Graphic for MPD #0773

MESOSCALE PRECIPITATION DISCUSSION 0773
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
906 AM EDT THU AUG 31 2017

AREAS AFFECTED...CENTRAL/NORTHEAST AR...FAR NORTHWEST MS...FAR
WESTERN TN...MO BOOTHEEL

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 311300Z - 311900Z

SUMMARY...HARVEY WILL CONTINUE TO FOSTER POCKETS OF HEAVY RAINFALL
SOME ADDITIONAL FLASH FLOODING LIKELY.

DISCUSSION...THE CENTER OF T.D. HARVEY CONTINUES TO ADVANCE
FARTHER INLAND ACROSS NORTHERN LA...AND IS PRODUCING A RATHER
LARGE AREA OF DISORGANIZED LIGHT TO MODERATE RAIN STILL OVER PARTS
OF CENTRAL/NORTHERN LA...BUT A SIGNIFICANT AMOUNT OF DRY AIR AS
SEEN IN NON-OPERATIONAL GOES-16 IMAGERY CONTINUES TO WRAP AROUND
THE CIRCULATION CENTER WHICH HAS GREATLY REDUCED THE RAINFALL
RATES ACROSS THESE AREAS. FARTHER NORTH...HOWEVER...AN AXIS OF
HEAVY RAIN WITH EMBEDDED STRONGER CONVECTIVE ELEMENTS HAS BEEN
DEVELOPING OVER AREAS OF CENTRAL/NORTHEAST AR AND FAR WESTERN TN.

THIS AXIS OF HEAVIER RAIN IS IN LINE WITH A CORRIDOR OF
STRENGTHENING FRONTOGENETICAL FORCING AND SURFACE CONVERGENCE NEAR
AN INVERTED TROUGH EXTENDING NORTH-NORTHEAST FROM HARVEY.
INSTABILITY PARAMETERS AROUND HARVEY ITSELF ARE VERY WEAK....BUT
THERE IS A CORRIDOR OF 500+ J/KG MLCAPE VALUES ADVECTING NORTHWEST
TOWARD THE NORTHEAST FLANK OF HARVEY WHICH WILL BE INTERACTING
WITH THE AFOREMENTIONED SURFACE TROUGH.

THE HIRES MODEL CONSENSUS SUPPORTS HEAVY RAINS BECOMING MORE
STRONGLY FOCUSED OVER AREAS OF CENTRAL/NORTHEAST AR AND IN TIME
ENCOMPASSING AREAS OF NORTHWEST MS/WESTERN TN AND ALSO THE
SOUTHEAST MO BOOTHEEL REGION GOING THROUGH EARLY TO MID-AFTERNOON.

RAINFALL RATES ARE CAPABLE OF REACHING 2 TO 2.5 INCHES/HR...WITH
PWATS STILL GENERALLY OVER 2 INCHES ACROSS THE MPD THREAT.
ADDITIONAL STORM TOTALS THROUGH MID-AFTERNOON OF 3 TO 6 INCHES ARE
EXPECTED WHICH IS CONSISTENT WITH THE LATEST HRRR GUIDANCE AND
SUPPORTED BY SOME RECENT COOLING OF CONVECTIVE TOPS OVER NORTHEAST
AR. THIS WILL LIKELY RESULT IN FLASH FLOODING.

ORRISON

ATTN...WFO...JAN...LZK...MEG...PAH...

ATTN...RFC...ABRFC...LMRFC...

LAT...LON   36798937 36388887 35728903 34369016 33719116
            33659205 34109255 34749249 35599179 36549052
           


Last Updated: 906 AM EDT THU AUG 31 2017