphere. The 00Z ECMWF (which handled the departing low better
than the other models did) is indicating 850 MB temperatures
between 23 and 25 DEG C over the San Joaquin Valley by 00Z Wed
with the 00Z GFS, 00Z GEM and 06Z WRF running only 1 DEG C lower.
This corresponds to widespread triple digit heat across the
valley by Tuesday afternoon.
Meanwhile, continued warming on Wednesday (850 MB temepratures
rise by another 1-2 DEG C) and rises in heights and thicknesses
will result in even warmer afternoon readings across our area
with afternoon highs expected to be well into the triple digits
across most of the San Joaquin Valley, southern Sierra foothills
and the Kern County Deserts.
The medium range models are indicating the ridge will slowly push
inland during the mid-week period with a continuation of the hot
daytime temperatures and dry conditions through late week. The
rising temepratures aloft will result in a capping inversion which
will inhibit diurnal convection over the Southern Sierra Nevada by
Tuesday and this inversion will only strengthen through the mid-
week period so do not expect much in the way of mountain
convection in our area after today until next weekend when an
upper low approaches the Socal coast and possibly pulls up and
spreads some mid/upper level tropical moisture our way. While the
models are in fairly good agreement with this upper low
approaching Socal by next Saturday and move it across Socal by
the end of next weekend, mid level dew points are not progged to
be high enough for convection to take place with out a good
lifting mechanism so will confine precipitation chances next
weekend to a slight chance near the Southern Sierra crest for
now. With the inclusion of increased mid/upper moisture by the
end of this week and airmass cooling expected toward the end of
the period as the low moves south of our area, have trended
temperatures toward seasonal normals by early next week.
Local MVFR ceilings are possible in isolated showers and thunderstorms
over the higher elevations of the Sierra between 19z today and 04z
Tuesday. Otherwise VFR conditions will prevail throughout the central
California interior during the next 24 hours.
.AIR QUALITY ISSUES...ON MONDAY MAY 30 2016... Unhealthy for
sensitive groups in Fresno... Kern and Tulare Counties. Further
information is available at Valleyair.org
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.