MESOSCALE PRECIPITATION DISCUSSION 0313
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
346 PM EDT SAT JUN 04 2016
AREAS AFFECTED...PORTIONS OF MS/AL/WESTERN FL
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 041945Z - 050145Z
SUMMARY...SHORT TRAINING BANDS OF CONVECTION ARE TRYING TO SET UP
ACROSS PORTIONS OF MS AS OF LATE, WHILE INSTABILITY CONTINUES TO
INCREASE. WITH HOURLY RAIN RATES UP TO 2.25" POSSIBLE, FLASH
FLOODING IS POSSIBLE.
DISCUSSION...AHEAD OF AN ORGANIZED CONVECTIVE CLUSTER IN LA,
SHOWERS AND THUNDERSTORMS ARE ATTEMPTING TO SET UP IN SHORT
TRAINING BANDS ACROSS NEAR A THERMAL DISCONTINUITY SNAKING ACROSS
EASTERN MS. PRECIPITABLE WATER VALUES ARE 1.8-2" PER GPS VALUES,
WHILE 850 HPA INFLOW OF 15-20 KTS IS FUNNELING IN MLCAPES OF
2000-2500 J/KG INTO THE AREA. DIVERGENCE ALOFT IS PLENTIFUL EAST
OF AN MCV IN LA AND NEAR THE SPLIT BETWEEN THE SUBTROPICAL JET
HEADING FOR FL AND THE SOUTHERN BRANCH OF THE WESTERLIES HEADING
TOWARDS THE OH VALLEY.
THE CAM/MESOSCALE GUIDANCE HAD A GOOD SIGNAL FOR HEAVY RAIN ACROSS
THE AREA, WITH LOCAL AMOUNTS OF 3-5" INDICATED PRIMARILY ACROSS
MS. THE ADDED OUTFLOW BOUNDARY/LOW-LEVEL CONVERGENCE LINE ON
VISIBLE SATELLITE IMAGERY IMPLIES THAT THE GUIDANCE COULD BE
UNDERSELLING POTENTIAL ACROSS WESTERN AND CENTRAL AL. IT IS
UNCLEAR IF ACTIVITY TO THE WEST IN LA COULD MOVE NORTHEAST AND
CAUSE SOME ADDITIONAL CELL MERGERS ACROSS MS, THOUGH A RECENT
SAB/NESDIS BRIEFING SUGGESTED THIS POSSIBILITY. THE 12Z SSEO
NEIGHBORHOOD PROBABILITIES SUGGEST THE GROUP OF GUIDANCE HAS BEEN
TOO SLOW TO UNFOLD THE ACTIVITY, WHICH IT HAD DEVELOPING PRIMARILY
AFTER 20Z. THE FLOW IS FAIRLY UNIDIRECTIONAL OUT OF THE
SOUTH-SOUTHWEST ABOVE THE SURFACE, WHICH IS LIKELY LEADING TO THE
SHORT TRAINING BANDS.
ROTH
ATTN...WFO...BMX...HUN...JAN...LIX...MEG...MOB...
ATTN...RFC...LMRFC...SERFC...
LAT...LON 34978687 34548644 33068667 31738661 30598662
30218721 30168763 30098912 29888997 30049060
30929014 32418954 33668895 34648821
Last Updated: 346 PM EDT SAT JUN 04 2016