Scientific Forecaster Discussion
fxus66 ksgx 251031
Area forecast discussion
National Weather Service San Diego California
331 am PDT Tue Jul 25 2017
monsoonal moisture will continue the chance of afternoon and early
evening thunderstorms for today. Slow warming and drying for
Wednesday through Friday. For Saturday through early next
week...monsoonal moisture will return with slight inland cooling
and with a slight chance for mainly afternoon and early
thunderstorms...mostly for the mountains and deserts.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Higher precipitable water values remain across the deserts and
adjacent mounntain areas with water vapor imagery showing upper
level drying not too far to the west with that drying moving
slowly towards the east. Model soundings show that higher level
moisture decreasing during the late morning and afternoon with
instability a little greater than recent days with lifted index
values around -4 for the afternoon with steering level flow
slowly towards the north to northeast. Some thunderstorm
development is expected for this afternoon along the desert slopes
of the mountains and northeastward across the upper deserts. With
greater instability...thunderstorms today could be a little
stronger than recent days with locally heavy rainfall and isolated
flash flooding possible.
Slow drying and warming for Wednesday through Friday with high
temperatures warming from near average to near to slightly above
average as the axis of high pressure aloft expands westward across
northern baja. Decreasing moisture will lessen chances for
afternoon thunderstorms for Wednesday with some continuing
afternoon clouds near the mountains for Thursday and Friday.
For Saturday into early next week...the axis of the high pressure
moves slowly toward the north with easterly flow bringing a return
of some monsoon moisture into Southern California returning the
chance for afternoon and early evening thunderstorms to the
mountains and deserts with high temperatures a few degrees cooler.
251005z...coasts/valleys...stratus with bases 1500-2000 ft mean sea level
extending up to 20 miles inland should clear 16-18z. Stratus re-
developing after 26/01z and spreading up to 25 miles inland
overnight. Bases will remain around 1500-2000 ft mean sea level with tops to
2500 ft mean sea level. Otherwise scattered-broken cloud layers at or above 10000 ft mean sea level through
Mountains/deserts...iso-sct showers/thunderstorms developing over
the mountains and deserts after 19z. Bases will likely be 8000 ft
mean sea level with tops to 35000 ft mean sea level. Strong up/downdrafts and local gusty
surface winds will be possible near storms. Otherwise scattered-broken cloud
layers at or above 10000 ft mean sea level through this evening.
no hazardous marine weather is expected through Saturday.
a south swell generated by Hurricane Hilary may produce high surf
along south facing beaches Friday through early next week.
Confidence in forecast surf heights is low as this will largely
depend on the intensity and track of the hurricane over the next few
Skywarn activation may be needed for the mountains and deserts for