MESOSCALE PRECIPITATION DISCUSSION 0052
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1103 AM EST TUE MAR 08 2016
 
AREAS AFFECTED...EASTERN TX...SOUTHEAST OK...SOUTHWEST AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 081603Z - 082003Z
 
SUMMARY...CONVECTION CONTINUES TO MOVE EAST NORTHEAST WITH
ISOLATED FLOOD THREAT.

DISCUSSION...CONVECTION CONTINUES TO MOVE EAST NORTHEAST ACROSS
PORTIONS OF OKLAHOMA AND TEXAS THIS MORNING. SYNOPTICALLY THIS IS
BEING FORCED BY A SUBTLE NORTHEASTWARD MOVING SHORTWAVE AND IN AN
INCREASINGLY DIVERGENT PATTERN ALOFT IN THE RIGHT ENTRANCE REGION
OF AN UPPER JET ACROSS THE CENTRAL PLAINS...AND IN THE LEFT EXIT
OF SUBTROPICAL JET EJECTING OUT OF NORTHERN MEXICO.

MOISTURE CONTINUES TO INCREASE ACROSS THE AREA IN THE DEEP
SOUTHERLY FLOW WITH INTEGRATED MOISTURE FLUX VALUES AROUND THE
99TH PERCENTILE. FOR NOW THE ATMOSPHERIC RIVER OF MOISTURE IS
PRIMARILY ORIGINATING FROM THE GULF OF MEXICO AND CARIBBEAN. IT IS
NOT UNTIL LATER TONIGHT THAT THE DUAL CONNECTION TO BOTH THE
PACIFIC AND CARIBBEAN REALLY SHOWS UP. HOWEVER STILL PRETTY
IMPRESSIVE MOISTURE VALUES...WITH PRECIPITABLE WATER GENERALLY
AROUND 1.3" ALONG/AHEAD OF THE CONVECTION PER GPS DATA AND RAP
FORECAST. HOWEVER GPS SHOWS VALUES ABOVE 1.5" ALONG THE TEXAS GULF
COAST...WHICH WILL CONTINUE TO ADVECT NORTHWARD THROUGH EAST
TEXAS...ARRIVING INTO SOUTHWEST AR BY AROUND 20Z. 

HIGH RES GUIDANCE HAS STRUGGLED WITH THIS ACTIVITY...WITH BOTH THE
0Z ARW AND NMMB WAY TOO PROGRESSIVE WITH THE CONVECTION AND OF
LITTLE USE FOR THIS FORECAST PERIOD. THE GLOBAL GUIDANCE...SUCH AS
THE 0Z ECMWF AND 06Z GFS ARE ACTUALLY HANDLING THE EVOLUTION
BETTER. ALSO BOTH THE HRRR AND EXPERIMENTAL HRRR HAVE CAUGHT
ON...AND WHILE NOT PERFECT...SHOULD BE OF SOME USE OVER THE NEXT
SEVERAL HOURS.

THE LINE HAS BEGUN TO FORWARD PROPAGATE ACROSS NORTHEAST TEXAS
NEAR DALLAS. HOWEVER WITH THE MEAN FLOW SOUTH TO NORTH...AND 40-50
KTS OF SOUTHERLY FLOW AT 850 MB...WILL LIKELY CONTINUE TO SEE SOME
BACKBUILDING AND SOME TRAINING...WITH SOUTH TO NORTH MOVING
CONVECTION INTERSECTING THE EASTWARD MOVING CONVECTIVE LINE. THIS
TRAINING MAY BE MOST CONCENTRATED ACROSS EAST CENTRAL TEXAS INTO
THIS AFTERNOON...WHERE SOME OF THIS IS ALREADY BEGINNING TO OCCUR.
FLASH FLOOD GUIDANCE IS HIGHER HERE...BUT A PRETTY GOOD SIGNAL FOR
3 HOUR TOTALS OF 1-3"...WITH ISOLATED 4" AMOUNTS...WHICH MAY CAUSE
ISOLATED FLASH FLOOD ISSUES. 

FURTHER NORTH ACROSS NORTHEAST TEXAS INTO SOUTHEAST OK AND
SOUTHWEST AR...THE MORE PROGRESSIVE NATURE OF THE CONVECTION
SHOULD KEEP AMOUNTS A BIT LOWER WITH AMOUNTS GENERALLY IN THE 1-2"
RANGE...LOCALLY HIGHER. FLASH FLOOD GUIDANCE IS LOWER IN THIS
AREA...SO THESE AMOUNTS COULD STILL POSE AN ISOLATED FLASH FLOOD
RISK. OVERALL THE THREAT SHOULD GENERALLY STAY ISOLATED OVER THE
NEXT SEVERAL HOURS...HOWEVER THIS RAIN WILL HELP SET THE STAGE FOR
THE POTENTIAL OF MORE SIGNIFICANT FLOODING AS WE HEAD INTO TONIGHT
WITH THE NEXT ROUND OF CONVECTION.

CHENARD

ATTN...WFO...EWX...FWD...HGX...LCH...LZK...OUN...SHV...TSA...

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

LAT...LON   35499632 35449374 34289317 32709381 30999420 
            30259446 30059488 29989536 29969597 30029665 
            30329742 31019774 31969772 32889682 33539659 
            33999676 34289698 34659727 34959752 35409755 
            35469645