859 
fxus66 khnx 191632 
afdhnx 


Area forecast discussion 
National Weather Service San Joaquin Valley - Hanford California 
932 am PDT Friday Mar 19 2010 


Synopsis... 
a ridge of high pressure along with above normal temperatures and 
dry conditions will prevail through the week and continue through 
the weekend. 


&& 


Update...first few visible satellite pics showing clear skies 
over the region with Thursday weather disturbance now over 
Arizona. Behind the trough...may see slightly cooler conditions 
today as the area remains under a northerly flow aloft. Models 
show the ridge axis shifting back over the state tonight into 
Saturday. 24 hour temperature change charts only showing a few 
degree-f cooler today. This should allow afternoon temperature/S to remain 
near Thursday/S levels. Will see better warming on Saturday and 
possibly Sunday. Surface pressure gradients from sfo to las have 
died off in the Post-trough environment which should only give the 
district light winds. Upper air observations from Reno...desert 
rock and Vandenburg continue to show a dry and stable atmosphere. 
All three soundings all show a cooling at the low levels which 
should support the cooling over the district today. No significant 
changes to the forecast needed this morning. 


&& 


Previous discussion... /issued 125 am PDT Friday Mar 19 2010/ 
a weak upper-level trough was moving out of the Kern County 
deserts this morning. Despite forecasted good convective 
parameters over the southern Sierra Nevada...the dynamics 
associated with this trough did not break the capping 
inversion...and there were no thunderstorms over the mountains. 
The trough did bring locally gusty winds and light rain to the 
Indian Wells Valley and the eastern Kern County desert. Both 
Edwards AFB and Ridgecrest reported traces of rain Thursday 
evening. 


The trough is forecast to be over the Rocky Mountains by 00z 
Saturday...allowing an upper-level east Pacific Ridge to move to the 
California coast. Behind this ridge is another trough...with its 
associated low forecast to reach 40n/140w by 00z Saturday. This low 
is forecast ride up the back side of the ridge...pushing it inland 
Friday night and weakening the ridge Saturday. The low is forecast 
to be over the Queen Charlotte islands by 00z Monday...with the 
trough moving onshore into the Pacific northwest. 


As the trough moves onshore...the ridge will be pushed east into The 
Four-Corners area. 500-mb heights over the Hanford warning/forecast 
area are forecast to fall from 5760 meters at 00z Sunday to 5700 
meters at 00z Monday...and to around 5670 meters by 00z Tuesday /or 
even lower if the 12z European model (ecmwf) is correct/. The models continue to 
forecast a low to close off in the base of the trough Sunday...with 
the low dropping south Monday and into Baja California California Tuesday. This 
creates a split flow pattern over California Sunday and Monday... 
but the northern branch digs south through Utah Monday night... 
reabsorbs the southern low Tuesday and moves over The Four-Corners 
region Wednesday. 


&& 


Aviation... 
the combination of an upper level disturbance and strong high 
pressure in the Great Basin will provide moderate offshore winds 
through Friday morning. Strong gusty NE winds will affect higher 
elevations of the Sierra and east to west oriented canyons of the 
southern Sierra through 18z Friday. Otherwise...VFR conditions will 
prevail across the central California interior through 18z Saturday. 


&& 


Air quality issues...none. 


&& 


Hnx watches/warnings/advisories...none. 


&& 


$$ 


Public...Molina 
AVN/fw...mv 
synopsis...wp 


Weather.Gov/Hanford