MESOSCALE PRECIPITATION DISCUSSION 0836
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
426 PM EDT WED SEP 27 2017

AREAS AFFECTED...CENTRAL/WESTERN NM...NORTHEAST/EAST-CENTRAL AZ

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

VALID 272025Z - 280225Z

SUMMARY...BANDS OF HEAVY RAINFALL ARE EXPECTED THROUGH THE
AFTERNOON AND EARLY EVENING HOURS. SOME LOCALIZED RUNOFF PROBLEMS
AND/OR FLASH FLOODING WILL BE POSSIBLE.

DISCUSSION...THE LATEST NON-OPERATIONAL GOES-16 RGB-AIRMASS
IMAGERY SHOWS A ROBUST UPPER LOW OVER CENTRAL AZ...WITH A RATHER
STRONG PV ANOMALY THAT IS SEEN EDGING SLOWLY EAST. THE NORTHEAST
FLANK OF THIS ANOMALY IS COUPLING WITH ROBUST DIURNAL HEATING AND
STEEP MID LEVEL LAPSE RATES FOR SCATTERED SMALL CLUSTERS OF RATHER
SLOW-MOVING CONVECTION OVER NORTHEAST AZ. MOISTURE ACROSS THIS
REGION THOUGH IS QUITE MODEST WITH PWATS OF GENERALLY ONLY A 0.50
INCH.

FARTHER EAST...THERE ARE SOME BANDS OF CONVECTION OVER WESTERN NM
IN ASSOCIATION WITH A RATHER DIVERGENT FLOW REGIME ALOFT TO THE
EAST OF THE UPPER LOW. CLOUD TOPS HERE HAVE BEEN COOLING A BIT
OVER THE LAST HOUR INDICATIVE OF AN UPTICK IN DEEP LAYER FORCING.
THE CONVECTION IS ALSO PRODUCING RELATIVELY HEAVY RAINFALL RATES
AND COINCIDING WITH AN AXIS OF NOTABLY DEEPER MOISTURE WHERE THERE
IS A BETTER MID LEVEL CONCENTRATION AS PER CIRA-LPW DATA ANALYSIS.
SOME DUAL-POL ESTIMATES HAVE ALREADY BEEN OCCASIONALLY EXCEEDING 1
INCH/HR.

THE LATEST HIRES MODEL CONSENSUS SUPPORTS THE IDEA OF SOME 1 TO 2+
INCH AMOUNTS...ESPECIALLY OVER AREAS OF CENTRAL/WESTERN NM THROUGH
00Z...WITH SOME ADDITIONAL HEAVY RAINS POSSIBLE AFTER 00Z AS THE
UPSTREAM UPPER LOW SLOWLY SHIFTS EAST AND INTERACTS WITH AT LEAST
A MODESTLY UNSTABLE BUT RELATIVELY DEEP MOISTURE AXIS. RAINFALL
AMOUNTS CLOSER TO THE UPPER LOW OVER NORTHEAST AZ WILL TEND TO BE
MITIGATED A BIT BY A DRIER BOUNDARY LAYER AND LOWER PWATS
OVERALL...BUT SLOWER CELL MOTION HERE WILL TEND TO COMPENSATE AND
MAY RESULT IN SOME SPOTTY 1 TO 2 INCH AMOUNTS. THESE AMOUNTS WILL
BE CAPABLE OF PRODUCING SOME LOCALIZED RUNOFF PROBLEMS AND/OR
FLASH FLOODING.

ORRISON

ATTN...WFO...ABQ...EPZ...FGZ...GJT...PSR...TWC...

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

LAT...LON   37020910 36930770 36500669 35420622 34100631
            32770689 32050738 31670836 32240930 33971024
            35071168 35971248 36701196 36991075