Special Weather Statement
... Cold storm with potential for mountain snow showers late Friday
night into Saturday...
The very warm and dry conditions occurring across the Southland today
will be short lived as a cold Pacific storm moves into California during
the next couple of days. The cold upper level low pressure system
will move into northern California on Friday... bringing a return
of onshore flow and cooler temperatures to southwest
California... especially north of Point Conception. The cold low
pressure system is then projected to slide southward towards
Southern California Friday night into Saturday.
There is still some uncertainty of the exact track of this cold
upper level low pressure system... which will have a significant
impact on the probability of rainfall and associated rainfall
amounts across our region. At this time... it appears that the
system will take a more over-land trajectory which would limit the
available moisture. However... there is still a slight chance this system
could take a more over-water trajectory which could bring an increased
threat of precipitation.
There is fairly high certainty this will be a cold storm system bringing
a rapid drop in temperatures to the entire region on
Saturday... with many areas expected to be over 20 degrees cooler
than today. The greatest threat of precipitation will be across
the mountains... where snow levels could fall as low as 4000 feet
on Saturday. As a result... there will be the potential for snow
across the upper portions of Interstate 5 near the Grapevine.
While the main system is expected to shift south and east of the
area on Saturday night... there is the chance of showers lingering
across north facing slopes... with snow levels expected to remain
around 4000 feet. There will be a smaller threat of precipitation
across coastal and valley areas. Any precipitation that does fall
with this system is generally expected to be light. However... if
this system does pick up more over-water trajectory... rainfall
amounts could be higher and there could even be a slight chance of
convective showers. Since the upper levels of the atmosphere will be
quite cold on Saturday... there will also be the potential for small
hail.
Behind this system... there will be a return of gusty northeast winds
across Southern California Sunday into Monday. Initially... the air mass
is expected to remain rather moist Sunday morning... but a drying
trend is expected later Sunday into Monday. While there will be heightened
fire weather concerns with this offshore event... it is still
unclear if weather and fuel conditions will reach critical red
flag thresholds.
Gomberg/Wofford
1235 PM PST Thu Nov 26 2009
... Cold storm with potential for mountain snow showers late Friday
night into Saturday...
The very warm and dry conditions occurring across the Southland today
will be short lived as a cold Pacific storm moves into California during
the next couple of days. The cold upper level low pressure system
will move into northern California on Friday... bringing a return
of onshore flow and cooler temperatures to southwest
California... especially north of Point Conception. The cold low
pressure system is then projected to slide southward towards
Southern California Friday night into Saturday.
There is still some uncertainty of the exact track of this cold
upper level low pressure system... which will have a significant
impact on the probability of rainfall and associated rainfall
amounts across our region. At this time... it appears that the
system will take a more over-land trajectory which would limit the
available moisture. However... there is still a slight chance this system
could take a more over-water trajectory which could bring an increased
threat of precipitation.
There is fairly high certainty this will be a cold storm system bringing
a rapid drop in temperatures to the entire region on
Saturday... with many areas expected to be over 20 degrees cooler
than today. The greatest threat of precipitation will be across
the mountains... where snow levels could fall as low as 4000 feet
on Saturday. As a result... there will be the potential for snow
across the upper portions of Interstate 5 near the Grapevine.
While the main system is expected to shift south and east of the
area on Saturday night... there is the chance of showers lingering
across north facing slopes... with snow levels expected to remain
around 4000 feet. There will be a smaller threat of precipitation
across coastal and valley areas. Any precipitation that does fall
with this system is generally expected to be light. However... if
this system does pick up more over-water trajectory... rainfall
amounts could be higher and there could even be a slight chance of
convective showers. Since the upper levels of the atmosphere will be
quite cold on Saturday... there will also be the potential for small
hail.
Behind this system... there will be a return of gusty northeast winds
across Southern California Sunday into Monday. Initially... the air mass
is expected to remain rather moist Sunday morning... but a drying
trend is expected later Sunday into Monday. While there will be heightened
fire weather concerns with this offshore event... it is still
unclear if weather and fuel conditions will reach critical red
flag thresholds.
