Why?

Why?

I was asked by someone I respect the dreaded question again.  Why didn't Houston evacuate?  

Space City Weather is generally regarded as one of the very best sources of weather news information in the Houston area.  They pride themselves on no hype and give well written, easy to understand information.  Here is how the week unfolded according to their site.  I lay this out to show how rapidly Harvey changed and the uncertainty that went along with it.  You can read each post for tons of details, but I have pulled a few selections and emphasized sections that stand out to me.  The magnitude of this was not, nor could ever have been, foreseen.  It is truly a natural disaster and we have very little control over those, no matter how much we like to think as humans we are conquerers of our planet.

As you go through please keep in mind the end result demonstrated in this graphic by @Terpweather

Image by @terpweather / terpweather.com 

Image by @terpweather / terpweather.com 


Monday August 21 (four days before landfall)
This weekend’s weather will largely be determined by the aforementioned moisture from Harvey. If enough of it moves into the Texas coast, we could see a couple of inches of rainfall, and if not, it could be drier and hotter (mid-90s).

Tuesday August 22 (1) (three days before landfall)
In the worst case scenario, we have the potential to see some widespread flooding. Some of the global forecast models have painted rain bullseyes of 10 to 15 inches of rain over parts of the Houston metro area.

Tuesday August 22 (2)
A tropical system that could very well move inland into Texas somewhere along the coast, more or less stall, and drop 10 to 15 inches of rain (or more) on someone’s head over a two or three day period. Widespread areas may see 4 to 8 inches....

The next question is, where will the heaviest rainfall occur? Frankly, there is no good answer to that right now. The data gathered by the Hurricane Hunter today will help, so hopefully by Wednesday we should have a slightly better idea. For example, a landfall near Brownsville would be a lot better for Houston than one near Corpus Christi.

Wednesday August 23 (1) (two days before landfall)
Without sounding alarmist, we should say that this is a nearly perfect scenario for continuous heavy rainfall and flooding. That does not mean it will happen, but at this point it seems likely. Large areas will likely see 5 to 15 inches of rainfall, and smaller areas may see in excess of 20 inches.

Wednesday August 23 (2) 
The rainfall hype is real and serious, and although it’s impossible to specifically forecast it at this time, you need to be aware of the threat.
The forecast is going change, and in systems like this trying to pin down who gets maximum rainfall is extraordinarily difficult. Patience required.
The rains will be spread out from Friday through Tuesday, but for Houston we continue to expect the heavier rain during the latter half of that period.

Wednesday August 23 (3) 
One thing is crystal clear, however. Harvey is going to pack a really potent punch of moisture. It is going to bring widespread areas of 10 to 15 inches over several days to Texas, and within those areas some locations are likely to see 20 inches or more. Most of the current model guidance shows 15 to 20 inches of rain over Houston from this storm, and even spread over several days this would cause significant flooding. I am hesitant to fully buy into that, because the track of Harvey is so uncertain.

LB: Referring back to the graphic at the top, we got 50 inches in four days, not 15 to 20.

Rainfall totals from TS Allison (NOAA)

Wednesday August 23 (4)
The figure above also shows the difficulty in predicting what areas will flood the most. In Harris County alone, rainfall totals ranged from less than 5 inches to nearly 40 inches during Allison. Any small change in the storm’s path or intensity is the difference between flooding or light precipitation. And to be clear, we are not saying Harvey will be another Allison, only that there is potential for severe inland flooding from Harvey.

Most weather models give us a general idea of how much rain will fall over the region, but they cannot say exactly how much rain will fall in a specific neighborhood or town. This is why we issue watches and warnings, and emphasize the need for awareness during an inland flooding event. If 15 inches of rain is forecast, prepare for 15 inches–but also, prepare for the possibility of more, or barely any at all. With rains from tropical storms, the amounts can be unpredictable, the rainfall rate can be high, and the flooding can be extremely localized.

LB: I think this is the point that Mayor Turner was talking about when he said if he had told people to evacuate they would have laughed him out of town.  Maybe 5 inches, maybe 15, maybe nothing? Most people would (and did) stay.

Thursday August 24 (1)  (one day before landfall)
Good morning. Tropical Storm Harvey has shown signs of better organization overnight, and now appears likely to become a Category 1 hurricane before landfall. However, given the warmth of the Gulf of Mexico and lowering wind shear levels, a stronger storm seems possible.
.... models are increasingly focused on a landfall between Brownsville and Corpus Christi.

By Tuesday morning, about one quarter of the models have dragged the low into south Texas, the majority have brought the center back to the coast near Corpus Christi, or offshore. The remainder have brought the center up to Galveston and Houston..... Since we are talking about weather events three to six days from now.

Thursday August 24 (2) (four hours later)
Harvey is now anticipated to come ashore with 115-mph winds, just over the threshold of Category-3..... Right now the hurricane center forecast predicts a landfall between Port Mansfield and just north of Matagorda.

NOAA’s Weather Prediction Center has started to put out accumulated precipitation forecasts to reflect the threat between now and next Wednesday. Here’s their latest forecast for Houston (graphic)

Thursday August 24 (3) (four hours later - 24 hours from landfall)
Today’s strengthening, and increasingly bullish model forecasts for intensity, have caused the National Hurricane Center to increase its predicted wind speed for Harvey’s landfall to 125 mph, just shy of Category 4 hurricane intensity.

Rainfall remains the primary threat. Saturday afternoon through Tuesday, travel may become difficult to impossible. Some areas will probably be fine, but others deluged. Totals are likely to be higher closer to the coast than for inland parts of the Houston metro area.

Thursday August 24 (4)
We’ve hammered this point for a couple of days, but the point remains that we can’t be sure where the storm is going to go after it reaches the coast. It’s like putting a bowling ball down in the middle of an alley—where will it roll? Harvey is going to be something like that.

The Euro special. Odds: 40 percent. Under such a scenario, depending upon the track, much of the Houston area would likely get 5 to 25 inches of rainfall, with the greater totals closer to the coast.
The wandering 59 special.  Odds: 35 percent. Such a scenario would likely bring 10 to 25 inches of rain to much of the Houston metro area, but totals might not necessarily be greatest along the coast.
Dying in the Rio special. Odds: 25 percent. Under this scenario Houston might get 5 to 10 inches of rain from Harvey—a lot of rain, but certainly manageable.

LB: Can we be realistic at this point?  Are we going to start evacuating the fourth largest city in the United States the day of landfall, or even the day before, considering the information we had up to this time?  The answer is no.

Friday August 25 (1) (Day of Landfall)
We can’t say exactly where the heaviest rainfall will come (there may be some isolated areas that receive a Tropical Storm Allison-like 35 inches), but we can say with growing confidence that a large region will see 10 to 25 inches of rain between Friday and Wednesday.

The timing and amounts of heavy rain in Houston are not precise. But be prepared for flooding, and tropical deluges from Sunday through Wednesday. Many roads will become impassable. Homes will be flooded. It will be pretty miserable for a lot of people.

LB: At this point many of the towns along the coast in the Houston area began issuing voluntary evacuations.

Friday August 25 (2)
The first thing to understand is that there remains a ton of uncertainty with the track forecast after about 24 to 36 hours. 

What we can say for sure is that a major rainfall event is almost certainly still in the cards for the greater Houston area from Harvey. All of the timing continues to suggest the really heavy precipitation will kick in later on Saturday or Sunday, so you still have some time to make preparations. But what happens after that, if the storm follows the hurricane center’s track, and moves up the coast Monday and Tuesday?

Friday August 25 (3)
Twenty-plus inches of precipitation in such a short period of time is daunting, especially when you consider Houston averages around 50 inches a year.

LB: That's how much we got in four days.

We’ve had a number of questions about how the area’s bayous will manage the rain. Surely, they could handle four inches a day, for five days, right? Unfortunately, for tropical systems like Hurricane Harvey, it isn’t the amount of rainfall that becomes a problem, as much as the rainfall rate.

Friday August 25 (4)
Texas will get the greatest amount of rainfall during the next several days, and that remains true given that there is such low confidence in Harvey’s evolution once it moves onshore. But I feel confident that a lot of people, perhaps most of the area between Corpus Christi and Beaumont, have a good chance of seeing a lot of rain. Like widespread 10 to 25 inches of rain over the next five or six days. Or maybe more.

LB: For those not familiar with Texas geography the distance between Corpus Christi and Beaumont is 300 miles.


At this point I can not read through old posts anymore.  It makes me heart sick.  Feel free to dig through the Space City Weather archives.
From this point on things deteriorated rapidly.  

  • Harvey came on shore as a Category 4 Friday evening in Rockport.  
  • The Houston area began receiving tornado warnings and rain bands early Friday evening.  Tornado warnings continued with regularity until Monday evening.
  • Saturday afternoon models were still predicting the heaviest of the rain in the Victoria area. 
  • Saturday night a large feeder band set up over the Houston area and then it stalled.  Most feeder bands wrap around the low, but this one did not.  Then it met up with another feeder band so it became one mass of rain sitting over the Houston area (which includes way more than just Harris county) and dumped rain at unheard of rainfall rates.
  • The National Weather Service issued three flash flood emergencies in one night (Saturday).  It has only issued one before in the five years that particular alert existed.

Most people in Houston do not question the lack of evacuation.  There are some that disagree of course, but most of the questioning seems to be coming from people that are not part of our community.  The very fact that political parties are brought into the discussion at all makes me so very angry, especially since the chatter began when we were still being inundated with rain and were in the middle of our rescues. 

Greater Houston is more than just the city of Houston and it is also more than just Harris County.  This is one of the things that is hard to explain if you don't live here.  The sheer size is just something that we have become used to, but I think it is difficult for outsiders in situations such as these.  The communities that had voluntary evacuations would be called part of Houston on any day, but many of them have their own mayors and government.  Focusing on one person for an entire region's worth of leadership decisions is unfair.  When you say you are from "Houston" that includes many counties and dozens of cities.

People need to accept their own decisions.  No one was prevented from evacuating.  People made choices and sometimes they are heart breaking and difficult and impossible to know if you picked the right course.  We all try our best.  The city/county government and the weather forecasters are not mind readers.  They are human and they try their best.  We should not look for someone to blame if things don't go well.  Sometimes things don't go well.  Sometimes there are tragedies and natural disasters.  Sometimes there are tsunamis or wildfires or earthquakes or blizzards.  We all try our best.

This storm will be studied for decades if not centuries.  It is NOT a textbook storm.  It is an extreme outlier.  People will use lessons learned to make all of us safer, but hopefully there will not be another storm like this for a long time. (Added: I am not here to debate climate change and future storms.  My focus is the evacuation.)

People will probably debate this for a long time.  People will turn a blind eye on the things that Houston (and Rockport and Orange and Beaumont and Corpus Christi) need in the coming months.  They will move on to the next topic du jour and we will be left to pick up the pieces.  But we will do it together because that is what Houston and what Texans do.  Texas, our Texas.  All hail the mighty state.

 

Harvey

Harvey