MESOSCALE PRECIPITATION DISCUSSION 0561
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1032 AM EDT TUE OCT 06 2015
 
AREAS AFFECTED...ARIZONA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 061431Z - 062031Z
 
SUMMARY...SLOW MOVING UPPER LOW WITH 2.5 ST. DEV. OF MOISTURE
ALLOWS FOR THE POTENTIAL FOR ISOLATED FLASH FLOOD THREAT.

DISCUSSION...DEEP VERTICALLY STACKED LOW CONTINUES TO SHIFT SLOWLY
EASTWARD.  WV LOOP SHOWS TWO MAIN VORT CENTERS...WITH THE STRONGER
ONE ROUNDING THE BASE ATTM INCREASING LOCALIZED PVA NEAR THE
CENTER WITH SOME ADDITIONAL DIVERGENCE IN THE UPPER LEVEL JET. 
THIS ALLOWS FOR VERY SLOW NEARLY ZERO CELL MOTION AND CORFIDI
VECTORS JUST A BIT NORTH OF THE LOW.  BLENDED TPW AND RAP ANALYSIS
INDICATE ALSO SUPPORTED BY WV LOOP SHOWS A RELATIVELY BROAD
CONCENTRIC AREA OF INCREASED MID-LEVEL MOISTURE NEAR THE UPPER
LOW...WITH TPWS AOA 1"...WHICH IS NEAR 2.5 STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR.  THIS MID-LEVEL MOISTURE ALSO
SUPPORTS MODERATE LAPSE RATES FOR SOME INSTABILITIES.  CURRENTLY
MUCAPES IN THE 500 J/KG HAVE SUPPORTED SOME NARROW CORE UPDRAFTS. 
STILL 12Z VEF/FGZ SOUNDINGS DO SUPPORT THE PROBABILITY OF
INCREASED SBCAPES WITH A BIT OF SOLAR INSOLATION.  AT THIS TIME IR
AND EARLY VISIBLE INDICATE BROKEN SKIES TO SUPPORT THIS THOUGHT. 
HOWEVER...WITHOUT A CAPPING AGENT...QUICK SURFACE TEMP RISES
SHOULD RESULT IN RELATIVE QUICK DEVELOPMENT TO LIMIT VERY
STRONG/ROBUST UPDRAFTS WITH MORE SCATTERED NATURE TO BE MORE
PREVALENT. 

ADDITIONALLY...IR LOOP SHOWS AN CONVERGENCE BAND/ARC WITH SOME
WEAK CELLS DEVELOPING ALONG IT...WITH 20-25KTS OF 7H INFLOW TO
SUPPORT CONTINUED CONVECTIVE GROWTH.  ACCIDENTAL TRAINING OF CELLS
MOVING NORTH TO NNE ARE POSSIBLE BUT ARC SHOULD PROGRESS EAST
ENOUGH TO ALLEVIATE LARGEST PROBLEMS. 
ADDITIONALLY...ENVIRONMENTAL COMPARISON TO YESTERDAY...LARGER
DEWPOINT DEPRESSIONS/LOWER INSTABILITY/WEAKER INFLOW SHOULD REDUCE
COVERAGE AND MAGNITUDE AS WELL.  CONFIDENCE IN OVERALL PATTERN IS
NOT PARTICULARLY HIGH GIVEN THE LARGE SPREAD IN THE HI-RES CAM
SOLUTIONS FOR QPF... ESPECIALLY GIVEN OPERATIONAL HRRR RUNS ARE
STARTING TO BACK OFF ON MAGNITUDE A BIT.  STILL THE 12Z HRRR...00Z
ARW REMAIN A PREFERRED SOLUTION.

LARGEST THREAT SHOULD BE NORTH AND NORTHEAST OF THE UPPER LOW
WHERE INSTABILITY/FORCING AND MOST IMPORTANTLY NEAR ZERO
PROPAGATION VECTORS WITH SOME MODERATE DIVERGENCE ALOFT SHOULD
SUPPORT COMPOUNDING TOTALS...WITH RATES OF .5-.75"/HR...TOTALS OF
1-2" ARE POSSIBLE.  ADDITIONAL...THREAT OF CELL TRACKS WITH
ENHANCED LIFT DUE TO OROGRAPHY OF THE MOGOLLON RIM COULD ALSO POSE
ISOLATED FLASH FLOOD THREATS PARTICULARLY LATER IN THE
MORNING/EARLY AFTERNOON.  

GALLINA

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

ATTN...RFC...CBRFC...

LAT...LON   36211349 36201198 35721019 34221034 32911124 
            32621242 32561347 33181367 33591382 33511435 
            34321447 35061456 35711423