MESOSCALE PRECIPITATION DISCUSSION 0586
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 PM EDT SUN OCT 18 2015
 
AREAS AFFECTED...S NEVADA...SW UTAH...NW ARIZONA...EXT SE
CALIFORNIA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 181856Z - 190056Z
 
SUMMARY...CONTINUED FLASH FLOOD THREAT 

DISCUSSION...OVERALL SYNOPTIC ENVIRONMENT CONTINUES TO PROVIDE
PROLIFIC ENERGY WITH EMBEDDED SHORTWAVE INTERACTIONS LEADING TO
FAVORED DIVERGENT ENVIRONMENT ALOFT.  THE S/W THAT DROVE THE
ONGOING CONVECTIVE WEDGE OVER S NYE COUNTY IS SLOWING IN FORWARD
PROGRESS WITH A BIT OF NORTHERLY SHIFT UNDER THE INFLUENCE OF THE
DIGGING OF THE MAIN TROF ACROSS THE CENTRAL VALLEY OF CALIFORNIA. 
THOUGH DIVERGENCE VALUES ARE FORECAST TO DECREASE...IT WILL BE
SLOW WITH INCREASED ANGLE OF DIFFLUENCE SHIFTING SLIGHTLY EAST
ACROSS S NV.  THIS ALSO ALIGNS WITH THE APEX OF THE SUBTROPICAL
RIDGE.  DRIER AIR ADVECTING IN WITH THE PVA OF THE
SHORTWAVE...WILL SUPPORT INCREASING INSTABILITIES FURTHER WEST BUT
SHOULD ALSO ALLOW FOR INCREASED COLD POOLS WITH PROPAGATION
EASTWARD INTO MORE FAVORABLE MID-LEVEL MOISTURE ENVIRONMENT INTO
THE LAS VEGAS VICINITY AND SW UTAH AND NW ARIZONA BY 00Z.  WITH
SPEED MAX/BASE OF VORT ENERGY ROUNDING INTO S CA... UPSTREAM
BACKBUILDING WILL SUPPORT REPEAT OR POTENTIALLY STATIONARY
DEVELOPMENT REGIONS PARTICULARLY OVER HIGHER PEAKS WHERE LOW LEVEL
ISENTROPIC FLOW MAXIMIZED MST CONVERGENCE.  INCREASING SBCAPES TO
2000 J/KG CAN BE SEEN IN RAP ANALYSIS AND FORECAST ACROSS THE
COLORADO RIVER VALLEY OF S NV...AND COINCIDENT TPWS OF .9 TO 1.1"
SHOULD SUPPORT RATES AND TOTALS OF 1.5-2" WITH ISOLATED 3" VALUES
SIMILAR TO VALUES REPORTED OVER THE LAST 6HRS IN THE JACKASS
FLATS/SKULL MOUNTAIN AREA.  HI-RES CAMS SUPPORT THIS IDEA
PARTICULARLY THE MORE FAVORABLE/CONSISTENT ARW AND NSSL-WRF...AS
WELL AS THE NAM-CONEST WITH THE POTENTIAL FOR RAINFALL IMPACTS
WITHIN THE LAS VEGAS URBAN CENTER OVER THE NEXT 6HRS. 

FURTHER NW NEAR ESMERALDA AND MINERAL COUNTY...INCREASED
DIFFLUENCE EXISTS HERE AS WELL VERY NEAR THE PIVOT OF THE OVERALL
LARGE SCALE CIRCULATION ALLOWING FOR NEAR ZERO CELL MOTIONS AND
THOUGH MOISTURE VALUES ARE SLIGHTLY LOWER (WITH LOWER RAIN RATES)
THE DURATION OF RAINFALL COULD MOISTEN THE PROFILE FOR EVENTUAL
EFFICIENT RATES CAPABLE OF FLASH FLOOD CONDITIONS OVER THE NEXT
3-4HRS.  

GALLINA 

ATTN...WFO...FGZ...LKN...REV...SLC...VEF...

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

LAT...LON   39561449 38881277 37901209 36451250 35411383 
            34991470 34651559 35441596 36401659 36721678 
            36891748 37021780 37771849 39031838 39201670