MESOSCALE PRECIPITATION DISCUSSION 0504
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
937 PM EDT SAT JUL 21 2018

AREAS AFFECTED...CENTRAL NV & VICINITY

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 220135Z - 220505Z

SUMMARY...SHOWERS AND THUNDERSTORMS CONTINUE DEVELOPING AHEAD OF
AN MCV AND NEAR A 700 HPA TROUGH.  HOURLY RAIN TOTALS TO 1.5"
SHOULD BE POSSIBLE THROUGH AT LEAST 05Z.

DISCUSSION...THUNDERSTORMS BEGAN ACROSS EAST-CENTRAL CA AROUND 23Z
IN THE VICINITY OF THE TAIL END OF A 700 HPA TROUGH.  AS AN MCV
APPROACHES FROM SOUTHERN NV, THUNDERSTORM/LIGHTNING ACTIVITY HAS
BEEN INCREASING FURTHER UP THE SLOW-MOVING 700 HPA TROUGH INTO
CENTRAL NV PER THE LIGHTNING DETECTION NETWORK.  ADDING TO THE
DIVERGENCE ALOFT IS THE RIGHT ENTRANCE REGION OF A JET STREAK 
PRECIPITABLE WATER VALUES OF 0.7-0.9" PER GPS DATA.  MU CAPE
VALUES ARE INCREASING IN THIS AREA, WITH VALUES OF 500-2000 J/KG. 
EFFECTIVE BULK SHEAR OF 25-35 KTS EXISTS IN CENTRAL NV WHICH MAY
ADD SOME CONVECTIVE ORGANIZATION.

THE MESOSCALE GUIDANCE IS DOING POORLY HERE.  BASED ON
DEVELOPMENTS YESTERDAY, BELIEVE CONVECTION SHOULD HOLD ON UNTIL AT
LEAST 05Z.  WITH THE INCOMING MCV AND JET STREAK ALOFT, IT IS
POSSIBLE THAT CONVECTION COULD HOLD ON EVEN LONGER.  HOURLY RAIN
TOTALS OF 1.5" SHOULD BE POSSIBLE GIVEN THE MOISTURE AND
INSTABILITY PRESENT.  

ROTH

ATTN...WFO...LKN...REV...STO...VEF...

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

LAT...LON   41071789 40581613 39441452 37971428 37131635
            37621864 38321968 39332019 40311997 41001918