MESOSCALE PRECIPITATION DISCUSSION 0003
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
406 AM EST WED JAN 06 2016
 
AREAS AFFECTED...CENTRAL COASTAL CALIFORNIA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 060906Z - 061506Z
 
SUMMARY...NARROW BAND OF CONVECTION WITH RATES UP TO .75"/HR FOR
ISOLATED FLASH FLOODING CONDITIONS PARTICULARLY OVER BURN SCARS. 

DISCUSSION...VIGOROUS UPPER LEVEL PATTERN WITH ELONGATED/STRONG
SHEAR AXIS EXTENDING EASTWARD FROM OCCLUDED CYCLONE NEAR 42N134W
WITH STRONG UNDERCUTTING FLOW WITH STRONG COLD
ADVECTION...INDICATED WELL BY NUMEROUSLY SCATTERED POLAR CELLS
BEHIND WELL DEFINED COLD FRONT.  WITH COLD ADVECTION ALOFT A
FORWARD TILTING FRONTAL ZONE WILL SUPPORT ENVIRONMENT FOR
PRE-FRONTAL CONVECTION TO BECOME DEEPER WITH MID-LEVEL LAPSE RATES
IN THE -7 TO -8 RANGE FOR MORE ROBUST RAINFALL PRODUCTION. STRONG
UPPER LEVEL JET UP TO 100 KTS PER SATELLITE DERIVED WINDS IS WELL
ORIENTED UPSTREAM OF THE DISCUSSION REGION FOR STRONG LEFT EXIT
REGION ASCENT TO COMPOUND ON THE INSTABILITY.  AT THE SURFACE...A
NARROW WEDGE OF WARM SECTOR IS NOTED WITH A NARROW PLUME OF
MODERATE MOISTURE UP TO 1.0" PER BLENDED TPW LOOP.  RAP ANALYSIS
AND BUOY OBSERVATIONS SUPPORT 20-30 KT SFC/NEAR SFC SOUTHERLIES IN
THE WARM SECTOR...WITH STRENGTHENING 25-30KT WESTERLIES POST
FRONTAL TO PROVIDE SUFFICIENT LOW LEVEL MST CONVERGENCE FOR ASCENT
TO TAP UPPER LEVEL SUPPORT.  RECENT AMSU PASS (LIMB) SUPPORTS RAIN
RATES OF .15-.2"/HR THOUGH EARLIER PASSES OF .3-.4"/HR WOULD BE
MORE REPRESENTATIVE BUT WITH INCREASING LIGHTNING WITHIN THE BAND
NOTED...RATES ARE LIKELY NEARING THE .5"/HR.  OROGRAPHIC ASCENT
LIKELY TO INCREASE THIS LIFT FURTHER FOR UP TO .75"/HR.  TIMING OF
THE FRONT APPEARS TO BE ABOUT 10-11Z NORTH OF SAN FRANCISCO BAY
AND 12-13Z ALONG MONTEREY BAY...AND SLIDING SOUTH TOWARD SAN LUIS
OBISPO BY 15Z.  

HI-RES CAMS APPEAR TO BE IN GOOD STANDING WITH TIMING AND RATES
THOUGH FAVORING THE  ARW/HRRR/ESRL EXP. HRRR.  ALL GENERALLY
SUPPORTING 1-1.5" ALONG THE COASTAL RANGE GIVEN THE SHORT DURATION
WITH THE FAST ONSHORE PROGRESSION OF THE LINE.  THIS COULD PROVIDE
ENOUGH RAINFALL IN A SHORT PERIOD TO LEAD TO ISOLATED FLASH FLOOD
CONDITIONS PARTICULARLY IN BURN SCARS.  

GALLINA

ATTN...WFO...HNX...LOX...MTR...STO...

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

LAT...LON   38782325 38562245 38172215 36612110 35301988 
            34932011 34942071 36342191 37322264 38232319 
            38442336 38612341