MESOSCALE PRECIPITATION DISCUSSION 0151
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
936 PM EDT FRI JUL 05 2013
 
AREAS AFFECTED...NWRN AL...CNTRL TN INTO W-CNTRL KY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 060136Z - 060536Z
 
SUMMARY...A FLASH FLOOD THREAT IS INCREASING WITHIN A VERY MOIST
ENVIRONMENT WITH TRAINING CELLS LIKELY INTO THE OVERNIGHT HOURS.

DISCUSSION...RECENT WATER VAPOR IMAGERY SHOWED TWO DEFINED
VORTICITY CENTERS OVER MISSOURI AND SERN ARKANSAS WITHIN A LARGE
MID-UPPER LEVEL TROUGH OVER THE LOWER/MID MISSISSIPPI VALLEY. 00Z
RAOB DATA INDICATED AN UPPER JET AXIS OF 90 - 110 KTS ORIENTED
FROM THE ARKANSAS/MISSISSIPPI BORDER...NNEWD INTO CNTRL ILLINOIS
WHICH PLACES THE RIGHT ENTRANCE REGION OVER NERN MISSISSIPPI /
NWRN ALABAMA. IN ADDITION...00Z RAOB ANALYSIS SHOWED VERTICAL
PROFILES WITH TALL/SKINNY CAPES WITH DEEP LAYERED HIGH RELATIVE
HUMIDITY AND PRECIPITABLE WATER VALUES NEAR AND JUST OVER 2 INCHES
ACROSS A SIGNIFICANT PORTION OF THE SOUTHEAST AND TENNESSEE
VALLEY. 

SHORT TERM RAP MODEL GUIDANCE SUGGESTS THIS JET AXIS WILL LIFT
NORTHWARD AS THE VORTICITY CENTER OVER SERN ARKANSAS LIFTS NNEWD
OVER THE NEXT FEW HOURS...WITH DIFLUENT FLOW INCREASING EARLY
TONIGHT ALONG WITH THE RIGHT ENTRANCE REGION OF THIS UPPER JET
MOVING OVER THE THREAT AREA. MEAN WIND SPEEDS OF 30 - 40 KTS FROM
THE SOUTH WITH SIMILAR LOW LEVEL MOIST INFLOW MAGNITUDE/DIRECTION
FAVORS TRAINING RAINS IN AND AROUND THE TENNESSEE VALLEY.
SUPPORTING GUIDANCE INCLUDING THE 18Z GFS...12Z HRW ARW AND RECENT
RUNS OF THE HRRR SUGGEST 2 - 4 INCHES IN 3 - 6 HOURS IS POSSIBLE
BUT OTHER GUIDANCE IS NOT AS AGREEABLE. ALTHOUGH THE LOWEST FLASH
FLOOD GUIDANCE OF 1 - 2 IN/HR IS ALONG THE EASTERN PORTION OF THE
THREAT AREA...THE FLASH FLOOD POTENTIAL ALONG THE WESTERN PORTION
OF THE SCALLOPED REGION IS ALSO PRESENT DUE TO SLOW MOVEMENT OF
CELLS CONTAINING 1 - 2 IN/HR. WE WILL CONTINUE TO MONITOR THE
SITUATION FOR UPDATES AS NEEDED.

OTTO

ATTN...WFO...LMK...OHX...BMX...HUN...PAH...MEG...

ATTN...RFC...LMRFC...MBRFC...OHRFC...SERFC...

LAT...LON   34008813 35128830 36368804 37608719 38198615 38328533
            38088485 37518498 36738564 34928636 33478736 34008813 
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