Tag Archive for: National Hurricane Center

Beta Moving Ashore Today Then Likely Tracking Slightly South of Houston

As of 10:00 a.m. Monday morning, the National Hurricane Center (NHC) still shows the center of Tropical Storm Beta located offshore. The latest forecasts from the NHC predict that Beta will move onshore near Matagorda Bay, then move up the coastline toward League City.

The NHC also advises that the storm has picked up speed. Yesterday, they estimated 3 mph; today 7 mph.

No one seems to predict that the storm will intensify before landfall.

“Dry air continues to work into and wrap around the large wind field of Beta yielding the disorganized precipitation field with the system.”

Jeff Lindner, Harris County Meteorologist
National Weather Service radar Image of Beta as of 10:04 am Monday 9/21/20.
Lake Houston Area is the blue dot in the center of the swirl. Red line is predicted path of Beta. Source: Weather Live.

Main Threat: Storm Surge

At this time, Beta’s main threat is to the coastline through storm surge. “Tides are currently running 4.0-4.5 feet in Clear Lake and across coastal sections of Harris County with several sites near the Gulf beaches running 4.0-4.5 feet. Coastal flooding is ongoing and will continue for much of the day. Several roadways are underwater along the coast and around Galveston Bay,” says Lindner.

Lindner continues, “As Beta makes landfall along the middle Texas coast later today, the storm will begin to slow and then turn ENE toward the upper TX coast. It will slowly weaken along the way. This track will keep onshore flow along the upper Texas coast tonight and Tuesday. Tides will remain high into the high tide tonight. Impacts along the coast will continue through the day and into tonight and likely Tuesday.”

Wind Forecast

The most likely arrival time of tropical storm force winds, if we get them, is later tonight.

Tropical storm force winds already cover a large part of the mid-Texas coast.

The storm will weaken as it moves toward the Houston Area and turn into a tropical depression. The further north you live from the coastline, the less intense winds will be.

Depending on where you live in Houston, you have a 30% to 100% chance of experiencing topical storm force winds. The Lake Houston Area is on the low end of that range. The National Weather Service predicts that the Lake Houston Area has a chance of seeing 39-57 mph winds. But Spaces City Weather advises that Beta is “not a significant wind threat.”

However, note that tropical-storm-force winds currently extend outward up to 175 miles (280 km) from the center of the storm.

Galveston has reported sustained winds of 39 mph and a gust of 43 mph during the past couple of hours.

Rainfall

Dry air has worked into the circulation of Beta, according to Lindner. “This has resulted in a more disorganized and scattered rainfall pattern. However, the system is still capable of heavy rainfall especially near the center later today and in bending structures east of the center for the next 48 hours.”

Models show several banding features developing during the next 48 hours over SE TX, But little consensus exists on where the heaviest rainfall totals may be.

Lindner advises that, “Given that much of the area will reside on the eastern side of a the tropical system, we should keep some level of concern of heavy rainfall and flooding in place through the next 48 hours.”

Lindner predicts that widespread rainfall amounts of 4-8 inches will be possible for areas along and south of I-10 with isolated totals of 10-12 inches under any training feeder bands. Totals to the north of I-10 will likely average 3-5 inches with isolated totals of 6-7 inches. 

However, the NHC predicts slightly less rain. See the map below.

As long as the rainfall spreads out over the next 48 hours, most of the creeks and bayous can handle the expected rainfall amounts, Lindner says. But should any training develop, flash flooding would be possible. 

Watches and Warnings in Effect

A Storm Surge Warning is in effect for Port Aransas, Texas to Rockefeller Wildlife Refuge, Louisiana. That includes Copano Bay, Aransas Bay, San Antonio Bay, Matagorda Bay, Galveston Bay, Sabine Lake, and Lake Calcasieu.

A Tropical Storm Warning is in effect for Port Aransas Texas to Morgan City Louisiana. That includes the Lake Houston Area.

National Hurricane Center

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

Lindner, the NHC and NWS all warn that tornadoes remain a threat with this storm. Especially, tonight and Tuesday.

Track

Yesterday, models predicted that Beta would track up US59 toward the Humble/Kingwood Area. However, today, forecasters think the storm will track closer to the coast. They put it on a line toward League City.

Wind shear will keep Beta’s track close to the coastline, but it will also affect the cyclone’s intensity along with land interaction. The closer the cyclone stays near the Gulf of Mexico, the more likely that bands of convection containing tropical-storm-force winds will continue to roll onshore the Texas coast through 36-48 hours.

Summary

Flash, urban, and isolated minor river flooding is possible, but the danger is “slight.”

National Hurricane Center

Net: Beta is still a threat. But it may be less of one than yesterday. That’s because of the dry air folding into the system and wind sheer which seem to be weakening it somewhat. Be hopeful, but cautious. Expect several inches of rain and high winds in the next two days with both tapering off Wednesday.

Posted by Bob Rehak on 9/21/2020 at noon based on data from NHC, NWS, Jeff Lindner, Space City Weather and Weather Live

1119 Days after Hurricane Harvey and 368 since Imelda

Hurricane Watch for Port Aransas to High Island

As of 4am Saturday, 9/19/20 (the 1-year anniversary of Imelda), the National Hurricane Center issued:

  • Hurricane Watches for Texas coast from Port Aransas to High Island
  • Tropical Storm Watches east of High Island into Louisiana and from Port Aransas to the Rio Grande
  • Storm Surge Watches from Port Mansfield, TX to Cameron, LA including all inland bays.

Discussion

There is an increasing risk of heavy rainfall and flooding along the northwest Gulf Coast Sunday through at least the middle of next week. Beta is forecast to move slowly toward and along or offshore of the coast through that time and create life-threatening storm surge.

Lake Friday, a USAF mission found a stronger tropical storm with winds of 60mph and a fairly large area of 40-50mph winds. Ships and oil platforms in the north-central Gulf of Mexico have reported winds above 40mph. The wind field is starting to expand toward the north.

Track: 

Beta is moving NNE at 12mph. Faster than expected. Beta will turn west around mid-day Saturday and decrease forward speed into early next week. This will bring Beta toward the middle Texas coast.

As Beta approaches the mid TX coast, weakening high pressure to the north will turn the storm toward the north and northeast. However, forecasters have lower-than-normal confidence as to when all this will happen.

The current National Hurricane Center forecast track is near the center of consensus for major global models, but shifts in this track will remain possible both toward the north or south.

Intensity: 

Beta intensified despite wind shear. As Beta moves over very warm western Gulf of Mexico waters, intensification will likely continue for the 24-48 hours. NHC now forecasts Beta to become an 80mph hurricane. As Beta begins to turn northeast and skirt the middle and upper TX coast, the storm may weaken. Some uncertainty remains in the intensity forecast.  

Tropical storm force winds will likely begin to arrive along the middle TX coast Sunday evening and spread northward into Matagorda Bay and along the upper TX coast by Monday. Hurricane conditions could reach the Matagorda Bay region on Tuesday.  

Impacts

Storm Surge: 

Water level rises along the upper TX coast will begin on Saturday and worsen Sunday into Monday due to the expansion of the tropical-storm-force wind field. This large wind field will also develop large swells over the NW Gulf of Mexico by Sunday into Monday with swells reaching 15-25 feet. On Sunday into Monday, expect 4-8 feet waves breaking on beaches. These large swells will lead to wave run up on top of elevated tides.

Large waves will accompany the higher tides. The prolonged nature of the event will result in significant beach erosion and damage to fragile dunes.

Expect inundation of low lying roads near the coast. Once the water begins to rise on Saturday evening, some low lying areas may remain flooded into the middle of next week.

Jeff Lindner, Harris County Meteorologist

Ferry operations at both the Galveston-Bolivar and the Lynchburg sites may be impacted. 

For SE Harris County:

From Saturday night into next week, coastal flooding will be possible in El Lago, Nassau Bay, Shoreacres, Seabrook and portions of Baytown near Goose Creek and Cedar Bayou.

This includes all areas around:

  • Clear Lake
  • Along Taylor’s Bayou in Shoreacres and Taylor Lake Village
  • Around the San Jacinto Monument and Lynchburg Ferry landing
  • In Seabrook areas along and east of Toddville Rd and in the waterfront area east of HWY 146.
  • The lower San Jacinto River at Rio Villa and other low lying areas south of US HWY 90.
  • Low lying areas in Galena Park and Jacinto City near the Houston Ship Channel
  • Lower portions of Greens and Hunting Bayous south of I-10.

Most flooding will happen in streets, low marsh lands, roads near Galveston Bay and around Clear Lake and some subdivisions streets.

Wave action from ENE/E winds across Galveston Bay of 2-4 feet will be possible on top of these tides along the west side of Galveston Bay and 1-3 feet in Clear Lake which may damage docks, bulkheads, and moored vessels. 

Rainfall

Rainfall will strongly depend on the track of Beta. Small changes could result in significant differences in rainfall amounts. Heaviest rains will likely be near the coast and offshore.

Any deviation of the track northward would bring the heavy rainfall further inland, likewise any south or east shift in the track would keep the heaviest rains off the coast.

  • Coast: 8-12 inches
  • Coastal counties: 6-8 inches
  • South of I-10: 4-6 inches
  • South of Hwy 105: 3-5 inches
  • North of Hwy 105: 1-3 inches

HCFCD models suggest that basin average rainfall totals of at least 6 inches would fill smaller creeks and bayous in Harris County (Willow Waterhole, Keegans Bayou, Willow Creek, Upper Little Cypress Creek).

Basin average amounts of 7-8 inches would fill Clear Creek, Hunting Bayou, Armand Bayou, Cypress Creek, Halls Bayou, Greens Bayou, White Oak Bayou, Buffalo Bayou, Cedar Bayou, and various smaller tributaries. 

Addicks and Barker Reservoirs are currently empty.

Winds: 

Tropical storm force winds may start Sunday evening around Matagorda Bay. Sustained 40mph winds likely spread northward along the upper TX coast on Monday including Galveston Bay.

Hurricane conditions will be possible near Matagorda Bay on Tuesday and across portions of coastal Matagorda, Brazoria, and Galveston Counties into Wednesday.

Across Harris County wind will increase into the 25-35mph range on Monday and possibly 40-50mph range on Tuesday into Wednesday with higher gusts, especially near Galveston Bay.  

Posted by Bob Rehak on 9/19/2020 at 4am based on data from the National Hurricane Center and Harris County Meteorologist Jeff Lindner.

1117 Days since Hurricane Harvey and 1 Year since Tropical Storm Imelda

Tropical Storm Beta Likely to Dump 4-6 Inches on Harris County, 10-12 Inches Near Coast

Preparations for Prolonged Coastal Flooding and Potential Inland Rainfall Flooding Should Begin now for Tropical Storm Beta.

As of 4PM CDT Friday, the National Hurricane Center predicts that storm surge, tropical storm and/or hurricane watches will likely be required for portions of the western Gulf coast tonight or on Saturday.

Forecast Track

Tropical Storm Beta is moving toward the north-northeast near 9 mph (15 km/h). This general direction should last through Saturday. Late Saturday or Saturday night, the storm should begin a slow westward drift into early next week. After that, Beta should recurve to the northeast.

Cone of uncertainty for TS Beta. Every point within the cone has an equal chance of receiving a hit from the center of the storm.

Don’t Focus on Exact Track Yet

Do not focus on the exact forecast track for Tropical Storm Beta, especially at days 3 to 5, as a high degree of uncertainty remains.

Regardless the forecast track, the center of Beta will approach western coast of the Gulf of Mexico Sunday night and Monday. Even if we don’t take a direct hit from Beta…

…Houston will likely be on the wet/dirty side of the storm.

10-20% Chance of Tropical Storm Winds for Houston

The Houston Area currently has a 10-20% chance of receiving tropical-storm force winds starting Sunday.

Probability of Houston receiving winds greater than 40 mph is 10-20%.
Those winds could arrive as early as Sunday morning.

Maximum sustained winds have already increased to near 40 mph (65 km/h) with higher gusts. Beta could reach near hurricane strength Sunday or Sunday night. Tropical-storm-force winds extend outward up to 105 miles (165 km) from the center.

Key Messages

According to the National Hurricane Center:

  1. Beta should strengthen and possibly become a hurricane, while moving slowly over the western Gulf of Mexico during the next few days.
  2. There is an increasing risk of heavy rainfall and flooding along the northwest Gulf Coast Sunday through at least the middle of next week as Beta is forecast to move slowly toward and along or offshore of the coast through that time. For additional information, see products from your local National Weather Service office.
  3. Monitor the progress of this system and future updates.

Beta could affect the Houston Area much of next week.

Impacts

Tides/Storm Surge: 

Strong ENE/E winds will push sea water toward the coast. Expect seas to build into the 8-15 foot range and waves to run up along the coast.

Expect at least 4.0-5.0 feet seas above the barnacle level. They could even reach near 6.0 feet. Impacts begin around 4.5 ft at several locations along the upper TX coast. 

Low lying roadways near the coast will likely flood at times of high tide and some locations could become isolated. Significant beach erosion is likely with elevated tides and large wave action lasting for several days and coastal infrastructure could be damaged. The expected tides on Sunday will likely be 1.5-2.5 feet higher than those experienced with Laura and Hanna.

DO NOT get caught off guard with the expected water level rise along the coast. Understand that low lying coastal roads may be inundated for a long period of time  

Rainfall: 

Squalls will increase in frequency and intensity into Sunday night and Monday and begin to spread farther inland. There will be a sharp cut off in the higher rainfall amounts from south to north over the area with amounts of 10-12 inches likely near the coast and even higher offshore. However, College Station will probably only see 1-3 inches.

Harris County Meteorologist Jeff Lindner predicts 4-6 inches over Harris County. 

These rainfall amounts will likely change

Winds: 

Tropical storm force winds could arrive by Sunday evening and slowly spread NE Monday and Tuesday. It is possible that some locations could see 24-48 hours of sustained tropical storm force winds with the slow movement of the system.

Posted by Bob Rehak on 9/18/2020 based on input from the National Hurricane Center and Jeff Lindner, Harris County Meteorologist

1116 Days after Hurricane Harvey and 365 Days after Tropical Storm Imelda

TD 19 Upgraded to Tropical Storm Sally

The National Hurricane Center (NHC) has just upgraded Tropical Depression 19 to Tropical Storm Sally. And they will likely upgrade it again to a Hurricane on Monday.

Miami and Tampa Bay radar currently show a defined center of circulation and deep convection across much of Florida Bay and the Florida Keys. 

The National Hurricane Center is now tracking seven storms lined up in the Atlantic.

Sally’s Likely Landfall in Louisiana

Sally’s cone of uncertainty no longer extends as far west as Houston. For now. See below.

On the forecast track, the center is forecast to move over the southeastern and eastern Gulf of Mexico later today and Sunday. Sally will then move over the north-central Gulf of Mexico Sunday night and Monday.

Hurricane Predicted

Maximum sustained winds have already increased to near 40 mph (65 km/h) with higher gusts. Sally will likely become a hurricane by late Monday. (Note how the S’s turn to H’s in the cone map above.)

Tropical-storm-force winds currently extend outward up to 80 miles (130 km) south and southeast of the center.

Intensity guidance is inching up some. Conditions over the eastern Gulf of Mexico make a hurricane likely at landfall. “In fact,” says the NHC, “the hurricane models show significant intensification of Sally. This will need to be closely monitored over the next 1-2 days.”

Rainfall

Florida

Sally should produce total rainfall of 3 to 6 inches with isolated 8 inch amounts over the Florida Keys through tonight. NHC expects 2 to 4 inches and isolated maximum amounts of 6 inches across southern Florida and the western Florida coast to Tampa Bay.

This rainfall will produce flash and urban flooding across Southern and Central Florida.

Central Gulf

Through Tuesday, NHC expects Sally to produce rainfall of 3 to 6 inches with localized amounts of 8 inches along the Gulf Coast between Florida and SE Louisiana. NHC predicts 2 to 4 inches farther inland over far southern Alabama, Mississippi and southeast Louisiana.

Flooding Likely

NHC says, “This is expected to be a slow-moving system. Sally will likely continue to produce heavy rainfall and considerable flooding near the central Gulf Coast through the middle of next week. Flash, urban and rapid onset flooding along small streams and minor to isolated moderate flooding on rivers is likely.”

Jeff Lindner, Harris County Meteorologist says, “Nearly all guidance slows Sally to around 5mph as the system approaches the coast. That will result in prolonged impacts and potentially devastating amounts of rainfall.” Remember Harvey?

Stay Alert

Even though Houston is outside of the cone of uncertainty today, stay alert. Remember how the tracks of Marco and Laura kept shifting hourly. The NHC cautions that “The average NHC track error at 96 hours is around 150 miles. In addition, winds, storm surge, and rainfall hazards will extend far from the center.”

Posted by Bob Rehak on 9/12/2020

1110 Days since Hurricane Harvey

How Close Was Laura?

After a week of worry! After adrenaline-fueled prep for two back-to-back hurricanes that could have wreaked havoc on Houston…I woke up refreshed this morning, walked to my weather window, and saw…nothing unusual. What happened? I checked my weather gauge. It read 0.00 inches of rain. Max winds since midnight: 3 mph.

It would appear the Houston Area dodged Laura’s silver bullet. But why? According to Harris County Meteorologist, Jeff Linder, two things spared us the wrath of Laura. First, Laura shifted slightly east. Second, as Laura intensified, the wind field pulled in tighter. That diminished feeder bands on the western side of the storm.

How Close Laura Came

Here are some radar and satellite images that show how close the storm came.

From Weather Live App at 5:55 am Thursday 8/27/2020
From the National Hurricane Center at 5:56 am. Houston is the bright spot on the SW side of the swirl.
From the National Weather Service at 1:53 CDT as Laura came ashore.
From Lake Charles Louisiana radar at 12:46 am CDT. (This and following images from RadarScope Pro app.)

The shot above and the radar loop below show dramatically how the storm shifted east last night. The National Hurricane Center had predicted eye of the storm to move up the Sabine River near Port Arthur, about 40 miles west.

Radar Loop showing Laura coming onshore that started at 11:28pm 8/26/2020.
Little Rock, Arkansas radar at 5:41 am CDT as Laura approaches

6 A.M. Update from NHC

At this instant, Laura has diminished to a Cat 2 storm. An update issued by the NHC at 6:00 a.m. says,

  • HURRICANE CONDITIONS SPREADING FARTHER INLAND ACROSS SOUTHWESTERN LOUISIANA…
  • CATASTROPHIC STORM SURGE, HURRICANE FORCE WINDS, AND FLASH FLOODING WILL CONTINUE THIS MORNING…
  • Fort Polk, Louisiana recently reported a sustained wind of 45 mph (72 km/h) and a wind gust of 70 mph (113 km/h). SUMMARY OF 600 AM CDT…1100 UTC…
INFORMATION
  • LOCATION…30.9N 93.3W ABOUT 55 MI…90 KM N OF LAKE CHARLES LOUISIANA
  • MAXIMUM SUSTAINED WINDS…105 MPH…170 KM/H
  • PRESENT MOVEMENT…N OR 355 DEGREES AT 15 MPH…24 KM/H
  • MINIMUM CENTRAL PRESSURE…964 MB…28.47 INCHES

Hurricane Guilt

After Hurricane Rita, which dodged Houston like Laura, I coined a term called “hurricane guilt.” It’s that feeling of elation you get when you realize the storm missed you…followed closely by the realization that it destroyed innocent lives elsewhere.

That’s what I feel right now. As I write this, the sun is rising and birds are singing. Soon images of Laura’s destruction will start to pour in. Only then will we know how lucky we were.

Posted by Bob Rehak at 6:45 am on 8/27/2020 based on information from NWS, NHC, RadarScope, and Jeff Lindner, Harris County Meteorologist

1094 Days since Hurricane Harvey

As of 1 p.m., Laura Now Category 4 Hurricane, Moving at 16 mph

Based on recent Hurricane Hunter aircraft measurements, the National Hurricane Center reported at 1 p.m. that Hurricane Laura’s maximum sustained winds have increased to near 140 mph with higher gusts. Laura is an extremely dangerous Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Maximum winds could reach 145 mph.

Laura is forecast to remain a category 4 hurricane through landfall tonight.

National Hurricane Center

350 Miles Across

Rapid weakening is expected after Laura reaches land. However, Hurricane-force winds extend outward up to 70 miles from the center and tropical-storm-force winds extend outward up to 175 miles (280 km). That’s 350 miles across!

Storm surge and tropical-storm-force winds will arrive within the warning areas well in advance of Laura’s center.

All preparations to protect life and property should be rushed to completion in the next few hours.

Louisiana Already Feeling Tropical-Storm-Force Winds

Tropical-storm-force winds have already reached the coast of Louisiana. An observing site at Eugene Island recently measured sustained winds of 39 mph (63 km/h) and a gust to 64 mph (104 km/h). The latest minimum central pressure estimated from reconnaissance aircraft data is 952 mb (28.11 inches). Very low!

20-Foot-High Storm Surge Could Reach 30 Miles Inland

According to the NHC, unsurvivable storm surge with large and destructive waves will cause catastrophic damage from Sea Rim State Park, Texas, to Intracoastal City, Louisiana, including Calcasieu and Sabine Lakes. This storm surge could penetrate up to 30 miles inland from the immediate coastline in southwestern Louisiana and far southeastern Texas.

Warnings in Effect

STORM-SURGE WARNING IS IN EFFECT FOR FREEPORT TEXAS TO THE MOUTH OF THE MISSISSIPPI RIVER

HURRICANE-WARNING IS IN EFFECT FOR SAN LUIS PASS TEXAS TO INTRACOASTAL CITY LOUISIANA

TROPICAL-STORM WARNING IN EFFECT FOR SARGENT TEXAS TO SAN LUIS PASS AND EAST OF INTRACOASTAL CITY LOUISIANA TO THE MOUTH OF THE MISSISSIPPI RIVER

Key Messages

1. Unsurvivable storm surge with large and destructive waves will cause catastrophic damage from Sea Rim State Park, Texas, to Intracoastal City, Louisiana, including Calcasieu and Sabine Lakes. This surge could penetrate up to 30 miles inland from the immediate coastline. Only a few hours remain to protect life and property and all actions should be rushed to completion.

2. Hurricane-force winds are expected tonight in portions of the hurricane warning area from San Luis Pass, Texas, to west of Morgan City, Louisiana, with catastrophic wind damage expected where Laura’s eyewall makes landfall. Hurricane-force winds and widespread damaging wind gusts will spread well inland across portions of eastern Texas and western Louisiana early Thursday.

3. Widespread flash flooding along small streams, urban areas, and roadways is expected to begin this afternoon into Thursday from far eastern Texas, across Louisiana and Arkansas. This will also lead to minor to isolated moderate freshwater river flooding. The heavy rainfall threat and localized flash and urban flooding potential will spread northeastward into the middle-Mississippi, lower Ohio and Tennessee Valleys Friday night and Saturday.

Posted by Bob Rehak at 2 p.m. CDT on 8/26/2020 based on input from National Hurricane Center and Jeff Lindner, Harris County Meteorologist

1093 Days after Hurricane Harvey

Impact Corridor of Hurricanes Much Wider than Cone of Uncertainty

Many people mistake the cone of uncertainty associated with a hurricane as the width of a storm. It’s not. It merely shows likely paths the hurricane’s eye could take as it comes ashore. There’s an equal probability of any path within the cone. Cones expand with more distant projections because uncertainty increases. But as forecasters always warn us, the impact of a major hurricane extends far beyond the cone of uncertainty.

Difference Visualized

Compare these two pictures to fully understand the difference.

Cone of uncertainty for Laura as of Wed. morning, 8/26/2020 at 10 a.m. CDT.
Satellite image of Laura taken at about the same time the cone image above was produced.

I have arbitrarily assigned the term “impact corridor” to the area between the two lines to help describe the difference. (No one uses this term but me, although they probably should.)

Of course, as you go further from the center of the storm, the intensity decreases and so do negative impacts.

Currently (12:30 pm CDT, 8/26/2020), hurricane-force winds extend outward up to 70 miles from the center and tropical-storm-force winds extend outward up to 175 miles. That’s 350 miles across!

Interesting Facts About Hurricanes

As you ride this one out with your children or grandchildren, make it a learning experience. Here are some interesting facts about hurricanes taken from Weather.gov.

  • Each year, an average of ten tropical storms develop over the Atlantic Ocean, Carribean Sea, and Gulf of Mexico. Many of these remain over the ocean. Six of these storms become hurricanes each year. In an average 3-year period, roughly five hurricanes strike the United States coastline, killing approximately 50 to 100 people anywhere from Texas to Maine. Of these, two are typically major hurricanes (winds greater than 110 mph).
  • Typical hurricanes are about 300 miles wide although they can vary considerably in size.
  • The eye at a hurricane’s center is a relatively calm, clear area approximately 20-40 miles across.
  • The eyewall surrounding the eye is composed of dense clouds that contain the highest winds in the storm.
  • The storm’s outer rainbands (often with hurricane or tropical storm-force winds) are made up of dense bands of thunderstorms ranging from a few miles to tens of miles wide and 50 to 300 miles long.
  • Hurricane-force winds can extend outward to about 25 miles in a small hurricane and to more than 150 miles for a large one. Tropical storm-force winds can stretch out as far as 300 miles from center of a large hurricane.
  • Frequently, the right side of a hurricane is the most dangerous in terms of storm surge, winds, and tornadoes.
  • A hurricane’s speed and path depend on complex ocean and atmospheric interactions, including the presence or absence of other weather patterns. This complexity of the flow makes it very difficult to predict the speed and direction of a hurricane.
  • Do not focus on the eye or the track. Hurricanes are immense systems that can move in complex patterns that are difficult to predict. Be prepared for changes in size, intensity, speed and direction.

What Hurricanes Need to Grow

Weather.gov lists six widely accepted conditions for hurricane development:

1. The first condition is that ocean waters must be above 79 degrees Fahrenheit. Below this threshold temperature, hurricanes will not form or will weaken rapidly. Ocean temperatures in the tropics routinely surpass this threshold.

2. The second ingredient is the Coriolis Force. Without the spin of the earth and the resulting Coriolis force, hurricanes would not form. Coriolis force causes a counterclockwise spin to low pressure systems, such as hurricanes, in the Northern Hemisphere and a clockwise spin to low pressure in the Southern Hemisphere.

3. The third ingredient is that of a saturated lapse rate gradient near the center of rotation of the storm. A saturated lapse rate insures latent heat will be released at a maximum rate. Hurricanes are warm core storms. The heat hurricanes generate is from the condensation of water vapor as it convectively rises around the eye wall. The lapse rate must be unstable around the eyewall to insure rising parcels of air will continue to rise and condense water vapor.

4. The fourth and one of the most important ingredients is that of a low vertical wind shear, especially in the upper level of the atmosphere. Wind shear is a change in wind speed with height. Strong upper level winds destroy the storms structure by displacing the warm temperatures above the eye and limiting the vertical accent of air parcels. Hurricanes will not form when the upper level winds are too strong.

5. The fifth ingredient is high relative humidity values from the surface to the mid levels of the atmosphere. Dry air in the mid levels of the atmosphere impedes hurricane development in two ways. First, dry air causes evaporation of liquid water. Since evaporation is a cooling process, it reduces the warm core structure of the hurricane and limits vertical development of convection. Second, dry air in the mid levels can create what is known as a trade wind inversion. This inversion is similar to sinking air in a high pressure system. The trade wind inversion produces a layer of warm temperatures and dryness in the mid levels of the atmosphere due to the sinking and adiabatic warming of the mid level air. This inhibits deep convection and produces a stable lapse rate.

6. The sixth ingredient is that of a tropical wave. Often hurricanes in the Atlantic begin as a thunderstorm complex that moves off the coast of Africa. It becomes what is known as a midtropospheric wave. If this wave encounters favorable conditions such as stated in the first five ingredients, it will amplify and evolve into a tropical storm or hurricane. Hurricanes in the East Pacific can develop by a midtropospheric wave or by what is known as a monsoonal trough.

Posted by Bob Rehak on 8/26/2020 based on data from Weather.gov.

1093 Days since Hurricane Harvey

As of 7 a.m., Laura Predicted to Make Landfall at Sabine Pass as Cat 4 Hurricane

This update on Hurricane Laura is based on information from Harris County Meteorologist Jeff Lindner and the National Hurricane Center based on their 4 a.m. and 7 a.m. updates on Wednesday 8/26/2020.

Laura rapidly strengthening…now a 115 mph Category 3 hurricane, predicted to reach Cat 4.

Extremely dangerous hurricane will make landfall near Sabine Pass tonight with catastrophic impacts.

All preparations must be completed by 6:00 p.m. this evening.

Conditions will begin to deteriorate late this afternoon and evening over the region.

Rainfall predictions for the Lake Houston Area increased overnight. We could now receive up to six inches.

The Lake Houston Area now has a 60-80% chance of experiencing topical-storm-force winds from Laura.
Tropical-storm-force winds could arrive as early as mid-afternoon.
The most likely time, however, for the arrival of tropical-storm-force winds is later this evening.

Discussion 

Laura became a large and dangerous hurricane overnight with expansion of the wind field. USAF missions indicate the central pressure continues to fall. Winds are increasing. And Laura has experienced a 40 knot increase in winds in the last 24 hours. (A knot = 1.15 mph.) The eye of the hurricane is starting to clear out. Further rapid intensification is likely today.

The cone of uncertainty now shows Houston will NOT experience a direct hit from the storm, but we will still feel it. Effects from the Laura extend well outward from the center.
Track

The center of Laura should cross the coast near Sabine Pass, TX, near the Texas/Louisiana Border. Models have tightly clustered just either side of the state line. There is high confidence that Laura will make landfall in the areas between Sea Rim State Park and Cameron LA early Thursday morning. The hurricane should move rapidly northward, up the Sabine River Valley on Thursday. 

Given the fast forward motion, significant wind impacts will extend well inland along the track of Laura with wind damage likely extending 100-200 miles inland over eastern Texas and western Louisiana.

Intensity: 

Laura will pass over warm Gulf waters today and upper air conditions that favor intensification through landfall. The National Hurricane Center forecasts a category 4, 130 mph hurricane at landfall.

Hurricane force winds extend outward 70 miles from the center and tropical storm force winds 175 miles.

Wind damage and storm surge impacts will extend well beyond the center.

Jeff Lindner, Harris County meteorologist

Impacts

Storm Surge: 

Expect a catastrophic storm surge event over extreme SE TX and much of coastal Louisiana.

Strong north winds tonight may drive water levels along the north side of Galveston Island and Bolivar to elevated levels and water levels in the NW part of Galveston Bay may fall well below normal.

The following values are above ground level:

Galveston Bay: 1-3 ft

Bolivar: 2-5 ft

High Island to Sea Rim State Park: 6-9 ft

Sea Rim State Park to Intracoastal City (Including Beaumont and Lake Charles): 10-15 ft.

Large destructive waves will accompany storm surge.

Winds: 

West of I-45: 30-40mph

East of I-45: 45-55mph

Chambers, Liberty, Polk Counties: 50-65mph

Jefferson, Orange Counties and Lake Charles: 110-120mph

Higher gusts will occur in squalls. 

Hurricane-force winds currently extend outward up to 70 miles from the center and tropical-storm- force winds extend outward up to 175 miles.

The Harris County line is 75 miles from Sabine Pass; Lake Houston 80 miles.

Rainfall: 

West of I-45: 1-2 inches

East of I-45: 2-6 inches, isolated totals up to 8 inches.

Sabine River Valley: 8-12 inches

Overnight, rainfall predictions for the Lake Houston Area increased 2 inches. The six inches now predicted roughly equals the amount of rain the Lake Houston Area received on May 7th last year. Elm Grove residents: Please note: the volume of detention ponds now on Woodridge Village should be enough to protect you unless there is a design flaw.

The main rainfall threat comes from rapid, intense rains which can cause street flooding.

Actions

Complete all preparations by 6:00 pm this evening. Earlier the better.

If in evacuation areas, evacuate immediately…especially in the Beaumont and Lake Charles area.

Lake Report

Lake Houston as of 6:30 a.m. was at 41.17 feet (full pool 42.4). The Coastal Water Authority will continue releasing water from Lake Houston until it reaches 41 feet.

Lake Conroe is not releasing water and stands at 199.72 feet (full pool is 201).

For More Up-to-the-Minute Information

For the most up-to-date rainfall totals and water levels in bayous, creeks, and rivers, visit www.harriscountyfws.org. This system relies on a network of gage stations that have been strategically placed throughout Harris and surrounding counties.

Also visit the National Hurricane Center and the National Weather Service.

Posted by Bob Rehak at 7:12 a.m. on 8/26/2020 based on input from the National Hurricane Center and Jeff Lindner, Harris County Meteorologist.

1093 Days after Hurricane Harvey

Laura Intensifying into Major Hurricane; Prepare for Big Winds, Power Outages

These warnings were just issued by Jeff Lindner, Harris County Meteorologist, the National Hurricane Center, and City of Houston:

Hurricane warnings issued from San Luis Pass into Louisiana.

Landfall of a devastating hurricane likely between Galveston Bay and Sabine Pass tomorrow night.

Rush to complete preparations to protect life and property.

Heed all evacuation recommendations.

Discussion

Laura – now a hurricane with sustained winds of 75mph – is continuing to intensify. The hurricane will likely rapidly intensify over the next 24-36 hours, right up to landfall along the upper TX coast. The National Hurricane Center predicts Laura will become a major hurricane with sustained winds over 110 mph by tomorrow night or early Thursday morning when it makes landfall somewhere between Galveston Bay and Sabine Pass.

Track: 

Everyone should be planning for the landfall of a very serious hurricane between Galveston Bay and Sabine Pass on the Louisiana border. Additional shifts in the track are possible that could bring the core of Laura into Galveston Bay and Harris/Galveston Counties.

The large wind field will result in strong winds likely 100-150 miles inland across east Texas.

Prepare for power outages extending well inland along with significant wind damage and extended outages.  

Intensity:

Prepare for the impact of a major hurricane (cat 3 or higher). Once the inner core of Laura forms, significant intensification is likely, and conditions look very favorable for intensification. 

Tropical Storm force winds will begin along the coast at around 8:00 pm Wednesday evening.

Advice from City, Lake Status

“Rainfall amounts in the Lake Houston Watershed over the next six days are expected to be 2 – 4 inches with isolated accumulation of 6 inches possible,” said Dave Martin. “Currently, the Lake Houston Watershed is dry and the projected impact to our area will be to our east with the largest possible impact expected along the East Fork of the San Jacinto River. Lake Houston is already down one foot from normal pool with the possibility of being lowered additionally, if necessary. Please make sure all property along the shoreline is secured in the event additional lowering is ordered.”

“Regardless of where this storm lands,” said Martin, “it is important all residents prepare themselves and have a plan. Hurricane Laura will likely be similar to Ike with severe wind impacts and power outages. The City of Houston has prepared resources to help you get ready for upcoming disasters and make sure you are prepared for this one. Please visit www.readyhoustontx.gov to learn more.

Actions

  • Prepare for the landfall of a major hurricane along the SE TX coast
  • Bring in anything in your yard, such as lawn furniture, that could become airborne.
  • All preparations will be to be competed by 6:00 p.m. Wednesday evening.
  • Heed all evacuation orders. 

For hurricane preparation tips from the National Weather Service, click here.

Posted by Bob Rehak on 8/24/2020 based on input from the National Hurricane Center and Jeff Lindner, Harris County Meteorologist.

1091 Days after Hurricane Harvey

Laura Upgraded to Hurricane; Will Intensify Through Landfall; Mandatory Evacuation for Galveston Island

Overnight, Laura turned into a hurricane. At 5:25 this morning, Jeff Lindner, Harris County Meteorologist, issued the following:

Hurricane Watches extended west to San Luis Pass…now include Harris and Galveston Counties

Major hurricane forecast in the NW Gulf of Mexico Wednesday

Enact hurricane plans now. Follow all recommendations from local officials.

At 7:00 a.m., he issued another warning saying that:

Laura upgraded to a hurricane…intensification will continue through landfall.

Mandatory evacuation order for Galveston Island effective immediately.

Discussion 

Laura is now over the SE Gulf of Mexico and moving toward the WNW after having jogged westward overnight. Deep convection has developed over and near the center this morning. Some light northerly system continues to impact Laura, which continues to track to the south of predictions. 

Track: 

The steering pattern that will bring Laura to the NW Gulf of Mexico remains somewhat in flux this morning. Laura will turn northwest and then north. But uncertainty remains as to when Laura will make this turn. Overnight model guidance now delays this turn a little longer and brings Laura more toward the upper Texas coast. NHC may have to shift their forecast track a bit more westward later this morning.

Forecast track shifted back west overnight bringing Houston into cone of uncertainty. Track forecast could shift further westward later this morning, bringing Houston closer to center of storm.

While uncertainty remains in the eventual outcome of Laura, preparations for landfall of a major hurricane along the upper TX coast should be well underway.

Jeff Lindner, Harris County Meteorologist

Tropical storm force winds will begin to arrive along the coast Wednesday evening and spread inland Wednesday night into Thursday morning.

Intensity: 

A central core is starting to form with Laura and overall circulation of the system is looking better defined. Conditions in the central Gulf today favor a period of rapid intensification. Laura is forecast to make landfall as a major hurricane along the SE TX/SW LA coast late Wednesday.

Laura is a fairly large storm and impacts will be far reaching from the impact point extending both west and east.

Tropical-storm-force winds currently extend outward up to 175 miles (280 km) from the center.

Impacts

Rainfall:

Will rainfall forecast at 2-4 inches east of I-45 and 1-3 inches west of I-45, but this may need to be increased later today. WPC has placed areas east of I-45 in a slight risk for flash flooding.

Most of Houston falls into the light and dark green bands on the left, predicted to get 1-4 inches of rain.
NHC how gives the Houston Area a slight chance of flash flooding (10-20%).
Storm Surge: 

Still looking at 2-4 feet above ground level in Galveston Bay and 4-6 feet on Bolivar with levels of 7-11 feet east of High Island into Louisiana. Should the track shift more west, these values around Galveston Bay would potentially need to be increased significantly.  

Wind: 

Tropical storm force winds will be moving into the area Wednesday evening. Expect winds of 40-50mph across Harris County northward along I-45 with hurricane conditions becoming increasingly likely over Liberty and Chambers Counties. Any additional shift westward in the track will bring stronger winds across the area.

Be prepared for power outages starting Wednesday evening. 

Actions

Enact hurricane plans now.

Follow all recommendation on evacuation from local officials.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT

The National Hurricane Center advises that:

Storm Surge Watch is in effect for San Luis Pass Texas to Ocean Springs Mississippi.

  • High Island TX to Morgan City LA including Sabine Lake, Calcasieu Lake, and Vermilion Bay…7-11 ft
  • Port Bolivar TX to High Island TX…4-6 ft
  • San Luis Pass TX to Port Bolivar TX…2-4 ft
  • Galveston Bay…2-4 ft

Hurricane Watch is in effect for San Luis Pass Texas to west of Morgan City Louisiana

Tropical Storm Watch is in effect for…

  • San Luis Pass to Freeport Texas
  • Morgan City Louisiana to the Mouth of the Mississippi River

A Storm Surge Watch means there is a possibility of life-threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours.

A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous.

For inland watches and warnings, monitor the local National Weather Service forecast office.

Posted by Bob Rehak on 8/25/2020 with input from CoH, Harris County, National Hurricane Center, National Weather Service, and ReadyHarris.

1092 Days After Hurricane Harvey