Graphic for MPD #0616
MESOSCALE PRECIPITATION DISCUSSION 0616
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1019 AM EDT WED AUG 02 2017

AREAS AFFECTED...SOUTHEAST ARIZONA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 021420Z - 021920Z

SUMMARY...LINGERING UPPER LEVEL TROF...SLOW MOVING CELLS AND ABOVE
AVERAGE MOISTURE POSE FLASH FLOODING RISK AND UPGRADE TO SLIGHT
RISK FOR 15Z EXCESSIVE RAINFALL OUTLOOK.

DISCUSSION...GOES-WEST WV DEPICTS A HIGHLY ELONGATED MID TO UPPER
LEVEL TROF EXTENDING FROM S CA ACROSS S AZ INTO N CHIHUAHUA. ALONG
THE TROF THERE ARE WEAK INDIVIDUAL WAVES.  ONE SUCH WAVE IS
LOCATED OVER NW SONORA WHICH SUPPORTS A WEAK BOUNDARY
LAYER/SURFACE WAVE OVER THE SANTA CRUZ FLATS.  THE INCREASED
CURVATURE SUPPORTS LOCALIZED INCREASED ESELY FLOW SUPPORTING
MODEST MOISTURE CONVERGENCE ACROSS S PINAL MOUNTAINS TOWARD SANTA
CATALINA RANGE AROUND TUS.  RAP ANALYSIS FIELDS EVEN SUGGEST A FEW
UNITS OF 85-7H FRONTOGENETIC FORCING WITHIN THIS BAND. 
ADDITIONALLY...MOISTURE IS POOLED ALONG THE LOW LEVEL TROF WITH
1.8" TPWS NOTED IN 12Z TUS RAOB AND AS MUCH AS 1.5" AS FAR WEST AS
EPZ.  GIVEN MOISTURE PROFILE THERE IS MODEST CONCERN FOR EFFICIENT
RAINFALL RATES UP TO 1.5"/HR .

RECENT EARLY MORNING VISIBLE/IR SUGGEST INCREASING LOW LEVEL
CU/TCU WITH A FEW CBS AT LOCATIONS OF BEST MST CONVERGENCE.  WEAK
OVERALL FLOW TOWARD THE ENE COUNTER BALANCED BY 5-10KTS OF SE
PROPAGATION VECTORS SUGGEST NEAR STATIONARY/VERY SLOW MOVING CELLS
ALLOWING FOR COMPOUNDED TOTALS WITH 1-2" TOTALS POSSIBLE BEFORE
MODEST INSTABILITY IS EXHAUSTED.

WITH TIME AND SOLAR INSOLATION WILL INCREASE INSTABILITY FURTHER
SOUTH.  THIS COMBINED WITH FORCING FROM SLOW SOUTH/SSE MOTION OF
THE WEAK LOW LEVEL INFLECTION IS EXPECTED TO OCCUR SUBSEQUENTLY
INCREASING THREAT FOR SIMILAR SLOW MOVING ACROSS PIMA/SANTA CRUZ
AND COCHISE COUNTIES TOWARD 17-19Z.  STILL CONVECTION SHOULD BE
RELATIVELY SCATTERED WITH MODERATE TO SMALL UPDRAFT/DOWNDRAFT
CORES...LIMITING THE OVERALL AREAL THREAT TO ISOLATED LOCALS. 
STILL WITH THE HIGHER THAN EXPECTED MOISTURE PER SOUNDING AND
FORCING...WPC WILL BE UPGRADING THE THREAT OF EXCESSIVE RAINFALL
TO SLIGHT RISK WITH THE 15Z ISSUANCE ACROSS SE AZ.

GALLINA

ATTN...WFO...TWC...

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

LAT...LON   32941076 32941013 32320948 31440913 31250928
            31271020 31381130 31821234 32451173 32861108
           


Last Updated: 1019 AM EDT WED AUG 02 2017