MESOSCALE PRECIPITATION DISCUSSION 0553
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
425 PM EDT SUN OCT 04 2015
 
AREAS AFFECTED...PORTIONS OF THE CAROLINAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 042024Z - 050224Z
 
SUMMARY...A BAND OF THUNDERSTORMS WITH HEAVY RAINFALL CONTINUES IN
THE EASTERN CAROLINAS.  FLASH FLOODING REMAINS LIKELY IN AN AREA
WITH SATURATED SOILS.

DISCUSSION...A BROKEN BAND OF HEAVY RAINFALL STRETCHED FROM
SOUTHEAST NC INTO CENTRAL SC, WITH RADAR ESTIMATES OF HOURLY RAIN
RATES ~2".  RAINFALL ESTIMATES DURING THE PAST SIX HOURS OF 4-5"
HAVE A RECURRENCE INTERVAL OF 25-50 YEARS.  IT LIES WITHIN A WARM
CONVEYOR BELT/ATMOSPHERIC RIVER WRAPPING AROUND THE NORTH SIDE OF
A DEEP LAYERED CYCLONE, WHICH CONTINUES TO DRAW IN SOME OF
HURRICANE JOAQUIN'S PERIPHERAL MOISTURE.  PRECIPITABLE WATER
VALUES ARE 1.7-2.3" IN THIS REGION PER GPS VALUES AND RECENT RAP
FORECASTS, TWO SIGMAS ABOVE THE MEAN FOR EARLY OCTOBER.  INFLOW AT
850 HPA IS 25-45 KTS PER RECENT VAD WIND PROFILES, NEAR THE
MAGNITUDE OF THE 850-400 HPA MEAN WIND.

CAM GUIDANCE ADVERTISES LOCAL AMOUNTS OF 3-6" DURING THE NEXT
SEVERAL HOURS, THOUGH A BIT FARTHER TO THE SOUTH OF WHERE THE
ONGOING RAIN IS FALLING.  THIS WOULD COMPOUND EXISTING FLOOD AND
FLASH FLOOD ISSUES.  THERE ARE INDICATIONS WITHIN RAP MASS FIELDS
(850 HPA WIND, MUCAPE, AND BOUNDARY LAYER MOISTURE CONVERGENCE)
THAT SOME SOUTHWARD SHIFT/REDEVELOPMENT IS POSSIBLE OVER THE NEXT
SEVERAL HOURS.  AS CIN REDEVELOPS THIS EVENING, THE RAIN BAND
COULD MAKE GREATER PROGRESS INLAND, SIMILAR TO LAST NIGHT. 
SOUTHERN REGION PRECIPITATION ESTIMATES INDICATE THAT LOCAL
AMOUNTS OF 20"+ HAVE FALLEN ACROSS PORTIONS OF THIS AREA OVER THE
PAST THREE DAYS, CLOSE TO IF NOT EXCEEDING HISTORIC RAIN EVENT
RECORDS FOR THE CAROLINAS. CLOSE TO 30" OF RAIN HAVE FALLEN DURING
THE PAST COUPLE WEEKS, JUST OVER HALF OF WHAT USUALLY FALLS IN A
GIVEN YEAR. SOILS ARE SATURATED.  AVAILABLE MOISTURE CONTINUES TO
SUPPORT HOURLY RAIN RATES UP TO 3" WHERE CELLS TRAIN.  FLASH
FLOODING REMAINS LIKELY, WHICH COULD BE LOCALLY CATASTROPHIC. 
THIS AREA/INFORMATION WAS COORDINATED WITH SAB/NESDIS.

ROTH

ATTN...WFO...CAE...CHS...ILM...MHX...RAH...

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

LAT...LON   34987637 34647656 34387723 34137756 33807791 
            33697869 33237903 32997920 32647984 32528004 
            32028097 32218117 32528126 32728149 33068161 
            33508196 33698221 34078155 34398077 34578009 
            34837839