Lindner Archives - Reduce Flooding

Intro to Flooding in Southeast Texas

Jeff Lindner, Harris County’s Meteorologist, has produced an excellent 20-minute video that explains flooding in Southeast Texas and how you can increase your situational awareness during extreme weather events. It’s now on YouTube and is called “Understanding Flooding in Southeast Texas.”

By Jeff Lindner, Harris County Meteorologist

Brief Outline of Video

The video begins with a description of things that make this area unique – namely extreme rainfall on flat topography.

Then Lindner begins by reminding us of extreme rainfalls, such as Tropical Storm Claudette in 1979 which set the U.S. 24-hour rainfall record – 43 inches in one day! To put that in perspective, it took Hurricane Harvey FOUR days to dump 47.4 inches.

Tropical Storm Allison in 2001 dumped 28.5 inches in just 12-hours. It turns out that…

Six of the ten wettest tropical cyclones ever to strike the US mainland struck Southeast Texas!
Jeff Lindner, Harris County Meteorologist

Then the video:

Defines watersheds, describes local watersheds, and explains how water flows throughout Harris and surrounding counties
Discusses ponding and sheet-flow flooding, unrelated to watersheds
Explains how streets are designed as part of the floodwater retention system
Talks about the Harris County Flood Warning System and the distribution of gages in surrounding counties
Digs into some of the System’s features, such as Near-Real-Time Inundation Mapping
Tells you how sign up for Notification Alerts and explains different types of alerts you can set
Reviews the limitations of home insurance and flood insurance policies.

Who Can Benefit from Watching?

Many types of people can benefit from watching this video:

People new to the area
Young people
Anyone buying property or new homes
Long-term residents who have had close calls during previous floods
Those without flood insurance or those considering buying it.

Regarding insurance, Lindner reminds us that it takes 30-days for flood insurance to go into effect and that you can’t buy flood insurance when there’s a named storm in the Gulf. So the time to buy it is well before hurricane season, which starts on June 1.

It’s also important to remember that flooding can happen in non-tropical storms that occur in virtually any month of the year. Tax Day and Memorial Day storms are good examples. The Tax Day storm dumped 23.5 inches of rain in 12-hours!

Of the 154,170 estimated homes that flooded across Harris County during Harvey, only 36% had active flood insurance policies in place the day before the storm struck…64% did not have flood insurance.

If you think that government disaster relief will make you whole soon after a flood, think again. Five and a half years after Harvey, people are still waiting for aid or in the process of rebuilding their homes.

Posted by Bob Rehak on 3/26/2023

2035 Days since Hurricane Harvey

HCFCD Issues Reports on Late January Flooding, Tornados

Jeff Lindner, Harris County Meteorologist, has issued a report on January flooding, heavy rainfall and a significant tornado on January 24, 2023. He also released intensity tables for 24^th to the 31^st. They help us understand the cumulative impact of back-to-back heavy rainfalls on the 24^th and 29^th.

Overview

Says Lindner, “Early on the 24th, surface low pressure developed over south-central Texas. It helped draw a warm front northward. It eventually formed a line from near Sealy to Downtown Houston to Chambers County. This warm front when combined with strong lift, impressive low level wind shear, and winds changing direction, resulted in the formation of supercell thunderstorms along a line from near Victoria to Sealy to Conroe.

They trained across northwest Harris County. Rainfall amounts southeast of US59 ranged from 1-2 inches, but 2-6 inches northwest of 59.

One of the storms along the front produced a tornado over southern Fort Bend County. Another formed over northern Brazoria county near Pearland. Rotation increased as it tracked through SE Houston, Pasadena, Deer Park and Baytown.

Duration and Rates

The heaviest rainfall occurred over portions of west, northwest, and northern Harris County in a 3 to 6 hr period. Several locations in northwest Harris County recorded 1.0-3.0 inches of rainfall in an hour during the late morning hours. Additionally, as the line of storms moved eastward, numerous locations recorded 1.0-2.0 inches of rainfall in 15-45 minutes. That resulted in rapid street flooding over many portions of Harris County during the early to mid afternoon hours.

*From Harris County Flood Control District report.*

Total Amounts

Total 6-hr rainfall amounts ranged from 3.0-6.0 inches from north of Katy along west/north of FM 1960 into the Humble and Kingwood areas. The highest amount was at John Paul Landing Park in northwest Harris County where 5.48 inches was recorded in 3 hours. Unfortunately, most of this rain fell on grounds that were still wet from heavy rainfalls on January 8 and 9. This maximized runoff into area creeks.

Lindner points out that, “Heavy rainfall and flooding can occur every month of the year in Harris County and there have been other recent heavy rainfall events in January. Compare rainfall duration and intensity in the table below.”

*“Cool season” events tend to be short in duration with the majority of the rain occurring in 6 hours or less*,” *says Lindner.*

Interestingly, all of the January flooding events listed above had identical contributing factors: a surface warm front, high moisture levels, and training movement over the same area.

Rainfall amounts for the 1- and 3-hour time periods ranged from 2- to 10-year rains on the Atlas 14 scale. For the most part, channels could accommodate the rainfall. No widespread house flooding occurred although streams came out of their banks at numerous locations and came dangerously close to homes. See below.

*Homes surround by floodwaters near West Fork San Jacinto on 1/30/23.*

Tornado Impacts

The tornados were a different story, though. As they swept across the southern part of the county at 40 to 60 mph, they produced significant damage.

Lindner said, “Video obtained from the City of Deer Park indicated a tornado heavily shrouded in heavy rainfall with very little if any visibility of a condensation funnel or lofted debris. Unlike tornadoes in the Great Plains, many of the tornados along the US Gulf coast are hidden within heavy rainfall and very difficult to observe.”

Damage assessments as of February 7, from the cities impacted indicate approximately 1,635 single family homes were damaged, 855 multi family units, and 15 mobile homes. The tornados ranged from EF0 to EF2 in intensity. EF2 winds range from 111-135 mph.
Jeff Lindner, Harris County Meteorologist

For a complete listing of rainfall intensities and damage assessments at different locations through the county, see Lindner’s report here. It contains an interesting history of tornados in Harris County.

The pictures below were taken by a retired Kingwood resident, John Knoerzer, who owned a business in one of the hardest hit areas. They illustrate damage in Pasadena at one of his former employee’s home and shop.

*Roof and walls torn away by winds. Note sheet metal twisted around tree in upper right. That came from a neighbors home several hundred feet away.*

Sheet metal from same building shredded the power lines in this 23-second video.

Never Bet Against Mother Nature

Lindner’s report and these images provide powerful reminders of why we should never take flood or wind risk for granted. And why we need to see flood-mitigation projects through to completion.

These were only 5-year storms. But remember. Those exceedance probabilities are like odds on a Las Vegas roulette wheel. I once saw the same number come up six consecutive times!

Don’t bet against Mother Nature. Insurance gives you much better odds.

To explore historical rainfall in your area, consult the Harris County Flood Warning System.

Posted by Bob Rehak on 2/8/23 with thanks to John Knoerzer for his images and Jeff Lindner for his reporting

1989 Days since Hurricane Harvey

Powerful Thanksgiving Storms Could Bring Flooding

Rainfall predictions associated with approaching Thanksgiving storms keep increasing. Jeff Lindner, Harris County’s meteorologist now says approaching storms will bring widespread impacts from Thursday through Saturday. He also warns that heavy rainfall may lead to street flooding and rises on area creeks/bayous. Models now show a band of 5-7 inches of rain in places.

Thursday

Lindner says a surface warm front will approach the upper TX coast early Thursday and move inland. He expects showers to increase in coverage and intensity near the front, which may approach the US 59 corridor by midday before slowing and potentially stalling Thursday afternoon.

Along and south of the warm front be prepared for isolated severe storms and excessive rainfall with inflow off the Gulf. All the elements are in place for flash flooding “and warm fronts are notorious in these sort of setups for producing excessive rainfall,” says Lindner.

The best case for inland areas is that the warm front is held closer to the coast.

Friday – Saturday

Models have now slowed down the movement of an upper level low to our west. Lindner now predicts a break in the rainfall Friday morning, before another round of widespread, heavy rains move back into the area Friday afternoon and evening.

Expect grounds to become increasingly saturated and runoff to increase. Showers may linger into midday Saturday, before this system finally exits to the east.

Rainfall Amounts

Predicted rainfall associated with the Thanksgiving storms has increased compared to earlier forecasts. That’s because of the potential for slow moving and training thunderstorms Thursday afternoon and the longer duration of rainfall now expected into Friday and Saturday.

Widespread amounts of 1-3 inches can be expected on Thursday afternoon with isolated totals upwards of 5-6 inches.

Some models show a band of 5-7 inches near the warm front Thursday afternoon and this is concerning.

Hourly rainfall rates of 2-3 inches may be possible Thursday afternoon and this will lead to rapid street flooding and significant rises on creeks and bayous.
Jeff Lindner, Harris County Meteorologist

Additional rainfall amounts of 1-3 inches can be expected Friday/Saturday on top of what falls on Thursday and this will only worsen ongoing run-off from the Thursday rainfall.

Runoff

Soils are primed for run-off with recent wetting rainfall over the region. Our main concern is street flooding, but Lindner cautions us about the potential for significant rises on area watersheds, especially if the higher totals are realized in portions of Harris County.

His greatest concern is for the southern and southeastern portions of Harris County where soils are the wettest and potential rainfall the highest. But he still isn’t confident enough to pinpoint the exact locations of the highest rainfall.

He says most watersheds can handle 3-4 inches. But if we start to exceed 5 inches, the concern for flooding from the bayous and creeks listed below will increase.

IF 5-7 inches, streams most in danger of flooding will be:

Clear Creek and its tributaries
Armand Bayou
Hunting Bayou
Halls Bayou (upper around I-45)
Little Cypress Creek
Willow Creek
South Mayde Creek (lower near Greenhouse)
Keegans Bayou (lower near Beltway 8/US 59/Wilcrest area)
Willow Waterhole
Brickhouse Gully
Spring Branch Creeks (Spring Branch, Buttermilk, Briar Branch)

Thursday’s Excessive Rainfall Potential

If you’re out and about over the holidays, remember. Be wary of underpasses and bridges. If you can’t see the roadway, you don’t know how deep the water is. Turn around and don’t drown.

Also remember. Seven inches was the amount of rain Woodridge Village received on May 7, 2019. Woodridge now has much more stormwater detention capacity. But there are plenty of other clearcut areas around the area that don’t have much if any yet.

Friday’s Excessive Rainfall Potential

Keep your eye on the sky if you head out the door this holiday. Don’t let the Thanksgiving storms ruin your holidays.

Posted by Bob Rehak on 11/23/22 based on a forecast by HCFCD

1912 Days since Hurricane Harvey

Strong Thunderstorms, Street Flooding, Tornados Possible Tomorrow

Update: 10/28/22 11am: Today’s reports indicate the highest severe storm risk is shifting SW of Houston and offshore. Experts now predict 1-2 inches of rain for the Houston area today. Areas offshore are already getting 2-4 inches per hour.

Tomorrow will likely bring strong thunderstorms. Rainfall rates could exceed the capacity of street drains leading to localized street flooding. And the severe weather may also spin up some tornados, according to Harris County’s meteorologist and the National Weather Service (NWS).

Heavy Rainfall

NWS predicts two to three inches of rain could fall on Friday, as warm, moist air pushing in from the Gulf collides with a cold front pushing in from the northwest. Jeff Lindner, Harris County meteorologist, predicts the worst period for us will be Friday afternoon.

Tornados Possible

The NWS Storm Prediction Center in Norman, Oklahoma, issued this warning for Friday . It shows a marginal risk of severe weather for the entire Houston area and a slightly higher risk for areas south and west of us.

Reasons for Concern

For the weather wonks reading this, Lindner cites an unusual convergence of storm systems at different levels of the atmosphere.

A trough will begin to move eastward toward Texas later today. Surface pressures will begin to fall this afternoon as low pressure develops ahead of the approaching mid-level low. Southeast winds will increase today, letting Gulf moisture quickly return to coastal Texas.

As the mid-level low approaches us, it will meet the northward-moving, moisture-laden warm front moving in from the Gulf.

Severe threats will be highest along the boundary. Tropical moisture will march quickly northward tonight on a 30-knot low level jet. Precipitable waters – the amount of moisture in a column of air – will equal 1.8 inches by Friday morning over much of the region.

As large-scale lift increases over the developing warm sector, showers and thunderstorms will develop from southwest to northeast across the region.

The cold front associated with the mid-level low will sweep west to east across southeast Texas on Friday afternoon, touching off more thunderstorms. The front will slow Friday night, so showers will linger over the area.

Severe Threat:

The surface low approaching from the northwest will meet the warm front coming from the opposite direction along a NW to SE axis on Friday. This warm front will extend from near San Antonio to near Freeport during the day and produce strong to severe thunderstorms. Low-level winds near the warm front will circle back toward the ESE and enhance low-level storm rotation.

Such collisions are notorious for tornado production, according to Lindner. Discrete cells may develop ahead of the line of storms approaching from the west. The location of the greatest severe risk will depend on where the warm front sets up Friday morning. Areas along and south of the front will have the highest risk.

If the warm front moves just a few miles farther north, it will increase risk to the Houston metro area. Kingwood was struck by tornados in a similar setup earlier this year.

Damaging winds will be the main threat. The worst of the storms should be over by 3-5 pm Friday, but lighter rains may linger well into the evening hours.

Heavy Rainfall:

Moisture will deepen Thursday into Friday. By Friday morning, a saturated air mass will be in place over the region. “Strong divergent lift coupled with low-level inflow will increase the potential for heavy rainfall along with cell training from southwest to northeast.”

Lindner describes himself as “aways wary of such setups.” They can help anchor and train convection.

The overall pattern favors supercell formation with both a tornado and heavy rainfall risk.
Jeff Lindner, Harris County Meteorologist

These storms could become significant rainfall producers – if they become sustained along the warm frontal boundary. The good news is that the ground is dry and can handle several inches of rainfall. “However, rainfall rates may exceed localized drainage capacities and result in some street flooding regardless of the dry ground conditions,” says Lindner.

Weekend:

Cloudiness should linger much of Saturday keeping temperatures in the 50’s under northerly winds. South of the cloud line temperatures will warm into the 70’s. Where that line will be Saturday is hard to determine. Clouds should erode Saturday night with mostly clear skies. Sunday will be mild.

Tropics:

The hurricane season has another month to go. It isn’t over yet! The National Hurricane Center now gives an area of low pressure moving WNW across the Caribbean a 50% chance of turning into a tropical depression in the next five days. No one is yet predicting what will happen if it does.

Posted by Bob Rehak on 10/27/22 based on information from Jeff Lindner, NWS, and NHC

1885 Days since Hurricane Harvey

NHC Gives 40% Chance of Formation to 91L Within 5 Days

Another tropical wave is moving into the Caribbean along the same track as Ian. As of Monday morning at 8 a.m., the National Hurricane Center gives it a 40% chance of developing within 5 days. Currently, the tropical wave is several hundred miles east of the Windward Islands and moving westward at 15-20mph. The NHC has designated this area of investigation as 91L.

*Atlantic tropical waves and directions.* *Invest 91L is orange.*

While Invest 91L looks fairly impressive on satellite images (see below), Jeff Lindner, Harris County meteorologist says, “There does not appear to be any closed low-level circulation yet. This wave should reach the eastern Caribbean Sea around mid-week and the western Caribbean by this weekend.”

*91L is the storm north of the Guyanas and Suriname on the north coast of South America.*

Says Lindner, “Conditions generally become favorable for development along the track of 91L, but when compared to Ian, model solutions are much more varied with development potential and also much more scattered. Some models take the storm into Central America, others predict it will track toward Puerto Rico and the Dominican Republic.

For now, watch and wait.

Orlene Moves Inland Over Mexico

In the meantime, the eastern Pacific is fairly active. NHC is tracking three storms. Two are moving northwest parallel to the Mexican coast as a third – Hurricane Orlene moves inland near Mazatlán.

Mid- and high-level moisture from Orlene will stream across our area later in the week. However, our air is so dry right now that precipitation aloft will likely not reach the ground.

Glancing Blow from Frontal Boundary Later in Week

Lindner also predicts, “Toward the end of this week, moisture may return to Texas from the Gulf of Mexico ahead of a front that will drop into the eastern U.S. The front should only strike a glancing blow to Texas. Most of it will head more southeast toward the Tennessee Valley. So rainfall potential for Houston will remain low. Our dry pattern will likely continue.”

The National Weather Service Storm Prediction Center sees little to no severe threat.

Posted by Bob Rehak on 10/3/2022 at 11:30 am

1861 Days since Hurricane Harvey

Why Hurricanes Often Track Like Boomerangs

Ever wonder why so many hurricanes track like boomerangs? They don’t all follow this pattern, of course, but when you look at the 1370 hurricanes between 1851 and 2006, a pattern clearly emerges.

*From the US Department of Commerce book “Tropical Cyclones of the North Atlantic 1851 -2006.”*

Interaction of Complex Systems

In my research, I found several possible explanations for the pattern above.

Harris County Meteorologist Jeff Lindner provided this explanation. “Many of the storms that form in the eastern or central tropical Atlantic tend to get pulled northward by mid-latitude troughs over the western Atlantic as they attempt to move westward. Storms that make it all the way across tend to happen only when strong ridges of high pressure are in place.”

“Once a system is ‘captured’ by a mid-latitude trough, it will turn NW then N and then NE and E ahead of and along the trough axis. That’s why so many tracks are of this fashion over the open central and north Atlantic.”
Jeff Lindner, Harris County Meteorologist

Lindner added, “The further south a storm develops the less likely it is to be influenced by any sort of trough and a more westward track is then favored. Tracks into the Caribbean Sea from the east usually continue westward and those are what we tend to worry most about here along the Gulf Coast.”

“It is very rare for storms to cross central America or Mexico due to the high mountains in this area. The mountains quickly destroy the low-level circulations. A few in history have survived the trek, but they are few,” said Lindner.

Shifts in Bermuda High

The mother of all high-pressure ridges in the Atlantic is sometimes called the Bermuda or Azores high. NOAA defines it as “a semi-permanent, subtropical area of high pressure that migrates east and west between Bermuda and the Azores depending on the season.”

*Red arrow added to NOAA Image indicating migration of high between Bermuda and the Azores.*

The Meteorology 101 blog says, “During the summer, [the Bermuda high] is located just off the east coast of the United States. The clockwise circulation around this high pressure area helps direct the path of hurricanes and helps determine where they will make landfall. … During the winter months, the Bermuda High is located farther east of the US towards the middle of the Atlantic Ocean.

Depending on the Bermuda high’s location at any given time, it can block storms from going north. Or it can spin storms around in the boomerang pattern in the first image above. That’s because winds circulate in a clockwise fashion around high-pressure systems in the northern hemisphere.

Also note, sometimes gaps open in the high, letting storms slip north and get caught up in that clockwise circulation.

Highs Sometimes Block Storms from Curving North

HurricaneScience.org says, “Atlantic hurricanes typically propagate around the periphery of the subtropical ridge, riding along its strongest winds. If the high is positioned to the east, then hurricanes generally propagate around the high’s western edge into the open Atlantic Ocean without making landfall.”

“However, if the high is positioned to the west and extends far enough to the south, storms are blocked from curving north and forced to continue west, putting a large bulls-eye on Florida, Cuba, and the Gulf of Mexico.” This helps explain the wide spread of tracks on the left of the first image.

Influence of Trade Winds

This post from the National Oceanographic and Atmospheric Administration (NOAA) explains the relationship between the Sahara Desert and the formation of many hurricanes. Prevailing winds blowing from east to west (often called trade winds) come off the hot, dry Sahara Desert where they meet the cooler, wetter environment of the Atlantic Ocean west of Africa.

*Prevailing global wind circulation patterns, courtesy of NASA*

The prevailing winds in this latitude are so steady that in the days of sailing ships, mariners from Europe going to the Americas would first sail south to Africa. There, they would ride the reliable winds west to conduct commerce in the New World. Hence the name “trade winds.” The trade winds steer hurricanes, too.

In higher latitudes, the trade winds reverse direction. So sailors returning to Europe would sail north before returning to Europe and catch a tailwind home.

Opposing trade winds at least partially explain the boomerang pattern shown above.

If you ever get to Seville, Spain, make sure you visit the Archive of the Indies. There you will find the story of every Spanish treasure fleet that made the round trip between Europe and the Americas. I was struck by how many fleets sank in hurricanes while riding the trade winds.

Meteorology, or lack thereof, has influenced the fate of empires.

Coriolis Force

Many scientists also cite the Coriolis Force as a reason for why hurricanes try to drift north of dominant west-to-east winds. Frankly, the physics are beyond me. It has to do with the rotation of the earth at different speeds in different latitudes, and the rightward drift of objects (like hurricanes) not anchored to the earth while traveling over long distances. The Coriolis Force is also used to explain why hurricanes rotate in a counter-clockwise direction.

Posted by Bob Rehak on 8/31/2022 with input from Jeff Lindner, HCFCD

1828 Days since Hurricane Harvey

Another Tropical Wave Headed Toward Gulf

By this weekend, the second tropical wave in two weeks will make its way into the Gulf of Mexico. The National Hurricane Center (NHC) is monitoring a disturbance in the southwestern Caribbean. They predict it will track northwest across Central America and the Yucatan. Then it should emerge into the Gulf of Mexico later this week.

It’s too early to tell the exact track, timing or degree of development. That depends on many factors such as steering currents and frontal boundaries. But as of 7am Houston time on 8/16/22, NHC gives the disturbance a 20% chance of developing into a named storm within 5 days.

NHC says an area of low pressure could form on Friday. Gradual development of this system is possible while it moves northwestward over the southwestern Gulf of Mexico through the weekend.

*15:20 Zulu time is 10:20 Houston time. Note the cloud formation in lower left over Nicaragua and Honduras.*

Harris County Meteorologist Jeff Lindner says conditions will become increasing favorable for tropical cyclone development in the Bay of Campeche (the area with the yellow circle). He points to a frontal boundary dropping south toward the Texas coast late this week and says areas south of that boundary will become increasingly favorable for a low pressure system to develop along the axis of the tropical wave.

*Weather Service Storm Prediction Center 3-Day Outlook shows front moving across southern plains on Friday.*

However, there’s no reason to panic now. Just watch the National Hurricane Center website closely over the next several days for any changes.

Almost exactly 5 years ago, a storm followed a similar track across the Yucatan. It eventually became known as Hurricane Harvey.

Posted by Bob Rehak on 8/16/2022

1813 Days since Hurricane Harvey

Slight Chance of Tropical Formation In Gulf This Weekend

The National Hurricane Center (NHC) issued a tropical weather outlook today that shows a 10% chance of tropical formation in the Gulf. This is your “heads up.” Hurricane season is ramping up.

NHC will provide an update on chances for development later this evening, but models show growing support that a tropical depression or weak tropical storm is possible along the middle or lower TX coast by Sunday. The system will then moving inland over south Texas late Sunday into Monday, according to Jeff Lindner, Harris County’s meteorologist.

Latest Satellite Imagery

Here’s what the Gulf looks like on satellite Friday evening. The system will track W to WSW over 85-90 degree waters toward the mid- or lower-Texas coast on Sunday.

Currently, disorganized showers and thunderstorms over the north-central Gulf of Mexico are associated with an area of low pressure centered just offshore of the southern coast of Louisiana. There’s no tropical formation yet. But that could change.

As of 2PM EDT today, NHC listed the formation chance through:

48 hours…low…10 percent.
5 days…low…10 percent.

Rainfall Potential

Regardless of development, locally heavy rains are possible along portions of the Texas coast through the weekend. For more information about the potential for heavy rainfall, please see the National Weather Service site and the Weather Prediction Center.

Highest rain chances in next few days for SE Texas are around mid-day Saturday.

Decent rain chances exist for the next three days, especially along the coastline south of I-10.

Jeff Lindner, Harris County’s meteorologist says, he expects most of the shower and thunderstorm development associated with this low pressure system to happen near the coast and offshore. He expects lesser chances inland to the north as high pressure and drier air begins to build southward from the northeast.

Forecasters use a measurement called PWS (Precipitable Waters) to predict amounts of rainfall. PWS measures the amount of water vapor in a column of air. This weekend with PWS of 2.2-2.3 inches and possible cell training, Lindner warns that a quick 2-3 inches of rainfall in less than an hour will be possible. Even though grounds are dry and should be able to handle the rainfall, some street flooding will be possible with those rates.

No River Flooding Expected

However, National Weather Service expects no significant river flooding in the next five days.

Tide Report

According to Lindner, tides are already elevated along the coast due to the full moon. Easterly and southeasterly low-level winds on the north side of the low may bump seas up a bit over the weekend and push tides a little higher. He expects water to be way up on the beaches at high tides over the weekend.

Monitor forecasts closely over the weekend for any changes.

Posted by Bob Rehak on 8/12/2022

1809 Days since Hurricane Harvey

Western Caribbean Could Get Active This Week

(Updated at 1:30p.m. 6/13/14 to reflect increased risk) According to Harris County Meteorologist Jeff Lindner, a tropical system may form over the western Caribbean Sea this week. The National Hurricane Center has increased the probability of formation from 20% to 30% to 40% so far today.

*NHC gives the yellow area a 30% chance of formation as of 8am EDT on 6/13/22.*

*Upgraded to 40% chance of formation as of 1PM Houston time, 6/13/22.*

Converging Systems

Currently, a trough of low pressure extends from the eastern Pacific Ocean (south of Mexico) across central America into the far western Caribbean Sea. It is producing numerous clusters of showers and thunderstorms. Additionally, a westward moving tropical wave is starting to interact with the eastern part of that trough. See below.

*Satellite image of Atlantic Basin as of 9:50 Houston time on 6/13/22. Note the area starting to curve around Central America and the westward moving storm off the cost of South America.*

Thunderstorm clusters over the eastern Pacific are in the formative stages of tropical development. Meanwhile, showers and thunderstorms over the western Caribbean remain disorganized and in an environment generally of strong upper level westerly wind shear.

Global forecast models show varying degrees of development over the western Caribbean Sea east of Honduras by mid week.
Jeff Lindner, Harris County Meteorologist

Most models indicate development very near the eastern coast of central America. And it is possible that no development happens due to the close proximity to land and/or wind shear.

Should this surface low actually develop, the sprawling ridge of high pressure over the southern plains responsible for our current heat wave will affect forecasts.

Without any sort of defined center for the Caribbean system, confidence is low on where anything may form and eventually move. However, the majority of the global models keeps this disturbed area close to central America and then potentially in the Bay of Campeche.

National Hurricane Center Forecast

The National Hurricane Center agrees. It currently gives the feature a 40% chance of formation over the next 5 days. That’s up from 20% yesterday and 30% this morning.

At a minimum, the NHC predicts that an area of low pressure will develop by the middle part of this week over the southwestern Caribbean Sea. Forecasters add: “Some slow development of this system is possible thereafter while it drifts generally northwestward off the coasts of Nicaragua and Honduras.”

Check National Hurricane Center Daily During Season

This should serve as a reminder that we are in hurricane season. And it is a good idea to check the tropical weather outlook at least once per day.

The best place to do that is the National Hurricane Center website. While the statistical peak of hurricane season is still three months away (September 11), life threatening tropical systems do strike in early in the season. Here’s an interesting article about devastating June storms.

Many people in the Houston area will remember Tropical Storm Allison in 2001. It killed 22 people and dumped almost as much rain as Harvey. It caused all the flood maps to be revised at the time.

Posted by Bob Rehak on 6/13/2022

1749 Days since Hurricane Harvey

Cone of Nicholas Shifts East, Now Includes Houston, Hurricane Watch Expanded

The 10 AM update from the National Hurricane Center shows that the eye of Nicholas is reforming yet again – further east from where it first reformed earlier today near Brownsville. This means that the cone of uncertainty for Nicholas has expanded. It now includes the entire Houston Area. And although chances of a hurricane are low, the hurricane watch has been extended northward to San Luis Pass.

Nicholas’ Cone Now Includes All of Houston

*Remember that every place within the cone has an equal change of having the storm pass over it.*

Main Threats from Tonight to Tomorrow Night

Bands of heavy rainfall and gusty winds continue to spread inland from the coast and will increase in frequency and intensity this afternoon into tonight. Core of Nicholas will move across southeast Texas….especially areas south of I-10 overnight into Tuesday with significant rainfall likely.

Harris County Meteorologist Jeff Lindner warns that while Nicholas is not forecasted to become a hurricane, it is possible that it could landfall as a minimal hurricane….but this does NOT change the impacts.

Impact Predictions Remain Unchanged Since Last Update

Rainfall, wind, and storm surge impacts remain unchanged from my post earlier this morning.

Significant rains will begin early this evening and likely continue into Tuesday morning.

Rainfall rates of 2-4 inches per hour will be possible yielding rapid street flooding and significant rises on bayous and creeks.

Lindner’s main concern is watersheds south of I-10 (Clear Creek, Armand Bayou, Vince and Little Vince Bayous, Keegans Bayou, and possibly Brays Bayou). However, Lindner still sees risk north I-10.

Some bayous and creeks may overflow their banks. Structure flooding is possible tonight. The majority of the rainfall is going to be tonight into Tuesday morning.

Residents should stay where they are after 6:00 PM this evening and remain there through the duration of Nicholas.
Jeff Lindner, Harris County Meteorologist

Best Ways to Monitor Nicholas

Closely monitor bayou and creek conditions and rainfall trends. The best way to do that is through the Harris County Flood Warning System.

Also, closely monitor the National Hurricane Center website. This page contains their latest satellite image updates. During storms like this, they update them hourly. Here’s one from 11:46 AM Houston time.

*Nicholas as of 11:46 AM on Monday, 9/13/2021.*

Posted by Bob Rehak on 9/13/2021 at 10:30 AM and again at Noon

1476 Days since Hurricane Harvey

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