SWOMCD
SPC MCD 041953
AZZ000-042200-
MESOSCALE DISCUSSION 2222
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT TUE OCT 04 2011
AREAS AFFECTED...PORTIONS OF AZ
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 041953Z - 042200Z
A MARGINAL/ISOLATED SVR THREAT MAY OCCUR THIS AFTERNOON INTO THE
EVENING.
LATEST WATER VAPOR IMAGES INDICATE A COMPACT PV MAX...WITHIN THE
BASE OF A CONUS-FULL-LATITUDE TROUGH WEST OF THE ROCKIES...CURRENTLY
PROGRESSING EWD TOWARD THE LOWER CO RIVER VALLEY. ATTENDANT 500-MB
HEIGHT FALLS /OVER 60 GEOPOTENTIAL METERS PER 12 HRS/ AND STRONG
DCVA WILL CONTINUE OVERSPREADING AZ DURING THE NEXT SEVERAL
HOURS...OFFERING ABUNDANT DEEP-LAYER ASCENT FOR SCATTERED TO
NUMEROUS CONVECTION. THE HIGHEST CONCENTRATION OF CONVECTION WILL BE
FOUND AROUND THE MOUNTAINS AND NEAR AN EWD-ADVANCING SFC COLD FRONT
/CURRENTLY ARCING FROM AROUND THE GRAND CANYON SWD INTO THE GILA
RIVER VALLEY/. FURTHERMORE...DURING THE NEXT FEW HOURS...THE UPSLOPE
COMPONENT OF THE LOW-LEVEL FLOW AND THREAT FOR CONVECTION WILL
INCREASE ALONG THE MOGOLLON RIM...AS AN ISALLOBARIC RESPONSE TO SFC
PRESSURE FALLS AROUND 2 MB PER 2 HOURS ACROSS PARTS OF CNTRL/NRN AZ.
AREA VWP DATA DEPICT DEEP SLY TO SWLY FLOW WITH SPEEDS OF 30-40 KT
WITHIN THE 3-7-KM-AGL LAYER SUPPORTING EFFECTIVE BULK SHEAR
MAGNITUDES OF 25-35 KT. THESE SHEAR PROFILES COULD FOSTER
OCCASIONALLY ORGANIZED STORM STRUCTURES...WITH STRONG WIND GUSTS AND
SMALL HAIL BEING THE PRIMARY THREATS. ONE OR TWO INSTANCES OF
MARGINALLY SVR WINDS AND HAIL CANNOT BE RULED OUT ON AN ISOLATED
BASIS IN ASSOCIATION WITH SHORT LINE SEGMENTS AND/OR WEAK SUPERCELL
STRUCTURES. THE DMGG WIND THREAT MAY BE LOCALLY AUGMENTED AFTER 21Z
AS STORMS ENCOUNTER THE DEEPLY MIXED/HOT BOUNDARY LAYER OVER THE
LOWER ELEVATIONS OF SRN AZ FEATURING DCAPE VALUES IN EXCESS OF 1300
J/KG. PW VALUES AROUND 150 PERCENT OF NORMAL PER AMSU/SSMI DATA WILL
ALSO SUPPORT A THREAT FOR RAINFALL RATES AOA 1 IN/HR OVER THE HIGHER
ELEVATIONS OF CNTRL AZ.
A MORE ROBUST SVR THREAT WILL LARGELY BE MITIGATED BY ONLY MARGINAL
INSTABILITY /MLCAPE VALUES AOB 750 J PER KG ACCORDING TO RUC
ANALYSIS AND FORECAST SOUNDINGS/. THIS IS DUE TO SFC
PREFRONTAL/NON-CONVECTIVELY-INFLUENCED DEWPOINTS REMAINING AOB 50F
PER CURRENT SFC OBSERVATIONS AND EXPECTATION THAT STRONG VERTICAL
MIXING WILL OFFSET ANY SUBSTANTIAL DEWPOINT INCREASE PROVIDED BY
MOISTURE ADVECTION FROM THE GULF OF CALIFORNIA. THE 16Z OBSERVED
SOUNDING FROM YUMA PROVING GROUNDS PROVIDES FURTHER BACKING FOR THIS
NOTION...INDICATING WEAK 700-500-MB LAPSE RATES -- I.E. AROUND 6.6
C/KM.
..COHEN.. 10/04/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...TWC...FGZ...PSR...VEF...
LAT...LON 32121333 32871313 34161314 34281315 35491351 36321384
36781346 36781243 36131126 34251049 33031077 32231131
31801226 32121333
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