MESOSCALE PRECIPITATION DISCUSSION 0168
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1137 PM EDT SAT APR 29 2017

AREAS AFFECTED...CENTRAL/EASTERN AR...EXTREME SOUTHEAST MO...FAR
WESTERN KY...FAR WESTERN TN

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 300337Z - 300930Z

SUMMARY...SHOWERS AND THUNDERSTORMS WITH INTENSE RAINFALL RATES TO
OVER 2 INCHES/HR ARE EXPECTED TO BECOME A BIT MORE CONCENTRATED
OVER THE NEXT FEW HOURS. FLASH FLOODING IS LIKELY.

DISCUSSION...GOES-16 EXPERIMENTAL 6.9 MICRON/WV IMAGERY SHOWS AN
EXTREMELY DIFFLUENT CLOUD PATTERN OVER THE LOWER AND MID MS VALLEY
AS A DEEP UPPER TROUGH CONTINUES TO EJECT GRADUALLY EAST OUT
ACROSS THE SOUTHERN HIGH PLAINS. THIS IS REFLECTIVE OF THE STRONG
UPPER JET FORCING OVER THE REGION...AND STRONG CONVECTION
CONTINUES TO DEVELOP ALONG AND AHEAD OF A COLD FRONT GIVEN THE
DEEPER LAYER ASCENT COUPLING WITH A VERY MOIST AND UNSTABLE
BOUNDARY LAYER.

CIRA-LPW IMAGERY DEPICTS A NOSE OF 1.75 TO 2 INCH PWATS NOSING
NORTH ACROSS THE LOWER MS VALLEY WITH THE SUPPORT OF A PERSISTENT
40 TO 60 KT LOW LEVEL JET. MEANWHILE...MUCAPE VALUES ARE AS HIGH
AS 2000 TO 3000 J/KG OVER AREAS OF CENTRAL/SOUTHERN AR...WITH EVEN
GREATER VALUES FARTHER SOUTH OVER EASTERN TX/LA. THIS ENERGY WILL
CONTINUE TO BE TRANSPORTED NORTH OVERNIGHT...AND WILL BE
RESPONSIBLE FOR DRIVING FOCUSED AREAS OF STRONG CONVECTION AND
HEAVY RAINFALL ACROSS CENTRAL/EASTERN AR AND FAR SOUTHEAST MO.
TRENDS WILL NEED TO ALSO BE MONITORED FOR WESTERN TN AND WESTERN
KY.

RAINFALL TOTALS AS PER THE LATEST HRRR/HRRRX GUIDANCE ARE ON THE
ORDER OF 2 TO 4 INCHES WITH ISOLATED AMOUNTS AS HIGH AS 5 TO 6
INCHES ACROSS CENTRAL/NORTHEAST AR AND FAR SOUTHEAST MO THROUGH
09Z. SEE NO REASON TO DOUBT THESE NUMBERS GIVEN THE LATEST
SATELLITE/RADAR TRENDS. FORWARD CONVECTIVE PROPAGATION MAY BRING
SOME OF THE HEAVIER TOTALS LATER IN THE NIGHT CLOSE TO AREAS OF
WESTERN TN AND WESTERN KY. FLASH FLOODING WILL BE LIKELY GIVEN
THESE EXPECTED TOTALS.

ORRISON

ATTN...WFO...LZK...MEG...PAH...SGF...SHV...

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

LAT...LON   37208822 36758807 35848866 34999009 33819156
            33109262 32979357 33169406 33709402 33969389
            34809363 35599298 36229209 36529108 36888973