MESOSCALE PRECIPITATION DISCUSSION 0222
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
208 AM EDT TUE MAY 29 2018

AREAS AFFECTED...CENTRAL AND SOUTHERN ALABAMA...

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

VALID 290615Z - 291215Z

SUMMARY...SUB-TROPICAL DEPRESSION ALBERTO CONTINUES TO TRACK
SLOWLY N TO NNE.  HEAVIEST/LONGEST DURATION LEFT OF TRACK.

DISCUSSION...RECENT TRENDS SHOW WARMING TOPS TO THE REMAINING
CLOUD SHIELD AS BEST DPVA FOR MESOSCALE SHORTWAVE IS NOW ALONG THE
EASTERN SIDE ROTATING NORTH.  AS SUCH...NEW CONVECTION IS
DEVELOPING TO THE NORTH OF THE SURFACE CIRCULATION CURRENTLY ALONG
BUTLER/CRENSHAW COUNTY LINE.  INFLOW OF SLIGHTLY INCREASED
INSTABILITY TRANSPORTED OFF THE GULF IS STARTING TO CONVECT ON
MULTIPLE BANDS NORTH (WITH THE INNER MOST SUPPORTING THE
DEEPEST/COLDEST TOPS ATTM). RAP ANALYSIS DEPICTS THIS HIGHER
THETA-E AIR NOSING NORTH WITH MUCAPES AOA 500 J/KG.  AS SUCH THIS
CONVECTIVE BANDS WILL HAVE GREATER DEPTH OF RAINFALL PRODUCTION
WITH THE CAPABILITY OF HIGHER RATES PERHAPS AS HIGH AS 1-1.25"/HR.
 HOWEVER...DURATION WILL BE MORE LIMITED AND NOT LIKELY TO EXCEED
SHORTER (1-3 HR) HIGH FFG VALUES IN THE REGION.  STILL MULTIPLE
BANDS (CURRENTLY APPEARS TO BE 3 OR 4) AS THEY LIFT NORTH ARE
LIKELY TO LEAD TO SOME REPEATING OVER THE NEXT 6HRS.  

AN EFFECTIVE BOUNDARY EXTENDS NEARLY DUE NORTH OF THE SURFACE LOW
AND IS GENERALLY PARALLEL TO THE EXPECTED NORTHWARD TRACK.
 CONVECTION WILL CROSS AND LIFT ENHANCING A BROADER MODERATE TO
HEAVY RAINFALL SHIELD ON THE LEFT SIDE OF THE FORECAST TRACK. 
RAIN RATES MY BE REDUCED TO .5-.75"/HR ON THIS LEFT SIDE BUT
BROADER ZONE OF ISENTROPIC ASCENT WILL LEAD TO A LARGER EXPANSE OF
THE SHIELD LEADING TO LONGER DURATION ALLOWING FOR TOTALS OF 3-4"
OVER THE NEXT 6HRS TO PERSIST.  LIKE THE LAST 6HRS...THIS WILL
NEAR OR BARELY EXCEED THE HIGHER 6HR FFG VALUES BUT NOT THE
SHORTER DURATION VALUES...SUGGESTING FLASH FLOODING WILL BE MORE
THROUGH INUNDATION THAT RAPID RISE THREATS. 

GALLINA

ATTN...WFO...BMX...MOB...

ATTN...RFC...SERFC...

LAT...LON   33838708 33758640 33228581 32788584 32358603
            31708618 31168638 31068664 31178725 32168736
            32658759 33158777 33588752