October 2015 - Severe Storms/Moderate Risk Excessive Rainfal

[Paul Robison]

Evening briefing from Jeff:

Long fetch easterly winds of 15-20kts between high pressure over the SE US and low pressure over the southern Gulf of Mexico is resulting in elevated tides along the upper TX coast. Last high tide this afternoon resulted in coastal overwash on HWY 87 at HWY 124 at the east end of Bolivar. High tide within Galveston Bay peaked at 3.2 ft at Shoreacres and 3.1 ft at Seabrook. The 3.2ft at Shoreacres is only about .5 ft below flooding threshold when both east and west Bayou Dr south of Shoreacres Dr becomes flooded with sea water. Flooding thresholds around Clear Lake are around 4.5 ft or about 1.5 ft higher than the high tide today.

Not expecting much of an increase in the persistent easterly wind over the next few days which will continue to produce elevated tides of 1-2 feet above normal. Wave heights at the buoy 20NM east of Galveston have actually fallen from around 7ft this morning to around 4.5 ft this evening. High wave action this morning may have helped to add a little run-up on the Gulf beach front resulting in some of the overwash. Maximum water level expected to peak at 2.5 ft above MSL at Galveston Pleasure Pier tomorrow afternoon/evening which will be about .5 ft higher than today. This could result in some coastal flooding around Shoreacres and the Galveston Bay side of Seabrook (Toodville Rd area) as well as the west bound approach to the Lynchburg Ferry Landing during high tide.

Water Level Plot of HCFCD Gage 610 (Shoreacres) from the midday high tide:

10202015 Jeff 3 unnamed.png

Forecasted Total Water Level plots for Galveston Pleasure Pier:

10202015 Jeff 4 unnamed.jpg

Formation of TD 20-E off the Mexican coast this afternoon and forecast to become a category 2 hurricane and landfall along the west Mexican coast late this week will likely play a part in the upcoming rainfall event over TX. It is likely that mid and high level moisture from this tropical system will become entrained into the deep upper level trough digging into the SW US and will be drawn NNE to NE into TX this weekend. In fact some of the guidance shows the upper level vort associated with the system being drawn toward coastal TX by late Saturday into Sunday.

10202015 Jeff 5 unnamed.gif

[/i]

The Memorial Day floods on steroids. Oh, my!

[Ptarmigan]

This setup kinda reminds me of the recent South Carolina floods or October 1994 flood.

[Paul Robison]

This setup kinda reminds me of the recent South Carolina floods or October 1994 flood.

That's kinda what I'm afraid we'll have here in Houston. Seriously, look what's happened to them:

From TWC:

The 1,000-year rain event has set records all over the state, flooding entire towns. At least six people have died from the floods in South Carolina since the rain began to fall days ago.

The rain hasn't subsided everywhere yet. In northeastern South Carolina, where areas like Myrtle Beach experienced severe flooding on Sunday, heavy rainfall continued Monday, and officials warned life-threatening impacts would persist into the week.

\"The flooding is unprecedented and historical," said Dr. Marshall Shepherd, a meteorologist and director of the atmospheric sciences program at the University of Georgia, in an email to The Associated Press.

The University of South Carolina announced Monday classes will be canceled due to the floods. Parts of Columbia, including the USC campus, lost water service, and plans were being made to deliver bottled water and portable restrooms to the students Monday morning.

Officials claim it may take weeks or months to assess all of the closed roads and bridges, including a 75-mile stretch of I-95, the freeway that connects Miami to Washington, D.C. to New York.
Hundreds of roads remain closed Monday across the state

City officials have released a statement issuing a boil water advisory to all 375,000 of its water customers, advising them to vigorously boil their water for a full minute at the least. Any ice made from water that was not boiled beforehand should also not be used.

Swift-water rescue teams plucked hundreds of residents from stranded cars and flooded homes all over the state.

"Move to higher ground now. This is an extremely dangerous and life-threatening situation," wrote the National Weather Service's Charleston office in a Sunday morning flash flood statement.

Hundreds of roads remain closed Monday across the state.

Multiple dam breaches were reported Sunday morning in Columbia, according to the city's fire department.

Conditions around Charleston improved Sunday to the point that residents and business owners were allowed to enter the downtown area on a limited basis.
In Dorchester County, emergency managers reported at least 100 people had to be rescued at about 3 a.m.

Nearly 30,000 customers lost power at the height of the storms.

The seawall at Edisto Beach has been breached, resulting in heavy flooding, SCEMD reported Saturday evening, and a state of emergency has been declared for the town. (same thing may happen in Galveston)

Multiple shelters have been opened;

Governor Nikki Haley declared a state of emergency Thursday evening in advance of any potential impacts from flooding. President Barack Obama also declared a state of emergency and ordered federal aid to help the recovery in South Carolina.



Ptarmigan, IMHO, I believe you're right on the ball if you're thinking, like I am, that similar events will take place in Texas, with Houston as a possible ground zero.

Unless you know of an advantage we have that South Carolina didn't.

[srainhoutx]

Tropical Storm Patricia forms in the Eastern Pacific. 00Z Track and Intensity forecasts...

TROPICAL STORM PATRICIA DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202015
1000 PM CDT TUE OCT 20 2015

Although cloud tops have warmed since the previous advisory, the
overall convective cloud pattern has become a little better
organized. Dropsondes released from a NASA WB-57 aircraft conducting
research in Patricia earlier this afternoon for the Office of Naval
Research's Tropical Cyclone Intensity (TCI) experiment was helpful
in locating the low-level center, and also confirmed the development
of a weak mid-level eye-like feature noted in recent passive
microwave images. The initial intensity has been increased to 35 kt
based on a satellite intensity estimates of T2.5/35 kt from TAFB and
T2.9/43 kt from UW-CIMMS ADT, making the cyclone the 16th named
storm of the 2015 eastern North Pacific hurricane season. This
intensity is also supported by dropsonde data in the southeastern
quadrant of the cyclone between 2000-2200Z, which indicated surface
winds of 34-36 kt and also a fairly deep layer of 37-39 kt winds
from 1000-925 mb. Winds west of the center were 30 kt, suggesting
that the Gulf of Tehuantepec gap wind gale event may be subsiding.

The initial motion estimate is 255/04 kt. There is no significant
change to the previous forecast track or reasoning. Patricia is
expected to move west-southwestward to westward for the next 12
hours or so as the aforementioned gap wind event forces the cyclone
a little southward. After that time, Patricia is forecast to turn
west-northwestward on Wednesday and northwestward on Thursday as the
cyclone rounds the southwestern periphery of a deep-layer ridge that
extends from the central Gulf of Mexico southwestward into central
Mexico. Although there is some spread in the NHC track guidance, the
models are in fairly good agreement that Patricia should turn
north-northwestward to northward by 72 hours, making landfall in
southwestern Mexico. The new forecast track is similar to the
previous track and lies close to the consensus models TVCE and GFEX.

The large-scale environment of vertical shear less than 5 kt, very
high mid-level humidity values in excess of 80 percent, and SSTs
greater than 30C support at least steady strengthening until
landfall occurs. The possibility of rapid intensification (RI)
exists once a distinct eye feature develops, which could develop in
36 hours or so. The intensity forecast is similar to the previous
advisory in calling for Patricia to become a hurricane before making
landfall in Mexico, and closely follows the LGEM intensity model.
However, if RI should occur, then Patricia will likely be stronger
at landfall than the current forecast is indicating. After landfall,
the cyclone should quickly weaken and dissipate over the mountains
of Mexico.

A tropical storm or hurricane watch may be required by Wednesday
morning for portions of southwestern Mexico.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0300Z 13.1N 95.3W 35 KT 40 MPH
12H 21/1200Z 13.0N 96.5W 40 KT 45 MPH
24H 22/0000Z 13.3N 98.3W 50 KT 60 MPH
36H 22/1200Z 14.2N 100.3W 60 KT 70 MPH
48H 23/0000Z 15.5N 102.0W 75 KT 85 MPH
72H 24/0000Z 18.8N 103.7W 85 KT 100 MPH...INLAND NEAR COAST
96H 25/0000Z 22.6N 105.1W 40 KT 45 MPH...INLAND
120H 26/0000Z...DISSIPATED

$$
Forecaster Stewart

[Paul Robison]

Tropical Storm Patricia forms in the Eastern Pacific. 00Z Track and Intensity forecasts...

TROPICAL STORM PATRICIA DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202015
1000 PM CDT TUE OCT 20 2015

Although cloud tops have warmed since the previous advisory, the
overall convective cloud pattern has become a little better
organized. Dropsondes released from a NASA WB-57 aircraft conducting
research in Patricia earlier this afternoon for the Office of Naval
Research's Tropical Cyclone Intensity (TCI) experiment was helpful
in locating the low-level center, and also confirmed the development
of a weak mid-level eye-like feature noted in recent passive
microwave images. The initial intensity has been increased to 35 kt
based on a satellite intensity estimates of T2.5/35 kt from TAFB and
T2.9/43 kt from UW-CIMMS ADT, making the cyclone the 16th named
storm of the 2015 eastern North Pacific hurricane season. This
intensity is also supported by dropsonde data in the southeastern
quadrant of the cyclone between 2000-2200Z, which indicated surface
winds of 34-36 kt and also a fairly deep layer of 37-39 kt winds
from 1000-925 mb. Winds west of the center were 30 kt, suggesting
that the Gulf of Tehuantepec gap wind gale event may be subsiding.

The initial motion estimate is 255/04 kt. There is no significant
change to the previous forecast track or reasoning. Patricia is
expected to move west-southwestward to westward for the next 12
hours or so as the aforementioned gap wind event forces the cyclone
a little southward. After that time, Patricia is forecast to turn
west-northwestward on Wednesday and northwestward on Thursday as the
cyclone rounds the southwestern periphery of a deep-layer ridge that
extends from the central Gulf of Mexico southwestward into central
Mexico. Although there is some spread in the NHC track guidance, the
models are in fairly good agreement that Patricia should turn
north-northwestward to northward by 72 hours, making landfall in
southwestern Mexico. The new forecast track is similar to the
previous track and lies close to the consensus models TVCE and GFEX.

The large-scale environment of vertical shear less than 5 kt, very
high mid-level humidity values in excess of 80 percent, and SSTs
greater than 30C support at least steady strengthening until
landfall occurs. The possibility of rapid intensification (RI)
exists once a distinct eye feature develops, which could develop in
36 hours or so. The intensity forecast is similar to the previous
advisory in calling for Patricia to become a hurricane before making
landfall in Mexico, and closely follows the LGEM intensity model.
However, if RI should occur, then Patricia will likely be stronger
at landfall than the current forecast is indicating. After landfall,
the cyclone should quickly weaken and dissipate over the mountains
of Mexico.

A tropical storm or hurricane watch may be required by Wednesday
morning for portions of southwestern Mexico.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0300Z 13.1N 95.3W 35 KT 40 MPH
12H 21/1200Z 13.0N 96.5W 40 KT 45 MPH
24H 22/0000Z 13.3N 98.3W 50 KT 60 MPH
36H 22/1200Z 14.2N 100.3W 60 KT 70 MPH
48H 23/0000Z 15.5N 102.0W 75 KT 85 MPH
72H 24/0000Z 18.8N 103.7W 85 KT 100 MPH...INLAND NEAR COAST
96H 25/0000Z 22.6N 105.1W 40 KT 45 MPH...INLAND
120H 26/0000Z...DISSIPATED

$$
Forecaster Stewart

Aw, nuts! Guess we'll get the same kind of floods they had in South Carolina outta this.

[DoctorMu]

If the Southern Jet really got cranking we could see severe training effects. The drought may be a saving grace. The ground in the Carolinas were already saturated when the tongue of deep moisture hit.

1994 was a remarkable event. 18 in of rain in less than 18 hrs in College Station and worse in the Trinity basin. I kicked down the fence to drain the backyard.

[Paul Robison]

If the Southern Jet really got cranking we could see severe training effects. The drought may be a saving grace. The ground in the Carolinas were already saturated when the tongue of deep moisture hit.

1994 was a remarkable event. 18 in of rain in less than 18 hrs in College Station and worse in the Trinity basin. I kicked down the fence to drain the backyard.

1. Is the Southern Jet expected to get cranking and cause training or is that only if?

2. How does the drought save us?

[Andrew]

First off, this system is nothing like the Carolina flooding. That event was an extremely rare event where an "atmospheric river" setup over the area from Joaquin and a nearly stationary mid-level low. This resulted in huge amount of training over the same region for several days. Moving on, I do have my suspicions about P-totals around SE Texas. Models (in particular the GFS) are really trending towards a non-favorable setup for precipitation over the region. First off the trough that is currently situated over the four corners region looks to lift north and shear out faster than previously anticipated. The Texas Panhandle will see a good shot of training over the region as an upper level diffluent pattern helps to support plenty of divergence. This is only exaggerated as a 50kt LLJ enters the region late Wednesday night, advecting plenty of moisture from the Gulf Of Mexico. Furthermore, the parallel orientation of the jet will only help to increase training of storms as the whole axis of precipitation slowly progresses eastward.

By Friday, the trough axis should shift into North Texas and become Quasi-stationary, setting up another chance of heavy rains. While upper levels dynamics are not overly impressive, various shortwaves rotating around the base of the exiting trough paired with strong moisture advection from both the gulf and Patricia will send Pwats into the 2+ inch range. Soundings show a near completely saturated profile, meaning plenty of rain for North Texas on Thursday, Friday, and maybe Saturday.

Finally, further south into SE Texas many of the global and mesoscale models indicate that a lot of questions remain. If the trough axis present over North Texas on Thursday and Friday doesn't shift further south on Saturday I suspect a lot of moisture could remain centered too far north. Phasing between Patricia, the trough, and gulf moisture will be key. The good news though is Pwats look to rise into the 2-2.2 inch range, which usually makes it pretty hard to not see some measurable precipitation. Unfortunately the dynamics just don't look as impressive as North Texas and the Panhandle. Of course development in the gulf and the track of Patricia can change that.

[Katdaddy]

A few showers off the Upper TX Coast this morning as the moisture continues to increase. Rain chances will gradually increase into the weekend. The ridge is now forecast to retreat slower which may allow the heavy rains to hold off until Friday night. Heavy rains and the potential for flooding will likely exist through the weekend across portions of SE TX. EPAC TS Patricia is forecast to become a CAT 2 at landfall in MX and move toward TX bringing additional tropical moisture into the mix. This will be a widespread rain event across TX which is very good news for areas in drought conditions however some areas will get more than needed over the next 5 days.

[unome]

check out the weather story map, compliments of NWS Western Region, very easy to access another forecast office quickly: http://www.wrh.noaa.gov/FXC/

close to home, from HGX this am

[redneckweather]

Looks to me like good rainfall is trending away from Southeast, TX with this event....now down to MAYBE 1-2 inches. Not liking the trend.

[stormlover]

Not necessarily, go look at the gfs 06 run

[Cromagnum]

I would happily take 1-2 inches with this, and then a week from now another 1-2. We don't need 5-6 all at once.

[jasons2k]

Looks to me like good rainfall is trending away from Southeast, TX with this event....now down to MAYBE 1-2 inches. Not liking the trend.

Usually the case. I've noticed a trend of a less favorable setup with this system since all the hype started last week. The low in the gulf along with the phasing of the systems looked a lot more promising last week, as is often the case 7-10 days away.

As they say,'the trend is your friend' in forecasting....or in this case not so much if you were hoping for a drought buster. We'll see what unfolds over the next couple of days. Our only hope is if the GFS is up to its usual tricks...seeing something in the long range, losing it in the mid range, and then bam! Comes back in the short term.

[Texaspirate11]

HGX Disco

A CONSENSUS OF THE MODELS HAS LESS CHANCES OF RAIN OVER THE
FORECAST AREA TODAY THROUGH FRIDAY. THIS IS DUE MAINLY TO THE FACT
THAT THE RIDGE WILL SLOWLY RETREAT EASTWARD AS THE UPPER LEVEL
SYSTEM SHEARS OUT AS IT MOVES NORTHEASTWARD ACROSS THE ROCKIES
INTO THE PLAINS. THE MAJORITY OF THE MOISTURE ASSOCIATED WITH THIS
SYSTEM IS FORECAST BY THE MODELS TO STAY MORE OVER THE SOUTHERN
AND CENTRAL PARTS OF THE STATE. THE TROPICAL MOISTURE MOVING
NORTHWARD FROM THE PACIFIC WILL AID IN KEEPING SOME POPS IN
PLACE...HOWEVER DEEPER LAYER MOISTURE FROM PATRICIA SOUTH OF
MEXICO WILL PROBABLY NOT ARRIVE UNTIL FRIDAY NIGHT OR SATURDAY
MORNING. THIS SHOULD BE THE CATALYST FOR THE MORE WIDESPREAD
RAINFALL EVENT FORECAST BY THE MODELS THAT HAS THE POTENTIAL FOR
HEAVY RAINFALL ON SATURDAY AND SUNDAY.

[stormlover]

gFS 06 run says other wise lets see what the run shows at noon

[davidiowx]

gFS 06 run says other wise lets see what the run shows at noon

Pretty much the low right over us and drops copious amounts of rain. Will see if the trend continues or if this is just an outlier.

[srainhoutx]

12Z Track and Intensity for TS Patricia:

[jasons2k]

The updated Patricia track is actually better for us if you're like me wishing for a soaker....

[davidiowx]

The updated Patricia track is actually better for us if you're like me wishing for a soaker....

Was thinking the same. This could end up being quite a rain/flood event this weekend. That is if it all lines up correctly.