MESOSCALE PRECIPITATION DISCUSSION 0152
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1203 PM EDT FRI MAY 29 2015
 
AREAS AFFECTED...PORTIONS OF THE MIDDLE AND LOWER MS VALLEY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 291603Z - 292103Z
 
SUMMARY...FLASH FLOODING WILL BECOME LIKELY ACROSS PORTIONS OF THE
HIGHLIGHTED AREA THIS AFTERNOON AS A VIGOROUS MCV INFLUENCES THE
REGION.

DISCUSSION...A STRONG MCV WILL MOVE INTO EASTERN OKLAHOMA THIS
AFTERNOON AND TAP INTO AND ENTRAIN AN INCREASINGLY DEEP AND
UNSTABLE MOISTURE PLUME TO SUPPORT STRONG AND DEEP CONVECTION
CAPABLE OF HIGH RAINFALL RATES.

SURFACE AND VWP ANALYSIS PREFERENCE SHOW A DEEPER SURFACE LOW AND
STRONGER LOW LEVEL JET IN ASSOCIATION WITH THE MCV THAN SHOWN BY
00-06Z GUIDANCE.  MEANWHILE...NEARLY FULL INSOLATION OVER EASTERN
ARKANSAS HAS ALREADY CONTRIBUTED TO SBCAPES OF NEARLY 3000 J/KG
WHICH IS SUPPORT BY MODIFYING THE 12Z KLZK RAOB. GIVEN THESE
CONDITIONS ALONG WITH AVERAGE CLOUD LAYER WINDS OF 15 KNOTS AND
ALMOST UNIDIRECTIONAL WINDS WITH HEIGHT...SLOW CELL MOTIONS AND
TRAINING WILL CONTRIBUTE TO HIGH RAINFALL RATES.

THE 12Z NAM AND RECENT RUNS OF THE HRRR SEEM TO CAPTURE THE
ONGOING EVOLUTION WHICH DEPICT HEAVIER AND MORE WIDESPREAD
RAINFALL THAN SHOWN IN PREVIOUS GUIDANCE.  GIVEN 1 FFG VALUES OF 1
TO 1.5 INCHES AND 3 HOUR FFG VALUES 2 TO 2.5 INCHES IN SOME MANY
AREAS...EXCEEDING THESE GUIDANCE IS LIKELY. 

JAMES

ATTN...WFO...EAX...ICT...LSX...LZK...OUN...SGF...SHV...TOP...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...

LAT...LON   39559475 38399372 39209095 36989161 35369318 
            34349511 34379636 36839607 38709597