MESOSCALE PRECIPITATION DISCUSSION 0401
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
657 PM EDT MON SEP 29 2014
 
AREAS AFFECTED...CENTRAL HIGH PLAINS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 292257Z - 300257Z
 
SUMMARY...THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS
ARE BEGINNING TO TRAIN NEAR AND POLEWARD OF A FRONTAL BOUNDARY. 
WITH HOURLY RAIN RATES UP TO 1.5" EXPECTED, FLASH FLOODING IS
POSSIBLE IN THIS REGION.

DISCUSSION...THUNDERSTORMS ARE BEGINNING TO TAKE ON THE LOOK OF A
TRAINING SIGNATURE FROM EASTERN CO NORTH-NORTHEAST INTO WESTERN NE
NEAR A FRONTAL BOUNDARY.  CAPE VALUES OF 1000-1500 J/KG INHABIT
THE REGION, AND LOW-LEVEL INFLOW IS BROAD INTO THE FRONT ON THE
ORDER OF 25-40 KTS.  PRECIPITABLE WATER VALUES ARE PASSING 1" IN
THE REGION, WHICH COMBINED WITH THE STRONG INFLOW AND HIGHER CAPE
VALUES IN ADVANCE OF THE CONVECTION ARE LEADING TO FORWARD
PROPAGATION ON THE ORDER OF 35 KTS.  THE THUNDERSTORM BAND IS
BEGINNING TO ALIGN ALONG THE AXIS OF FORWARD PROPAGATION,
INCREASING THE RISK OF FLASH FLOODING FROM CELL TRAINING.

PRECIPITABLE WATER VALUES OVER THE NEXT SEVERAL HOURS SHOULD
INCREASE TO 1.25", NEAR THE THRESHOLD FOR EXCESSIVE RAINFALL IN
THE HIGH PLAINS, WHILE LOW-LEVEL INFLOW IS EXPECTED TO RAMP UP
FURTHER, TO 45-50 KTS.  CELL TRAINING AND THE FLASH FLOOD THREAT
ARE EXPECTED TO EXIST FOR ABOUT FOUR HOURS PER RECENT RAP
GUIDANCE, WHICH INDICATES CAPE VALUES PLUNGING BELOW 1000 J/KG BY
03Z.  FLASH FLOOD GUIDANCE NEAR THE CO/NE BORDER IS FAIRLY LOW, ON
THE ORDER OF 1.5" IN THREE HOURS.  THE SIGNAL WITHIN THE AVAILABLE
MESOSCALE GUIDANCE IS MODEST, INDICATING THAT LOCAL AMOUNTS OF
2-3" ARE POSSIBLE IN THIS REGION.  THROUGH 03Z, FLASH FLOODING IS
CONSIDERED POSSIBLE.

ROTH

ATTN...WFO...BOU...CYS...GLD...LBF...PUB...UNR...

ATTN...RFC...ABRFC...MBRFC...

LAT...LON   43080306 43060027 42469992 40880202 38790331 
            38300437 39510501 39620503 41260492 42440430