May 2015 Record Setting May Rainfall Totals For Region

[srainhoutx]

Morning briefing from Jeff:

Our break in excessive rainfall events appears to be ending with the threat returning Thursday and Friday and then potentially a much more serious threat over the weekend.

Weak frontal boundary over N TX this morning resulting in training convection along the Red River. The front itself and associated convective outflow boundaries should gradually push southward into SE TX late this afternoon and overnight. Weak upper level ridging has developed a weak cap over the region since late yesterday afternoon and expect this feature to hold much of today limiting rain chances. Cap erodes this evening with approach of the front and thunderstorm activity from the north.

Frontal boundary nears I-10 on Thursday and stalls with the air mass becoming increasingly unstable. Expect numerous slow moving thunderstorms with heavy rainfall along this boundary and the flash flood potential will be increasing on Thursday. Front remains stalled over the region into Friday with more thunderstorms expected…some containing heavy rainfall.

Weekend:
Main focus is shifting toward a potential excessive rainfall and flash flood event over the upcoming holiday weekend. A strong upper level storm system will move into the SW US while a surge of deep tropical moisture with PWS approaching 2.0 inches starting late Saturday. Numerous disturbances will begin to cross the area by early Sunday and expect rain chances to gradually increase. Upper level become increasingly vented with upper level divergence and this aspect has been strongly coupled with the recent flash flood events over the region. Potential is there for slow moving thunderstorm complexes with very heavy rainfall Sunday-early next week with both flash flooding and river flooding.

Hydro:
Area rivers still passing flood flows from the recent heavy rainfall.

Trinity River:
Overbanks flooding in progress above Lake Livingston and from above Liberty to below Moss Bluff. River will remain overbanks into the weekend.

Brazos River:
Flood wave from Monday’s heavy rainfall is progressing toward Richmond this morning. River is expected to crest below flood stage at Richmond, but may rise to near or above flood stage at Rosharon late this week.

Colorado River:
Upstream flood wave is cresting near Wharton this morning and will move downstream to Bay City later this week. River remains within banks with no significant impacts expected.

Guadalupe River:
River is overbanks from below Gonzales, TX to below Bloomington TX. Near moderate flood levels are forecasted near Victoria, TX through Saturday morning.

Additional rainfall Thursday and Friday and again this week on already swollen rivers will only worsen ongoing flooding. New rises can be expected pushing some rivers above flood stage.

Residents are urged to pay close attention to the weather forecast this weekend especially across central TX where flash flooding of normally dry creeks and rivers will be possible.

Giddings, TX Tornado:
A weak tornado rated EF-0 with 80mph winds impacted the town of Giddings, TX yesterday around midday (1225pm) injuring 1 person. The tornado developed from an ill define thunderstorm which would not be expected to produce a tornado. Visible satellite images early yesterday morning revealed a low level outflow boundary in place from Austin to Giddings from thunderstorm over N TX. As the thunderstorms developed south of this boundary during the late morning hours and then crossed the boundary while moving north it produced the tornado. This is a good example of backed low level winds from the ENE north of the boundary and southerly winds ahead of the boundary producing a gradient of low level shear and horizontal rotation in the atmosphere that was then stretched by the thunderstorm. Tornado production would not have been likely without this boundary in place. Such tornadoes tend to be very weak EF-0 or EF-1 and produce mainly vegetation damage or minor structural damage.

[BlueJay]

It appears to be cloudying up now. Maybe its pop-up shower time for this part of Montgomery County.

[djjordan]

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD ADVISORY FOR...
NORTHERN BRAZORIA COUNTY IN SOUTHEASTERN TEXAS...
SOUTH CENTRAL HARRIS COUNTY IN SOUTHEASTERN TEXAS...
EAST CENTRAL FORT BEND COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 345 PM CDT

* AT 150 PM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
THUNDERSTORMS. THIS WILL CAUSE MINOR FLOODING IN THE ADVISORY
AREA. TWO INCHES OF RAIN HAVE ALREADY FALLEN OVER THE CLEAR CREEK
WATERSHED NEAR HIGHWAY 288. AN ADDITIONAL INCH OF RAIN WILL BE
POSSIBLE BY 230 PM.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
NORTHWESTERN PEARLAND...NORTHERN MISSOURI CITY...WEST UNIVERSITY
PLACE...ASTRODOME AREA...UNIVERSITY PLACE...FRESNO...GREATER THIRD
WARD...GREATER HOBBY AREA...DOWNTOWN HOUSTON...MIDTOWN HOUSTON...
MACGREGOR...GREATER EASTWOOD...NEARTOWN / MONTROSE...WESTERN SOUTH
BELT / ELLINGTON...ARCOLA...BROOKSIDE VILLAGE...GOLFCREST /
BELLFORT / REVEILLE...WILLOWBEND...MINNETEX AND SOUTH MAIN.

[djjordan]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
256 PM CDT WED MAY 20 2015

TXC201-202200-
/O.NEW.KHGX.FA.Y.0097.150520T1956Z-150520T2200Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
HARRIS TX-
256 PM CDT WED MAY 20 2015

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD ADVISORY FOR...
CENTRAL HARRIS COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 500 PM CDT

* AT 254 PM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
THUNDERSTORMS. THIS WILL CAUSE MINOR FLOODING IN THE ADVISORY
AREA. UP TO TWO INCHES OF RAIN HAVE ALREADY FALLEN. A STORM
SPOTTER REPORTED VISIBILITY LESS THAN 500 FEET AND PONDING OF
WATER ON HIGHWAY 290 WEST OF THE BELTWAY IN HEAVY RAIN.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
JERSEY VILLAGE...ALDINE...GREATER GREENSPOINT...HIDDEN VALLEY...
WILLOWBROOK...CARVERDALE...FAIRBANKS / NORTHWEST CROSSING...GREATER
INWOOD...WESTBRANCH AND NORTHWESTERN ACRES HOME.

[unome]

our "dry" day...

http://weather.cod.edu/satrad/nexrad/in ... X-N0Q-1-96

[srainhoutx]

Some much for a 'dry day' today. Shower and storms have developed with the heat of the day along a outflow boundary from the overnight storms across N Texas that reached Central and SE Texas. The latest visible satellite imagery clearly shows where the low clouds are behind the cold front that is slowly moving into the northern reaches of the Hill Country. This frontal boundary is expected to stall basically along or near the I-10 Corridor tonight into early tomorrow. A fairly potent shortwave is approaching from the West near the Baja Peninsula and that should be the trigger for rounds of heavier storms with heavy rainfall rates through Friday. The 12Z European and GFS continue to advertise a very potent upper low dropping further south into Northern Mexico that what has happened recently. Multiple embedded disturbances are noted in the Westerly flow of the Pacific Ocean headed generally toward Mexico and Texas for the Memorial Day Weekend Holiday period. Again, we urge those with outdoor plans during the Holiday Weekend to keep a weary eye to the sky as we may well have an extremely eventful weather pattern heading into the weekend and early next week.

05202015 2025Z TX VIS latest.jpg

05202015 12Z Euro 96 ecmwf_z500a_sd_namer_5.png

05202015 12Z GFS 96 gfs_z500a_sd_namer_17.png

[srainhoutx]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
300 PM CDT WED MAY 20 2015

LLANO-BURNET-WILLIAMSON-VAL VERDE-EDWARDS-REAL-KERR-BANDERA-
GILLESPIE-KENDALL-BLANCO-HAYS-TRAVIS-BASTROP-LEE-KINNEY-UVALDE-
MEDINA-BEXAR-COMAL-GUADALUPE-CALDWELL-FAYETTE-MAVERICK-ZAVALA-
FRIO-ATASCOSA-WILSON-KARNES-GONZALES-DE WITT-LAVACA-DIMMIT-
INCLUDING THE CITIES OF...LLANO...BURNET...GEORGETOWN...DEL RIO...
ROCKSPRINGS...LEAKEY...KERRVILLE...BANDERA...FREDERICKSBURG...
BOERNE...BLANCO...SAN MARCOS...AUSTIN...BASTROP...GIDDINGS...
BRACKETTVILLE...UVALDE...HONDO...SAN ANTONIO...NEW BRAUNFELS...
SEGUIN...LOCKHART...LA GRANGE...EAGLE PASS...CRYSTAL CITY...
PEARSALL...PLEASANTON...FLORESVILLE...KARNES CITY...GONZALES...
CUERO...HALLETTSVILLE...CARRIZO SPRINGS
300 PM CDT WED MAY 20 2015

...HEAVY RAINFALL WILL BRING AN ELEVATED RISK FOR FLASH FLOODING
DURING THE MEMORIAL DAY WEEKEND...

A POTENT UPPER LEVEL SYSTEM IS EXPECTED TO BRING WIDESPREAD HEAVY
RAINFALL TO SOUTH CENTRAL TEXAS SATURDAY EVENING THROUGH SUNDAY
AND POSSIBLY THROUGH MEMORIAL DAY. A FEW ISOLATED EPISODES OF
HEAVY RAIN WILL BE POSSIBLE BETWEEN NOW AND THE WEEKEND...WHICH
WILL ONLY FURTHER INCREASE THE RISK FOR FLASH FLOODING AND RIVER
FLOODING BY THE TIME THE MORE WIDESPREAD THREAT ARRIVES THIS
SATURDAY EVENING.

RAINFALL TOTALS THROUGH THE WEEKEND ARE EXPECTED TO RANGE FROM
2-4 INCHES WITH ISOLATED AMOUNTS OF UP TO 7 INCHES POSSIBLE IN
LOCATIONS WHERE STORM TRAINING MAY DEVELOP. ALSO DEPENDING ON
WHERE THESE AREAS DEVELOP...AREA RIVERS AND STREAMS WHICH ARE
ALREADY ELEVATED OR EVEN AT FLOOD STAGE WILL BE AT RISK FOR
FURTHER...MORE IMPACTFUL...FLOODING OVER THE WEEKEND.

DETAILS OF THE FORECAST FOR THE WEEKEND MAY CHANGE SO IT WILL BE
IMPORTANT TO STAY TUNED FOR THE LATEST FORECAST UPDATES. IF
CONDITIONS CONTINUE TO INDICATE THIS POTENTIAL...FLASH FLOOD
WATCHES MAY BE ISSUED. IT WILL BE IMPORTANT TO HEED ANY WARNINGS
OR ADVISORIES.

[unome]

a bit off-topic, but "The GOES-R Proving Ground at the Hazardous Weather Testbed" blog is awesome & gives some fantastic insight: http://goesrhwt.blogspot.com/

ditto for "RAMMB: GOES-R Proving Ground Blog": http://rammb.cira.colostate.edu/researc ... ound/blog/

[Katdaddy]

The weak frontal boundary continues to drift S into SE TX this morning and may lead to the potential of heavy rains through Friday on already saturated grounds. In addition some isolated strong to severe storms are possible this afternoon. Of more concern is the possibility of very heavy rains Sunday and Monday during the Memorial holiday as the upper level low approaches SE TX.

[Katdaddy]

Very cool unome! Thanks for sharing "The GOES-R Proving Ground at the Hazardous Weather Testbed" and "RAMMB: GOES-R Proving Ground" blogs.

[srainhoutx]

Jeff offered a briefing last night regarding the long Memorial Day Holiday Weekend:

Threat for excessive rainfall will return to the region Thursday and Friday…but the main focus will be on the weekend with an increasing threat for excessive rainfall amounts and flash flooding/river flooding.

Frontal boundary over north TX currently will move into SE TX tonight. Air mass over the region is moist and unstable clearly seen by scattered thunderstorms this afternoon. As the boundary begins to interact with this air mass expect to see an increase in showers and thunderstorms later tonight. This activity will move southward into the region. Will also need to keep an eye on extensive convection ongoing west of the Rio Grande and near/south of San Angelo in case some sort of thunderstorm complex comes at us from the west tonight.

Convection the next two days will focus on outflow boundaries and the frontal boundary which should stall near the coast late Thursday into Friday. Storm motions will become increasingly slow so rainfall rates will be gradually greater with time. Grounds are still saturated and rivers high…some in flood…so additional heavy rainfall has little choice but the run-off. Could easily see rainfall rates of 1-2 inches per hour under the stronger storms on Thursday and Friday. Overall not looking at organized heavy rainfall…but more spotty in nature according the to meso scale guidance.

Weekend:
Of bigger concern is the arrival of a deep upper level storm system into TX over the Memorial Day weekend. Moisture levels will begin to surge upward on Saturday as the old frontal zone near the coast washes out. PWS rise to near 2.0 inches by Sunday at the same time lift arrives from the west. Upper level winds become increasingly divergent with time on Sunday into Monday and numerous disturbances move ENE/NE out of MX…sound familiar. Surface boundaries will likely help focus/anchor storms and copious moisture levels certainly support excessive rainfall. Large thunderstorm complexes will likely result out of NE MX Sunday-Tuesday with excessive rainfall rates likely. Way too early to attempt to pin point any likely areas of excessive rainfall…but widespread amounts of 2-4 inches with significantly higher totals possible.

Given the already wet grounds (rainfall for the first two weeks of May 90-600% of normal), swollen rivers, and reservoir releases ongoing, rainfall of this magnitude will certainly cause additional flooding and flash flooding.

Residents should remain aware of weather conditions this weekend and be prepared for possible flooding conditions. This is especially true for areas of C TX where normally dry river and creek beds can respond very quickly to excessive rainfall and visitors can be caught off guard in flash flood prone areas.

[srainhoutx]

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
752 AM CDT THU MAY 21 2015

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
SOUTHWESTERN HOUSTON COUNTY IN SOUTHEASTERN TEXAS...
EASTERN MADISON COUNTY IN SOUTHEASTERN TEXAS...
NORTHWESTERN WALKER COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 1045 AM CDT

* AT 752 AM CDT...DOPPLER RADAR INDICATED A THUNDERSTORM PRODUCING
HEAVY RAIN ACROSS THE WARNED AREA. UP TO THREE INCHES OF RAIN HAVE
ALREADY FALLEN. FLASH FLOODING IS EXPECTED TO BEGIN SHORTLY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
NORTHWESTERN HUNTSVILLE...AUSTONIO...MIDWAY AND CRABBS PRAIRIE.

[srainhoutx]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
754 AM CDT THU MAY 21 2015

POLK TX-HOUSTON TX-TRINITY TX-
754 AM CDT THU MAY 21 2015

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD ADVISORY FOR...
NORTHERN POLK COUNTY IN SOUTHEASTERN TEXAS...
EAST CENTRAL HOUSTON COUNTY IN SOUTHEASTERN TEXAS...
EASTERN TRINITY COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 1100 AM CDT

* AT 753 AM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
THUNDERSTORMS. THIS WILL CAUSE MINOR FLOODING IN THE ADVISORY AREA.
ONE TO THREE INCHES OF RAIN HAVE ALREADY FALLEN.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
APPLE SPRINGS...CORRIGAN...GROVETON AND CENTRALIA.

[srainhoutx]

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
808 AM CDT THU MAY 21 2015

TXZ163-164-176>179-195>200-210>214-226-227-235>238-221315-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
808 AM CDT THU MAY 21 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...TODAY AND TONIGHT

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE POSSIBLE
TODAY INTO THIS EVENING AS A WEAK FRONTAL BOUNDARY SETTLES OVER
THE REGION. THIS BOUNDARY WILL ACT AS A FOCUS FOR DEVELOPMENT AS
DISTURBANCES MOVING IN FROM THE WEST WILL HELP TO PRODUCE STRONG
STORMS. LOCALLY HEAVY RAINFALL IS POSSIBLE IN THE SLOWER MOVING
STORMS OR WHERE ANY TRAINING SETS UP. IF SO...FLOODING IS POSSIBLE
ESPECIALLY AT LOCATIONS THAT HAVE SATURATED GROUNDS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

ELEVATED RAIN CHANCES WILL CONTINUE INTO FRIDAY AS THE WEAK
FRONTAL BOUNDARY LINGERS OVER THE REGION.

ANOTHER PERIOD OF HEAVY RAINFALL WILL BE POSSIBLE SUNDAY INTO
MONDAY...AND THIS COULD POSE TRAVEL IMPACTS DURING THE HOLIDAY
WEEKEND. VERY DEEP GULF MOISTURE COMBINED WITH FAVORABLE WINDS
ALOFT WILL HELP TO PRODUCE STRONG STORMS WITH LOCALLY HEAVY RAINS.
THESE STORMS MAY ALSO BE SLOW MOVING. GIVEN THAT WET GROUNDS MIGHT
ALREADY BE IN PLACE...IF THIS FORECAST DOES VERIFY WE COULD BE
FACING A POTENTIALLY DANGEROUS SITUATION BY MONDAY.

[srainhoutx]

Update from Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 05/21/15 1325Z
SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404
LATEST DATA USED: GOES0-13 1315Z HANNA
.
LOCATION...LOUISIANA...TEXAS...
.
ATTN WFOS...LCH...SHV...HGX...
ATTN RFCS...LMRFC...WGRFC...
.
ALTHOUGH THE OFFICIAL PERIOD FOR SPENES RETIREMENT APPEALS HAS ENDED,
NESDIS WILL CONTINUE TO ACCEPT ADDITIONAL APPEALS THROUGH EMAILS TO
JOHN.SIMKO@NOAA.GOV
.
EVENT...SATELLITE FEATURES FOR LOCALIZED HEAVY RAIN THREAT
.
SATELLITE ANALYSIS AND TRENDS...AN AREA OF VERY SLOW FORWARD PROPAGATING
CLUSTER OF CONVECTION HAS BEEN SLOWLY DROPPING SE THIS MORNING AND WAS
IN THE VIC OF LFK. FORCING APPEARS TO BE DRIVEN BY ENHANCED AREA OF
FRONTAL CONVERGENCE AHEAD OF WEAK FRONTAL WAVE JUST NW OF LFK AND WAS
ALSO ENHANCED BY DIFFLUENT MID LEVEL FLOW JUST S OF JET STREAK OVER THE
S PLAINS REGION. ALTHOUGH LOW LEVEL FLOW INTO COMPLEX WAS MEAGER THERE
DID APPEAR TO BE ENOUGH OF A COMPONENT JUXTAPOSED WITH INSTABILITY AXIS ON
MORNING UA ANALYSIS THAT HAS ALLOWED FOR SOME WEAK UPSTREAM REGENERATION
THAT HAS MERGED INTO THE SW PORTION OF COMPLEX. MORNING SOUNDINGS WERE
SUGGESTING ENOUGH THETA-E DIFFERENTIALS TO CONTINUE TO SUGGEST FORWARD
PROPAGATION BUT WITH THAT SAID THOUGH STORM MOTIONS VECTORS AND FORWARD
PROPAGATING VECTORS WERE VERY WEAK TO THE SE. THIS ALL IMPLIES A SLOW
SE MOTION TO CONTINUE OVER THE NEXT FEW HOURS WITH CONTINUED LOCALIZED
HEAVY RAIN THREAT. IT DOES APPEAR AS THOUGH CLOUD TOPS HAVE BEGUN TO
WARM ON THE MOST RECENT GOES IMAGE AND FEEL AS THOUGH ANY LOCALIZED HEAVY
RAIN THREAT SHOULD DIMINISH AS ALREADY WEAK LOW LEVEL FLOW WEAKENS EVEN
FURTHER BETWEEN NOW AND 16Z.

[ticka1]

looks like the rain moved north of us and the system out to the west is moving south and will move offshore. Anyone see anything different?

[srainhoutx]

looks like the rain moved north of us and the system out to the west is moving south and will move offshore. Anyone see anything different?

Some of the shorter range meso guidance suggest redevelopment late today into tomorrow along and N of the stalling boundary, but as always the various computer models are having a very difficult time with the meso features and cannot accurately 'predict' the number of features involved well beyond 6 to 12 hours. The next couple of days will be very challenging forecasting wise, so expect changes throughout the day. The weekend looks particularly concerning as the upper flow swings around to that of a Southwesterly flow aloft that tends to increase strong to severe storm chances and slow moving heavy training thunderstorm potential where those strong storms develop.

[BlueJay]

There is some serious looking cloud action and rumbling going on around here.

[unome]

Very cool unome! Thanks for sharing "The GOES-R Proving Ground at the Hazardous Weather Testbed" and "RAMMB: GOES-R Proving Ground" blogs.

even CIMSS Satellite Blog has Texas in it's viewfinder as of late - I guess because we've been so stormy

Their current post has GOES-14 in Super Rapid Scan over Texas - just awesome

http://cimss.ssec.wisc.edu/goes/blog/

[srainhoutx]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1050 AM CDT THU MAY 21 2015

HARRIS TX-SAN JACINTO TX-MONTGOMERY TX-
1050 AM CDT THU MAY 21 2015

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD ADVISORY FOR...
NORTHWESTERN HARRIS COUNTY IN SOUTHEASTERN TEXAS...
SOUTHWESTERN SAN JACINTO COUNTY IN SOUTHEASTERN TEXAS...
SOUTHERN MONTGOMERY COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 1245 PM CDT

* AT 1049 AM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
THUNDERSTORMS. THIS WILL CAUSE MINOR FLOODING IN THE ADVISORY AREA.
UP TO TWO INCHES OF RAIN HAVE ALREADY FALLEN.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
CONROE...TOMBALL...PINEHURST...THE WOODLANDS...OAK RIDGE NORTH...
SHENANDOAH...MAGNOLIA...CUT AND SHOOT...STAGECOACH...WOODLOCH...THE
WOODLANDS PAVILLION AND CHATEAU WOODS.