Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
139 PM PDT Wednesday Jul 1 2015
favorable conditions will continue the possibility of isolated to
scattered showers and thunderstorms through this afternoon. Heavy
downpours...gusty winds and frequent lightning strikes are
expected near storms. Otherwise...humid conditions will continue
with warm weather today. Precipitation chances will lower Thursday
and Friday as drier air moves into the region. Dry and more
seasonal high temperatures will end the week...with a slow return
of coastal/valley night/morning low clouds over the weekend and
early next week.
..for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
At 1 PM PDT...water vapor satellite imagery displayed an upper-
level high stretching from central Nevada to northwest New Mexico...and
an upper-level low around 500 miles SW of San Diego. Composite
radar showed scattered showers and thunderstorms moving west-
northwest across the High Desert.
Moist monsoonal flow...diurnal heating and a weak upper-level
disturbance moving across the region will continue the chances of
showers and thunderstorms across most of the region today. Increased
middle and upper-level cloud cover has limited storm development over
and west of the mountains. However...the weak upper-level wave
forecast to traverse the region this afternoon and some breaks in
the clouds are expected to create help generate isolated to
scattered showers and thunderstorms across most areas through
early this evening. Recent high-res models runs have backed off
slightly on precipitation development this afternoon...but do
continue the possibility of isolated to scattered showers and
thunderstorms this afternoon. The main threats near strong
thunderstorms will be gusty winds and lightning. High precipitable
water values will help generate heavy downpours at times.
Although...fast storm speed will limit widespread flash flooding. The
best chances for precipitation will be over the mountains and High
Desert today. Another weak wave will create a slight possibility
of showers/thunderstorms over the region tonight.
The upper-level high will begin to shift south on Thursday and
switch middle-level flow from southeast to more southerly. This will start
to dry the atmosphere over SW California...and mainly limit slight chance
of afternoon thunderstorms to the mountains and high deserts
Thursday and Friday. The upper-level high will eventually sag
south over the weekend into early next week. This will shift flow
aloft to west/southwest...creating seasonal dry weather with near
normal highs and night/morning low clouds over the coast and
012008z...bkn-ovc cloud decks within the 10000-30000 feet mean sea level layer
throughout the area...with scattered-to-numerous showers/isolate
thunderstorms over the high deserts moving off to the west by 2200
UTC...while thunderstorms/showers possibly develop over the mountains and
valleys through the 02/0100 UTC time-period. There is a chance for
some storms making it into the coastal areas this afternoon...while
the lower deserts experience primarily dry conditions and
unrestricted visible. Thunderstorm cumulonimbus tops to 40000-45000 feet mean sea level.
Thunderstorms could produce locally heavy rain and strong downdraft
winds. Local visible at or below 5sm possible under heavy rain. Lessening
chances for thunderstorms/showers 02/0100-1800 UTC. Chance that
patchy stratus/fog...with bases 400-800 feet mean sea level and tops around 1000
feet mean sea level...could form within 10-15 sm of the coast during the 02/0900-
1500 UTC time-period...but confidence is low on occurrence.
Elsewhere...clouds becoming scattered-few in the 10000-30000 feet mean sea level layer
from east to west with primarily unrestricted visible during that time-
West winds 15-25 knots with gusts 30-35 knots over mountain
ridges...through/below canyons/passes and into adjacent desert areas
will produce moderate-strong uddfs/low level wind shear over and east of the mountains after
108 PM...slight chance for showers and thunderstorms over the
coastal waters through early evening as an upper level disturbance
moves over the region from the east. Otherwise...no hazardous
weather is expected through Monday.
108 PM...there is a chance that some thunderstorms could develop and
move over the beaches from time to time today...mainly during the
afternoon and early evening hours. Thunderstorms can produce
dangerous lightning strikes at the beaches.
Skywarn activation is requested for all areas for today. Spotters
are requested to send any reports of severe weather to the
National Weather Service or via County Skywarn nets.