MESOSCALE PRECIPITATION DISCUSSION 0019
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
556 AM EDT SAT APR 27 2013
 
AREAS AFFECTED...NORTHEAST ARKANSAS...WESTERN TENNESSEE...FAR
SOUTHEAST MISSOURI...FAR SOUTHWEST KENTUCKY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 270955Z - 271525Z
 
SUMMARY...THROUGH MID MORNING FOCUSED MESOSCALE LIFT WILL PRODUCE
WIDESPREAD 1-INCH AND LOCALLY HEAVIER RAINS WHERE GROUND WAS
ALREADY SATURATED.

DISCUSSION...RECENT OBSERVATIONAL AND MODEL TRENDS HAVE LED TO
INCREASED CONFIDENCE IN THE PLACEMENT OF A PRECIPITATION EVENT
THIS MORNING. THE NOSE OF A BROAD 40 KT LOW LEVEL JET WILL IMPINGE
UPON A PERSISTENT MID LEVEL BAROCLINIC ZONE CROSSING THIS REGION
FROM WNW TO ESE. THIS WILL OCCUR BENEATH DIFLUENT UPPER FLOW AND
WITHIN AN AIRMASS CHARACTERIZED BY PRECIPITABLE WATER VALUES 1.25
TO 1.50 INCHES.

INSTABILITY IS SOMEWHAT LACKING PER MODEL FIELDS AND MODEL
SOUNDINGS...BUT INCREASING INTENSITY OF RADAR ECHOES AND LIGHTING
FREQUENCY OVER NORTHEAST ARKANSAS AND WESTERN TENNESSEE SUGGEST
LARGER SCALE FORCING WILL BE SUFFICIENT TO FORCE SOME UPRIGHT
CONVECTION WITHIN A BROAD DEVELOPING REGION OF MODERATE RAIN
SHOWERS/STORMS. HIRES WRF ARW...NMM...AND NSSL WRF ARE VERY
SIMILAR IN PLACING AN AXIS OF AT LEAST 1-INCH AREAL AVERAGE RAIN
OVER THE OUTLINED AREA THROUGH 15-16 UTC. THE SAME MODELS YIELD
EMBEDDED HIGHER SWATHS OVER 2 INCHES WHICH APPEARS PLAUSIBLE. THIS
BECOMES A CONCERN PRIMARILY DUE TO OBSERVED AND RADAR-ESTIMATED
RAINFALL OF AT LEAST 1-3 INCHES EARLIER IN THE NIGHT...WHICH
SUGGESTS A GREATER LIKELIHOOD OF RAPID RUN-OFF/FLOODING.

BURKE


ATTN...WFO...OHX...PAH...MEG...LZK...SGF...

LAT...LON   35159000 35378851 35828759 36258753 36658801 36848895
            36848994 36819049 36689109 36419158 35749188 35239157
            35079095 35159000