WPC Met Watch
Posted by cypresstx on 8/27/2017, 2:22 pm
 MESOSCALE PRECIPITATION DISCUSSION 0743 NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 209 PM EDT SUN AUG 27 2017 AREAS AFFECTED...SOUTHEAST TX & SOUTHERN LA CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY VALID 271808Z - 280008Z SUMMARY...RAINFALL FROM HARVEY CONTINUES PROGRESSING INTO LA WHILE PERSISTING IN SOUTHEAST TX. SIGNIFICANT TO CATASTROPHIC FLASH FLOODING CONTINUES IN SOUTHEAST TX WHILE IT EXPANDS FARTHER INTO LA. DISCUSSION...RADAR IMAGERY HAS SHOWN AS EASTWARD MOVEMENT TO HARVEY AS OF LATE, WHICH MOVED THE EARLIER BANDS FROM SOUTHEAST TX INTO SOUTHWEST AND SOUTH-CENTRAL LA. NEW BANDS CONTINUE TO FORM NEAR AND WEST OF HOUSTON, BUT REMAIN 50 MILES AWAY FROM ITS CENTER. THE INNERMOST BAND IS TRYING TO WRAP AROUND ITS NORTHERN SIDE AS ELEVATED CONVECTION. OVERALL, THUNDERSTORM ACTIVITY REMAINS MAINLY WITHIN THE SYSTEM'S NORTHEAST QUADRANT. DRIER AIR AT THE SURFACE AND ALOFT CONTINUES SWEEPING AROUND ITS WESTERN AND SOUTHERN PERIPHERY WHICH IS GIVING ITS CLOUD PATTERN AN INCREASING COMMA-LIKE APPEARANCE; DEW POINT FALLS OF 10F WERE SEEN OVER THE PAST SEVEN HOURS AT BROWNSVILLE TX. PRECIPITABLE WATER VALUES ARE 2.2-2.7" PER RECENT GPS DATA. INFLOW AT 850 HPA IS CYCLONIC OUT OF THE SOUTHEAST AT 20-45 KTS, 50-100% GREATER THAN THE MEAN 850-400 HPA WIND. THE ORGANIZED THUNDERSTORM BANDS ARE BEING AIDED BY FAIRLY UNIDIRECTIONAL FLOW WITH HEIGHT IN THE LOW- TO MID-LEVELS OF THE TROPOSPHERE AND 25-35 KTS OF EFFECTIVE BULK SHEAR. THE MESOSCALE GUIDANCE AT 12Z SHOWED A DISTINCT SHIFT TO THE EAST IN THE RAINFALL PATTERN, WHICH GENERALLY MATCHES RECENT RADAR TRENDS AND MOTION OF HARVEY. RAIN BANDS SHOULD CONTINUE RADIATING EASTWARD OUT OF HARVEY UNTIL AT LEAST SUNSET, WITH THE EASTWARD LIMIT DEFINED BY THE FLOW AROUND THE BACKSIDE OF A DEEPENING LOW OFFSHORE GA. HOURLY RAIN TOTALS UP TO 3" ARE EXPECTED WITHIN THIS MOIST AIR MASS. THE MESOSCALE GUIDANCE SHOWS A GOOD SIGNAL FOR 6" OF RAIN, WHICH IS BELIEVABLE WITHIN THIS CONVECTIVE CYCLONE. THE THREAT OF FLASH FLOODING IS INCREASING ACROSS SOUTHERN LA AS SOILS SATURATE, WHILE SIGNIFICANT TO CATASTROPHIC FLASH FLOODING CONTINUES ACROSS PORTIONS OF SOUTHEAST TX, INCLUDING THE HOUSTON METROPOLITAN AREA. THE AVERAGE RAINFALL WITHIN THE HARRIS COUNTY EMERGENCY MANAGEMENT NETWORK HAS EXCEEDED THAT OF TROPICAL STORM ALLISON (2001) IN ALMOST HALF OF THE TIME (2-3 VERSUS 5 DAYS). HISTORIC FLOODING IS EXPECTED TO CONTINUE IN THE HOUSTON METROPOLITAN AREA THROUGH THE FORESEEABLE FUTURE. ROTH ATTN...WFO...CRP...EWX...FWD...HGX...LCH...LIX...SHV... ATTN...RFC...LMRFC...WGRFC... |
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In this thread:
- Re: WPC Met Watch - Chris in Tampa, 8/27/2017, 3:59 pm
- Re: WPC Met Watch - Chris in Tampa, 8/27/2017, 4:12 pm
- How's it going in Cypress?? - freesong, 8/27/2017, 3:21 pm
- we are doing well - cypresstx, 8/27/2017, 3:42 pm
- Re: we are doing well - Holly_Texas, 8/27/2017, 4:23 pm
- Re: we are doing well - Chris in Tampa, 8/27/2017, 3:55 pm
- we are doing well - cypresstx, 8/27/2017, 3:42 pm
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