Post by SKYSUMMIT on Jul 24, 2017 8:36:56 GMT -6
MESOSCALE PRECIPITATION DISCUSSION 0552
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1029 AM EDT MON JUL 24 2017
AREAS AFFECTED...EASTERN TX...CENTRAL LA...SOUTHERN MS...SOUTHERN
AL...WESTERN FL PANHANDLE
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 241430Z - 241930Z
SUMMARY...LONG STRUNG OUT CONFLUENCE ZONE WITHIN UNSTABLE VERY
MOIST ENVIORMENT AND WEAK FLOW SUPPORT THREAT FOR CONTINUED FLASH
FLOODING RISK.
DISCUSSION...GOES-EAST WV LOOP SHOWS THE TRAILING EDGE OF A TROF
ACROSS THE DEEP SOUTH WITH SOME AMPLIFICATION TOWARD A WEAK CLOSED
LOW ACROSS NE TX/N LA GIVEN THE WEAKENED FLOW. IN THE LOW
LEVELS...850-7H IS A WEAK CONFLUENT TROF FROM EASTERN TX TO THE W
FL PANHANDLE WITH A FEW WEAK INFLECTIONS ALONG IT SOME
CONVECTIVELY INDUCED (SUCH AS E TX). THIS CONFLUENCE/RETURN FLOW
FROM THE WESTERN GULF PROVIDES SUFFICIENT CONVERGENCE AS WELL AS
MOISTURE/INSTABILITY FLUX TO MAINTAIN ONGOING CONVECTION AS WELL A
SUPPORT DOWNSTREAM/REACTIVATION ALONG OUTFLOW BOUNDARIES OUT FROM
ORIGINAL CONVECTION. MLCAPES TO 2500 J/KG AND TPWS OVER 2" AND
LOCALIZED MAXIMA OVER 2.25" SUPPORT HIGHLY EFFICIENT BUT DEEP
CONVECTIVE SHOWERS WITH RATES UP TO 2.5"/HR POSSIBLE. GIVEN WEAK
MID-LEVEL FLOW CELL MOTIONS HAVE BEEN NEAR ZERO AND PROPAGATION
OCCURS AS LOCALIZED COLD POOLS/OUTFLOW BOUNDARIES OCCUR. THIS
ALLOWS FOR TOTALS OF 2-4" IN SHORT-ORDER ALLOWING FOR FLASFH
FLOODING CONCERNS. HI-RES RAPIDLY REFRESHING GUIDANCE (HRRR/RAP)
SUGGEST THIS CONFLUENT FLOW WILL LIKELY CONTINUE THROUGH THE EARLY
AFTERNOON.
EASTERN TX...GOES-16 EXPERIMENTAL VISIBLE IMAGERY SHOWS A SHALLOW
7H WAVE OVER NE TX DROPPING SOUTH TOWARD THE MCV NEAR W OF LFK/SW
OF OCH. THIS MAY SUPPORT A BINARY INTERACTION WHICH SHOULD HELP
TO KEEP THE MCV FAIRLY CLOSE TO MAINTAIN FORCING AND LOCALIZED
ADVECTION OF ADDITIONAL UNSTABLE/MST AIR TO LEAD TO CONTINUED
LIKELY FLASH FLOODING RISK. RECENT VIS TRENDS ALSO SUGGEST FURTHER
DOWNSTREAM DEVELOPMENT INTO CENTRAL LA.GIVEN MCV
STRENGTH...PROPAGATION VECTORS IN THIS AREA HAVE POTENTIAL FOR
BACKBUILDING ALONG THE CONFLUENCE LINE TO ALLOW FOR REPEATING
TRACKS.
GALLINA
