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Latest Barry Update and How to Interpret a Cone Map

There’s a lot more in a cone map than meets the eye. The map below shows the latest forecast track for Tropical Storm Barry. Here’s a short tutorial on some other things you can get out of it.

Status of Tropical Storm Barry as of 1PM CDT, Friday July 12, 2019

As you can see, the trajectory continues to favor landfall in Louisiana and then movement up through Arkansas. However, these maps convey much more information that may not be apparent at first glance.

What Cone Map Symbols Mean

This graphic shows an approximate representation of coastal areas under a hurricane warning (red), hurricane watch (pink), tropical storm warning (blue) and tropical storm watch (yellow).

The orange circle indicates the current position of the center of the tropical cyclone.

The black line, when selected, and dots show the National Hurricane Center (NHC) forecast track of the center at the times indicated.

The dot indicating the forecast center location will be black if the cyclone is forecast to be tropical and will be white with a black outline if the cyclone is forecast to be extratropical.

If only an L is displayed, then the system is forecast to be a remnant low. The letter inside the dot indicates the NHC’s forecast intensity for that time: 

D: Tropical Depression – wind speed less than 39 MPH
S: Tropical Storm – wind speed between 39 MPH and 73 MPH
H: Hurricane – wind speed between 74 MPH and 110 MPH
M: Major Hurricane – wind speed greater than 110 MPH

Forecasting Uncertainty

NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast “cone”, the solid white and stippled white areas in the cone map graphic.

The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5.

Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time. So about 2 out of 3 times.

How the NHC Forms Cone Maps

To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

Big Difference Between Cone Size and Storm Size

Realize also that a tropical cyclone is not a point. Their effects can span many hundreds of miles from the center.

The area experiencing hurricane force (one-minute average wind speeds of at least 74 mph) and tropical storm force (one-minute average wind speeds of 39-73 mph) winds can extend well beyond the white areas shown enclosing the most likely track area of the center.

Other Linked Graphics Complete the Story

The distribution of hurricane and tropical storm force winds in this tropical cyclone can be seen in this linked Wind History graphic.

Considering the combined forecast uncertainties in track, intensity, and size, the chances that any particular location will experience winds of 34 kt (tropical storm force), 50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in tabular form for selected locations and forecast positions. This information is also presented in graphical form for the 34 kt50 kt, and 64 kt thresholds.

All things considered, the latest forecast shows that there’s only a 5% chance that Houston will see tropical storm force winds from this event.

If you have relatives or friends living closer to the center of the projected path, the tabular data above, will show you the exact percentages for dozens of cities.

To Find the Latest Cone Maps

Go to the National Hurricane Center and click on two-day or five-day. Then scroll to the bottom of the page for many linked graphics that tell the story of the storm.

Rainfall Graphic

Latest rainfall map projects that Houston may get up to an inch of rain, while parts of Louisiana are getting more than 16 inches.

Posted by Bob Rehak with Info from the National Hurricane Center on July 12, 2019

682 Days since Hurricane Harvey

Hurricane Likely for Louisiana Coast; Tropical Storm Force Winds Could Hit Houston on Saturday

NOAA predicts Invest 92L will become Hurricane Barry and hit southwest Louisiana by Saturday morning. That could leave Houston with tropical storm force winds in the 45-70 mph range.

Current forecasts indicate landfall in southwest Louisiana on Saturday morning with the storm strengthening to 85mph just before landfall.
Tropical storm force winds in the 40 to 70 mph range could also hit Houston on Saturday morning. Intensity depends on your location. See map above.
Definite rotation showing, but not yet wound tight. Hurricane hunter planes will fly into the storm this afternoon and weather stations along the coast have doubled their upper air soundings.

Watches Likely To Extend Westward Later Today or Early Thursday, Potentially Include Upper Texas coast

Mid level circulation over the east-central Gulf of Mexico continues to develop. Current ship and buoy data in the central and eastern Gulf of Mexico indicate surface winds of 20-35 knots are already being experienced under deep convection. The US Air Force will fly the area early this afternoon to determine if/where a center of circulation has formed.

NOAA and USAF plan multiple low- and high-level missions. Effective today, weather offices along the US Gulf coast will begin launching upper air soundings every 6 hours instead of every 12. 

Track Remains Uncertain

There is still considerable uncertainty concerning the track of the storm. Adjustments remain possible and all residents within the error cone should make preparations.

85 MPH Winds Predicted at Landfall

The National Hurricane Center predicts an 85 mph hurricane before landfall in Louisiana. Much of this intensification occurs within the last 24 hours before landfall. While conditions in the near term (next 24-36 hours) are generally favorable for development, consolidation of the inner core will take some time. Much of the development should occur as the system nears the coast.

Tropical storm force winds in the 40 to 70 mph range could hit Houston – also on Saturday morning.

Jeff Lindner, Harris County Meteorologist, feels, “This will likely be a case where an intensifying hurricane is approaching the coast on Saturday.”

Storm Surge Watch In Effect for Texas Coast

Tropical storm and hurricane conditions are likely along portions of the Louisiana coast starting Friday and more likely into Saturday. Large long period swells will move into the upper Texas coastal waters starting late Thursday and building Friday into the weekend. This could push tides up along the Gulf facing beaches late Friday into the weekend (Bolivar).

Should the forecast track adjust westward any, impacts to the upper TX would be increased.

Recommended Actions

A large portion of southeast Texas remains in the official error cone. If the track shifts westward again, as it did last night, it could produce greater impacts to our area.

  • Have hurricane plans ready to be enacted if the track shifts to the west.
  • Stock hurricane supplies.
  • Monitor forecasts frequently. 

Posted by Bob Rehak on July 10, 2019 at 12:30pm

680 Days since Hurricane Harvey