Graphic for MPD #0641

MESOSCALE PRECIPITATION DISCUSSION 0641
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
441 AM EDT MON AUG 07 2017

AREAS AFFECTED...ARKLATEX THROUGH NORTHERN MS

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

VALID 070840Z - 071440Z

SUMMARY...SHOWERS AND THUNDERSTORMS ARE ATTEMPTING TO BRIDGE
ACROSS FROM NORTHEAST TX IN NORTHERN MS.  HOURLY RAIN RATES UP TO
2.5" WITH LOCAL AMOUNTS TO 5" POSSIBLE.

DISCUSSION...THUNDERSTORMS HAVE RECENTLY TRIED TO REORGANIZE IN
FAR NORTHEAST TX ON RADAR IMAGERY, WITH A RECENT HALT TO CLOUD TOP
WARMING NOTED ON NON-OPERATIONAL GOES-16 IMAGERY.  RADAR IMAGERY
SHOWS ATTEMPTS TO BRIDGE, USING NEW WIDELY SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY ACROSS SOUTHERN AR AND NORTHWEST MS SOUTH OF
A SHORTWAVE IN WESTERN TN, TO A CLUSTER OF THUNDERSTORMS OVER
NORTHEAST MS.  INFLOW AT 850 HPA IS 15-25 KTS PER VAD WIND
PROFILES, NEAR THE MAGNITUDE OF THE 850-400 HPA WIND, WHICH IS
MAINTAINING 1000-2000 J/KG MU CAPE VALUES ACROSS THE REGION. 
EFFECTIVE BULK SHEAR IS ~20 KTS.  PRECIPITABLE WATER VALUES ARE
2-2.25" PER RECENT GPS DATA.

INFLOW AT 850 HPA IS EXPECTED TO PICK UP TO 25-40 KTS AS AN MCV
MOVES EASTWARD FROM NORTHEAST TX, WHICH SHOULD INCREASE
PRECIPITATION EFFICIENCY WITH TIME AS THE MEAN 850-400 HPA WIND
WEAKENS TO 10-15 KTS.  THE MESOSCALE GUIDANCE GENERALLY AGREES
THAT SOMEWHERE IN THIS REGION SHOULD RECEIVE LOCAL AMOUNTS OF
4-5", BUT NOT PRECISELY WHERE. THE 00Z SSEO NEIGHBORHOOD
PROBABILITIES SHOW POCKETS OF 50%+ EXCEEDANCE OF THE THREE HOUR
FLASH FLOOD GUIDANCE VALUES SPREADING ACROSS NORTHEAST TX AND
SOUTHWEST AR WITH TIME WITH LOWER VALUES ACROSS NORTHERN
MS/NORTHWEST AL.  THE 00Z CANADIAN REGIONAL WAS THE MOST BULLISH
WITH THE EXTENT OF 3"+ AMOUNTS.  HOURLY RAIN AMOUNTS UP TO 2.5"
SHOULD BE POSSIBLE OVER THE NEXT SEVERAL HOURS. 

ROTH

ATTN...WFO...BMX...FWD...JAN...LZK...MEG...SHV...

ATTN...RFC...ABRFC...LMRFC...SERFC...WGRFC...

LAT...LON   34469205 34238835 32988818 32499199 32499585
            33869529


Last Updated: 441 AM EDT MON AUG 07 2017