652
AWUS01 KWNH 111114
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-111700-
MESOSCALE PRECIPITATION DISCUSSION 1478
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
713 AM EDT SUN OCT 11 2026
AREAS AFFECTED...SOUTHWEST U.S.
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 111113Z - 111700Z
SUMMARY...POST.T.C RACHEL CONTINUES TO RAPIDLY LIFT NORTHEASTWARD
AND INLAND ACROSS SOUTHEAST CA, WITH ITS MOISTURE AND RELATED
HEAVY RAINFALL CONTINUING TO IMPACT THE BROADER SOUTHWEST U.S.
ADDITIONAL AREAS OF FLASH FLOODING ARE EXPECTED GOING THROUGH THE
MORNING HOURS, WITH LOCALLY SIGNIFICANT IMPACTS POSSIBLE.
DISCUSSION...THE LATEST GOES-W IR SATELLITE IMAGERY, SURFACE
OBSERVATIONS AND RADAR DATA SHOWS THE LOW CENTER ASSOCIATED WITH
POST-T.C. RACHEL ADVANCING QUICKLY TO THE NORTHEAST ACROSS
SOUTHEAST CA. HEAVY RAINFALL ASSOCIATED WITH AN EXPANDING
MID-LEVEL DEFORMATION ZONE AND FRONTOGENESIS AXIS IS SEEN LIFTING
QUICKLY ACROSS SOUTHEAST CA UP THROUGH SOUTHERN NV AND INTO
SOUTHWEST UT.
SOME DISCRETE AREAS OF CONVECTION ARE NOTED SOUTH AND EAST OF THE
LOW CENTER IMPACTING ADJACENT AREAS OF SOUTHERN CA UP THROUGH FAR
SOUTHERN NV AND ACROSS CENTRAL TO NORTHWEST AZ. A NOSE OF MUCAPE
VALUES REACHING 500 TO 1000 J/KG IS ALIGNED WITH THE DEEPER LAYER
SOUTHERLY FLOW AROUND THW EASTERN FLANK OF RACHEL. THIS COUPLED
WITH VERY STRONG 850/700 MB MOISTURE FLUX AND OROGRAPHIC ASCENT
OVER AREAS OF HIGHER TERRAIN WILL ENCOURAGE ADDITIONAL AREAS OF
CONVECTION GOING THROUGH THE MORNING HOURS. IN FACT, THE LATEST
RAP ANALYSIS SHOWS MEAN LAYER WINDS BETWEEN 850/700MB ON THE ORDER
OF 50 TO 60 KTS IMPACTING CENTRAL AND WESTERN AZ AND FAR SOUTHEAST
CA WHICH IS NOSING TOWARD SOUTHERN NV AND SOUTHWEST UT.
RAINFALL RATES WILL BE CAPABLE OF REACHING UP TO 1.5 INCHES/HOUR
WITH THE STRONGER CONVECTIVE CELLS. HOWEVER, THE RAPID MOTION OF
RACHEL OFF TO THE NORTHEAST OVER THE NEXT SEVERAL HOURS WILL AT
LEAST LOCALLY MITIGATE THE HEAVY RAINFALL THREAT TO AN EXTENT.
REGARDLESS, THE 06Z HREF/REFS CONSENSUS WOULD SUGGEST AN
ADDITIONAL 1 TO 3 INCHES OF RAIN NEAR THE PATH OF RACHEL, WITH
POTENTIAL FOR ISOLATED MAX TOTALS NEAR 5 INCHES GIVEN THE VERY
STRONG MOISTURE TRANSPORT AND OROGRAPHIC FORCING/UPSLOPE FLOW INTO
THE TERRAIN.
GIVEN THE RAINFALL RATES AND TOTALS EXPECTED OVER THE NEXT SEVERAL
HOURS. ADDITIONAL AREAS OF FLASH FLOODING ARE EXPECTED, AND THE
MORE SENSITIVE BURN SCAR LOCATIONS, SLOT CANYON AREAS, AND
NORMALLY DRY WASHES WILL BE SUSCEPTIBLE TO IMPACTS WHICH MAY
LOCALLY BE SIGNIFICANT.
ORRISON
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...FGZ...GJT...LKN...LOX...PSR...SGX...SLC...TWC...
VEF...
ATTN...RFC...RSA...STR...NWC...
LAT...LON 39441346 39151187 38341099 37461074 35721068
33860981 33021023 32851112 33591311 33821438
33381562 32521633 32671739 33921798 35461725
37571660 39221509
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