MESOSCALE PRECIPITATION DISCUSSION 0299
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1009 PM EDT SUN JUN 04 2017

AREAS AFFECTED...SOUTHERN KY...NORTHERN TN...MO BOOTHEEL

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 050210Z - 050800Z

SUMMARY...INCREASING CONVECTION CAPABLE OF 2"/HR LIKELY TO TRAIN
EASTWARD ACROSS TN VALLEY OVERNIGHT POSING FLASH FLOOD THREAT.

DISCUSSION...GOES-E WV DENOTES MCV FROM EARLY GULF COAST MCS HAS
LIFTED NORTHWARD INTO CENTRAL AR WITHIN BEST RIDGING ON NORTHEAST
SIDE OF PARENT DOMINANT CONSOLIDATED UPPER LOW OVER W TX ATTM. 
ADDITIONALLY A SHEARING SHORTWAVE ACROSS THE WESTERN GREAT LAKES
IS DESCENDING SOUTH LEADING TO INCREASED CONFLUENT FLOW ACROSS THE
TN VALLEY...HELPING TO FOCUS FLOW AND SETTING UP A NARROW CORRIDOR
FOR TRAINING CONVECTION TO SETUP.  ADDITIONALLY THE STRENGTHENING
JET AND ORIENTATION WITH THE SHORTWAVE IS ENHANCING SWLY LLJ
ACROSS THE LOWER MS RIVER VALLEY TRANSPORTING DEEPLY SATURATED
PROFILE PER 00Z LZK ROABS WITH TPS OVER 2.0" ADVECTING INTO SW TN
ATTM.  WHILE LAPSE RATES ARE NEAR MOIST ADIABATIC...THERE IS
SUFFICIENT INSTABILITY ACROSS THE SOURCE REGION WITH 1000-1500
J/KG OF MUCAPE AVAILABLE.  AT THE LEADING EDGE OF THIS INCREASED
LLJ THERE IS SUFFICIENT DEEP LOW LEVEL MST CONVERGENCE FOR BROAD
ISENTROPIC ASCENT FROM SE MO ACROSS TO TN. ONE OF THE GREATEST
QUESTIONS THROUGH THE AFTERNOON HOURS (BASED ON HI-RES CAMS AND
OBSERVATIONS) WAS THE TIMING OF CONVECTIVE DEVELOPMENT...RECENT
GOES-16 EXPERIMENTAL EIR AND RADAR MOSAIC SEEMS TO PRESENT THE
CASE FOR SLIGHTLY EARLIER THAN EXPECTED AS NUMEROUS SMALL CORES
ARE POPPING UP ACROSS SW KY ATTM EVEN A FEW HOURS EARLIER THAN
RECENT HRRR RUNS. 

GIVEN THE TIMING OF THE ACTIVATION IS A BIT FASTER THAN THE
FOCUSING DYNAMICS FURTHER N ...CONVECTION MAY BE A BIT
DISORGANIZED INITIALLY BUT WILL INCREASE IN FOCUS.  STILL IN THE
NEAR TERM...PROPAGATION VECTORS AND MEAN CELL MOTIONS ARE
GENERALLY WEAK WITH A SLOW EASTWARD TRACK...POTENTIALLY
EXACERBATING AREAS AFFECTED BY MORE THERMODYNAMICALLY DRIVEN
RAINFALL OVER THE LATE EVENING HOURS...FURTHER COMPLICATING
FLOODING CONCERNS.   HOWEVER...WITH INCREASING CONVECTIVE COVERAGE
AND CONFLUENT STEERING LEVEL FLOW...TRAINING IS LIKELY THROUGH THE
OVERNIGHT HOURS ALONG THE KY/TN BORDER.  WITH RAIN RATES UP TO
2"/HR...THIS MAY LEAD TO LARGER AREAL COVERAGE OF FLASH FLOODING
CONDITIONS WITH 2-3" EXPECTED THROUGH 08Z WITH ISOLATED TOTALS
NEARING 4" POSSIBLE FALLING IN LINE WITH RECENT FEW RUNS OF THE
OPERATIONAL HRRR.  

GALLINA

ATTN...WFO...JKL...LMK...MEG...MRX...OHX...PAH...

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

LAT...LON   37308562 37018442 36558426 35868472 35858629
            35888689 36038870 36128923 36468981 37048958
            37198871 37268726