texoz wrote:I know a lot of people going to ACL Fest in Austin this weekend are curious about the chances & timing of this rain event.
Is the tropical system in the Pacific the main variable?
Actually it is a combination of the Western trough, increasing Gulf moisture, a potent cold core upper low crossing the 4 Corners Region and a Pacific boundary dropping S across Central Texas and pulling up stationary. It appears that 94E will begin to spread its moisture across Mexico as a rather strong short wave/upper air disturbance drops S to the base of that Western trough and pulls 94E toward the Baja Sunday into Monday. For you folks in Central Texas, this has a chance of being a potential significant event and would certainly help the ongoing drought situation. It appears Saturday may be the better day weather wise before things begin to turn rather wet and stormy on Sunday into early next week.
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texoz wrote:I know a lot of people going to ACL Fest in Austin this weekend are curious about the chances & timing of this rain event.
Is the tropical system in the Pacific the main variable?
Actually it is a combination of the Western trough, increasing Gulf moisture, a potent cold core upper low crossing the 4 Corners Region and a Pacific boundary dropping S across Central Texas and pulling up stationary. It appears that 94E will begin to spread its moisture across Mexico as a rather strong short wave/upper air disturbance drops S to the base of that Western trough and pulls 94E toward the Baja Sunday into Monday. For you folks in Central Texas, this has a chance of being a potential significant event and would certainly help the ongoing drought situation. It appears Saturday may be the better day weather wise before things begin to turn rather wet and stormy on Sunday into early next week.
Thanks, srainhoutx. I think most will be happy with good weather for 2/3 (Frid/Sat) of the weekend knowing how much we need the rain.
12Z GFS has scattered light showers for Austin Saturday & Sunday. About 1/4" or less each day. Highs in the mid 80s. No heavy rain event indicated in the latest GFS runs. 12Z Euro has the heavy rain staying well north of Austin - up through the Abilene area. Just a little more rain than the GFS is indicating this weekend for Austin.
It appears wxman57 that NWS Austin/San Antonio (EWX) isn't putting much stock in the 12z GFS run as evidenced from the comments in their afternoon AFD. We in south central Texas look to be heading towards a very wet and possibly excessively wet period from Friday into next week. Below is the "long term" portion of EWX's afternoon AFD:
.LONG TERM (FRIDAY THROUGH WEDNESDAY)...
ON FRIDAY...A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WILL
CONTINUE GENERALLY ALONG AND EAST OF THE I-35 CORRIDOR AS THE
ENVIRONMENT BECOMES MORE TROPICAL. PWATS OF 1.5 INCHES PUSH
NORTHWARD OVER THIS AREA. HIGHS FRIDAY IN THE 80S. RICH GULF
MOISTURE WILL CONTINUE ITS SURGE INTO SOUTH CENTRAL TEXAS LATE
FRIDAY NIGHT INTO SATURDAY AS PWATS RISE TO NEAR 2 INCHES OVER
EASTERN AND SOUTHERN SECTIONS OF THE CWA. THE INCREASINGLY
BUOYANT AIR-MASS WILL RESULT IN MORE FAVORABLE CHANCES FOR
SHOWERS AND THUNDERSTORMS...ESPECIALLY ALONG AND EAST OF THE
EASTERN HILL COUNTRY. MOSTLY CLOUDY SKIES SATURDAY WITH HIGHS
MOSTLY IN THE 80S WITH NEAR 90 SOUTHERN FRINGES. CONVECTION
OVER THE MEXICAN MOUNTAINS LATE SATURDAY INTO SUNDAY WILL
ADVECT NORTHEAST INTO OUR REGION SUNDAY ADDING ADDITIONAL
MOISTURE AND INSTABILITY. AT LEAST A GOOD CHANCE OF SHOWERS
AND THUNDERSTORMS ON SUNDAY OVER A LARGE SWATH OF THE CENTRAL
CWA. HIGHS IN THE 80S. TROPIC-LIKE CONDITIONS WILL CONTINUE
MONDAY WITH HIGHS IN THE 80S TO NEAR 90. WITH THE AREA UNDER
A PROLONG PERIOD OF TROPIC-LIKE CONDITIONS FRIDAY THROUGH
MONDAY...THE BUOYANT ATMOSPHERE WILL PRODUCE LOCALLY HEAVY RAINS
SOME OF WHICH MAY GIVE LOCALIZED FLOODING. THE UPPER TROUGH
SHIFTS INTO THE U.S. SOUTHERN PLAINS ON TUESDAY...A COLD FRONT IS
EXPECTED TO SLIP THROUGH OUR REGION TUESDAY WITH CONTINUED CHANCES
FOR SHOWERS AND STORMS. COOLER DRIER WEATHER WILL FOLLOW BY THE
MIDDLE OF NEXT WEEK.
Interesting battle of forecasts for C. Texas. The one that has the bulk of the rain North and NW of Austin is actually the better one for the drought as it will help fill the lakes.
The operational 12Z GFS has trended a bit 'wetter' for Central and SE Texas and has shifted the axis of heavier rainfall to near the I-35 Corridor and points S. There has been a lot of volatility in the day to day guidance and even the ensembles have shown that volatility. Much of this is due an rather anomalously deep Western trough and a Rex Block down stream over the Atlantic Ocean due to the strong WPAC tropical systems crossing the Pacific Ocean after they have become extra tropical in nature and heading E toward the North America and buckling the jet stream. All that said to suggest there still are a lot of uncertainties in the weekend forecast extending into next week as EPAC 94E becomes involved and moisture spreads inland across Mexico toward Texas and multiple short wave disturbances round the base of the Western trough that looks to remain anchored across the Four Corners Region.
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1121 AM EDT THU OCT 10 2013
VALID 12Z SUN OCT 13 2013 - 12Z THU OCT 17 2013
...SYNOPSIS...
THE RECENT PROGRESSIVE FLOW OF MEDIUM WAVELENGTH SYSTEMS IS
TRENDING TOWARD SLOWER...HIGHER AMPLITUDE FLOW. CONTRIBUTING TO
THIS ARE AN OMEGA BLOCK THAT DEVELOPED FROM THE NORTH ATLANTIC TO
EUROPE...AND HIGH AMPLITUDE RIDGING DEVELOPING TOWARD SOUTHEAST
ALASKA...IN PART DUE TO INFUSION OF POST-TROPICAL TYPHOON DANAS.
THE RESULTANT LONGWAVE PATTERN FAVORS MAINTENANCE OF WEAKLY
DEFINED RIDGING OVER THE EASTERN U.S...UPSTREAM OF THE OMEGA
BLOCK...AND DEEP TROUGHING ACROSS WESTERN NORTH
AMERICA...DOWNSTREAM OF THE DEVELOPING ALASKA RIDGE.
...MODELS...
THE MODELS AGREE REASONABLY WELL TO THIS PATTERN...ALTHOUGH THE
OPERATIONAL GFS SHOWS FASTER PROGRESSION...AS IS TYPICAL. THE GEFS
MEAN IS SLOWER...AND MAY BE USABLE THROUGH ABOUT DAY 5...BUT WE
FOUND LITTLE REASON TO INCORPORATE THE GEFS WHEN THE ECMWF AND
CANADIAN LOOKED LIKE BETTER OPTIONS. THE 00Z ECMWF... ECMWF
ENSEMBLE MEAN... AND CANADIAN SOLUTIONS LARGELY SUPPORT ONE
ANOTHER THROUGH DAY 5. AFTER THAT TIME THERE ARE SOME DIFFERENCES
RELATING TO THE PHASING OR LACK THEREOF BETWEEN NORTHERN STREAM
SHORTWAVES APPROACHING THE GREAT LAKES...AND SOUTHERN STREAM
SHORTWAVE EMANATING FROM THE BASE OF THE LONGWAVE OVER THE GREAT
BASIN. IN A CASE LIKE THIS THE ENSEMBLE MEAN IS PULLED A LITTLE
FORWARD OF THE OPERATIONAL RUNS...AS IT RESPONDS TO THE ENSEMBLE
MEMBERS THAT PHASE THE STREAMS. WE PREFER SEPARATION...AND...IN
PARTICULAR...A LONGER LIVED PERIOD OF ANOMALOUSLY LOW HEIGHTS OVER
THE GREAT BASIN...GIVEN THE STRENGTH OF THE UPSTREAM RIDGE. THE
00Z ECMWF PROVIDED THESE DETAILS WHILE KEEPING IN STEP WITH THE
ENSEMBLE MEAN ACROSS THE REST OF THE HEMISPHERE...WHICH GAVE US
SOME CONFIDENCE IN USING A HEALTHY PROPORTION OF THE OPERATIONAL
RUN IN OUR MODEL BLEND EVEN OUT TO DAY 7. WE GAVE SOME WEIGHT TO
THE CANADIAN THROUGH DAYS 3-4.
...IMPACTS...
THE COASTAL LOW TRAPPED WITHIN THE LARGE SCALE RIDGE ALONG THE
ATLANTIC SEABOARD WILL CONTINUE TO INFLUENCE THE WEATHER FROM THE
DELMARVA SOUTHWARD THROUGH THE CAROLINAS INTO DAY 4 OR EARLY DAY
5...MON/TUE. INFLUENCE...IN TERMS OF CLOUD COVER AND ODDS OF RAIN
WILL THEN DECREASE AS THE SYSTEM GETS A GENTLE NUDGE EASTWARD INTO
THE ATLANTIC...OWING TO A SHORTWAVE EJECTING FROM THE GREAT BASIN.
THE GREAT BASIN SHORTWAVE WILL DRAG A WAVE ALONG THE POLAR
FRONT...CROSSING THE CENTRAL PLAINS AND MIDWEST BEFORE DAMPENING.
THIS WAVE WILL PRODUCE AREAS OF MODERATE TO HEAVY PRECIPITATION IN
THE NORTHERN ROCKIES...NORTH CENTRAL PLAINS AND UPPER MIDWEST WITH
THE COMMA HEAD DEFORMATION SHIELD EXITING NORTHEAST COLORADO...DAY
5. AT THE SAME TIME A RATHER PRONOUNCED SURGE OF GULF MOISTURE
WILL ENCOUNTER THE FRONT OVER THE SOUTHERN PLAINS. IN ADDITION TO
THE UPPER HEIGHT FALLS AND ASCENT ALONG THE FRONT...SOME SUBTLE
UPGLIDE MAY CONTRIBUTE TO LIFT NORTH OF THE REMNANT POLAR BOUNDARY
SITTING OVER THE GULF. A SECOND WAVE SHOULD EJECT BY DAY 6/7...IF
WE ARE CORRECT IN TRUSTING THE TIMING OF THE ECMWF/CANADIAN...WITH
ANOTHER ROUND OF ORGANIZED PRECIPITATION...SOME HEAVY...IN THIS
SAME REGION. THIS RESULTS IN SOME GENEROUS SEVEN DAY RAIN TOTALS
FROM TEXAS TO MISSOURI.
BURKE
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey
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Going to Dallas for the State Fair this weekend. I see 50 percent chance of rain for Saturday and Sunday from the NWS. I see 60 percent for rain from Steve McCauley on his Facebook. So, do you think it would be a washout ( I am seeing the model trends go higher and higher) or would it stay at 50-60 percent?
QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 PM EDT THU OCT 10 2013
PRELIM DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID OCT 11/0000 UTC THRU OCT 14/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR
...DAYS 2/3...
...UPPER MIDWEST/UPPER GREAT LAKES INTO TEXAS...
THE COLD FRONT WILL WEAKEN AND SLOW WHILE CROSSING THE GREAT LAKES
THIS WEEKEND...WITH A BLEND OF THE SLIGHTLY FASTER GFS AND SLOWER
ECMWF PREFERRED OVER THE QUICK NAM. WITH THE ACCOMPANYING
SHORTWAVE TROUGH LIFTING INTO CANADA...PRECIPITATION TOTALS SHOULD
REMAIN LIGHT. MEANWHILE...THE FRONT WILL STALL AND BEGIN TO
REFORM AS A WARM FRONT OVER TEXAS...WITH A BROAD REGIME OF
INCREASINGLY MOIST ISENTROPIC UPGLIDE DEVELOPING OVER THE WEEKEND
AS A LARGE TROUGH DIGS INTO THE GREAT BASIN. THE BROAD NATURE OF
THE ASCENT MAKES IT DIFFICULT TO DETERMINE WITH PRECISION WHERE
THE LARGEST PRECIPITATION TOTALS WILL OCCUR. FROM A MODEL QPF
PERSPECTIVE...THE MODELS CLUSTER OVER CENTRAL TEXAS...BUT WITH
LARGE DIFFERENCES IN TIMING AND AMOUNTS. CONSIDERING THAT THE
STRONGEST INFLOW WILL OCCUR FROM THE WEST AND SOUTH WITH MOISTURE
ONLY DEEPENING...MODEL QPF'S MAY BE A BIT TOO FAR NORTH AND EAST.
THEREFORE...USED A CONSENSUS OF THE GFS/ECMWF FOR QPF DETAILS
WHILE SHIFTING THE AXIS A LITTLE IN THE UPWIND DIRECTION. FFG
VALUES REMAIN HIGH...BUT IT IS POSSIBLE THAT PRECIPITATION AMOUNTS
WILL BE HIGHER THAN EXPECTED...WHICH COULD APPROACH FFG.
ORAVEC/JAMES
NOTE: FFG= Flash Flood Guidance
Attachments
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srainhoutx wrote:QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 PM EDT THU OCT 10 2013
PRELIM DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID OCT 11/0000 UTC THRU OCT 14/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR
...DAYS 2/3...
...UPPER MIDWEST/UPPER GREAT LAKES INTO TEXAS...
THE COLD FRONT WILL WEAKEN AND SLOW WHILE CROSSING THE GREAT LAKES
THIS WEEKEND...WITH A BLEND OF THE SLIGHTLY FASTER GFS AND SLOWER
ECMWF PREFERRED OVER THE QUICK NAM. WITH THE ACCOMPANYING
SHORTWAVE TROUGH LIFTING INTO CANADA...PRECIPITATION TOTALS SHOULD
REMAIN LIGHT. MEANWHILE...THE FRONT WILL STALL AND BEGIN TO
REFORM AS A WARM FRONT OVER TEXAS...WITH A BROAD REGIME OF
INCREASINGLY MOIST ISENTROPIC UPGLIDE DEVELOPING OVER THE WEEKEND
AS A LARGE TROUGH DIGS INTO THE GREAT BASIN. THE BROAD NATURE OF
THE ASCENT MAKES IT DIFFICULT TO DETERMINE WITH PRECISION WHERE
THE LARGEST PRECIPITATION TOTALS WILL OCCUR. FROM A MODEL QPF
PERSPECTIVE...THE MODELS CLUSTER OVER CENTRAL TEXAS...BUT WITH
LARGE DIFFERENCES IN TIMING AND AMOUNTS. CONSIDERING THAT THE
STRONGEST INFLOW WILL OCCUR FROM THE WEST AND SOUTH WITH MOISTURE
ONLY DEEPENING...MODEL QPF'S MAY BE A BIT TOO FAR NORTH AND EAST.
THEREFORE...USED A CONSENSUS OF THE GFS/ECMWF FOR QPF DETAILS
WHILE SHIFTING THE AXIS A LITTLE IN THE UPWIND DIRECTION. FFG
VALUES REMAIN HIGH...BUT IT IS POSSIBLE THAT PRECIPITATION AMOUNTS
WILL BE HIGHER THAN EXPECTED...WHICH COULD APPROACH FFG.
ORAVEC/JAMES
NOTE: FFG= Flash Flood Guidance
There is also Invest 94E, which may become Octave. If it forms and makes landfall, it may produce heavy rain, like what happened in 1994 or 1998. The 1994 flood had a warm front, where all the heavy rain formed.
A potential multi day heavy rainfall event is developing for Texas and portions of the Southern Plains extending E into Arkansas. A combination of a very deep Western trough with multiple short waves dropping S along California into the Great Basin along with increasing tropical moisture from the Gulf of Mexico and the EPAC as well as a very slow moving frontal boundary paint a very wet pattern across the Region extending into mid next week.
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Rain chances continue to look good for us in south central Texas. Periods of showers/storms will occur for the next 3-4 days until a mid-week frontal passage. If the crazy Canadian is right, we could be looking at a Rosa Redux along the southern half of the I-35 corridor. The Canadian develops a tropical system in the Pacific and ultimately moves it into Central Texas about the same time the front is supposed to move through during the Wed-Thur timeframe. Could get real interesting!
THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A
* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
NORTHERN GRIMES COUNTY IN SOUTHEAST TEXAS...
SOUTHWESTERN TRINITY COUNTY IN SOUTHEAST TEXAS...
NORTHERN BRAZOS COUNTY IN SOUTHEAST TEXAS...
SAN JACINTO COUNTY IN SOUTHEAST TEXAS...
SOUTHWESTERN POLK COUNTY IN SOUTHEAST TEXAS...
WALKER COUNTY IN SOUTHEAST TEXAS...
MADISON COUNTY IN SOUTHEAST TEXAS...
* UNTIL 845 PM CDT
* AT 545 PM CDT...LOCAL LAW ENFORCEMENT REPORTED HEAVY RAIN ACROSS
SOUTHERN MADISON COUNTY DUE TO RECENT THUNDERSTORMS. THIS HAS
CAUSED LOCAL ROAD FLOODING. LOCALLY 3 TO 4 INCHES OF RAIN HAVE
FALLEN OVER THE PAST TWO HOURS.
* SOME LOCATIONS THAT WILL EXPERIENCE MINOR FLOODING INCLUDE
HUNTSVILLE...LIVINGSTON...MADISONVILLE...ONALASKA...COLDSPRING...
POINT BLANK...RIVERSIDE...BEDIAS...GOODRICH...LAKE LIVINGSTON STATE
PARK...HUNTSVILLE STATE PARK...WEST LIVINGSTON...IOLA...CRABBS
PRAIRIE...OAKHURST AND NORTH ZULCH.
ADDITIONAL RAINFALL OF 1 TO 2 INCHES IS EXPECTED OVER THE AREA. THIS
ADDITIONAL RAIN WILL CAUSE MINOR FLOODING.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.
EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...AS WELL AS FARM AND COUNTRY ROADS. DO NOT
ATTEMPT TO TRAVEL ACROSS FLOODED ROADS. FIND ALTERNATE ROUTES.
DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.
TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE.
