Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
200 PM PDT Monday Sep 15 2014
high pressure aloft will continue the hot weather through Tuesday
with isolated thunderstorms over the mountains...foothills and parts
of the inland Empire...mainly in the afternoons. Moisture from
Hurricane Odile will increase from the southeast and bring a better
chance of thunderstorms Wednesday into Thursday with locally heavy
rainfall possible Wednesday. There will also be cooler but humid
weather. There is a slight chance of thunderstorms Friday over the
mountains and deserts...then partly cloudy weather with seasonal
temperatures will occur over the weekend as an area of low pressure
moves in from the Pacific.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Cumulus clouds developed over the mountains and foothills late this
morning and early this afternoon...but no thunderstorms have formed
yet. There is a cap around 600 mb which so far have limited tstorm
development...but there is a slight chance that convection could
make it through the cap and form isolated thunderstorms through
early evening. Precipitable water values were mostly around 1.4
inches at the coast and in the lower deserts. Temperatures over 100 degrees
covered the inland Empire...inland Orange County and the far inland
San Diego County valleys/foothills...and of course the lower deserts.
Hurricane Odile is currently over southern Baja California California...near
26n/112w and is weakening due to the over-land trajectory. The
trajectory has trended further east in the past 24 hours...with the
center of the storm headed towards the Gulf of California and northwest
Sonora. Despite this trajectory further east...we should have
reasonable amounts of moisture...with around 1.5 to 1.75 inches of
precipitation water near the coast and possibly around 1.75 to 2 inches in
the deserts. With light flow aloft...strong surface-based cape and
surface convergence over our area...there could be thunderstorms
with locally heavy rains which could produce local flash flooding
mainly Wednesday. However...models are trending downward with
precipitation...and GFS and ecm are not showing much precipitation at all.
Also...I have removed precipitation chances near the coast and coastal
waters due to limited elevated cape there and lack of dynamics.
Chances are decent though along the Elsinore convergence zone in the
inland Empire. For Thursday...the flow turns more westerly...so
thunderstorms will more likely be restricted to the
mountains/deserts...with GFS/ecm basically dry versus the wetter
NAM. Will opt out of the Flash Flood Watch for Wednesday due to downward
trend in moisture. It will be cooler but more humid Wednesday...so heat
index values may only be a few degrees lower Wednesday versus Tuesday. Further
cooling will occur Thursday with maximum temperatures possibly near normal Thu/Fri.
Upper level low pressure will approach from the west over the
weekend...but some residual moisture will bring partly cloudy
conditions. Temperatures will probably not drop much partly due to all the
warm sea surface temperatures around.
152000z...mostly unrestricted visible through Tuesday morning. There is
a small chance that low clouds/fog could form within 5 sm of the
coast during the 16/0500-1500 UTC time-period...but confidence is
too low to include in the tafs. Through 16/0300 UTC
time-frame...sct-bkn clouds at or above 8000 feet mean sea level with isolated
thunderstorms/showers may develop over the
mountains...deserts...eastern San Diego valleys and the inland
Empire. Thunderstorms may produce small hail...gusty/erratic winds
and lowered visible due to heavy rain. Cumulonimbus tops to 35000 feet mean sea level possible.
100 PM...no hazardous marine weather expected through Saturday.
California...heat advisory until 7 PM PDT Tuesday for the Orange County
coastal areas...San Bernardino and Riverside County
valleys-the inland Empire...San Diego County valleys...
Santa Ana Mountains and foothills.