Graphic for MPD #0013
 
MESOSCALE PRECIPITATION DISCUSSION 0013
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
439 AM EST TUE JAN 10 2017
 
AREAS AFFECTED...NORTHWEST CA...EXTREME SOUTHWEST CORNER OF ORE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 100938Z - 102138Z
 
SUMMARY...ANOTHER PLUME OF MOISTURE OVER THE EASTERN NORTH PACIFIC
WILL BE APPROACHING NORTHERN CA AND FAR SOUTHWEST CORNER OF OREGON
THROUGHOUT THE MORNING.  THERE WILL BE INCREASING MOISTURE
TRANSPORT INTO THE REGION LEADING TO INCREASING COVERAGE AND
INTENSITY OF RAINFALL ACROSS THE REGION. 

DISCUSSION...INCREASING LOW LEVEL WINDS AHEAD OF AN AREA OF LOW
PRESSURE AT THE SURFACE WILL CONTINUE TO DRAW A SURGE OF PACIFIC
MOISTURE WITH A SUBTROPICAL CONNECTION TOWARDS THE COAST OF
NORTHWEST CALIFORNIA THIS MORNING AND EARLY AFTERNOON. 
PRECIPITABLE WATER STANDARDIZED ANOMALIES APPROACHING +2 WILL BE
DRAWN TOWARD THE COAST AND THEN INLAND BY 850 MB WINDS WHICH
ACCELERATE TO BETWEEN 35 AND 50 KTS.  WHILE THE ORIENTATION OF THE
LOW LEVEL FLOW WILL NOT BE EXACTLY NORMAL TO THE
TERRAIN...OROGRAPHICALLY ENHANCED LIFT AND PRECIPITATION IS STILL
EXPECTED TO AID RAINFALL RATES/AMOUNTS ACROSS NORTHERN CA.  DEEP
LAYERED ASCENT WILL BE SUPPORTED BY AN UPPER LEVEL COUPLED JET
STRUCTURE WHICH SHOULD BE MOVING IN AFTER 15Z TODAY.  

GIVEN THE WET ANTECEDENT CONDITIONS AND MODEST INSTABILITY...THERE
WILL BE THE POTENTIAL FOR SOME FLASH FLOODING ESPECIALLY IN AREAS
OF BURN SCARS OR OTHER SUSCEPTIBLE AREA. UNLIKE THE EVENT A COUPLE
OF DAYS AGO...SNOW LEVELS HAVE COME DOWN WHICH SHOULD LIMIT THE
AREAL COVERAGE OF ANY EXCESSIVE RAINFALL. 

THE LATEST HI-RES GUIDANCE IS INDICATING 1 TO LOCALLY 3 INCHES OF
RAINFALL BY 18Z TUESDAY WITH SOME ADDITIONAL RAINFALL AFTER THIS
TIME.  THE HIGHEST AMOUNTS ARE EXPECTED FOR PARTS OF THE SISKIYOU
AND SHASTA RANGES DOWN TOWARDS MT SHASTA.  IN ADDITION...RAINFALL
RATES WILL BE INCREASING LATER THIS MORNING AND EARLY AFTERNOON
ACROSS PARTS OF THE NORTHERN SIERRA NEVADA RANGE.  

BANN

ATTN...WFO...EKA...MFR...STO...

ATTN...RFC...CNRFC...NWRFC...

LAT...LON   42662400 42562364 41322319 40362312 39492296 
            38972366 40672468 42292482 


Last Updated: 439 AM EST TUE JAN 10 2017