WPC Met Watch |
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Mesoscale Precipitation Discussion: #0497 (2017) |
(Issued at 223 PM EDT MON JUL 17 2017
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0497
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
223 PM EDT MON JUL 17 2017
AREAS AFFECTED...CENTRAL/SOUTHERN AZ...SOUTHWEST NM
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 171820Z - 180020Z
SUMMARY...SLOW-MOVING SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS
AFTERNOON AND BE CAPABLE OF PRODUCING 2.5 INCH/HR RAINFALL RATES.
SOME FLASH FLOODING IS LIKELY.
DISCUSSION...THE LATEST EXPERIMENTAL GOES-16 0.64 MICRON/VIS
IMAGERY SHOWS AN EXTREMELY WELL-DEFINED MCV OVER SOUTHWEST AZ
WHICH IS FOSTERING PLENTY OF CYCLONIC FLOW OVER CENTRAL/SOUTHERN
AZ AND SOUTHWEST NM...AND IS ENHANCING A VERY MOIST SOUTHEAST LOW
LEVEL FETCH OVER THE REGION. THIS CONTINUES TO REINFORCE THE
MONSOONAL SET-UP FOR HEAVY CONVECTIVE RAINFALL AS AN INCREASE IN
DIURNAL HEATING/BOUNDARY LAYER INSTABILITY THIS AFTERNOON ALONG
WITH MODEST FORCING AROUND THE EASTERN FLANK OF THE MCV WILL FAVOR
CONVECTIVE DEVELOPMENT/EXPANSION THROUGH THE AFTERNOON HOURS.
ALREADY CONVECTIVE INITIATION IS UNDERWAY ACROSS AREAS OF
SOUTHWEST NM...SOUTHEAST AZ AND LOCALLY UP NEAR THE SOUTHEAST
FLANK OF THE MOGOLLON RIM. 12Z RAOB DATA FROM PHX/TUS THIS MORNING
SHOWED A VERY MOIST COLUMN WITH HIGH PWATS IN THE 1.8 TO 1.9 INCH
RANGE WHICH IS 2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL. THE 15Z
CIRA-LPW DATA CONFIRMS A DEEP MOIST COLUMN THAT HAS PERSISTED AND
WITH A NOTABLY CONCENTRATED POOL OF MOISTURE UP IN THE 500/300 MB
LAYER. THIS WILL CONTRIBUTE TO HIGHLY EFFICIENT RAINFALL PROCESSES
FOR ENHANCED RAINFALL RATES. THIS COUPLED WITH THE DEVELOPMENT OF
RELATIVELY COLD-TOPPED CONVECTION THIS AFTERNOON SHOULD FOSTER
RAINFALL RATES OF UP TO 2.5 INCHES/HR.
THE LATEST ARW/NMMB AND NSSL-WRF SOLUTIONS SUPPORT A RATHER
SIGNIFICANT EXPANSION OF CONVECTION THIS AFTERNOON FROM SOUTHWEST
NM WEST ACROSS ADJACENT AREAS OF SOUTHEAST AZ AND NORTH UP INTO
CENTRAL AZ INCLUDING THE MOGOLLON RIM AREA. EXPECT RAINFALL TOTALS
OF AS MUCH AS 3 TO 4 INCHES AT LEAST LOCALLY...AND SOME ISOLATED
HEAVIER AMOUNTS CANNOT BE RULED OUT GIVEN THE RELATIVELY SLOW CELL
MOTION AND INTENSE RAINFALL RATES.
FLASH FLOODING WILL BE LIKELY OVER AREAS THAT SEE THESE HEAVIER
TOTALS THROUGH THE AFTERNOON HOURS. AREA DRY WASHES AND ARROYOS
WILL BE SENSITIVE TO FLASH FLOODING...BUT ALSO AREAS OF STEEP AND
LOCALLY CHANNELED TERRAIN WHERE RUNOFF WILL BE GREATLY ENHANCED
WILL BE PARTICULARLY PRONE TO FLASH FLOODING. WILL CONTINUE TO
MONITOR.
ORRISON
ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...VEF...
ATTN...RFC...CBRFC...WGRFC...
LAT...LON 35671158 34941077 34570977 34270894 33540812
32910781 31830798 31330844 31250902 31180994
31321120 31521195 31681254 32021288 32591288
33121318 33511369 34271372 34771350 35141305
35551239
Last Updated: 223 PM EDT MON JUL 17 2017
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