WPC Met Watch |
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Mesoscale Precipitation Discussion: #0678 (2017) |
(Issued at 332 AM EDT SUN AUG 13 2017
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0678
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
332 AM EDT SUN AUG 13 2017
AREAS AFFECTED...CENTRAL/SOUTHERN AZ
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 130730Z - 131030Z
SUMMARY...SHOWER AND THUNDERSTORM ACTIVITY WILL TEND TO LINGER FOR
A FEW MORE HOURS. SOME ADDITIONAL FLASH FLOODING CONCERNS ARE
POSSIBLE BEFORE.
DISCUSSION...THE LATEST SATELLITE AND RADAR IMAGERY SHOWS
CONVECTION PERSISTING OVER AREAS OF SOUTH-CENTRAL AND SOUTHEAST
AZ. THE CONVECTION HAS BEEN TENDING TO MAINTAIN ITSELF WITHIN A
MODESTLY UNSTABLE ENVIRONMENT...WITH 500 TO 1000 J/KG OF
MLCAPE...BUT ALSO WITHIN A RATHER DIVERGENT FLOW REGIME ALOFT
COURTESY OF A SHORTWAVE TROUGH FARTHER NORTH THAT IS EJECTING EAST
ACROSS CENTRAL/SOUTHERN UT.
INCREASING BOUNDARY LAYER CINH GIVEN THE LOSS OF DAYTIME HEATING
SHOULD GRADUALLY ALLOW FOR THE CONVECTION TO WEAKEN OVER THE NEXT
SEVERAL HOURS...BUT THERE WILL STILL BE SOME LOCALLY HEAVY
RAINFALL AT LEAST IN THE NEAR-TERM AS SUGGESTED BY SOME OF THE
RECENT COOLING CONVECTIVE TOPS JUST TO THE SOUTH AND SOUTHEAST OF
PHOENIX...AND EAST OF GILA BEND.
THE LATEST HRRR GUIDANCE SUPPORTS SOME ADDITIONAL RAINFALL AMOUNTS
OF LOCALLY 1 TO 1.5 INCHES...OF WHICH MUCH OF THAT WOULD TEND TO
FALL IN A 1 TO 2 HOUR PERIOD GOING THROUGH ABOUT 10Z.
THEREAFTER...CONDITIONS SHOULD IMPROVE...BUT THERE ARE STILL SOME
LINGERING NEAR-TERM FLASH FLOOD CONCERNS.
ORRISON
ATTN...WFO...EPZ...FGZ...PSR...TWC...VEF...
ATTN...RFC...CBRFC...
LAT...LON 35111316 34261204 33091058 32420918 31820892
31400951 31361057 31561148 31951225 32571301
33431372 34571439 35041420
Last Updated: 332 AM EDT SUN AUG 13 2017
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