Flash Flood Guidance
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000
AWUS01 KWNH 280146
FFGMPD
CAZ000-280800-

MESOSCALE PRECIPITATION DISCUSSION 0066
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
845 PM EST MON FEB 27 2017

AREAS AFFECTED...SOUTHWEST CALIFORNIA

CONCERNING...HEAVY RAINFALL

VALID 280140Z - 280800Z

SUMMARY...RAINFALL/MOISTURE FLUX HAS PEAKED THOUGH A FEW
ADDITIONAL HOURS (THROUGH 07Z) OF MODERATE RAINFALL (OVER .5"/HR)
ARE EXPECTED COMPOUNDING FLOODING CONCERNS ALONG SAN
JACINTO/LAGUNA RANGES.

DISCUSSION...GOES-W/POLAR SUITE OF  SATELLITE PRODUCTS AND RADAR
MOSAIC DEPICTS THE MAIN THRUST/AXIS OF MOISTURE TRANSPORT HAS
DROPPED SOUTH OF THE US/MEXICO BORDER STREAMING INTO THE LOWER CO
RIVER VALLEY TOWARD THE CENTRAL VALLEY OF AZ INTO THE MOGOLLON RIM
AREA.  THESE PRODUCTS ALSO SUGGEST A BIT OF MID-LEVEL COOLING HAS
DROPPED SOUTH TO SUPPORT STEEPENED LAPSE RATES NORTH OF THE
MOISTURE AXIS ALLOWING FOR SOME MODEST 100-250 J/KG CAPES PER THE
HRRR DIRECTED TOWARD SAN DIEGO.  VIS LOOP SHOWS THAT FAVORABLE
COUPLING OF RIGHT ENTRANCE OF POLAR JET EXITING THE SOUTHERN
SIERRAS INTO S UT AND THE LEFT EXIT OF THE 150KT SUBTROPICAL JET
SUPPORTS CONTINUED BROAD SCALE ASCENT.  THIS MANIFESTS BY WEDGE
PRESENTATION OF THE WARM CONVEYOR ASCENT SHIELD THAT HAS SOME
CONVECTIVE SHAPE/ELEMENTS WITHIN THE NEARLY SOLID TRANSVERSE
BANDING.  THIS FAIRLY STEEP ASCENT AND MODEST BUT THINNING
MOISTURE (NEAR 1.0" TPW) SHOULD CONTINUE TO SUPPORT RATES OVER
.5"/HR ACROSS N SAN DIEGO COUNTY INTO THE SAN JACINTO RANGE OVER
THE NEXT HOUR OR SO.  STILL FORWARD PROGRESS OF THE UPPER LEVEL
TROF AND EXITING JET WILL CONTINUE TO SHUNT THIS RIBBON OF
CONVECTION SOUTH ENDING IN SAN DIEGO PROPER BY 07Z AND LAGUNA MTNS
08-09Z.   AS SUCH AN ADDITIONAL 1.5-2" CAN BE EXPECTED IN THE
HIGHER TERRAIN OF SAN DIEGO COUNTY WITH .5-1.0" FOR THE LOWER
COASTAL REGION POSSIBLE EXACERBATING ONGOING FLOODING CONCERNS IN
THE AREA.

GALLINA

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...SGX...

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

LAT...LON   34001682 33851650 33351645 33041640 32781624
            32471606 31891575 31681604 31451659 32071692
            32461719 32841731 33121745 33301756 33431759
            33791719


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