MESO: Mesoscale Discussion 1733

ACUS11 KWNS 171910
SWOMCD
SPC MCD 171909
NMZ000-AZZ000-UTZ000-NVZ000-172115-

MESOSCALE DISCUSSION 1733
NWS STORM PREDICTION CENTER NORMAN OK
0209 PM CDT SAT AUG 17 2013

AREAS AFFECTED...AZ...NV...UT...NM

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 171909Z - 172115Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...THUNDERSTORMS SHOULD CONTINUE TO INCREASE IN COVERAGE
ACROSS A LARGE AREA OF THE GREAT BASIN THROUGH THE AFTERNOON. A FEW
CELLS COULD PRODUCE HAIL AND LOCALLY GUSTY/ERRATIC WINDS. LACK OF
GREATER STORM ORGANIZATION SHOULD PRECLUDE WATCH ISSUANCE.

DISCUSSION...RELATIVELY STRONG BUOYANCY HAS DEVELOPED WITH HEATING
OF THE DAY FROM NRN AZ/WRN NM NWD ACROSS MUCH OF UT GIVEN VERY STEEP
LAPSE RATES IN EXCESS OF 9C/KM AND PLUME OF MONSOONAL MOISTURE /PW
VALUES NEARING 1 INCH/ ENTRAINED WITHIN MID-LEVEL RIDGE AXIS ACROSS
THE REGION. A WEAK DISTURBANCE TRANSLATING NNEWD ALONG THE WRN FLANK
OF THE MID/UPPER RIDGE AND TERRAIN/DIFFERENTIAL HEATING EFFECTS WERE
LIKELY AIDING IN SOME OF THE MORE ROBUST CONVECTIVE DEVELOPMENT OVER
THE PAST COUPLE OF HOURS. WHILE EFFECTIVE SHEAR ACROSS THE AREA IS
FORECAST TO REMAIN MARGINAL FOR GREATER ORGANIZATION...THERE APPEARS
TO BE SUFFICIENTLY STRONG UPPER FLOW TO AID IN MASS EVACUATION AT OR
NEAR ANVIL LEVEL. FGZ SOUNDING ADJUSTED FOR CURRENT CONDITIONS WOULD
SUPPORT HAILSTONE SIZE UP TO 1 INCH IN DIAMETER. FURTHERMORE...AS
STORMS SPREAD ACROSS HEATED/MIXED BOUNDARY LAYER...WHERE SFC T/TD
SPREADS ARE IN EXCESS OF 30-40F IN SOME AREAS...THE THREAT FOR
ISOLATED STRONG TO DAMAGING AND ERRATIC WIND GUSTS WILL LIKELY
INCREASE.

THE CHAOTIC/RANDOM NATURE OF THE CONVECTION...AND THE LIKELIHOOD
THAT STRONGEST CELLS ARE PRONE TO HAVE RELATIVELY SHORT LIFETIMES
GIVEN LACK OF STRONG SHEAR AND FORCING...SHOULD PRECLUDE THE
ISSUANCE OF A WATCH OVER THE AREA THIS AFTERNOON.

..CARBIN/KERR.. 08/17/2013

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

ATTN...WFO...ABQ...GJT...TWC...FGZ...SLC...VEF...LKN...

LAT...LON 38291000 37640955 36070862 33610890 34591239 35621377
36691389 37431445 37551500 37961551 38601552 39591503
40081439 40371313 40251243 40141144 38291000

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