ATL: IMELDA - Post-Tropical - Discussion

[jasons2k]

The center is quickly approaching the Harris/Brazoria county line and wobbling/rotating a little NNW now.

It’s gonna be a long night of nowcasting.

[storm_in_a_teacup]

Since it already made landfall could this be the shortest lived TS of all time?

It hasn't been downgraded yet.

I feel like tropical storms can stay tropical storm strength for a while in this area since they can pull moisture in from the Gulf and the flooded ground. “Brown ocean effect” and all that, I think...

[TeamPlayersBlue]

CoC is moving much faster than expected. Great news. I live near Sugar Land, SW of Houston, i' currently in this strong ban, getting 3.5" per hour rain rate. Coming own pretty good. As long as these bands dont pause over like other events, we will be ok.

[Steve]

CoC is moving much faster than expected. Great news. I live near Sugar Land, SW of Houston, i' currently in this strong ban, getting 3.5" per hour rain rate. Coming own pretty good. As long as these bands dont pause over like other events, we will be ok.

Big fat band rotating out the center. This is all bonus rain. Models yesterday show the most rain tomorrow afternoon into Thursday (obviously not for points farther south).

[1900hurricane]

Mesoscale Precipitation Discussion 0860
NWS Weather Prediction Center College Park MD
442 PM EDT Tue Sep 17 2019

Areas affected...Upper Texas Coast

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

Valid 172041Z - 180241Z

Summary...As Tropical Storm Imelda continues to slowly drift
further inland, there will be an increasing threat of flash
flooding into the evening hours on the Upper Texas Coast. This may
include portions of the Houston Metro Area.

Discussion...There are two primary areas of concern for flash
flooding associated with Tropical Storm Imelda as it continues to
move inland late this afternoon and into the evening. The first
area would be associated with tropical rain bands to the east of
the track of the center, embedded within a ribbon of persistent,
enhanced moisture flux and stronger low-level flow in the eastern
semi-circle of the storm. Places around Galveston Bay would be the
most likely to be impacted by these rain bands. The second area
would be associated with increasing coastal convergence in the
coastal counties of Matagorda, Brazoria and Galveston. Winds
offshore would be likely to back slightly (increasing southerly
component) and remain stronger relative to over-land winds as
Imelda's center moves inland. This could increase convergence
closer to the coast, and coincide with a slight increase in
instability as more unstable air over the Gulf gets advected just
onshore. The combination of low-level convergence and instability
may support increasingly organized and stronger rain bands.
Overall, these expectations align with numerical model predictions
of the heaviest rain falling to the east and south of the center.
Given the slow motion of Imelda (likely to move only about 50
miles in 9 hours based on the official NHC forecast), organized
tropical rain bands may persist in these two areas for an extended
period of time, which would lead to an increasing flash flood
threat.

Rain rates in the stronger rain bands would be likely to reach the
2-3 in/hr range, and could exceed that if stronger instability can
develop onshore and coincide with low-level forcing mechanisms
mentioned above. If that occurs, rain rates into the 3-5 in/hr
range could occur on an isolated basis in the strongest, most
organized rain bands. Several gages in southern Harris County near
the Sam Houston Tollway and I-45 have measured 1.16 inches of rain
in 30 minutes (20:00 to 20:30Z), and 5-minute rain rates have been
as high as 0.36 inches. This is an early indicator of very high
instantaneous rain rates in the tropical rain bands, but thus far
the rain bands have been relatively narrow and transient relative
to stationary locations. However, if larger rain bands can become
established, more substantial hourly rain rates would be likely,
and this would be more likely to have notable flash flood impacts.

The concern for the overnight hours is if several inches of rain
from early rain bands pre-condition the ground along the Upper
Texas Coast this afternoon and early this evening, and then
another burst of convection develops closer to Imelda's center
overnight. Convection tends to concentrate closer to the center of
circulation in the overnight period of the diurnal cycle, and this
could enable additional heavy rain over areas that already
received heavy rainfall earlier in the day. The NHC forecast also
calls for the center to move very close to Houston by 06Z, which
would place a potentially favored area for nocturnal convection
directly over a major metro area. This will continue to be
monitored into the evening hours.

Lamers

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

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

LAT...LON 30629511 30399453 29589427 29039473 28589552
28449632 28449633 28959641 29489602 30189564

[SoupBone]

CoC is moving much faster than expected. Great news. I live near Sugar Land, SW of Houston, i' currently in this strong ban, getting 3.5" per hour rain rate. Coming own pretty good. As long as these bands dont pause over like other events, we will be ok.

Big fat band rotating out the center. This is all bonus rain. Models yesterday show the most rain tomorrow afternoon into Thursday (obviously not for points farther south).

It still appears to be moving quicker than forecast though, which would ultimately mean less time to hang around dropping rain. Someone needs to calculate the movement in the last 5-6 hours!

[bohaiboy]

I work on the 36th floor of a building in downtown Houston, rain is hitting windows pretty hard so I have to assume the wind is blowing pretty good also. Just in time for rush hour too.

[tropicwatch]

I work on the 36th floor of a building in downtown Houston, rain is hitting windows pretty hard so I have to assume the wind is blowing pretty good also. Just in time for rush hour too.

Might not be a bad night to sleep at the office.

[CaptinCrunch]

New Record set @ DFW

1st time since 1889 (ever) the first 16 days of September reached 95 or better, that has never happened before.

Now back to our regular programming

[1900hurricane]

That big band just S of the center looks like bad news for tonight, especially with the center beginning to knuckleball around and lose direction.

[TeamPlayersBlue]

This west movement of the CoC is concerning.

Pretty intense wobble.

[Steve]

CoC is moving much faster than expected. Great news. I live near Sugar Land, SW of Houston, i' currently in this strong ban, getting 3.5" per hour rain rate. Coming own pretty good. As long as these bands dont pause over like other events, we will be ok.

Big fat band rotating out the center. This is all bonus rain. Models yesterday show the most rain tomorrow afternoon into Thursday (obviously not for points farther south).

It still appears to be moving quicker than forecast though, which would ultimately mean less time to hang around dropping rain. Someone needs to calculate the movement in the last 5-6 hours!

I don’t think it’s going to be a sheared off mid level circulation. And the source will still be the gulf. So points east of the circulation are going to get it.

[SconnieCane]

Since it already made landfall could this be the shortest lived TS of all time?

It hasn't been downgraded yet.

I feel like tropical storms can stay tropical storm strength for a while in this area since they can pull moisture in from the Gulf and the flooded ground. “Brown ocean effect” and all that, I think...

If I'm remembering correctly, Harvey plummeted from its 115kt landfall intensity but then remained a 35kt TS for over a day.

[HouTXmetro]

Looks like COC made a W to WSW jog. Heavy rain setting up to move in to heavily populated urban areas into the night. This is not good.My mother is in the South belt area of Houston and she stated street flooding was already occuring from one of the early rain band and the main event has yet to move in.

[TeamPlayersBlue]

Looks like COC made a W to WSW jog. Heavy rain setting up to move in to heavily populated urban areas into the night. This is not good.My mother is in the South belt area of Houston and she stated street flooding was already occuring from one of the early rain band and the main event has yet to move in.

For many areas, the waters will rise quickly, but if they get a 45 minutes break, the water retreats quickly. As long as there are a few breaks here and there, they will make it. It's terrible that so many people in this city have to be nervous everytime we have heavy rain.

[Jr0d]

That escalated quickly. Even 12 more hours over water could have been significant.

Regardless, this is a rain maker and hopefully those at risk have a flood plan.

[jasons2k]

It is doing a cyclonic loop and has basically stalled in place, at least for now. It's going to be a LONG night for metro Houston, especially the SE side.

[Highteeld]

Nice structure really.

[Hypercane_Kyle]

...IMELDA WEAKENS TO A DEPRESSION... ...HEAVY RAINS AND LIFE-THREATENING FLASH FLOODING WILL CONTINUE TO SPREAD INLAND OVER SOUTHEAST TEXAS DURING THE NEXT DAY OR TWO...
7:00 PM CDT Tue Sep 17
Location: 29.6°N 95.4°W
Moving: N at 7 mph
Min pressure: 1007 mb
Max sustained: 35 mph

[cycloneye]

Does anyone has the stats about the list of the shortest time as Tropical Storms on record?