Graphic for MPD #0717

MESOSCALE PRECIPITATION DISCUSSION 0717
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
554 PM EDT WED AUG 23 2017

AREAS AFFECTED...FAR SOUTHEAST VA...EASTERN NC

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

VALID 232200Z - 240100Z

SUMMARY...CONVECTION TRAINING ALONG A FRONTAL BOUNDARY IN A HIGH
MOISTURE ENVIRONMENT COULD RESULT IN A FLASH FLOOD THREAT THROUGH
THE EARLY EVENING HOURS.

DISCUSSION...REGIONAL RADARS ACROSS SOUTHEAST VA/CENTRAL AND
NORTHERN NC HAVE SHOWED CONVECTION AHEAD OF A SLOW MOVING FRONT
STRETCHED ACROSS SOUTHEAST VA INTO CENTRAL AND EASTERN NC. THE
CONVECTION IS FORMING/MOVING IN AN AXIS OF 1500-200 J/KG MLCAPE
AHEAD OF THE FRONT...WHERE THE MOST RECENT RAP ANALYSIS SHOWED A
RIBBON OF 2.00 INCH PRECIPITABLE WATER AIR...AND SURFACE
OBSERVATIONS SHOWED SURFACE DEW POINTS ARE IN THE MID TO UPPER 70S
OVER EASTERN NC.

THE KAKQ RADAR INDICATED HOURLY RAINFALL RATES BETWEEN 2.00 AND
2.25 INCHES OVER HALIFAX COUNTY NC...WHERE TRAINING WAS OCCURRING
SOUTH OF THE FRONT. THESE VALUES ARE CLOSE TO THOSE SEEN EARLIER
ACROSS DARE COUNTY NC...WHERE CONVECTION WAS MOVING MORE SLOWLY.
SIMILAR RAINFALL RATES ARE POSSIBLE MAINLY ACROSS EASTERN NC
THROUGH THE LOSS OF DAYTIME HEATING EARLY THIS EVENING. THE MOST
RECENT RAP INDICATED THAT THE BEST INSTABILITY IS EXPECTED OVER
FAR SOUTHEAST VA AND EASTERN NC THROUGH THE EARLY EVENING...AND
THE GREATEST THREAT FOR FLASH FLOODING IS EXPECTED HERE WHERE
CONVECTION TRAINS.

THE MOST RECENT HRRR INDICATED LOCAL 3.00-4.00 INCH RAINFALL
AMOUNTS OVER EASTERN NC THROUGH 01Z. THESE AMOUNTS SEEM
REASONABLE...GIVEN THE HOURLY RAINFALL RATES SEEN OVER EASTERN NC
EARLIER. THESE AMOUNTS ARE MOST LIKELY WHERE TRAINING OCCURS...AND
BECAUSE OF THIS...FLASH FLOODING IS ONLY CONSIDERED POSSIBLE.

HAYES

ATTN...WFO...AKQ...MHX...RAH...

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

LAT...LON   37047635 36857577 36247557 35877599 35627717
            35527808 36257858 36927712


Last Updated: 554 PM EDT WED AUG 23 2017