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I’m looking out the office window to the southwest over towards Katy, and I can see towers going-up, like afternoon thunderstorms. They are bubbling-up. It’s gonna be a long night.

I just posted photo on Storm2k...

Could see the storms really blossom south of I-10 here in the next hour. Seabreeze is about to run into the outflow of the storms moving in from the north. Had some decent sun today in Pasadena, temperatures got up to about 86 degrees.

5:00 PM Update from Jeff:

Center of tropical depression Imelda located between Conroe and Cleveland currently drifting toward the north.

Clearing skies in the last few hours southwest of the circulation center has resulted in the air mass becoming increasingly unstable and the development of scattered bands that over Wharton into Fort Bend and Harris Counties. Thus far these bands have been transient with brief heavy rainfall at any location, but there is some level of concern that the low level convergence area is increasing over portions of Harris, Fort Bend, northern Brazoria, and northern Galveston Counties. Some of the high resolution models continue to suggest additional banding will develop and impact the region into the evening and overnight hours, but confidence remains low on where any sustained banding may develop. The most likely outcome is the potential for more sustained banding over the eastern portions of Harris County generally along and east of I-45 and SH 288.

Additional rainfall amounts of 2-4 inches with isolated amounts up to 6 inches will be possible in this area with totals west of I-45 generally less than 2 inches.

Given wet grounds east of I-45, the expected rainfall would likely lead to significant amounts of run-off and rises on watersheds in those areas: Clear Creek, Armand Bayou, Cedar Bayou, East Fork of the San Jacinto River.

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Houston/Galveston TX
501 PM CDT Wed Sep 18 2019

The National Weather Service in League City has issued a

* Tornado Warning for...
Northwestern Chambers County in southeastern Texas...
East central Harris County in southeastern Texas...

* Until 530 PM CDT.

* At 500 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Mont Belvieu, or near Highlands, moving east at 20
mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without
shelter. Mobile homes will be damaged or destroyed.
Damage to roofs, windows, and vehicles will occur. Tree
damage is likely.

* This dangerous storm will be near...
Mont Belvieu around 520 PM CDT.
Cove around 525 PM CDT.
Old River-Winfree around 530 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Wallisville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

TORNADO WARNING:

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Houston/Galveston TX
501 PM CDT Wed Sep 18 2019

The National Weather Service in League City has issued a

* Tornado Warning for...
Northwestern Chambers County in southeastern Texas...
East central Harris County in southeastern Texas...

* Until 530 PM CDT.

* At 500 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Mont Belvieu, or near Highlands, moving east at 20
mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without
shelter. Mobile homes will be damaged or destroyed.
Damage to roofs, windows, and vehicles will occur. Tree
damage is likely.

* This dangerous storm will be near...
Mont Belvieu around 520 PM CDT.
Cove around 525 PM CDT.
Old River-Winfree around 530 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Wallisville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Tornado Warning for Chambers and Harris County until 5:30.

Watching new storms develop further W in Colorado/Austin Counties.

Hearing lots of thunder here in Stafford, but think everything is north of us thus far.

Big storms in Wharton County. Finally!

mckinne63 wrote: ↑Wed Sep 18, 2019 5:37 pm Hearing lots of thunder here in Stafford, but think everything is north of us thus far.

No, there’s actually a lot of new development to your south and west now. Looks like that sun being out earlier did the trick.

Jeff states the Air 11 has that tornado on air

Flood Advisory
National Weather Service Houston/Galveston TX
519 PM CDT Wed Sep 18 2019

TXC157-201-182315-
/O.NEW.KHGX.FA.Y.0145.190918T2219Z-190918T2315Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Fort Bend TX-Harris TX-
519 PM CDT Wed Sep 18 2019

The National Weather Service in League City has issued a

* Flood Advisory for...
Northeastern Fort Bend County in southeastern Texas...
Southern Harris County in southeastern Texas...

* Until 615 PM CDT.

* At 518 PM CDT, Doppler radar and automated rain gauges indicated
heavy rain due to thunderstorms. This will cause minor flooding in
the advisory area. Rainfall rates of 1 to 1.5 inches per hour have
been reported with this band of thunderstorms.

* Some locations that will experience flooding include...
Pasadena, northeastern Sugar Land, northwestern Baytown, northern
Missouri City, La Porte, Deer Park, Stafford, South Houston,
Bellaire, West University Place, Galena Park, Jacinto City, Hunters
Creek Village, Bunker Hill Village, Piney Point Village,
Cloverleaf, Downtown Houston, Greenway / Upper Kirby Area, Spring
Branch North and Second Ward.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don`t drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

The Storm Prediction Center has issued a Mesoscale Discussion for SE Texas regarding the Tornado threat. 5% chance of a Watch at this time...
Mesoscale Discussion 1982
NWS Storm Prediction Center Norman OK
0531 PM CDT Wed Sep 18 2019

Areas affected...Portions of Southeast Texas

Concerning...Severe potential...Watch unlikely

Valid 182231Z - 190000Z

Probability of Watch Issuance...5 percent

SUMMARY...A localized tornado threat will persist for the next hour
or two between Houston and Beaumont.

DISCUSSION...Several mini-supercells have exhibited low-level
rotation in the past hour with the cluster of storms between Houston
and Beaumont. One of these cells showed a tight low-level couplet
and probable TDS in far eastern Harris County around 22Z. Daytime
heating south of this activity has increased temperatures into the
80s with dewpoints remaining in the mid to upper 70s. This has
yielded MLCAPE around 1500 to 2000 J/kg. The KHGX VWP shows some
low-level SRH, but the low-level shear is more favorable at KLCH
with 0-1 SRH around 125 m2/s2. However, the environment in southern
Louisiana is more stable due to ongoing precipitation. Therefore,
there is a narrow corridor where this better low-level shear and
instability overlaps where the environment is favorable for a brief
tornado threat. Given the limited area and the expected short
duration of this threat, a watch is unlikely.

..Bentley.. 09/18/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LCH...HGX...

https://origin.wpc.ncep.noaa.gov/metwat ... 64&yr=2019

Mesoscale Precipitation Discussion 0864
NWS Weather Prediction Center College Park MD
654 PM EDT Wed Sep 18 2019

Areas affected...Southeast Texas, Far Southwest Louisiana

Concerning...Heavy rainfall...Flash flooding possible

Valid 182250Z - 190345Z

Summary...Tropical rain bands and embedded thunderstorms will
continue into the evening hours, primarily across southeast Texas.
Rain rates may exceed 2-3 inches per hour at times, which could
lead to flash flooding, particularly in areas that have already
received heavy rainfall in the past 24 hours.

Discussion...Tropical Depression Imelda continues to slowly drift
across southeast Texas. Stronger convective rain bands have
redeveloped this afternoon around the periphery of the storm,
closer to the Upper Texas Coast and the stronger instability near
and over the Gulf of Mexico. These rain bands have become
increasingly organized, but observed storm motions have suggested
they are not oriented in a configuration for extended periods of
training yet. Relatively high instantaneous rain rates are
suggested by the combination of strong instability and very high
PW values (as high as 2.5 inches or so), a very deep warm cloud
layer associated with the tropical system, and relatively high KDP
values sampled by the KHGX radar. This should pose a risk of some
flash flooding in the next few hours along the Upper Texas Coast.
The highest changes would be in far SE TX into far SW LA, or
roughly between HOU and LCH. Recent runs of the HRRR have been
very consistent in concentrating heavy rain bands in this area
between 23-03Z, and it aligns with current radar trends and the
strongest low-level moisture convergence analyzed by the RAP (and
projected over the next few hours). Two recent GPS observations
between Galveston Bay and the Sabine River provided PW values of
2.6 to 2.7 inches, so that is also very close to a maximum in
tropsopheric moisture, and any rain bands would be expected to be
very efficient in that area.

Observed rain bands to the southwest of Houston as of 2230Z had a
relatively significant component of the storm motion perpendicular
to the major axis of the bands. This suggests continued
propagation toward the Matagorda and Brazoria County coasts and a
more localized flash flood risk in the next few hours.
Instantaneous rain rates will be quite high, and the thunderstorm
cluster near ARM was one of the largest on radar at this time, so
localized swaths of heavy rainfall capable of producing flash
flooding cannot be ruled out -- particularly as the convective
clusters approach the areas that have seen over 10 inches of rain
from last night into this morning.

As we move later into the evening, there is potential for
additional convective development closer to the center of Imelda,
and upstream along the instability gradient from the expected
concentrated area of convection in SE TX. Many (but not all)
hi-res model runs, including recent HRRR runs, depict a scenario
like this. Model forecasts do show an increase in low-level
convergence closer to the center later this evening, and this
seems plausible with an existing instability gradient. The
gradient is reflected by a band of low clouds in GOES-16 visible
satellite imagery from near TPL-CXO, and this same area (or
perhaps just to the south) would be favored for additional
development closer to 03Z. It is worth monitoring the locations
just southwest of Imelda's center this evening, as hi-res models
suggest the convective bands would be likely to be very slow
moving and efficient rainfall producers, which could develop into
the dominant flash flood threat during the overnight hours.

Lamers

ATTN...WFO...HGX...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...

New band just exploded across North/NW Harris County

a view of TPW via CIMSS' MIMIC-TPW2m

looped here, can change the layer, etc...: http://tropic.ssec.wisc.edu/real-time/m ... anim=html5

srainhoutx wrote: ↑Wed Sep 18, 2019 6:35 pm New band just exploded across North/NW Harris County

sun popped out here, warming things up & it feels like 200% humidity outside even though we had less than 1" of rain so far

There has been a long string of HRRR runs showing a line forming and back building in the central/nw part of the area overnight and in the morning. The mesoscale precip discussion mentions the black circled area above in unome post. That could be the deluge for the Harris county area for the night along with the current area now in the south part.