MESOSCALE PRECIPITATION DISCUSSION 0416
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
204 PM EDT FRI OCT 10 2014
 
AREAS AFFECTED...FAR NORTHERN AL...TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 101755Z - 102200Z
 
SUMMARY...PCOKETS OF FLASH FLOODING MAY BECOME A CONCERN THIS
AFTERNOON AS THE POTENTIAL FOR BACKBUILDING AND TRAINING
CONVECTION INCREASES SOMEWHAT.

DISCUSSION...THE LATEST VIS SAT IMAGERY SHOWS A FAIRLY WIDESPREAD
CU/TCU FIELD OVER AREAS OF NRN MS/NRN AL AND SWRN TN...AND FOCUSED
SOUTH AND SOUTHWEST OF A LOOSELY ORGANIZED BUT BROKEN BAND OF HVY
SHWRS/TSTMS IMPACTING CNTRL/SRN TN. A GRADUAL INCREASE IN CLOUD
STREET ACTIVITY OVER ESP NRN MS AND SWRN TN THE LAST COUPLE OF
HOURS SUGGESTS AN INCREASE IN SFC-BASED INSTABILITY WHICH IS
CONFIRMED BY THE LATEST RAP ANALYSIS INDICATING A POOL OF SBCAPE
VALUES OF 1500 TO 2000 J/KG ACROSS THIS REGION. THE ONGOING
CONVECTION IS ALREADY INTERACTING WITH A MOIST SWLY H85 JET OF 30
KTS AND IS BEING AIDED SOMEWHAT ON THE LARGE SCALE BY SOME
MODESTLY DIFFLUENT FLOW ALOFT.

MEANWHILE...THE LATEST GOES-SOUNDER PWAT IMAGERY SHOWS AN
INCREASING FETCH OF DEEPER MOISTURE ADVANCING NNEWD FROM THE LWR
MS VLY WHICH WILL INTERACT WITH A STALLED OUT FRONTAL ZONE AND
WITH WHAT APPEARS TO BE A WEAK PRE-FRONTAL TROUGH/OUTFLOW BNDRY
OVER CNTRL AND ERN TN. THIS IS WHERE MUCH OF THE ONGOING
CONVECTION IS FOCUSED AND WITH AN INCREASE IN MOIST/UNSTABLE AIR
ALONG THE SWRN FLANK OF THE ACTIVITY COUPLED WITH A FURTHER
INCREASE IN DIURNAL HEATING...ADDITIONAL CONVECTION IS
LIKELY...AND THERE WILL BE A FAVORABLE ENVIRONMENT FOR
BACK-BUILDING AND TRAINING CONVECTION GIVEN THE MEAN LYR FLOW
BEING NEARLY PARALLEL TO THE AFOREMENTIONED SFC BNDRYS. RAINFALL
RATES OF 1 TO 2 INCHES/HR ARE POSSIBLE...AND SO FLASH FLOODING
WILL BE POSSIBLE WHERE REPEATING/TRAINING CELLS OCCUR.

HIRES MODELS ARE NOT HANDLING THE ONGOING ACTIVITY WELL AT
ALL...AND SO THIS ASSESSMENT IS ALL BASED ON THE LATEST SAT AND
RADAR TRENDS.

ORRISON 

ATTN...WFO...HUN...MEG...MRX...OHX...PAH...

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

LAT...LON   36538810 36468702 36388604 36368500 36188412 
            35838388 35588405 35318456 35118525 34888656 
            34918737 35298813 35688902 36298900