NOAA Hydrological Concerns

This is the current (as of 1/15/10 at 10 pm) hazardous outlook concerns regarding hydrology from NOAA:

AS THE FIRST AND WEAKEST SYSTEM MOVES THROUGH…ONLY LIGHTER RAIN IS EXPECTED FROM SATURDAY INTO THE MID MORNING HOURS ON SUNDAY WITHRAINFALL TOTALS LIKELY A HALF INCH OR LESS.

THE RAIN IS FORECAST TO INTENSIFY DURING THE DAY SUNDAY…INITIALLY ACROSS THE NORTH BAY AND THEN EXTEND SOUTHWARD. BY DAYBREAK ON MONDAY RAINFALL TOTALS ARE EXPECTED IN THE 1 TO 2 INCH RANGE WITH 3 INCHES A POSSIBILITY OVER THE COASTAL RANGES. THROUGH THIS TIME PERIOD THERE ARE NO CRITICAL HYDROLOGICAL CONCERNS OTHER THAN NUISANCE AND LOCALIZED FLOODING ON ROADWAYS AND LOW LYING AREAS. MANY SMALLER
STREAMS SHOULD START TO SHOW AN AMPLE RESPONSE TO THE RAINS BUT NO MAJOR FLOODING IS EXPECTED THROUGH MONDAY.

THE NEXT SYSTEM BRINGS HEAVY RAIN POTENTIAL ON MONDAY AND MONDAY EVENING WITH AN ADDITIONAL 1 TO 3 INCHES OF RAIN FORECAST. OF NOTE BY MONDAY NIGHT…FOR THE MOST PART SOILS SHOULD BE NEAR SATURATION AND ADDITIONAL RAIN COULD RESULT IN RAPID AND SUBSTANTIAL RISES ON
LOCAL STREAMS.

AFTER A BRIEF BREAK MONDAY NIGHT THE RAIN PICKS UP AGAIN ON TUESDAY THROUGH TUESDAY EVENING…THIS TIME A SLIGHTLY STRONGER SYSTEM. AN ADDITIONAL 1 TO 3 INCHES BY TUESDAY EVENING IS EXPECTED WITH 4 INCHES NOT OUT OF THE QUESTION.

MOST IMPORTANTLY…TUESDAY THROUGH FRIDAY IS WHEN HYDROLOGICAL CONCERNS BECOME THE MOST SERIOUS AND FLASH FLOODING ON MANY SMALLER STREAMS COULD BECOME A REALITY. BY THIS POINT THOUGH…THE MAIN STEM RIVERS SHOULD ALL STILL BE WELL WITHIN THEIR BANKS.

AFTER ANOTHER BRIEF BREAK TUESDAY NIGHT THE RAIN PICKS UP AGAIN ON WEDNESDAY WITH THE MOST SIGNIFICANT RAINFALL POTENTIAL STORM OF THE WEEK. THIS LARGER SCALE TROUGH IS FORECAST TO PERSIST OFF THE CALIFORNIA COAST UNTIL WELL INTO FRIDAY BEFORE HEADING INLAND. THIS COULD MEAN SEVERAL WAVES OF MODERATE TO HEAVY RAIN ACROSS CENTRAL CALIFORNIA DURING THAT TIME. RAINFALL TOTALS FOR WEDNESDAY THROUGH FRIDAY COULD EASILY REACH AN ADDITIONAL 3 TO 6 INCHES. THE WORST OF IT WOULD CONTINUE TO BE EXPECTED AROUND THE COASTAL RANGES.

THIS HYDROLOGIC OUTLOOK IS INTENDED TO UNDERSCORE A HAZARDOUS FLOOD SCENARIO THAT APPEARS TO BE DEVELOPING. ALTHOUGH NOT COMPLETELY CERTAIN AT THIS TIME WHAT LEVEL OF SEVERITY THIS WEEKS EVENTS WILL REACH…AT A MINIMUM CONFIDENCE IS HIGH THAT IT WILL BE SIGNIFICANT.

EVERYONE NEEDS TO SERIOUSLY PLAN FOR THEIR WEEK AHEAD. THIS IS THE STRONGEST STORM OF THE WINTER SO FAR AND IF YOU COMBINE THE RAIN POTENTIAL WITH THE VERY STRONG WINDS THAT MAY DEVELOP…CONDITIONS WOULD LIKELY BECOME SEVERE. PEOPLE LIVING NEAR RIVERS AND STREAMS OR
OTHER FLOOD PRONE AREAS SHOULD BE ALERT FOR THE POSSIBILITY OF FLOODING…PARTICULARLY OVER THE LAST HALF OF THE WEEK AHEAD. REMEMBER…IT TAKES AS LITTLE AS ONLY 1 FOOT OF MOVING WATER TO SWEEP AWAY A VEHICLE.