MESOSCALE PRECIPITATION DISCUSSION 0045
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
710 AM EST TUE FEB 07 2017
 
AREAS AFFECTED...CENTRAL/ERN AR...WRN TN...NW MS...SE MO...SW KY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 071209Z - 071609Z
 
SUMMARY...WEST TO EAST TRAINING ALONG EDGE OF A DEEP ELEVATED
MIXED LAYER MAY LEAD TO 2 INCH / HOUR ACCUMULATIONS AND FLASH
FLOODING.

DISCUSSION...AT 12Z WIDESPREAD MODERATE TO STRONG HEIGHT FALLS
WERE OCCURRING AHEAD OF A BROAD TROUGH DRIVING THROUGH THE PLAINS
AND LOWER MISSISSIPPI VALLEY. THUNDERSTORMS WERE ONGOING AT THE
EDGE OF THE DEEPER ELEVATED MIXED LAYER / CAPPING
INVERSION...ROUGHLY THE 12C ISOTHERM AT 850 MB. CONVECTIVE
DEVELOPMENT WAS AIDED BY UPGLIDE ALONG THE 300K SURFACE OVER
CENTRAL AND NORTHEAST ARKANSAS EASTWARD INTO TENNESSEE AND
SOUTHWEST KENTUCKY.

ALTHOUGH THE CONVECTION WAS ROBUST...WORKING ON MUCAPE VALUES
GREATER THAN 1000 J/KG...STORMS WERE ROOTED ABOVE THE SURFACE AND
FEEDING ON STRONG AND NEARLY UNIDIRECTIONAL INFLOW IN THE 850-700
MB LAYER...MEANING COLD POOLS WERE INEFFECTIVE AT PUSHING THE
EVENT ALONG TO THE SOUTH...AND RESULTING IN SSW-ENE TRAINING. THIS
TRAINING WAS MOST PRONOUNCED OVER ARKANSAS...BUT MAY BECOME MORE
OF AN ISSUE INTO ADJACENT MO/TN/MS/KY WITH TIME...AS THE MID LEVEL
TROUGH PROGRESSES...WITH THE RAP PUSHING A SUBTLE 700 MB WIND
SHIFT THROUGH THE LONGITUDE OF MEMPHIS BY 15Z. 

THE HRRR AND FSL EXPERIMENTAL HRRR WERE DOING THE BEST JOB OF
PICKING UP ON THIS ACTIVITY SPATIALLY. IN TERMS OF MAGNITUDE THE
PRECIPITABLE WATER ENVIRONMENT WAS SOMEWHAT MARGINAL WITH PW NEAR
OR BELOW 1.3 INCHES. SOME HAIL CONTAMINATION MAY ALSO AFFECT
RADAR-BASED RAIN ESTIMATES...ALTHOUGH DUAL POL SHOULD BE MORE
IMMUNE TO THIS. KLZK ESTIMATED HOURLY RATES AS MUCH AS 3
INCHES...ALTHOUGH 1 TO 2 INCHES PER HOUR WILL BE MORE COMMON THIS
MORNING. IN ANY CASE...IT IS LIKELY THAT FFG WILL BE EXCEEDED IN A
FEW LOCATIONS...WITH THE EMPHASIS SHIFTING DOWNSTREAM AND
ESPECIALLY INTO WESTERN TENNESSEE WHERE OUTFLOW BOUNDARIES FORMED
EARLIER THIS MORNING MAY FOCUS UPGLIDE AND ENHANCED COVERAGE AND
DURATION OF HEAVY RAIN.

BURKE

ATTN...WFO...LMK...LZK...MEG...OHX...PAH...

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

LAT...LON   37028836 36788652 36168663 35038869 34069222 
            34559314 35329211