California Apparel News

...Potential flooding later this week in the North Bay and Santa
Cruz Mountains due to Atmospheric River Event...
A late season storm system with unseasonably high moisture
content will bring periods of rain, possibly heavy at times, to
the San Francisco Bay Area and Monterey Bay Area later this week.
Light rain is forecast to develop in the North Bay by Thursday
afternoon. Rainfall is then expected to spread south across the
rest of the San Francisco Bay Area and into the Monterey Bay Area
late Thursday and Thursday night. Rainfall intensity through
Thursday night is expected to be light to moderate.
Rainfall intensity is forecast to increase on Friday and rain
rates could be heavy at times by Friday afternoon. Periods of
heavy rain are then possible through Friday night and into early
Saturday morning. Rainfall is expected to taper off by midday
Saturday. Rainfall totals from late Thursday through midday
Saturday are forecast to range from 2 to 4 inches across the North
Bay, except 4 to 6 inches in the North Bay Mountains. Rainfall
totals forecast for the Santa Cruz Mountains are also in the 4 to
6 inch range. Local amounts of more than 6 inches are possible in
the wettest locations of the North Bay Mountains and Santa Cruz
Mountains.
Based on current rainfall projections, mainstem rivers such as the
Russian River and Napa River are forecast to see significant
rises late this week and into the weekend, but remain well within
their banks. However, smaller rivers and streams could flood,
especially if heavy rain rates persist across a watershed longer
than anticipated. Flooding would be most likely in low lying and
flood prone areas. In addition, heavy rain rates across the North
Bay burn scars could trigger flash flooding or mudslide/debris
flows across and downstream from the burn scars. Outside of the
burn scars, widespread landslides are not expected from this
event. This is because there has been a sufficiently long period
of time since the last rain event for drying to occur. However,
localized landslides or rockslides may still be possible outside
of burn scar areas, especially in areas of steep terrain.
Persons living near rivers and streams or other flood prone areas
should be alert for the possibility of flooding during this
Atmospheric River event late in the week. Flood watches may be
issued once forecast confidence concerning rainfall amounts
increases, especially if subsequent forecast models indicate
higher rainfall totals or more intense rain rates. Please stay
tuned to bulletins from NWS, NWS social media (NWSBayArea), or
from other sources of local weather information.

SERIES OF STORM SYSTEMS TO ARRIVE IN CALIFORNIA
BEGINNING AS EARLY AS THURSDAY, MARCH 3, THE BAY AREA`S PREVIOUS
MID-WINTER DRY SPELL WILL MAKE AN ABOUT-FACE INTO A PREDOMINANTLY
WET PATTERN. RAINFALL ON THURSDAY WILL BE LIGHT, WITH ACCUMULATION
GENERALLY WELL LESS THAN AN INCH AND MOSTLY CONCENTRATED FROM THE
SANTA CRUZ MOUNTAINS NORTHWARD. BY FRIDAY MORNING ONLY THE SANTA
CRUZ MOUNTAIN AND THE COASTAL MOUNTAINS OF SONOMA COUNTY MAY
RECEIVE RAINFALL IN EXCESS OF AN INCH. AGAIN, LIGHT RAIN IS
EXPECTED THROUGH FRIDAY, BUT RAINFALL INTENSITY IS EXPECTED TO
INCREASE IN THE OVERNIGHT HOURS. TOTALS FOR THE 24-HOUR PERIOD
BEGINNING FRIDAY AT 4AM LOCAL EXTENDING TO SATURDAY 4AM ARE LIKELY
TO REACH 1-2 INCHES IN COASTAL MOUNTAINS THROUGHOUT THE SERVICE
AREA, INCLUDING THE SANTA LUCIAS IN MONTEREY COUNTY. A
CONTINUATION OF INTENSE RAIN WILL FOLLOW, WITH SEVERAL MORE INCHES
FALLING OVER SATURDAY AND SUNDAY, AGAIN CONCENTRATED IN COASTAL
RANGES. SIX-DAY TOTALS, EXTENDING FROM WEDNESDAY MARCH 2 THROUGH
EARLY TUESDAY MORNING, SHOULD YIELD 4-7 INCHES IN COASTAL
MOUNTAINS AND 1-3 INCHES IN VALLEY FLOORS AND INLAND AREAS.
UNCERTAINTY REMAINS ON THE SPECIFICS OF WEATHER PATTERNS FOR NEXT
WEEK. ALTHOUGH MOST MODELS AND FORECASTER INPUT SUGGEST CONTINUED
WET WEATHER THROUGH NEXT WEEK, THE EXACT TIMING, LOCATION, AND
AMOUNT REMAIN UNCERTAIN. WITH WET WEATHER EXPECTED FOR NEXT WEEK,
FOLLOWING SEVERAL INCHES OF RAIN OVER THE WEEKEND, RAIN WILL
LIKELY BE FALLING ON NEAR-SATURATED TO SATURATED SOILS. THUS
WATERSHEDS WILL BE PRIMED TO QUICKLY CONVERT RAIN INTO RUNOFF AND
WILL ALSO HAVE THE POTENTIAL TO GENERATE DEBRIS FLOWS AND
LANDSLIDES IN SATURATED AREAS WHERE RAINFALL RATES EXCEED 1-INCH
PER HOUR.
IMPACTS ASSOCIATED WITH THE RAINFALL EXTENDING THROUGH THE WEEKEND
WILL LIKELY BE LIMITED TO URBAN FLOODING IN AREAS WHERE STORM
DRAINS BECOME CLOGGED OR OVERWHELMED BY RUNOFF DURING INTENSE
BURSTS OF RAIN. LOW LYING AGRICULTURAL AREAS MAY ALSO EXPERIENCE
PONDING AND RUNOFF MAY ENTER ROADWAYS ADJACENT TO POORLY DRAINED
FIELDS. THE EXTENT TO WHICH CREEKS MAY JUMP THEIR BANKS WILL
LARGELY DEPEND ON THE INTENSITY OF RAINFALL: INTENSE BURSTS
SEPARATED BY LIGHT RAIN OR REPRIEVES MAY PROVIDE INITIALLY DRY
WATERSHEDS TO INFILTRATE RAINFALL AND CONTAIN RUNOFF WITHIN
CHANNELS. PROTRACTED INTENSE RAIN, WHICH IS POSSIBLE (AND APPEARS
LIKELY OVER THE WEEKEND), MAY CAUSE SOME FAST RESPONDING BASINS TO
FLOOD. EXAMPLES OF THIS TYPE OF BEHAVIOR ARE LIKELY TO OCCUR IN
VALLEY SETTINGS OF THE NORTH BAY, PARTICULARLY IN THE PETALUMA
BASIN, AND THE VALLEY FORD, BODEGA, AND BLOOMFIELD AREAS FED BY
STEMPLE CREEK, SALMON CREEK, AND THE ESTERO AMERICANO. THE LOWER
LAGUNA DE SANTA ROSA MAY ALSO EXPERIENCE ROUTINE FLOODING AND
DRAINAGE IMPACTS. QUICK URBAN DRAINAGE IN THE SANTA CLARA VALLEY
CREEKS THAT ORIGINATE IN THE SANTA CRUZ MOUNTAINS MAY ALSO
EXPERIENCE PROBLEMS. NOTABLY, WE WILL BE WATCHING THE LOS GATOS-
GUADALUPE BASIN CLOSELY, AS WELL AS UPPER LLAGAS, SARATOGA,
STEVENS, PERMANENTE, AND OTHER INTERVENING LOCAL DRAINAGES.
HOWEVER, MOST CREEKS AND RIVERS IN THE SERVICE AREA WILL REMAIN
BELOW FLOOD LEVELS, BASED ON THE EXPECTED RAINFALL RATES DESCRIBED
HERE. SHOULD RAINFALL FORECASTS INCREASE, THIS STORY MAY CHANGE,
SO PLEASE STAY TUNED TO UPDATES FROM THE SAN FRANCISCO BAY AREA
NWS OFFICE.
PLEASE STAY TUNED TO LOCAL MEDIA OUTLETS AND OUR OWN NWS SOCIAL
MEDIA ACCOUNTS AND WEB PAGE FOR ADDITIONAL AND UPDATED INFORMATION
PRECEDING AND DURING THE STORM. AND PLEASE STAY SAFE!