MESOSCALE PRECIPITATION DISCUSSION 0133...CORRECTION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 AM EDT SAT APR 22 2017

CORRECTION TO WORDING OF FIRST DISCUSSION PARAGRAPH

AREAS AFFECTED...WESTERN & CENTRAL TN

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

VALID 220711Z - 221311Z

SUMMARY...THUNDERSTORMS WITH COOLING CLOUD TOPS ARE SPREADING
ACROSS WESTERN TN. HOURLY RAIN RATES TO 1.5", WITH LOCAL AMOUNTS
OF 2-3", COULD LEAD TO FLASH FLOODING, PARTICULARLY IN CENTRAL TN.

DISCUSSION...SINCE 05Z, THUNDERSTORMS HAVE BEEN BUILDING ACROSS
WESTERN TN AHEAD OF A SHORTWAVE APPARENT IN SATELLITE AND RADAR
IMAGERY NEAR THE BOOTHEEL OF MO.  BULK SHEAR IN THE 0-6 KM LAYER
IS NEAR 35 KTS PER SPC MESOANALYSES.  INFLOW INTO THE STORMS IS
SLIGHTLY CONVERGENT AND OUT OF THE SOUTHWEST AT 30-40 KTS, WITH
WINDS NEARLY UNIDIRECTIONAL WITH HEIGHT.  AT THE TIME OF THIS
DISCUSSION'S WRITING, PROBLEMS RELATED TO THE RAINFALL IN WESTERN
TN HAVE BEEN LIMITED TO TYPICAL URBAN FLOODING PER RECENT FEEDBACK
FROM MEG/THE MEMPHIS TN FORECAST OFFICE. PRECIPITABLE WATER VALUES
OF 1.1-1.5" EXIST IN THIS AREA PER GPS DATA.  PERIODS OF RAIN OVER
THE PAST SEVERAL HOURS SHOULD HAVE SATURATED THE ATMOSPHERE ACROSS
CENTRAL AND WESTERN TN (LEADING TO TALL SKINNY CAPES), ALLOWING
THE ATMOSPHERE TO RESPOND MORE EFFECTIVELY TO LOWERED INSTABILITY.
 THE LATEST SPC MESOANALYSIS SHOWS AN AREA OF 500+ J/KG MUCAPES
ACROSS SOUTHWEST TN AND NEAR THE MS/AL/TN BORDER JUNCTION.

WITH INSTABILITY EXPECTED TO BE STEADY STATE, OR POSSIBLY INCREASE
SLIGHTLY FURTHER IN THE DIVERGENT ATMOSPHERE ALOFT AHEAD OF A
CLOSED LOW NEAR THE SOUTHERN KS/MO BORDER, BELIEVE HEAVY RAIN
CONCERNS COULD PERSIST INTO THE MORNING HOURS.  THIS WOULD BE MOST
PROBLEMATIC IN CENTRAL TN WHERE SOILS HAVE BEEN PARTIALLY
SATURATED BY RECENT RAINFALL.  THE 00Z SPCWRF APPEARS TO HAVE THE
BEST MATCH TO THE PRECIPITATION PATTERN EXPECTED THIS PERIOD. 
HOURLY RAIN RATES UP TO 1.5", WITH LOCAL AMOUNTS IN THE 2-3"
RANGE, ARE POSSIBLE THROUGH 13Z, WHICH COULD LEAD TO FLASH
FLOODING.

ROTH

ATTN...WFO...HUN...MEG...MRX...OHX...

ATTN...RFC...LMRFC...OHRFC...

LAT...LON   36588533 36588447 36358427 36088415 35698473
            35008567 35018732 35008886 35168995 36288926
            36508754 36578599