951
AWUS01 KWNH 151919
FFGMPD
AZZ000-NVZ000-CAZ000-160115-
MESOSCALE PRECIPITATION DISCUSSION 1225
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
219 PM EST SAT NOV 15 2025
AREAS AFFECTED...DESERT REGIONS OF CA INTO SOUTHERN NV AND FAR
WESTERN AZ
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 151917Z - 160115Z
SUMMARY...PERIODS OF HEAVY RAIN SHOULD BECOME LIKELY ACROSS THE
DESERT REGIONS OF EASTERN/SOUTHERN CA INTO SOUTHERN NV AND FAR
WESTERN AZ THROUGH 01Z. PEAK HOURLY RAINFALL BETWEEN 0.5 AND 1.0
INCHES (LOCALLY HIGHER) IS EXPECTED WHICH MAY RESULT IN ISOLATED
TO WIDELY SCATTERED INSTANCES OF FLASH FLOODING.
DISCUSSION...RADAR MOSAIC IMAGERY ACROSS SOUTHERN CA INTO SOUTHERN
NV AT 19Z SHOWED AN ARCING BAND OF HEAVY SHOWERS CONTINUING TO
MOVE INLAND, FROM THE PENINSULAR RANGES TOWARD THE FAR SOUTHERN
SAN JOAQUIN VALLEY. OBSERVED HOURLY RAINFALL WITHIN THIS AXIS HAS
BEEN IN THE 0.5 TO 0.9 INCH RANGE OVER THE PAST 2-3 HOURS.
ADDITIONAL SHOWERS WERE NOTED FROM JUST WEST OF THE LOWER CO RIVER
INTO WESTERN CLARK COUNTY IN SOUTHERN NV WITH MRMS-DERIVED HOURLY
RAINFALL IN EXCESS OF 1 INCH IN EASTERN IMPERIAL COUNTY. THESE
SHOWERS WERE FORCED IN RESPONSE TO LIFT AHEAD OF A NEGATIVELY
TILTED SHORTWAVE TROUGH LOCATED ~100 MILES OFF OF THE SOUTHERN CA
COAST, SWINGING TOWARD INTERIOR SOUTHERN CA. IN ADDITION,
DIVERGENCE AND DIFFLUENCE WERE INCREASING ACROSS SOUTHERN CA
WITHIN THE LEFT-EXIT REGION OF A 90-110 KT UPPER LEVEL JET MAX
LOCATED JUST SOUTH OF THE SHORTWAVE TROUGH AXIS. MOISTURE WAS
HIGHLY ANOMALOUS FOR MID-NOVEMBER WITH REGIONAL PW STANDARDIZED
ANOMALIES OF 4 TO 5+ THROUGHOUT THE AREA, WITH A SOURCE REGION
STEMMING FROM THE TROPICAL EASTERN PACIFIC AS SEEN ON OSPO ALPW
IMAGERY.
AS THE CLOSED LOW AND NEGATIVELY TILTED SHORTWAVE TROUGH CONTINUES
TO ADVANCE EAST OVER THE NEXT 6 HOURS, LOW LEVEL MOISTURE WILL
CONTINUE TO ADVECT INTO THE DESERTS WITH A TRANSIENT SWATH OF 6.0
TO 6.5 C/KM 700-500 MB LAPSE RATES (COINCIDENT WITH THE SHORTWAVE)
WHICH SHOULD HELP TO BRIEFLY BOOST INSTABILITY, DESPITE THE LACK
OF SURFACE HEATING BENEATH CLOUDS/RAIN. ALSO OF NOTE WERE THE
850-700 MB WINDS ORIENTED FROM THE SOUTHEAST AT 30-35 KT OVER
SOUTH-CENTRAL CA, FORCING AN UPSLOPE COMPONENT ALONG THE EASTERN
SLOPES OF THE SOUTHERN SIERRA NEVADA. WITH LITTLE CHANGE TO THE
LOW TO MID-LEVEL WIND FIELDS ANTICIPATED OVER THE NEXT 3-6 HOURS,
STEADY UPSLOPE FORCED HEAVY RAIN IS EXPECTED INTO THE TERRAIN.
FARTHER EAST, EMBEDDED HIGHER RAINFALL RATES ARE EXPECTED TO
DEVELOP THROUGH THE AFTERNOON WITHIN THE SCATTERED
SHOWER/STRATIFORM RAIN REGIME. WHILE CAPE VALUES ARE GENERALLY
FORECAST TO STAY BELOW 500 J/KG (OUTSIDE OF THE LOWER CO VALLEY),
THE ANOMALOUS MOISTURE SOURCE SHOULD CONTRIBUTE TO EMBEDDED HIGHER
RAINFALL VALUES WITH PERIODS OF BRIEF TRAINING, ALLOWING FOR
HOURLY RAINFALL IN THE 0.5 TO 1.0 INCH RANGE (LOCALLY HIGHER).
PEAK TOTAL RAINFALL OF 1 TO 2 INCHES IS EXPECTED (LOCALLY HIGHER
NEAR TERRAIN) THROUGH 01Z WHICH MAY RESULT IN AREAS OF FLASH
FLOODING.
OTTO
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...HNX...LKN...LOX...PSR...REV...SGX...VEF...
ATTN...RFC...RSA...STR...NWC...
LAT...LON 38051725 37481583 36161447 35111412 33431409
32231432 32471532 32481594 33171615 33501626
33671637 33951653 34111664 34231678 34311702
34391729 34501763 34651808 34781841 34911860
35061867 35231863 35381859 35491856 35641849
35721842 35801837 35891833 35961828 36081823
36181815 36311810 36411813 36481817 36601822
36661826 36751829 36851834 36931837 37031839
37121843 37211847 37261852 37321860 37421865
37621866 37861848 38041808
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