Tag Archive for: NHC

NHC Upgrades Chances of Topical System Formation in Gulf to 80%

Update: This post was created at 10 a.m. As of 1 p.m. the National Hurricane Center upgraded the chances of tropical development another 10% to 90%.

Pacific Tropical Storm Amanda moved into Central America and southern Mexico last weekend. It is now poised to re-emerge into the Gulf of Mexico and may form another tropical system. Since yesterday morning, the National Hurricane Center (NHC) upgraded the chances of formation within the next two days from 40% to 80%. The NHC also upgraded chances of formation within five days from 50% to 80%.

Remnants of Pacific Tropical Storm Amanda over the Yucatan and Central America. Source: NOAA. Motion is toward the northwest.
Source: NOAA National Hurricane Center. As of 7am 6/1/2020.

Will Likely Move into Bay of Campeche

NHC expects this large area of disturbed weather to move northwestward over the southeastern portion of the Bay of Campeche later today or tonight. Environmental conditions there are expected to be conducive to support development.

A new tropical depression is likely to form within within the next day or so.

National Hurricane Center

The system is moving around the northern side of a nearly stationary central American monsoon trough.

Conditions over the Bay of Campeche appear favorable for slow development of a surface low pressure system. Those conditions include:

  • Warm sea surface temperatures
  • Light upper level winds
  • Rising air motions
  • An envelope of tropical moisture.
Water vapor intensity and circulation. Source: University of Wisconsin Madison Space Science and Engineering Center.

Heavy Rainfall for Southern Neighbors For the Moment

Regardless of tropical cyclone formation, heavy rainfall should continue over portions of southern Mexico, Guatemala, El Salvador, Belize, and western Honduras during the next few days.

System Likely to Loop in Bay of Campeche Before Moving North

The tropical system will loop or remained stalled in the Bay of Campeche (the bay between the Yucatan and Mexican mainland) for the next 2-4 days. After that, most models take it toward the US Gulf coast, but there is little agreement among the models at this early stage of formation. Currently, they indicate landfall anywhere between Mexico and Florida. We should have a better indication of the track toward the middle of this week.

Official Start of Hurricane Season Today

Today marks the first day of the Atlantic hurricane season, which will run until November 30. The list of names for 2020 follows:

Two tropical storms, Arthur and Bertha, already formed this year in May. The next named storm that develops this season will be Cristobal.

The NHC monitors significant areas of disturbed weather and their potential for tropical cyclone formation. NHC updates forecasts at 1 AM, 7 AM, 1 AM, and 7 PM CDT.

What You

Harris County Flood Control meteorologist Jeff Lindner advises residents along the US Gulf coast to closely monitor the progress of this system. “Now is a very good time to review plans and fully stock preparation kits,” he says.

Posted by Bob Rehak on 6/1/2020 at 10am with thanks to NHC, HCFCD and Univ. of Wisconsin

1006 Days after Hurricane Harvey

NHC Gives 40-50% Chance of Tropical Cyclone Formation In Gulf This Week

NHC Special Tropical Weather Outlook NWS National Hurricane Center Miami FL 805 AM EDT Sun May 31 2020 For North Atlantic, Caribbean Sea and Gulf of Mexico:

Source: National Hurricane Center 5 Day Tropical Outlook for Atlantic as of 7:05AM CDT on 5/31/2020

The National Hurricane Center (NHC) forecasts the Eastern Pacific Tropical Storm Amanda, now centered inland over southeastern Guatemala, to weaken into a remnant low or dissipate over Guatemala or southeastern Mexico by tonight.

However, the NHC also predicts that the remnants of Amanda will move northwestward within a broader area of disturbed weather, possibly emerging over the southeastern Bay of Campeche on Monday.

If the remnants move back over water, environmental conditions appear conducive to support some redevelopment of the system while it moves little through the middle of this week.

Regardless of redevelopment, heavy rainfall is likely to continue over portions of southern Mexico during the next few days. For additional information on the rainfall threat, see products from your national meteorological service.

The next Special Tropical Weather Outlook will be by 3 PM EDT today, or earlier if necessary.

  • Formation chance through 48 hours…medium…40 percent.
  • Formation chance through 5 days…medium…50 percent.

 If it does become a named storm, it would be Cristobal.

Tropical Storm Amanda will likely cross into the Gulf of Mexico on Monday. (Source: NOAA via Space City Weather).

Too Early to Predict Direction of Storm

Jeff Lindner, Harris County Flood Control District meteorologist, says, “Where exactly any center forms will determine what sort of longer term track would be possible … across the Gulf of Mexico.”

“Regardless of development,” he continues, “a large plume of tropical moisture will be moving into the SW and eventually the western Gulf of Mexico this week. Some of this moisture will likely get directed toward the Texas coast by late week and next weekend.”

“As with any tropical system in this stage of potential development, there is lots of uncertainty.”

“The best course of action is to monitor weather forecasts daily and National Hurricane Center outlooks for any changes.”

Jeff Lindner, Harris County Flood Control meteorologist

Preparedness

Hurricane season starts tomorrow. The NHC predicts above-average activity this hurricane season.

Source: National Hurricane Center prediction on 5/21/2020.

Now would be a good time to prepare. The major risks in the Lake Houston area include river and street flooding (as we saw with Harvey, Allison and Imelda) and wind damage (as we saw with Ike). Ike led to prolonged power outages due to trees falling against power lines.

Make sure you have fresh batteries and a backup supply, as well as a weather radio.

Also make sure you have a way to charge your cell phone (vehicle or power block). And make sure you learn how to use the Harris County Flood Warning System to increase your situational awareness.

Familiarize yourself with the LINKS page of this website. It contains links to many useful sites specializing in preparedness and weather.

Remember: the COVID crisis presents an extra layer of complication this year.

Lake Level Report

As of this morning, the level of Lake Conroe was 200.23 feet and the SJRA continues releasing 1581 cubic feet per second. Their goal: to bring the lake down to 200 feet by tomorrow.

Also as of this morning, the Coastal Water Authority indicates that the level of Lake Houston is down approximately one foot.

Lake Level41.46 ft.
Normal Pool42.4 ft.
Source: Coastal Water Authority readings as of 7:30am 5/31/2020.

Posted by Bob Rehak on 5/31/2020

1006 Days after Hurricane Harvey

Potential for Heavy Rainfall, Flash Flooding Increasing This Week

Low-pressure System Will Meander Near Coast

Lake Charles and Houston radars show numerous clusters and bands of heavy rainfall across Gulf waters associated with deep tropical moisture. These bands will soon begin to move onshore.

Lake Charles radar shows numerous bands of heavy showers just offshore headed this way.
Houston Hobby radar shows similar banding.

Cumulative Rainfall Potential Through Friday

Excessive Rainfall Outlook on Wednesday this Week.

According to Jeff Lindner, Harris County meteorologist, the National Weather Service and National Hurricane Center, models have come into agreement. They predict a surface-low pressure system may form just offshore on Tuesday and drift inland over southeast Texas Tuesday night into Wednesday. The National Hurricane Center currently gives the system only a 10% chance of tropical formation…

…BUT regardless heavy rainfall should result.

Ingredients appear to be coming together late Tuesday through Thursday for a heavy rainfall event over the region. 

Endless Supply of Tropical Moisture

According to Jeff Lindner, Harris County meteorologist, “An endless supply of moisture will pump into the region. Formation of slow-moving, training rain bands appears likely over portions of the area.”

This weather system could produce excessive rainfall, enough to saturate dry ground in a short period of time. Rains today and Tuesday especially south of I-10 will saturate dry ground. Conditions by Wednesday should support much more run-off, over a wider area.

10-15 Inches Possible

Widespread rainfall amounts of 3-6 inches will be likely over much of the area with isolated totals of 10-15 inches possible. 

Hourly rainfall rates of 3-4 inches will be possible under any training bands and any slow-moving clusters resulting in rapid-onset urban flash flooding. The threat for creek, bayou, and river flooding will increase by mid-week as grounds become increasingly saturated and run-off increases.

Flash flooding will be possible.

Posted by Bob Rehak on 9/16/2019 as of 9 a.m.

748 Days since Hurricane Harvey