Wet Times Ahead In SE Texas.Good Discussion
Posted: Sat Jul 01, 2006 2:48 pm
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
245 PM CDT SAT JUL 1 2006
...PROLONGED HEAVY RAINFALL EVENT ON THE WAY...
.DISCUSSION...
VERY CONCERNING SET OF 12Z MODEL RUNS TODAY. EVEN DEEPER MOISTURE
ASSOCIATED WITH THE TROFFINESS IN THE WESTERN GULF SET TO BEGIN
COMING INLAND SUNDAY AND INCREASE EVEN MORE ON MONDAY - AND PERSIST
INTO A GOOD PORTION OF NEXT WEEK. HERE`S A TABLE DEPICTING MODEL
AVERAGE PW VALUES IN SE TX THIS MIDWEEK:
SUN MON TUE WED THU FRI
GFS 2.0-2.2" 2.3-2.4" 2.3-2.4" 2.1-2.3" 2.1-2.4" 1.7-2.3"
NAM 2.0-2.4" 2.2-2.4" 2.1-2.3"
THE HIGH PW VALUES SHOWN ABOVE ARE KNOWN TO PRODUCE THE TORRENTIAL
2-4"/HR RAINFALL RATES DESPITE WHETHER THERE IS A BOUNDARY TO WORK
OFF OF OR NOT. AND AS WE ALL VERY WELL KNOW - EVEN WITHOUT A
DISTINCT SURFACE BOUNDARY IN PLACE TO ACT AS A TRIGGER/FOCUS - WEAK
MESOSCALE BOUNDARIES FREQUENTLY DEVELOP IN THE WEAK FLOW REGIMES
LIKE WE ARE IN (OUTFLOW BOUNDARIES, SEABREEZE/BAYBREEZE, ETC).
EXTREMELY CONCERNED ABOUT THIS TYPE OF SCENARIO PLAYING OUT AND
WOULD NOT DOUBT IF LOCALIZED 8-12+ INCH AMOUNTS OCCURRED SOMEWHERE
IN OUR CWA DURING THE NEXT 2-5 DAYS...AND POSSIBLY IN A SHORT PERIOD
OF TIME. IN ADDITION...THE UPPER LEVEL PATTERN IS ALSO FAVORING A
HEAVY RAIN EVENT AS THE MID LEVEL LOW NOW IN W TX IS FCST TO SLOWLY
GET PUSHED BACK EASTWARD TOWARD US EARLY IN THE WEEK AS THE WESTERN
RIDGE TRIES TO BUILD BACK IN (THOUGH MODELS NOT QUITE IN AGREEMENT
ON PLACEMENT/TIMING JUST YET).
UNFORTUNATELY...WITHOUT SEEING SOMETHING MORE DISTINCT...WE`RE JUST
NOT ABLE TO PINPOINT THE HIGHEST THREAT AREA ATTM. SUSPECT WE`LL END
UP NEED TO ISSUE A FLOOD WATCH IN THE 18-24 HOURS...BUT THINK WE`LL
HAVE ENOUGH TIME TO LOOK AT ANOTHER 1-2 SETS OF FUTURE MODEL RUNS TO
SEE IF ANYTHING CHANGES OR WE CAN NARROW DOWN THE THREAT AREA.
ANTICIPATE DECREASED PRECIP COVERAGE WITH THE LOSS OF HEATING
TONIGHT WITH REDEVELOPMENT OFFSHORE AFTER MIDNIGHT. SUNDAY WILL
LIKELY START OUT SIMILAR TO TODAY WITH PRECIP BECOMING MORE
WIDESPREAD WITH DAYTIME HEATING (CONVECTIVE TEMPS IN THE LOW-MID
80S). PROBABLY HAVE A SIMILAR DIURNAL PATTERN OCCUR INTO EARLY NEXT
WEEK UNTIL IF/WHEN THE UPPER LOW GETS A BIT CLOSER AND CORE RAINS
BECOME A CONCERN.
THOUGH SOME AREAS WILL GET A GOOD SOAKING ON SUN - MOST CONCERNED
ABOUT MON/TUE AT THIS TIME. WILL WORRY ABOUT THE 2ND HALF OF THE
WEEK LATER AS DETAILS ARE BOUND TO CHANGE BETWEEN NOW AND THEN...BUT
THE PRECIP FOCUS MAY SHIFT INTO THE NORTHERN ZONES BEYOND THURS AS A
WEAK FRONT BACKDOORS INTO N/NE TX AND POSSIBLY PROVIDES A LLVL
FOCUS. WILL ISSUE AN UPDATED HWO LATER THIS AFTN. 47
&&
.AVIATION...
MOISTURE SURGE (AS INDICATED EARLIER BY GFS) TODAY RESULTED IN
SCATTERED TO NUMEROUS SHRA/TSRA SOUTHERN HALF OF CWFA...AFFECTING
GLS/LBX AND TO A LESSER EXTENT IAH/HOU. CONVECTIVE ACTIVITY EXPECTED
TO DECREASE IN AREAL COVERAGE RAPIDLY TOWARD SUNSET LEAVING BROKEN
TO OVERCAST MID TO HIGH CLOUDS. EXPECT LIGHT FOG TO AFFECT TAF SITES
TOWARD MORNING ESPECIALLY LBX. CONVECTION WILL FIRE UP AGAIN
(EARLIER FOR GLS AND LBX) IN THE MORNING. 37
&&
.MARINE...
WITH PW VALUES CREEPING UP AND STAYING HIGH THE NEXT SEVERAL DAYS...
AND WITH A LINGERING UPPER LEVEL DISTURBANCE OVER TEXAS...WE CAN
EXPECT A CONTINUED GOOD CHANCE OF TSRA/SHRA FOR THE WATERS. ONSHORE
WINDS WILL BE LIGHT TO MODERATE. COASTAL WATERS WAVE HEIGHTS
REMAINING BELOW SCEC THROUGH FORECAST PERIOD. 37
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 73 88 74 87 74 / 50 70 50 80 60
HOUSTON (IAH) 75 87 76 86 77 / 50 80 60 80 60
GALVESTON (GLS) 80 87 81 86 81 / 50 80 60 80 60
&&
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
245 PM CDT SAT JUL 1 2006
...PROLONGED HEAVY RAINFALL EVENT ON THE WAY...
.DISCUSSION...
VERY CONCERNING SET OF 12Z MODEL RUNS TODAY. EVEN DEEPER MOISTURE
ASSOCIATED WITH THE TROFFINESS IN THE WESTERN GULF SET TO BEGIN
COMING INLAND SUNDAY AND INCREASE EVEN MORE ON MONDAY - AND PERSIST
INTO A GOOD PORTION OF NEXT WEEK. HERE`S A TABLE DEPICTING MODEL
AVERAGE PW VALUES IN SE TX THIS MIDWEEK:
SUN MON TUE WED THU FRI
GFS 2.0-2.2" 2.3-2.4" 2.3-2.4" 2.1-2.3" 2.1-2.4" 1.7-2.3"
NAM 2.0-2.4" 2.2-2.4" 2.1-2.3"
THE HIGH PW VALUES SHOWN ABOVE ARE KNOWN TO PRODUCE THE TORRENTIAL
2-4"/HR RAINFALL RATES DESPITE WHETHER THERE IS A BOUNDARY TO WORK
OFF OF OR NOT. AND AS WE ALL VERY WELL KNOW - EVEN WITHOUT A
DISTINCT SURFACE BOUNDARY IN PLACE TO ACT AS A TRIGGER/FOCUS - WEAK
MESOSCALE BOUNDARIES FREQUENTLY DEVELOP IN THE WEAK FLOW REGIMES
LIKE WE ARE IN (OUTFLOW BOUNDARIES, SEABREEZE/BAYBREEZE, ETC).
EXTREMELY CONCERNED ABOUT THIS TYPE OF SCENARIO PLAYING OUT AND
WOULD NOT DOUBT IF LOCALIZED 8-12+ INCH AMOUNTS OCCURRED SOMEWHERE
IN OUR CWA DURING THE NEXT 2-5 DAYS...AND POSSIBLY IN A SHORT PERIOD
OF TIME. IN ADDITION...THE UPPER LEVEL PATTERN IS ALSO FAVORING A
HEAVY RAIN EVENT AS THE MID LEVEL LOW NOW IN W TX IS FCST TO SLOWLY
GET PUSHED BACK EASTWARD TOWARD US EARLY IN THE WEEK AS THE WESTERN
RIDGE TRIES TO BUILD BACK IN (THOUGH MODELS NOT QUITE IN AGREEMENT
ON PLACEMENT/TIMING JUST YET).
UNFORTUNATELY...WITHOUT SEEING SOMETHING MORE DISTINCT...WE`RE JUST
NOT ABLE TO PINPOINT THE HIGHEST THREAT AREA ATTM. SUSPECT WE`LL END
UP NEED TO ISSUE A FLOOD WATCH IN THE 18-24 HOURS...BUT THINK WE`LL
HAVE ENOUGH TIME TO LOOK AT ANOTHER 1-2 SETS OF FUTURE MODEL RUNS TO
SEE IF ANYTHING CHANGES OR WE CAN NARROW DOWN THE THREAT AREA.
ANTICIPATE DECREASED PRECIP COVERAGE WITH THE LOSS OF HEATING
TONIGHT WITH REDEVELOPMENT OFFSHORE AFTER MIDNIGHT. SUNDAY WILL
LIKELY START OUT SIMILAR TO TODAY WITH PRECIP BECOMING MORE
WIDESPREAD WITH DAYTIME HEATING (CONVECTIVE TEMPS IN THE LOW-MID
80S). PROBABLY HAVE A SIMILAR DIURNAL PATTERN OCCUR INTO EARLY NEXT
WEEK UNTIL IF/WHEN THE UPPER LOW GETS A BIT CLOSER AND CORE RAINS
BECOME A CONCERN.
THOUGH SOME AREAS WILL GET A GOOD SOAKING ON SUN - MOST CONCERNED
ABOUT MON/TUE AT THIS TIME. WILL WORRY ABOUT THE 2ND HALF OF THE
WEEK LATER AS DETAILS ARE BOUND TO CHANGE BETWEEN NOW AND THEN...BUT
THE PRECIP FOCUS MAY SHIFT INTO THE NORTHERN ZONES BEYOND THURS AS A
WEAK FRONT BACKDOORS INTO N/NE TX AND POSSIBLY PROVIDES A LLVL
FOCUS. WILL ISSUE AN UPDATED HWO LATER THIS AFTN. 47
&&
.AVIATION...
MOISTURE SURGE (AS INDICATED EARLIER BY GFS) TODAY RESULTED IN
SCATTERED TO NUMEROUS SHRA/TSRA SOUTHERN HALF OF CWFA...AFFECTING
GLS/LBX AND TO A LESSER EXTENT IAH/HOU. CONVECTIVE ACTIVITY EXPECTED
TO DECREASE IN AREAL COVERAGE RAPIDLY TOWARD SUNSET LEAVING BROKEN
TO OVERCAST MID TO HIGH CLOUDS. EXPECT LIGHT FOG TO AFFECT TAF SITES
TOWARD MORNING ESPECIALLY LBX. CONVECTION WILL FIRE UP AGAIN
(EARLIER FOR GLS AND LBX) IN THE MORNING. 37
&&
.MARINE...
WITH PW VALUES CREEPING UP AND STAYING HIGH THE NEXT SEVERAL DAYS...
AND WITH A LINGERING UPPER LEVEL DISTURBANCE OVER TEXAS...WE CAN
EXPECT A CONTINUED GOOD CHANCE OF TSRA/SHRA FOR THE WATERS. ONSHORE
WINDS WILL BE LIGHT TO MODERATE. COASTAL WATERS WAVE HEIGHTS
REMAINING BELOW SCEC THROUGH FORECAST PERIOD. 37
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 73 88 74 87 74 / 50 70 50 80 60
HOUSTON (IAH) 75 87 76 86 77 / 50 80 60 80 60
GALVESTON (GLS) 80 87 81 86 81 / 50 80 60 80 60
&&
It is amazing how we have gone from near drought conditions to extremely soggy in about 4 weeks! Ah....Southeast Texas weather, gotta love it!
