Graphic for MPD #0007
MESOSCALE PRECIPITATION DISCUSSION 0007
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
936 AM EST SAT JAN 07 2017
 
AREAS AFFECTED...NORTHERN CA...EXT SOUTHWEST OREGON 
 
CONCERNING...HEAVY RAINFALL 
 
VALID 071435Z - 072135Z
 
SUMMARY...THOUGH GREATEST FLOODING THREAT IS FURTHER
SOUTH...INCREASING MOISTURE AND BEST FORCING FURTHER NORTH ALLOWS
FOR MODERATE TO OCCASIONAL HEAVY RAIN TO POSE FLOODING THREAT
ACROSS N CA/SW OR AS WELL.

DISCUSSION...BLENDED TPW DENOTES HIGHLY ANOMALOUS MOISTURE PLUME
WITH VALUES EXCEEDING 1.5" DIRECTED TOWARD THE SOUTH CENTRAL CA
COAST ATTM.  HOWEVER GOES-W WV LOOP INDICATES STRONG JET STREAK
AND ASSOCIATED DEEPENING MID-LEVEL SHORTWAVE NORTH AND E OF THE
40N130W BENCHMARK WITH ENHANCING CLOUD TOPS INDICATIVE OF SOME
SLANTWISE ASCENT AND MOISTURE ADVECTION INTO THE BAY AREA AND
NORTHWARD.  RAP ANALYSIS AND BLENDED TPW LOOP INDICATE VALUES
TICKLING 1.25" WITHIN THIS CURL/SHORTWAVE ENHANCEMENT NEAR THE
APPROACHING SURFACE TRIPLE POINT.  LOCAL RADAR AND OBSERVATIONS
ALREADY SUPPORT ENHANCED RATES UP TO .3"/HR WITHIN THE KING RANGE
ENHANCED BY SSWLY OROGRAPHIC ASCENT.  SIMILAR SSW FACING OROGRAPHY
WHERE 850MB FLOW HAS INCREASED TO 50+ KTS WILL CONTINUE FOR THE
NEXT FEW HOURS BEFORE VEERING SLIGHTLY AND DECREASING THROUGH
17-18Z YET WITH BETTER ORTHOGONAL ASCENT TO THE OROGRAPHICS.  THIS
KEEPS MODERATE RAINFALL CONTINUING THROUGH THE EARLY MORNING/EARLY
AFTERNOON ESPECIALLY ACROSS MARIN/SONOMA COUNTIES IN THE NORTH BAY
AREA.  THE TOTAL DURATION OF THE FORCING/BEST ASCENT MAY LIMIT
EXTREME TOTALS SEEN FURTHER SOUTH BUT 6-12HR TOTALS IN THE 1-2"
RANGE ARE LIKELY IN BEST OROGRAPHICS ALONG THE COAST FROM SW OR TO
THE NORTH BAY.   

FURTHER WEST...SHORTWAVE AXIS WILL PROGRESS ACROSS S OR/N CA WITH
PERSISTENT ASCENT AND MST FLUX WITH NEARLY IDEAL ORTHOGONAL FLOW
VECTOR TO THE NORTHERN SIERRAS INTO THE LASSEN NATIONAL FOREST
REGION AND SHASTA COUNTY.  RATES OVER .3"/HR ARE LIKELY WITH SOME
SUPPORT/SUGGESTION GIVEN THE STRENGTH OF FLOW AND INCREASED
MOISTURE VALUES...RATES AS HIGH AS .5"/HR MAY BE POSSIBLE AROUND
THE 20-21Z TIME FRAME. THIS SHOULD LEAD TO TOTALS OF 1.5-3" ACROSS
THIS TERRAIN (GREATEST SOUTH AND EAST).  ADDITIONALLY WITH 7H
TEMPS NEAR ZERO AND SOME WAA THROUGH 18Z MAY BE ENOUGH TO KEEP
FREEZING LEVELS ABOVE 9000FT.  GIVEN THIS SHOULD INCREASE RATE OF
SNOW MELT DUE TO RAINFALL...RUNOFF SHOULD BE HIGHER THAN WHAT IS
TYPICAL WITH THESE RATES FURTHER COMPOUNDING ANY DOWNSTREAM
FLOODING CONCERNS.     

GALLINA

ATTN...WFO...EKA...MFR...MTR...REV...STO...

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

LAT...LON   43032436 42972394 42412357 41872311 41462189 
            40922150 40282108 39652044 39102015 38371984 
            38522054 38662091 38812112 38762170 38392201 
            38102249 37772245 38272326 39362386 39902405 
            40382444 40772436 41522427 42332456 42662465 
            


Last Updated: 936 AM EST SAT JAN 07 2017