Graphic for MPD #0015
 
MESOSCALE PRECIPITATION DISCUSSION 0015
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
133 AM EST WED JAN 11 2017
 
AREAS AFFECTED...CENTRAL AND PARTS OF SOUTHERN CA 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 110631Z - 111500Z
 
SUMMARY...SATELLITE IMAGERY SHOWED A PLUME OF MOISTURE WITH A
CONNECTION TO THE SUBTROPICS EASING SLOWLY SOUTHWARD.  SATELLITE
DERIVED RAINFALL RATES ON THE ORDER OF 0.4 INCHES PER HOUR ARE
STILL POSSIBLE AS LOW LEVEL WINDS CONTINUE TO DRAW THE MOISTURE
PLUME INLAND.  THERE SHOULD BE A GRADUAL DECREASE IN RAINFALL
RATES BY EARLY WEDNESDAY MORNING AS THE MOISTURE PLUME AND LOW
LEVEL WINDS WEAKEN. 

DISCUSSION...05Z WATER VAPOR IMAGERY SHOWED A PROGRESSIVE MID
LEVEL VORTICITY CENTER NEAR 38N 126W ADVANCING EASTWARD...WITH THE
PLUME OF DEEPER MOISTURE LOCATED TO THE EAST OF THERE AND MAKING
ITS WAY ONSHORE ALONG THE CENTRAL CA COAST.  BLENDED TPW IMAGERY
AND RECENT RUNS OF THE RAP INDICATE THAT PRECIPITABLE WATER VALUES
WITHIN THE PLUME WERE GENERALLY 1.0 TO 1.2 INCHES. GOES HIGH
DENSITY WINDS AS OF LATE TUESDAY EVENING INDICATED THAT THE LEFT
EXIT REGION OF A 130-150 KT JET STREAK WAS STILL MAKING ITS WAY TO
THE COAST BUT THAT THE DIVERGENCE VALUES WERE STARTING TO DECREASE
WITH TIME ACROSS THE AREA. SATELLITE DERIVED RAINFALL RATES HAD
DECREASED FROM EARLIER IN THE DAY BUT SOME VALUES APPROACHING 0.4
INCHES WERE STILL NOTED UPSTREAM OF THE CA COAST.  

FREEZING LEVELS HAD INCREASED DURING THE DAY AS SOUTHWESTERLY FLOW
DREW WARMER AIR TOWARDS THE CENTRAL AND SOUTHERN SIERRA.  IN
TIME...FREEZING LEVELS WILL DROP FOLLOWING THE PASSAGE OF A COLD
FRONT.  THINKING IS THAT HEAVY RAINFALL IS STILL POSSIBLE AT THE
LOWER ELEVATIONS OF THE SOUTH CENTRAL SIERRA NEVADA.  HIGH
RESOLUTION MODELS STILL DEPICT SOME PRECIPITATION AMOUNTS IN
EXCESS OF 2 INCHES BY 12Z WITH ADDITIONAL AMOUNTS IN THE PERIOD
FROM 12Z TO 15Z. WHILE THE GREATEST AMOUNTS LOOKS TO BE AT HIGHER
ELEVATION WHERE PRECIPITATION WOULD MOST LIKELY FALL AS
SNOW...THERE SHOULD STILL BE MODERATE TO LOCALLY HEAVY RAINFALL
AMOUNTS AT LOWER ELEVATIONS.  

IN ADDITION...LOCALLY HEAVY RAINFALL WILL FALL LATE THIS EVENING
AND DURING THE EARLY OVERNIGHT HOURS WHERE LOW LEVEL WINDS
INTERACT WITH THE COASTAL RANGES. 

BANN

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

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

LAT...LON   39422113 38192048 37301981 36771904 36241898 
            35751884 35491900 34991947 34541866 34361850 
            34211904 34291927 34512040 36242190 35542046 
            35721945 36671993 37412068 38332115 


Last Updated: 133 AM EST WED JAN 11 2017