Saturday, July 28, 2007

MESO: Mesoscale Discussion 1609

ACUS11 KWNS 290032
SWOMCD
SPC MCD 290032
AZZ000-290230-

MESOSCALE DISCUSSION 1609
NWS STORM PREDICTION CENTER NORMAN OK
0732 PM CDT SAT JUL 28 2007

AREAS AFFECTED...PORTIONS W-CENTRAL/SWRN AZ

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 290032Z - 290230Z

TSTMS ARE BECOMING BETTER ORGANIZED OVER PORTIONS SWRN YAVAPAI
COUNTY...S AND SW PRC. ACTIVITY SHOULD MERGE/STRENGTHEN INTO
COMPLEX CAPABLE OF STG-SVR GUSTS THAT MAY MOVE SWD OVER PORTIONS WRN
MARICOPA COUNTY...AND PERHAPS EXTREME ERN LA PAZ/YUMA AND EVENTUALLY
WRN PIMA COUNTIES. IN ADDITION...RAIN RATES LOCALLY NEAR 2
INCHES/HOUR WILL BE POSSIBLE FROM MERGING CONVECTION...ESPECIALLY
OVER SWRN YAVAPAI/NWRN MARICOPA COUNTIES. THESE RAIN/WIND HAZARDS
MAY INCLUDE I-10 FROM NEAR LUF WWD INTO SERN LA PAZ COUNTY.

HOT/UNSTABLE AIR MASS REMAINS ACROSS PROSPECTIVE PATH OF TSTM
CLUSTER WITH SFC TEMPS MID 90S/100 F...AND DEW POINTS LOW-MID 60S.
RELATED HIGH BOUNDARY LAYER THETAE OFFSETS WEAK MIDLEVEL LAPSE RATES
ENOUGH FOR ACCORDINGLY MODIFIED RUC SOUNDINGS TO YIELD MLCAPES IN
1500-2500 J/KG RANGE...ATOP INVERTED-V PROFILES CHARACTERISTIC OF
WELL MIXED SUBCLOUD AIR MASS. THIS SHOULD SUPPORT
MAINTENANCE/ACCELERATION OF DOWNDRAFT INTENSITY TO SFC ACROSS DESERT
FLOORS/VALLEYS NW-SW OF PHX...AS ACTIVITY PROPAGATES OVER AREA.
AMBIENT/WEAK NLYS IN MIDLEVELS COMBINED WITH FAVORABLE
STORM-RELATIVE INFLOW -- FROM SLY COMPONENT OF LOW LEVEL WINDS --
SHOULD SUPPORT SWD MOVEMENT OF ACTIVITY. EWD EXTENT OF STRONGEST
CONVECTION WILL BE RESTRICTED BY PRESENCE OF MERIDIONAL INSTABILITY
GRADIENT FROM ABOUT PHX SWD. THIS BOUNDARY IS NEAR W EDGE OF
CLOUD/PRECIP DEBRIS LEFT BEHIND BY EARLIER TSTMS OVER S-CENTRAL/SERN
AZ...AND COINCIDES WITH SEPARATE AREA OF STG/POSSIBLY SVR CONVECTION
NEAR CGZ. COLLECTIVE OUTFLOW SURGES FROM BOTH SETS OF TSTMS --
MOVING OUT OF YAVAPAI COUNTY AND CGZ AREA -- ALSO MAY CONTRIBUTE TO
VISIBILITY HAZARDS THROUGH BLOWING DUST/SAND.

.EDWARDS.. 07/29/2007

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

ATTN...WFO...TWC...FGZ...PSR...

32151374 33991335 34461266 33941240 33301225 32501238
31791256

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