May 2015 Record Setting May Rainfall Totals For Region

[jasons2k]

.75" yesterday
1.63" overnight
3.46" so far in May

More off to the west towards San Antonio...

[srainhoutx]

Update from Jeff regarding the staggering amounts of rainfall that fell overnight into the early morning hours across the Southern half of Metro Houston:

Report: 11.98 inches over Bay Knoll Subdivision in 3-hr overnight. This rainfall rate exceeds our 500-yr rainfall frequency by 2.5 inches. Total 12-hr rainfall 13.58 inches.

Report: 7.33 inches in 3-hrs at JSC Building 30.

FWS gage: 8.32 inches in 5.0 hours at Horsepen Bayou and Bay Area Blvd.

Report: 8.92 inches at NASA CoCoRaHS gage


The next upper shortwave disturbance is advancing toward the Houston area from S Central Texas. Folks need to pay close attention today as the timing of the disturbance and the VERY tropical airmass could provide for extremely heavy rainfall rates. I have over 3 inches up here in NW Harris County in the rain gauge for the last 36 hours. The ground is saturated and it will not take much in the way of heavy rainfall to create issues.

[srainhoutx]

05132015 mcd0081.gif

MESOSCALE PRECIPITATION DISCUSSION 0081
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
829 AM EDT WED MAY 13 2015

AREAS AFFECTED...PORTIONS OF CENTRAL/WESTERN TX

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 131229Z - 131629Z

SUMMARY...DEEP MOISTURE AND LARGE SCALE LIFT BEING ENHANCED BY THE
APPRAOCHING SOUTHERN STREAM MID/UPPER LEVEL H5 S/WV WILL INCREASE
THE FLOODING POTENTIAL OVER PORTIONS OF CENTRAL AND WESTERN TX
DURING THE NEXT SEVERAL HOURS.

DISCUSSION...RECENT RADAR IMAGERY AND OBSERVATIONS SHOWING AN
INCREASE OVER THE PAST FEW HOURS OF ORGANIZED AND LOCALLY HEAVY
CONVECTION THRU PARTS OF WESTERN TX..NEAR THE MID RIO GRANDE
VALLEY AREA. EXPECT THIS CONVECTION TO CONTINUE TO INCREASE IN
COVERAGE AND POSE AN INCREASE IN FLASH FLOODING POTENTIAL INTO AT
LEAST THE LATER MORNING HOURS OVER PARTS OF WESTERN AND CENTRAL
TX. THE APPROACH OF THE WELL DEFINED SOUTHERN STREAM MID/UPPER
LEVEL TROF WILL SUPPLY THE LARGE SCALE LIFT..WITH THE PERSISTENT
SOUTHERLY LOW LEVEL JET CONTINUING TO BRING IN DEEPER GULF
MOISTURE. PWS ARE ALREADY NEAR 2 INCHES AND THE AIRMASS SHOULD
REMAIN QUITE MOIST DUE TO THIS CONTINUED SOUTHERLY LOW LEVEL FLOW.

A MAJORITY OF THE HIRES MODELS ARE INDICATING SIGNIFICANT RAINS
OVER THE NEXT 3-6 HOURS WITHIN THE THREAT AREA..INCLUDING THE
ARW..NMMB..WRF NSSL AND GEM REGIONAL. EXPECT SOME POSSIBLE 2 INCH
PER HOUR RAINFALL RATES..WITH SOME POSSIBLE 3-5 INCH RAINFALL
TOTALS BEFORE THE EVENT TAPERS OFF.

TERRY

ATTN...WFO...CRP...EWX...SJT...

[srainhoutx]

A quick update regarding the expected forecast for the remainder of this week into early next week. No real change is expected in the general synoptic pattern of a Western upper trough with embedded disturbances rotating beneath that trough as well as deep tropical moisture streaming off the Pacific Ocean and the Gulf of Mexico from the NW Caribbean Sea. Another wrinkle in the forecasting challenges is a very wet phase of the Madden Julian Oscillation (MJO) is steadily advancing East across the Pacific and will be in our Regional 'backyard' next week. The blue shading indicates a great deal of instability or is conducive for tropical showers and convection to develop while the red shades indicate a downward motion in the mid/upper level winds, meaning less thunderstorm development. All that said we see no change in the very unsettled pattern across Texas and Oklahoma with additional chances of very heavy rainfall almost daily into next week.

[srainhoutx]

The short term forecast offers challenges of its own. Some of the newly arriving short range meso guidance is suggesting the next round of very heavy rainfall with embedded strong to possibly severe storms could begin mid day across the Central and SE Texas areas extending into the evening rush hour. The best chance for the very heavy tropical like storms with very heavy rainfall rates appears to be timed between 3 and 7 PM this afternoon. As we have seen already, this complex and complicated synoptic setup is extremely difficult to forecast, so it is best to be aware throughout the day for rapidly changing weather conditions particularly before heading home from work this afternoon.

[srainhoutx]

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
921 AM CDT WED MAY 13 2015

BRAZORIA TX-HARRIS TX-GALVESTON TX-CHAMBERS TX-
921 AM CDT WED MAY 13 2015

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD WARNING FOR...
NORTHEASTERN BRAZORIA COUNTY IN SOUTHEASTERN TEXAS...
SOUTHEASTERN HARRIS COUNTY IN SOUTHEASTERN TEXAS...
GALVESTON COUNTY IN SOUTHEASTERN TEXAS...
WESTERN CHAMBERS COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 1215 PM CDT

* AT 916 AM CDT...ROAD FLOODING LEADING TO ROAD CLOSURES WAS STILL
OCCURRING IN AREAS ALONG INTERSTATE 45 BETWEEN HOBBY AIRPORT AND
LA MARQUE FROM AN ESTIMATED 6 TO 10 INCHES OF RAINFALL THAT FELL
ACROSS THE WARNED AREA OVERNIGHT. WATER IS RECEDING IN THESE
AREAS... HOWEVER SEVERAL ROADS ARE STILL IMPASSIBLE AND MOTORISTS
ARE URGED TO AVOID FLOODED AREAS UNTIL WATERS RECEDE COMPLETELY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
PASADENA...PEARLAND...LEAGUE CITY...BAYTOWN...TEXAS CITY...
FRIENDSWOOD...LA PORTE...DEER PARK...ALVIN...DICKINSON...SOUTH
HOUSTON...LA MARQUE...SANTA FE...SEABROOK...WEBSTER...HITCHCOCK...
MANVEL...KEMAH...CLEAR LAKE AND SOUTH BELT / ELLINGTON.

[BlueJay]

Last night gave a hint as to how it may have been on Noah's ark. Although we did not know at the time, on our patio there was a large black cat, two or three squirrels, maybe some birds and/or other small rodents taking shelter from the heavy rain. When the outdoor lights were flipped on to inspect the rain soaked backyard (our yard floods pretty badly), all of the patio inhabitants abruptly flurried into the wet elements of nature. The ark quickly had cleared.
Incredible but true.

Thanks for all of the weather reporting everyone!

[srainhoutx]

A Tornado Watch has been issued for portions of S Central and Central Texas until 5:00PM CDT.

[srainhoutx]

Update from Jeff:

Widespread excessive rainfall over the last 48 hours is resulting in numerous concerns on area watersheds.



West Fork San Jacinto River:
River is rising at Conroe, Porter, and Humble. Flooding is forecast at all three locations with the river expected to reach 3.0 ft above major flood status at Porter.

Overnight significant inflow from Lake Creek entered the river at I-45 with the flow increasing from 7000cfs yesterday afternoon to over 15000cfs this morning. Lake Conroe has maintained a steady release rate since yesterday morning of 6400cfs and is storing flood flow in their freeboard to help mitigate downstream flooding. The lake continues to rise and any additional rainfall over or above the lake will result in additional flood gate increases. Residents along the West Fork of the San Jacinto River from below Conroe to Humble should be prepared for overbank flooding and potentially being cut off. Subdivisions that may be impacted on the West fork include: Northshore, Rivercrest, Forest Cove, and Belleau Woods.

Trinity River:
River is rising and will rise above flood stage both above and below Lake Livingston over the next several days and hold at those levels into next week. Current forecast keep the river mainly below major flood levels and not homes are currently forecasted to be impacted. Some homes near/around Liberty may become cut-off however.

Navasota River:
River is rising and will rise to near moderate flood levels on Friday and hold near that level into next week.

Tres Palacios River:
River rose extremely fast overnight, but is cresting currently just below flood stage and will fall quickly today.

Brazos River:
Multiple flood waves are moving down the river. Forecast is forecast to remain below flood stage at all points, but will be high

East Fork of the San Jacinto River:
River is rising, but currently forecast to remain below flood stage at both Cleveland and New Caney.

Clear Creek:
Creek is overbanks from FM 2351 to east of I-45. Creek is near crest and should begin to slowly fall, but remain overbanks into midday. No structures are threatened.

Additional rainfall will only worsen ongoing flooding and slow recessions.

This is a serious flood threat across the region. Residents should remain aware of weather conditions and water levels and be prepared to act. As clearly shown this morning in southern Harris County…your vehicle is not going to win out again flood waters. Over 23 high water rescues had to be performed by HFD along I-45 with at least 200 vehicles flooded just along the I-45 feeder roads. Do NOT drive into flooded areas!

For current and Forecast River Levels visit: http://www.srh.noaa.gov/wgrfc/

Rainfall since Sunday Evening:

05132015 Jeff unnamed.png

[/i]

[tireman4]

As Srain alluded to, this could be a tipping point day. Please be careful out there. Traffic will be a mess going home. Stay tuned to here and the local media (NWS too) outlets during the day. With already saturated grounds, it will not take much to cause flooding. Turn around, do not drown.

[Andrew]

Update from Jeff:

"New forecast have been released for the West Fork of the San Jacinto River:

Porter: Major flooding is forecast
Humble: Moderate flooding is forecast

Based on the behavior of the river this morning the forecast crest at Humble has been revised upward to 50.0-50.5 ft.

At levels above 50.0ft subdivisions downstream of US 59 may become cut-off. These subdivisions include: Rivercrest, Northshore, Forest Cove, and Belleau Woods.

Note: City of Houston is working a press release to be released this afternoon to warn residents downstream of US 59 of the potential for rising water and becoming cut-off. HPD will be deployed into the above subdivisions to warn residents. "

[srainhoutx]

Update from Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 05/13/15 1551Z
SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404
LATEST DATA USED: GOES-13 1515Z HANNA
.
LOCATION...TEXAS...
.
ATTN WFOS...HGX...FWD...CRP...EWX...BRO...
ATTN RFCS...WGRFC...
.
EVENT...UPDATE TO EARLIER SPE REGARDING HEAVY RAIN THREAT
.
SATELLITE ANALYSIS AND TRENDS...CLUSTERS OF CONVECTION CONTINUE TO
FORWARD PROPAGATE THIS MORNING THROUGH PORTIONS OF S CNTRL TX WITH HOURLY
RAINFALL RATES OF 1.0-2.0"/HR THAT SHOULD APPROACH THE AUS/SAT VIC OVER
THE NEXT 30-60 MINUTES. OUTFLOW FROM THESE AREAS OF ORGANIZED CONVECTION
HAS BEEN REINFORCING REMNANT SYNOPTIC BOUNDARY THAT WAS MOST RECENTLY
ANALYZED EXTENDING FROM THE VIC OF GLS EXTENDING SW TOWARDS FAR S TX.
HAVE NOTED THAT LEAD AREA OF CONVECTION W OF CRP CONTINUES TO FEATURE
BACKBUILDING WHERE EARLIER MESONET RAINFALL REPORTS OF 4.00" WERE NOTED.
HAVE NOTED THAT 85H LLJ OUT OF BRO VWP WAS SOMEWHAT HIGHER THAN FORECAST
BY NWP GUIDANCE AND BELIEVE THE JUXTAPOSITION OF THIS ALONG WITH MODERATE
TO HIGH INSTABILITY AXIS NOTED JUST SE OF BRO SHOULD ALLOW FOR A CONTINUED
ENVIRONMENT FAVORABLE FOR BACKBUILDING CONVECTION ON THE SW PERIPHERY OF
OUTFLOW ENFORCED FRONTAL BOUNDARY. OVERALL PATTERN IS NOT DISSIMILAR TO
MADDOX FRONTAL/MESOHIGH TYPE HEAVY RAIN EVENT CONSIDERING PROXIMITY TO
MID LEVEL RIDGE AXIS. BELIEVE THIS WOULD TEND TO FAVOR BEST POTENTIAL
BACKBUILDING/QUASI-STATIONARY MCS POTENTIAL WITH DOWNSTREAM TRAINING FROM
THE APPROXIMATE VIC OF ALI/COT AND THEN EVENTUALLY DEVELOPING DOWNSTREAM
TOWARDS THE VIC OF 3T5/VCT. MOISTURE IS QUITE ANOMALOUS WITH A DEEP
ABOVE 0C LAYER WITH MINIMAL CLOUD LAYER SHEAR AND THIS SHOULD CONTINUE
TO FAVOR RAINFALL RATES OVER 2.0"/HR.

[srainhoutx]

05132015 mcd0082.gif

MESOSCALE PRECIPITATION DISCUSSION 0082
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
948 AM EDT WED MAY 13 2015

AREAS AFFECTED...SOUTHEAST TEXAS

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 131340Z - 131900Z

SUMMARY...MERGING CLUSTERS OF INTENSE CONVECTION ARE EXPECTED LATE
THIS MORNING THROUGH MID-AFTERNOON. VERY INTENSE RAINFALL RATES
WILL RESULT IN FLASH FLOODING.

DISCUSSION...A WELL-DEFINED SOUTHERN STREAM UPPER LEVEL TROUGH
EJECTING ACROSS THE UPPER RIO GRANDE VALLEY THIS MORNING WILL
EJECT EAST THROUGH MID-AFTERNOON AND DRIVE A WELL-DEFINED AXIS OF
CONVECTION TOWARD PORTIONS OF SOUTHERN AND SOUTHEAST TEXAS. THE
ACTIVITY ALREADY OCCURRING ALONG A LINE FROM KERV TO WEST OF KCOT
HAS BEEN CHARACTERIZED BY VERY COLD CONVECTIVE TOPS THE LAST
COUPLE OF HOURS AS STRONGLY DIVERGENT FLOW ALOFT INTERACTS WITH A
VERY MOIST AND MODESTLY UNSTABLE S/SE LOW LEVEL JET WHICH BASED ON
12Z RAOB DATA IS ON THE ORDER OF ABOUT 30 KTS.

THE MODELS SUGGEST SOME ADDITIONAL UPTICK IN THE LOW LEVEL JET
AIMED INTO THE SOUTHERN FLANK OF THE UPPER TROUGH AND ASSOCIATED
CONVECTION TODAY. THIS COUPLED WITH INCREASED DIURNAL HEATING
THROUGH THE DAY WILL ALSO SUPPORT A MODERATELY UNSTABLE AIRMASS
OUT AHEAD OF THE CURRENT ACTIVITY. SO...WILL BE EXPECTING ONGOING
CONVECTION TO SUSTAIN ITSELF AND EXPAND A BIT IN COVERAGE AND
ORGANIZATION THROUGH MIDDAY.

COMPLICATING MATTERS FURTHER IS THE ONGOING COLD-TOPPED CONVECTION
NEAR A WEAK INVERTED TROUGH IN BETWEEN KALI AND KCRP AND NORTH TO
NEAR KVCT. UPSTREAM CONVECTION IS LIKELY TO MERGE WITH THIS
ACTIVITY TOWARD MIDDAY OR EARLY AFTERNOON. THE RESULT WILL BE
EXTREMELY HEAVY RAINFALL POTENTIAL...WITH RATES OF OVER 3
INCHES/HR POSSIBLE. THE LATEST HRRR FAVORS ADDITIONAL RAINFALL
AMOUNTS OF 3 TO 6 INCHES WITH ISOLATED HEAVIER AMOUNTS.

THIS WILL SUPPORT FLASH FLOODING AND WILL EXACERBATE ONGOING
RUNOFF PROBLEMS FROM EARLIER HEAVY RAINS.

ORRISON

ATTN...WFO...CRP...EWX...FWD...HGX...

[Andrew]

MESOSCALE DISCUSSION 0632
NWS STORM PREDICTION CENTER NORMAN OK
1143 AM CDT WED MAY 13 2015

AREAS AFFECTED...SRN TX

CONCERNING...TORNADO WATCH 169...

VALID 131643Z - 131845Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 169 CONTINUES.

SUMMARY...ISOLATED/BRIEF TORNADOES REMAIN POSSIBLE ESPECIALLY ACROSS
SRN PARTS OF TORNADO WATCH 169.

DISCUSSION...A VERY MOIST AND UNSTABLE AIR MASS EXISTS ACROSS SRN TX
WHERE PWAT IS AROUND 2.00 INCHES. VAD WIND PROFILES CONTINUE TO
EXHIBIT VEERING WITH HEIGHT WITH SUFFICIENT SRH FOR SLOW-MOVING
SUPERCELLS. INDEED...RADAR CONTINUES TO INDICATE STORMS WITH
MESOCYCLONES...CURRENTLY OVER NRN DUVAL COUNTY.

THE PRIMARY TORNADO RISK SHOULD CONTINUE TO BE ACROSS SRN PORTIONS
OF THE WATCH IN PROXIMITY TO THE STRONGER INSTABILITY. TO THE
N...THE MORE STABLE AIR DUE TO EXPANDING OUTFLOW MAY HELP TO
MITIGATE THE THREAT...BUT LOCALLY STRONG WINDS WILL REMAIN POSSIBLE.

..JEWELL.. 05/13/2015

[tireman4]

I wonder ( this is a question for Srain, Andrew and Wxman57) if this is the "perfect setup" for a huge rainmaker. I mean two sides merging into one huge rainmaker?

[srainhoutx]

I wonder ( this is a question for Srain, Andrew and Wxman57) if this is the "perfect setup" for a huge rainmaker. I mean two sides merging into one huge rainmaker?

Most of the short term meso guidance weakens the area to our West except for the SPC/NCEP 4km WRF which keep the convection intact but mainly affects areas N and W of the HWY 59 Corridor. That said the various computer models have been less than stellar, so my suggestion is to watch the radars and follow any updates as the afternoon/evening wears on. Remember we are updating our Facebook and Twitter social media feeds regularly if you are away from the Weather Forum.

[jasons2k]

The atmosphere in our metro area is getting more unstable as temps reach the 80-degree mark. There's also a decent inflow with the low level jet above. You can observe the low clouds racing north. I also see trends of the 'blob' starting to show more signs of convection/lift and lightning out ahead of the imbedded main line. This all points to very heavy rains later today.

Here is a new post from Eric Berger regarding this afternoon:

http://blog.chron.com/weather/2015/05/i ... afternoon/

Be safe!!

[jasons2k]

Update from Jeff:

Large band of moderate to heavy rainfall approaching SE TX from the west early this afternoon. Overall line has been weakening some, but still producing rainfall amounts of 1-3 inches. Extrapolation of this line into the area indicates it reaching our western counties within the next hour and near I-45 around 4-5pm. Thus far the activity does not appear as organized as before over central TX, but given the ongoing flooding situation across the area…any additional rainfall is of concern. Will continue to monitor trends, but residents should be prepared for potential heavy rainfall during rush hour this evening.

Lake Conroe:

SJRA has held back as much water as they can and are going to have to increase their releases due to the incoming rainfall. Lake Conroe is now releasing 6978cfs, but 25,000cfs is going past the I-45 gauge. This indicates that 18,022 cfs is pouring into the river from Lake Creek uncontrolled. This means that 72% of the water flowing past I-45 is coming from Lake Creek and not Lake Conroe. With that said there has been no change in the forecast for Porter and Humble this afternoon, although some increase in crests levels may be required given the additional rainfall likely.

All persons across SE TX should remain aware of the weather situation and be prepared to act. Remember to not drive into high water…”Turn Around Don’t Drown.”

[srainhoutx]

A quick update regarding the coming weekend. The Global guidance continues to advertise a potential severe weather episode across portions of Texas into the Great Plains. The latest 12Z guidance is suggesting that the next cold core upper low may drop a bit further S into the SW United States than previously modeled. It appears that the severe weather threat may shift deeper into Texas with a continuation of heavy rainfall across the Region. The guidance is suggesting another stalling frontal boundary may offer additional forecasting challenges as well.

[Andrew]

MESOSCALE DISCUSSION 0634
NWS STORM PREDICTION CENTER NORMAN OK
0224 PM CDT WED MAY 13 2015

AREAS AFFECTED...PORTIONS OF ERN TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 131924Z - 132200Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...BANDS OF THUNDERSTORMS ADVANCING NNEWD ACROSS PARTS OF ERN
TX MAY PRODUCE STRONG OUTFLOW WINDS. AN ISOLATED DMGG WIND GUST
CANNOT BE RULED OUT...HOWEVER WW ISSUANCE IS UNLIKELY.

DISCUSSION...MOSAIC RADAR LOOPS INDICATE NNW/SSE-ORIENTED CONVECTIVE
BANDS DEVELOPING NNEWD FROM STRONGER CONVECTION FOCUSED OVER SRN TX.
THIS ACTIVITY LIES WITHIN A BROAD/DEEP MOIST PLUME AHEAD OF A
SHORTWAVE TROUGH OVER WRN TX. GPS DATA INDICATE PW VALUES AROUND
1.6-1.7 INCHES ACROSS THE AREA...WHICH SUGGESTS THAT PRECIP LOADING
COULD ENHANCE DOWNDRAFTS. FURTHERMORE...THE FWS VWP SAMPLES DEEP
MERIDIONAL FLOW AROUND 35 KT EXTENDING ABOVE 0.5 KM AGL...WHICH MAY
SUPPORT OCCASIONAL BOWING SEGMENTS EMBEDDED WITHIN THE CONVECTIVE
BANDS. AN ISOLATED DMGG WIND GUST CANNOT BE RULED OUT. HOWEVER...A
WIDESPREAD MULTI-LAYERED CLOUD CANOPY HAS STUNTED PBL DIURNAL
DESTABILIZATION AHEAD OF THIS ACTIVITY...AND POOR LAPSE RATES
ASSOCIATED WITH A DEEP...NEARLY MOIST-NEUTRAL PROFILE EXIST WITHIN
THE MOIST PLUME. AS SUCH...NORMALIZED CAPE/UPWARD ACCELERATIONS WILL
BE LIMITED WITH CONVECTION...THUS MITIGATING THE OVERALL SVR TSTM
RISK.