October 2015 - Severe Storms/Moderate Risk Excessive Rainfal

[srainhoutx]

Update from Jeff:

Austin Bergstrom has recorded 13.58 inches in 6-hrs which exceeds their entire May 2015 total!

Onion Creek at HWY 183 on the south side of Austin is 1 ft from the record flood crest of Halloween 2013 when over 1000 homes were flooded. Currently flowing 117,000 cfs under the HWY 183 bridge.

Extremely Dangerous Flash Flood in Progress:
Onion Creek
San Marcos River
Blanco River
Guadalupe River
Comal River
Cibolo Creek

Colorado River:
LCRA is operating flood gates on Tom Miller Dam due to extensive run-off into the river system below Lake Travis. Current inflows from Barton and Onion Creeks along with gate releases will generate a massive flood wave on the Colorado river below Austin. Persons downstream of Austin on the Colorado River should be prepared for possible flooding tonight (Bastrop and Smithville) and LaGrange on Saturday into Sunday.

Guadalupe River:
Massive flood wave being generated on the Guadalupe River due to inflow from the Blanco and San Marcos Rivers as well as the rainfall just below Canyon Lake of nearly 14 inches. Major flooding is likely along the entire river over the next several days from Caldwell County to the coast.

Discussion:
Models have not and are not handling this situation well at all and have little faith in their forecast solutions going forward tonight. Clearly this air mass is capable of some really big rainfall totals, but where and when is the question. Nothing is screaming big rainfall totals over SE TX tonight, but nothing suggested late evening either. Appears SE TX is being split with one disturbance passing to our north and the other to our south with most of our region staying dry at least for the moment.

Upper trough and lift is starting to approach from the west and expect to see activity begin to increase afternoon dark tonight. I am certainly worried about any potential for cell training and mergers which we clearly see what resulted over central TX, but have zero confidence in where this may happen if it happens at all.

Will maintain the thinking of 2-4 inches widespread with isolated amounts of 6 inches. Any cell training could easily result in much higher totals.

Tornado risk will also continue…although overall tornado activity has waned considerably this afternoon. Increase in nocturnal low level jet could help yield a few low topped supercells overnight.

[unome]

NWS Brownsville's radar knocked out by lightning - caught on video

https://twitter.com/NWSBrownsville/stat ... 2878242816

[djjordan]

Going to be keeping an eye of radar tonight watching for development. I'll be on the road overnight between Lake Conroe and Sugar Land so it may turn interesting.

[Katdaddy]

What a weather day across Central TX with dangerous life threatening flash flooding as everyone knows by now. I dislike being at work when significant weather events unfold across TX and cannot join in the fun. In addition to the flash flooding, there has been severe weather with 2 tornadoes in Central TX and wind damage in deep STX. Its has been overcast with strong gusting SE winds between 35-40MPH. across the Upper TX Coast this afternoon. Flash Flood Watch in effect through Saturday afternoon across SE TX with the potential for severe weather. SPC Mesoscale Discussion 1900 indicates possible watch to be issued for portions of Central and STX. A potentially active SE TX weather night and morning ahead. Our flight out of Hobby at 8AM tomorrow to DFW may likely be delayed.

[houstonia]

Safe travels Katdaddy!

[mckinne63]

Safe travels Katdaddy!

Yes, safe travels Katdaddy!

[mckinne63]

Any idea when the storms will hit the Houston area? The winds have picked up here off and on, but skies look clear.

[mckinne63]

Any idea when the storms will hit the Houston area? The winds have picked up here off and on, but skies look clear.

Well maybe not so clear now.

[srainhoutx]

Update from Jeff:

Flash Flood Watch effective from 1000pm until 100pm Saturday.

Have taken a good look at all the meso scale models and surface observations late this afternoon in an attempt to resolve what will transpire overnight. An important feature has shown up in the surface observations…a warm front…which extends from College Station to Hobby Airport to offshore of High Island. SW of this boundary dewpoints are in the mid to upper 70’s while NE of this boundary dewpoints are in the upper 50’s and low 60’s. Boundary is actually clearly defined in surface obs. Meso models with the exception of the HRRR so little development until Saturday morning, but the HRRR does attempt to fire off convection along the surface warm front around midnight tonight. This would fall in line with an increase in the low level jet as is usual during the overnight period which would add lifting along the boundary.

I am not confident in any of the solutions being offered after the miserable performance across C TX today where widespread 5-10 inches and isolated amounts of 16 inches fell. Austin recorded a staggering 14.53 inches today!

The air mass over the SW ½ of SE TX is certainly similar in moisture content to the air mass over C TX that produced the excessive rainfall (7 inches per hour in some areas)…and that activity was supercells being focused along the northward moving warm front. Less aggressive models likely are keying on to ongoing MCS over the Gulf waters which is helping to prevent inland inflow…however this activity appears to be shifting eastward with inflow increasing over the coastal bend.

If one has not decided by this point, I am not confident, in how things are going to unfold overnight and what the storm totals may look like at this time tomorrow. Think the warm front needs to be watched closely for any development that might want to anchor and also for any SW to NE moving cells that cross the higher low level shear along the boundary which could spin up a tornado. Will follow the squall line event being offered in most of the guidance for early Saturday morning 600am-900am. Main threat with this would likely be damaging winds and weak tornadoes with 1-3 inches of rainfall. The big question is if we get any kind of sustained development before the squall line which would result in cell training and much higher rainfall totals.

Will update again later this evening.

[srainhoutx]

Update from Jeff:

Flash Flood Watch effective from 1000pm until 100pm Saturday.

Have taken a good look at all the meso scale models and surface observations late this afternoon in an attempt to resolve what will transpire overnight. An important feature has shown up in the surface observations…a warm front…which extends from College Station to Hobby Airport to offshore of High Island. SW of this boundary dewpoints are in the mid to upper 70’s while NE of this boundary dewpoints are in the upper 50’s and low 60’s. Boundary is actually clearly defined in surface obs. Meso models with the exception of the HRRR so little development until Saturday morning, but the HRRR does attempt to fire off convection along the surface warm front around midnight tonight. This would fall in line with an increase in the low level jet as is usual during the overnight period which would add lifting along the boundary.

I am not confident in any of the solutions being offered after the miserable performance across C TX today where widespread 5-10 inches and isolated amounts of 16 inches fell. Austin recorded a staggering 14.53 inches today!

The air mass over the SW ½ of SE TX is certainly similar in moisture content to the air mass over C TX that produced the excessive rainfall (7 inches per hour in some areas)…and that activity was supercells being focused along the northward moving warm front. Less aggressive models likely are keying on to ongoing MCS over the Gulf waters which is helping to prevent inland inflow…however this activity appears to be shifting eastward with inflow increasing over the coastal bend.

If one has not decided by this point, I am not confident, in how things are going to unfold overnight and what the storm totals may look like at this time tomorrow. Think the warm front needs to be watched closely for any development that might want to anchor and also for any SW to NE moving cells that cross the higher low level shear along the boundary which could spin up a tornado. Will follow the squall line event being offered in most of the guidance for early Saturday morning 600am-900am. Main threat with this would likely be damaging winds and weak tornadoes with 1-3 inches of rainfall. The big question is if we get any kind of sustained development before the squall line which would result in cell training and much higher rainfall totals.

Will update again later this evening.

[Baseballdude2915]

Beginning to see some lift from the SW. Looks like a wet night ahead.

[jasons2k]

It's so windy outside. And I noticed before sunset the amount of low level shear in the clouds. I'm glad it's a Friday so I can stay up.

[houstonia]

Rain is pouring in southwest Houston. From the radar it looks like it's here for a while.

[Andrew]

Starting to see some training over southeast Texas. Mainly from Bay city up to Harris County. If this continues overnight it will be concerning. Right now it seems to be lifting just enough north to not be a huge concern but that could slow/stop as we head into the morning hours.

[Andrew]

Will probably see a flash flood warning for Harris County here soon

[869MB]

Rainfall rates have increased to at least 4.25 inches per hour in that rain band in Eastern Fort Bend County and Southern Harris County including the southern Houston Metro areas.

[869MB]

Drivers on Highway 288, 610 South Loop and I-45 South really need to be cafeful at this time because the 4.25 inch/hour rainfall rates continue with that heavy rain band on the south and southeast sides of town.

[869MB]

All travel on the south and southeast sides of the metro should be strongly discouraged at this time unitl this intense rain band lifts out. There are still some 4.25 inch/hour rainfall rates remaining at this time.

[Andrew]

Strong rotation SE of Fresno

[869MB]

Tornado Watch has been issued for Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty and Matagorda County until 10:00am.