Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 262210
SWOMCD
SPC MCD 262209
AZZ000-NVZ000-CAZ000-262315-

MESOSCALE DISCUSSION 1766
NWS STORM PREDICTION CENTER NORMAN OK
0509 PM CDT FRI SEP 26 2014

AREAS AFFECTED...LOWER CO RIVER VALLEY...SERN CA...FAR SERN NV...WRN
AZ

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 262209Z - 262315Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...AN ISOLATED THREAT FOR LARGE HAIL AND DMGG WIND GUSTS WILL
EXIST THIS AFTERNOON AND EVENING ACROSS THE LOWER CO RIVER VALLEY
AND SURROUNDING AREAS. A WW IS POSSIBLE.

DISCUSSION...SFC ANALYSIS FROM 22Z SHOWED AN AXIS OF MID-60S TO
LOW-70S F DEWPOINTS ALIGNED ALONG THE LOWER CO RIVER
VALLEY...CO-LOCATED WITH PW VALUES AOA 1.5 INCHES AND ESTIMATED
MLCAPE VALUES OF 1500-2500 J/KG /NEAR RECORDS FOR THE DATE/. TSTMS
WHICH INITIATED WITHIN THE PAST 1-2 HRS HAVE EXHIBITED OCCASIONAL
POTENTIAL FOR SVR HAIL /PER WDSS-2 MESH ALGORITHM/. STRONG HEATING
HAS ALSO YIELDED STEEP LOW-LEVEL LAPSE RATES...AND COMBINED WITH THE
ANOMALOUSLY MOIST AIR MASS...COULD RESULT IN ISOLATED WET
MICROBURSTS.

CURRENT CONVECTIVE TRENDS SUGGEST A SLOW INCREASE IN AREAL COVERAGE
OVER THE NEXT COUPLE HRS AS STRONGER FORCING FOR ASCENT SPREADS EWD.
PRIMARY UNCERTAINTY REGARDING WATCH CONSIDERATION IS THE DEGREE OF
TSTM ORGANIZATION THAT CAN BE ATTAINED...GIVEN 15-20 KT OF
UNIDIRECTIONAL LOW-MIDLEVEL FLOW AND MODEST EFFECTIVE SHEAR VALUES
AROUND 20 KT...FAVORABLE FOR PRIMARILY PULSE TO MULTICELL
CONVECTION. HOWEVER...ORIENTATION OF THE APPROACHING UPPER TROUGH
SUGGESTS STRONGER MIDLEVEL FLOW WILL GRADUALLY SPREAD EWD ACROSS NRN
HALF OF THE MCD AREA /MAINLY N OF EED/...ESPECIALLY THIS EVENING AND
OVERNIGHT.

TRENDS WILL CONTINUE TO BE MONITORED FOR A POSSIBLE INCREASE IN
COVERAGE/INTENSITY OVER THE NEXT COUPLE HRS...WHICH COULD REQUIRE WW
ISSUANCE.

..ROGERS/THOMPSON.. 09/26/2014

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...PSR...VEF...

LAT...LON   36421345 34091358 32401443 32481479 32581560 33701557
            35531552 36491487 36701387 36421345



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