MESOSCALE PRECIPITATION DISCUSSION 0708
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1045 PM EST SAT DEC 26 2015
 
AREAS AFFECTED...NORTHERN TX...EASTERN OK...NORTHWEST AR...EXTREME
SOUTHWEST MO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 270340Z - 270900Z
 
SUMMARY...WIDESPREAD AND LOCALLY SIGNIFICANT FLASH FLOODING IS
EXPECTED OVERNIGHT.

DISCUSSION...VERY HEAVY SHOWERS AND THUNDERSTORMS CONTINUE TO
REDEVELOP AND FOCUS ALONG AND JUST TO THE NORTHWEST OF A STRONG
FRONTAL ZONE DRAPED ACROSS THE MID MS VALLEY AND EXTENDING DOWN
INTO THE SOUTHERN PLAINS. ALL OF THIS IS OCCURRING AS A STRONG
UPPER TROUGH AND ASSOCIATED MID LEVEL LOW CENTER EJECTS OUT ACROSS
THE SOUTHERN HIGH PLAINS. VERY DIVERGENT FLOW ALOFT COURTESY OF
H25 RIGHT-ENTRANCE REGION JET DYNAMICS IS CREATING AN EXTENSIVE
AREA OF LARGER SCALE ASCENT IN VICINITY OF THE FRONT...AND THIS IS
INTERACTING WITH WHAT EQUATES TO A DEEP ATMOSPHERIC RIVER OF
ANOMALOUS MOISTURE SURGING NORTH FROM THE WESTERN GULF OF MEXICO
AND WELL NORTHEAST AROUND THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE NEAR THE SOUTHEAST.

PWATS AS PER THE LATEST GPS-DERIVED DATA ARE POOLING AS HIGH AS
1.5 TO 1.6 INCHES AND THIS IS AS MUCH AS 4 STD DEV ABOVE NORMAL
FROM THE RED RIVER VALLEY NORTHEAST INTO THE OZARKS. AREA VWPS ARE
INDICATING A 40 TO 50 KT SOUTH/SOUTHWEST LOW LEVEL JET AIMING INTO
THE FRONT AND THIS IS EXPECTED TO BE SUSTAINED OVERNIGHT AS A
STRONG MID LEVEL LOW CENTER AND ASSOCIATED HEIGHT FALLS GRADUALLY
EJECTS OUT THROUGH WEST TEXAS. MEANWHILE...IMMEDIATELY BEHIND THE
FRONT IN THE COLD SECTOR...THERE IS A 30 TO 40 KT NORTH/NORTHEAST
LOW LEVEL JET WHICH IS CAUSING VERY STRONG CONVERGENCE/FORCING IN
THE LOW LEVELS AND WILL CONTINUE OVERNIGHT IN CONJUNCTION WITH
ALREADY STRONG DEEP LAYER FORCING/JET DYNAMICS.

RAINFALL RATES CAN BE EXPECTED TO APPROACH 2 INCHES/HR
LOCALLY...AND WITH MEAN LAYER FLOW RUNNING PARALLEL TO THE
FRONT...THERE WILL BE A STRONG CONCERN FOR TRAINING CELLS.

ADDITIONAL RAINFALL AMOUNTS THROUGH 09Z ARE EXPECTED TO BE AS HIGH
AS 3 TO 4 INCHES WITH SOME ISOLATED AMOUNTS POSSIBLY REACHING 5
INCHES WHERE STRONGER CONVECTIVE CORES TRAIN OVER THE SAME AREA.
THE 12Z ARW AND LAST COUPLE RUNS OF THE HRRR SUPPORT THIS
SCENARIO. THEREFORE...THE THREAT OF WIDESPREAD AND LOCALLY
SIGNIFICANT FLASH FLOODING WILL CONTINUE THROUGHOUT THE NIGHT.

ORRISON

ATTN...WFO...FWD...LZK...OUN...SGF...SHV...SJT...TSA...

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

LAT...LON   37279449 36819443 36639401 36589377 36479321 
            36539219 35629353 34559485 32869633 32089702 
            31589806 31569867 31919891 32579882 33519836 
            34389771 35519669 36359571