August 2017: Looking Back at Harvey 5 Year Later

[Electric Lizard]

Let me introduce you to nocturnal core rains from tropical remnants.... starting tonight!

I understand - like we had in Allison. But don't they stay near the core?

[Freeporttx3334]

I guess I'm one of the morons..but inwas just wondering if hasn't rained here in Freeport in about 6 hours...r we done with the rain threat here? I notice the bands r to the east of houston

[houstonia]

Someone please provide an explanation of nocturnal rain core events and how they might be possible for us? Thank you!

[Ptarmigan]

Let me introduce you to nocturnal core rains from tropical remnants.... starting tonight!

I understand - like we had in Allison. But don't they stay near the core?

Someone please provide an explanation of nocturnal rain core events and how they might be possible for us? Thank you!

Core rains happen near the core or center of low pressure.

Core rains happen because the warm core low pressure and cooler ambient temperature. The thunderstorms happen near the center, hence the name core rain.

Core rains can occur with any low pressure as long it is a warm core low pressure. They can be non-tropical in origin.

List Of Core Rain Events
http://forums.khou.com/viewtopic.php?f=2&t=60&p=2936

[Electric Lizard]

Someone please provide an explanation of nocturnal rain core events and how they might be possible for us? Thank you!

See Lessons from Hurricane Ike, page 37 (Jeff Linder wrote this chapter):
https://books.google.com/books?id=gelBB ... ns&f=false

[mckinne63]

I guess I'm one of the morons..but inwas just wondering if hasn't rained here in Freeport in about 6 hours...r we done with the rain threat here? I notice the bands r to the east of houston

We had a brief downpour around 1pm, but nothing else since about 10am. I am wondering the same myself. I saw something earlier on the news radar that looked like we may get hammered overnight. I would like to hear from the Pro Mets here as to how this storm is transforming.

[TexasBreeze]

Feeder bands love to form at night and early morning.

[srainhoutx]

BULLETIN
Tropical Storm Harvey Advisory Number 26
NWS National Hurricane Center Miami FL AL092017
400 PM CDT Sat Aug 26 2017

...TROPICAL STORM HARVEY BARELY MOVING...
...TORRENTIAL RAINS WILL CONTINUE...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...29.1N 97.6W
ABOUT 45 MI...70 KM WNW OF VICTORIA TEXAS
ABOUT 60 MI...95 KM ESE OF SAN ANTONIO TEXAS
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...STATIONARY
MINIMUM CENTRAL PRESSURE...990 MB...29.24 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* Port Aransas to High Island Texas

A Tropical Storm Warning is in effect for...
* Baffin Bay to High Island Texas

A Storm Surge Warning means there is a danger of life-threatening
inundation from rising water moving inland from the coastline in the
indicated locations. For a depiction of areas at risk, please see
the National Weather Service Storm Surge Watch/Warning Graphic,
available at hurricanes.gov. This is a life-threatening situation.

For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 400 PM CDT (2100 UTC), the center of Tropical Storm Harvey was
located by Doppler radar near latitude 29.1 North, longitude 97.6
West. Harvey has been nearly stationary and little motion is
anticipated during the next few days.

Maximum sustained winds have decreased to near 65 mph (100 km/h)
with higher gusts. Additional weakening is expected during the
next day or two.

Tropical-storm-force winds extend outward up to 115 miles (185 km)
from the center.

The estimated minimum central pressure is 990 mb (29.24 inches).


HAZARDS AFFECTING LAND
----------------------
RAINFALL: Harvey is expected to produce additional rain
accumulations of 15 to 25 inches over the middle and upper Texas
coast through Thursday. Isolated storm totals may reach around 40
inches in this area. Elsewhere during the same period, Harvey is
expected to produce total rain accumulations of 5 to 15 inches
farther south toward the lower Texas coast, farther west toward the
Texas Hill Country and southwest and central Louisiana. Rainfall of
this magnitude will cause catastrophic and life-threatening
flooding. A list of rainfall observations compiled by the NOAA
Weather Prediction Center can be found at:
www.wpc.ncep.noaa.gov/discussions/nfdscc1.html

STORM SURGE: The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline. The water is
expected to reach the following heights above ground if the peak
surge occurs at the time of high tide...

Port Aransas to Sargent...4 to 7 ft
Sargent to High Island including Galveston Bay...2 to 4 ft
High Island to Morgan City...1 to 2 ft

The deepest water will occur along the immediate coast near the
area of onshore winds, where the surge will be accompanied by large
and destructive waves. Surge-related flooding depends on the
relative timing of the surge and the tidal cycle, and can vary
greatly over short distances. For information specific to your
area, please see products issued by your local National Weather
Service forecast office.

WIND: Tropical storm conditions are occurring in portions of
the tropical storm warning area, and are likely to persist along
portions of the coast through at least Sunday.

SURF: Swells generated by Harvey are affecting the Texas,
Louisiana, and northeast Mexico coasts. These swells are likely to
cause life-threatening surf and rip current conditions. Please
consult products from your local weather office.

TORNADOES: A few tornadoes are possible through Monday near the
middle and upper Texas coast into far southwest Louisiana.


NEXT ADVISORY
-------------
Next intermediate advisory at 700 PM CDT.
Next complete advisory at 1000 PM CDT.

$$
Forecaster Avila

[srainhoutx]

Tropical Storm Harvey Discussion Number 26
NWS National Hurricane Center Miami FL AL092017
400 PM CDT Sat Aug 26 2017

Harvey has continued to weaken while located inland over Texas.
Doppler radar data indicate that winds are now 55 kt, and since
there are no surface observations near the center, this is the
intensity used in this advisory. A continued weakening is
anticipated, and the NHC forecast uses the trend provided by the
SHIPS decay model. However, if a large portion of Harvey's
circulation remains over the Gulf of Mexico, the cyclone could
weaken at a slower rate than shown here.

Harvey has barely moved during the past few hours and little motion
is anticipated. Since the steering currents are forecast to remain
light, Harvey could easily meander for the next 4 to 5 days over
southeast Texas as indicated in the NHC forecast. Guidance disagrees
in which direction the cyclone will move, but all the models agree
that any motion will be quite slow.


Key Messages:

1. While Harvey's winds are decreasing, life-threatening hazards
will continue from heavy rainfall over much of southeastern
Texas and from storm surge along portions of the Texas coast.

2. Catastrophic and life-threatening flooding is expected across the
middle and upper Texas coast from additional rainfall of 15 to
25 inches, with isolated storm totals as high as 40 inches, through
Thursday. Please heed the advice of local officials and do not
drive into flooded roadways. Refer to products from your local
National Weather Service office and the NOAA Weather Prediction
Center for more information on the flooding hazard. A summary of
rainfall totals compiled by the Weather Prediction Center can be
found at: www.wpc.ncep.noaa.gov/discussions/nfdscc1.html

3. A Storm Surge Warning remains in effect for portions of the
Texas coast. Life-threatening storm surge flooding will be slow to
recede due to the slow motion of Harvey and a prolonged period of
onshore flow. For a depiction of areas at risk, see the Storm Surge
Watch/Warning Graphic at hurricanes.gov.


FORECAST POSITIONS AND MAX WINDS

INIT 26/2100Z 29.1N 97.6W 55 KT 65 MPH...INLAND
12H 27/0600Z 29.1N 97.6W 45 KT 50 MPH...INLAND
24H 27/1800Z 28.9N 97.7W 35 KT 40 MPH...INLAND
36H 28/0600Z 28.5N 97.3W 30 KT 35 MPH...INLAND
48H 28/1800Z 28.3N 97.1W 30 KT 35 MPH...INLAND
72H 29/1800Z 28.7N 97.0W 30 KT 35 MPH...INLAND
96H 30/1800Z 29.5N 97.0W 30 KT 35 MPH...INLAND
120H 31/1800Z 30.5N 97.0W 30 KT 35 MPH...INLAND

$$
Forecaster Avila

[srainhoutx]

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Houston/Galveston TX
340 PM CDT SAT AUG 26 2017

The National Weather Service in League City has issued a

* Tornado Warning for...
Southwestern Montgomery County in southeastern Texas...
Northeastern Waller County in southeastern Texas...
Northwestern Harris County in southeastern Texas...

* Until 415 PM CDT.

* At 340 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Addicks Park Ten, moving northwest at 35 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.

* Locations impacted include...
Prairie View, Pinehurst, Addicks Park Ten, northwestern Eldridge /
West Oaks, Spring Branch West, Hockley, Waller, Magnolia,
Stagecoach, Cypress, Addicks and Memorial.

[TexasBreeze]

Starting to see some redevelopment over Harris with a tornado warned cell in the western part...

[srainhoutx]

Mesoscale Discussion 1576
NWS Storm Prediction Center Norman OK
0344 PM CDT Sat Aug 26 2017

Areas affected...Southeastern Texas...far southwestern
Louisiana...and adjacent coastal waters

Concerning...Tornado Watch 468...

Valid 262044Z - 262145Z

The severe weather threat for Tornado Watch 468 continues.

SUMMARY...The tornado threat continues with outer bands and nearby
convection on the eastern periphery of Harvey.

DISCUSSION...The tornado threat continues across the WW area. The
highest short-term threat appears to be associated with a NNW-SSE
band of convection across portions of Tyler/Hardin/Jefferson
Counties, including near the BPT area. Additional, isolated
convection east of this band has had a history of brief tornadoes as
well. Convection in this region is somewhat more robust compared to
other areas with in the Watch, although a few of the storms within
the band have exhibited a weakening trend in the past 30 minutes or
so. Nevertheless, somewhat greater instability and low-level
veering exists in this region, and a tornado threat will continue to
be realized as convection migrates quickly north-northwestward.

Despite somewhat lesser destabilization in areas west of this band
(near the Houston metro area and on to western portions of the
Watch), a mix of both banded and cellular structures continue to
evolve within a very moist low-level environment containing ample
shear. Brief mesocyclonic structures have been observed, and
tornadoes remain possible with this activity. Given recent radar
trends and the presence of southeasterly flow, the primary tornado
threat within WW 468 may eventually shift into these areas over the
next few hours.

Harvey has stalled about 40 mi WNW of Victoria, Texas. The end
result will be a slowly evolving convective regime across the Watch
area, with an extended period of tornado potential -- lasting
through at least the currently scheduled expiration time (07Z
Sunday).

..Cook.. 08/26/2017

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

ATTN...WFO...LCH...SHV...HGX...CRP...EWX...

[Electric Lizard]

Starting to see some redevelopment over Harris with a tornado warned cell in the western part...

Yep. I keep seeing smaller cells converging over roughly the Meyerland area and heading NW as a large cell. The tornadic cell was one of those.

[srainhoutx]

Think how spread out this storm is AND it will barely move over the next 5 Day. Anyone that thinks this event is over is far from correct.

[srainhoutx]

The 19Z HRRR suggest a worse case scenario for Metro Houston. If that 18 hour precipitation forecast is correct, we could see significant flooding into DT Houston.

[Katdaddy]

Confirmed tornado on the ground!

At 401 PM CDT, a confirmed tornado was located near Cypress, or 11
miles southwest of Tomball, moving northwest at 35 mph. A Harris
County Precinct 5 Constable reported the tornado at Barker Cypress
and West Road.
Severe Weather Statement
National Weather Service Houston/Galveston TX
403 PM CDT SAT AUG 26 2017

TXC201-339-473-262115-
/O.CON.KHGX.TO.W.0109.000000T0000Z-170826T2115Z/
Montgomery TX-Waller TX-Harris TX-
403 PM CDT SAT AUG 26 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 415 PM CDT FOR
SOUTHWESTERN MONTGOMERY...NORTHEASTERN WALLER AND NORTHWESTERN HARRIS
COUNTIES...

At 401 PM CDT, a confirmed tornado was located near Cypress, or 11
miles southwest of Tomball, moving northwest at 35 mph. A Harris
County Precinct 5 Constable reported the tornado at Barker Cypress
and West Road.

HAZARD...Damaging tornado.

SOURCE...Radar confirmed tornado.

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.

Locations impacted include...
Prairie View, Pinehurst, Hockley, Waller, Magnolia, Stagecoach and
Cypress.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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.

[txsnowmaker]

The 19Z HRRR suggest a worse case scenario for Metro Houston. If that 18 hour precipitation forecast is correct, we could see significant flooding into DT Houston.

Thank you for keeping us updated srain. A couple of quick questions -- can't tell the color shaded for the western 1/2 of Harris County. How much rainfall is being depicted there? Also, does this tell you when most of the projected rainfall would fall (e.g. mostly overnight, with some later this evening/tomorrow morning), or is there no way to tell from the model?

[DoctorMu]

Event: Tornado Warning
Alert:
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 415 PM CDT FOR
SOUTHWESTERN MONTGOMERY...NORTHEASTERN WALLER AND NORTHWESTERN HARRIS
COUNTIES...

At 401 PM CDT, a confirmed tornado was located near Cypress, or 11
miles southwest of Tomball, moving northwest at 35 mph. A Harris
County Precinct 5 Constable reported the tornado at Barker Cypress
and West Road.
HAZARD...Damaging tornado.
SOURCE...Radar confirmed tornado.
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.
Locations impacted include...
Prairie View, Pinehurst, Hockley, Waller, Magnolia, Stagecoach and
Cypress.
TORNADO...OBSERVED
HAIL...0.00IN
Instructions: To repeat, a tornado is on the ground. 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.
Target Area:
Harris
Montgomery
Waller

[srainhoutx]

Had to get to my safe room. Jeff reports multiple reports Tornado on ground 290/99/Townlakes/West Rd/Baker Cypress. All I hear are sirens from first responders.

[DoctorMu]

Event: Tornado Warning
Alert:
The National Weather Service in Shreveport has issued a

* Tornado Warning for...
South central Angelina County in eastern Texas...

* Until 500 PM CDT

* At 407 PM CDT, a severe thunderstorm capable of producing a tornado
was located 7 miles north of Rockland, moving northwest 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...
Huntington around 450 PM CDT.
Other locations impacted by this tornadic thunderstorm include
Zavalla and Shawnee.
TORNADO...RADAR INDICATED
HAIL...<.75IN
Instructions: 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. Heavy rainfall may hide this tornado. Do not wait to see or hear the tornado. TAKE COVER NOW! To report severe weather contact your nearest law enforcement agency. They will send your report to the National Weather Service office in Shreveport.
Target Area:
Angelina