Flash Flood Guidance
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
000
AWUS01 KWNH 251721
FFGMPD
TNZ000-KYZ000-ALZ000-MSZ000-MOZ000-ARZ000-252319-

MESOSCALE PRECIPITATION DISCUSSION 0237
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
120 PM EDT WED MAY 25 2016

AREAS AFFECTED...CENTRAL AR INTO WESTERN TN

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

VALID 251719Z - 252319Z

SUMMARY...SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM ACROSS
PORTIONS OF NORTHEAST AR AND WESTERN TN SHORTLY.  HOURLY RAIN
RATES TO 2", WITH LOCAL AMOUNTS OF 2-4", COULD LEAD TO FLASH
FLOODING OVER SATURATED SOILS AND URBAN AREAS.

DISCUSSION...A THUNDERSTORM COMPLEX WITH A COMPANION MCV ARE
CURRENTLY MOVING THROUGH NORTHWEST AR.  AHEAD OF THIS SYSTEM,
THUNDERSTORMS ARE BEGINNING TO FORM ACROSS NORTHWEST TN ALONG AN
OUTFLOW BOUNDARY SET UP BY A DYING SHOWER/THUNDERSTORM AREA FROM
THIS MORNING, MOVING THROUGH THE MO BOOTHEEL AT THIS TIME.
MEANWHILE, A FIELD IS INCREASINGLY CUMULIFORM CLOUDS ARE
DEVELOPING ACROSS SOUTHERN AR, WHICH ARE EVEN APPARENT WITHIN
WATER VAPOR IMAGERY.  MLCAPES ARE 2000-2500 J/KG ACROSS NORTHEAST
TX, NORTHWEST LA, AND NORTHWEST MS.  THIS INSTABILITY IS BEING
IMPORTED INTO THE AREA BY CONVERGENT 850 HPA INFLOW OF 20-35 KTS.
PRECIPITABLE WATER VALUES IN THE AREA ARE 1.5-1.7" PER GPS
INFORMATION.

THE EXPECTATION IS FOR THE INCOMING OUTFLOW BOUNDARY AND MCV TO
ENHANCE THUNDERSTORM ACTIVITY OVER THIS AREA, WHICH COULD BRIEFLY
TRAIN.    AMONGST THE MESOSCALE/CAM GUIDANCE, THE 12Z ARW, 12Z
NMMMB, AND VARIOUS OPERATIONAL AND PARALLEL HRRR RUNS SUPPORT
LOCAL AMOUNTS IN THE 2-4" RANGE, WHICH COULD FALL QUICKLY.
CONSIDERING THE MOISTURE AVAILABLE, HOURLY RAIN RATES UP TO 2" ARE
POSSIBLE.  ORGANIZED CONVECTIVE CLUSTERS SHOULD MOVE
EAST-SOUTHEAST AT ROUGHLY 25 KTS, A COMPROMISE OF THE FORWARD
PROPAGATING CONVECTIVE VECTORS AND THE 1000-500 HPA THICKNESS
PATTERN.  THERE IS A POSSIBILITY OF CELL MERGERS, AS LESS
ORGANIZED CONVECTION SHOULD MOVE EAST-NORTHEAST AT 25-30 KTS. ONCE
SHOWERS AND THUNDERSTORMS ATTEMPT TO LEAVE WESTERN TN, DRIER AIR
ACROSS NORTHEAST MS, AL, AND CENTRAL TN SHOULD CAUSE THEM TO PETER
OUT. CONSIDERING RECENT RAINS, SOILS ARE PARTIALLY SATURATED.
FLASH FLOODING IS A CONCERN.

ROTH

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...HUN...LZK...MEG...OHX...PAH...

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

LAT...LON   36558858 36208755 35008817 34519067 34519268
            35839133 36409017



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.