Scientific Forecaster Discussion
fxus66 khnx 262122
Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
222 PM PDT Fri may 26 2017
Synopsis...high pressure will build over the area this weekend
and bring dry weather, light winds and a day to day warming trend.
Isolated afternoon and early evening thunderstorms are possible
along the Sierra crest Saturday through Memorial Day.
Discussion...a deep marine layer pushed into the San Joaquin
Valley overnight and brought with it cooler temperatures today
(5-10 degree f below yday at most locations), and a stratus deck to
the valley and southern Sierra foothills which has persisted into
this afternoon across the Eastern Valley and the southern Sierra
foothills although noticable thinning has taken place. Some strato
cumulus has formed over the west side of the San Joaquin Valley
where the stratus deck eroded. The stratus deck is expected to
completely erode by late this afternoon, and any remaining strato
cumulus should dissipate this evening. With p-grads expected to
decrease tonight and the offshore marine layer expected to mix
out, do not expect low clouds to push into the valley on Saturday.
WRF indicating an upper ridge pushing into the western Continental U.S. On
Saturday which will bring a warming trend to our area as heights
and thicknesses rise. Temperatures will remain below normal on
Saturday most noticably over the San Joaquin Valley where marine
cooled air will persist. The ridge is progged to strengthen
Sunday and Memorial Day which will provide for continued warming
across the area with daytime temepratures expected to be near to
slightly above seasonal normals by Sunday and well above normal
by Memorial Day. The WRF has been indicating sufficient
instability and cape for isolated afternoon thunderstorms along
the crest of the southern Sierra Nevada each afternoon and early
evening during the Memorial Day weekend as melting snow will
provide for a moisture source.
The medium range models continue to indicate an upper trough
pushing into California on Tuesday. The operational GFS is showing a
closed low forming over norcal on Wednesday and dropping
southward over our area Wednesday night and Thursday. The European model (ecmwf)
and the ensemble means are not as deep with the upper low and will
lean toward the ec as it is continuing to show better ensemble
agreement. After another day of warmer the normal temperatures on
Tuesday, a noticeable cooling trend will take place will take
place on Wednesday and Thursday was the trough moves through.
Increased onshore flow and height falls will result in
temperatures cooling to near to slightly below seasonal levels.
A warming trend will follow at the end of next week as shortwave
ridging is anticiapted to follow for next Friday and into the
first weekend of June as the trough moves east of the region.
Relative humidity progs are not indicating much in the way of moisture during
the middle of next week so any precipitation will be confined
diurnal convection near and along the southern Sierra crest.
Aviation...VFR conditions are expected across the central California
interior during the next 24 hours.
Air quality issues...none.
The level of certainty for days 1 and 2 is medium.
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.