8/28/21 8AM Hurricane Ida Update: Rapid Intensification underway

Taking a look at the forecast information from the National Hurricane Center as well as satellite data, and there is little doubt that Hurricane Ida has begun to rapidly intensify this morning.

Infrared imagery of Hurricane Ida // Courtesy: Tropical Tidbits


Current Observations

LOCATION…24.4N 85.7W
ABOUT 385 MI…620 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 440 MI…710 KM SSE OF NEW ORLEANS LOUISIANA
PRESENT MOVEMENT…NW OR 315 DEGREES AT 16 MPH…26 KM/H

MINIMUM CENTRAL PRESSURE…985 MB…29.09 INCHES
EYE DIAMETER 25 NM

MAXIMUM SUSTAINED WINDS…85 MPH…140 KM/H
WIND…… DISTANCE / DIRECTION
64 KT……. 20/NE || 0/SE || 0/ SW || 0/NW.
50 KT……. 50/NE || 30/SE || 0/SW || 30/NW.
34 KT…….100/NE || 60/SE || 40/SW || 70/NW.
12 FT SEAS..120/NE || 60/SE || 60/SW || 120/NW.

FORECAST POINTS
INIT 28/0900Z 24.0N 85.2W 70 KT 80 MPH
12H 28/1800Z 25.4N 86.9W 85 KT 100 MPH
24H 29/0600Z 27.1N 88.9W 105 KT 120 MPH
36H 29/1800Z 28.6N 90.5W 120 KT 140 MPH
48H 30/0600Z 30.1N 91.3W 85 KT 100 MPH…INLAND
60H 30/1800Z 31.6N 91.2W 45 KT 50 MPH…INLAND
72H 31/0600Z 33.2N 90.5W 30 KT 35 MPH…INLAND
96H 01/0600Z 36.0N 87.0W 25 KT 30 MPH…INLAND
120H 02/0600Z 37.5N 82.5W 20 KT 25 MPH…POST-TROP/REMNT LOW



Key Messages

  1. Hurricane and tropical storm conditions are ending over Cuba. However, Ida will continue to bring periods of heavy rain across western Cuba through today that may lead to flash flooding and mudslides.
  2. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana and Mississippi within the Storm Surge Warning area. Extremely life-threatening inundation of 10 to 15 feet above ground level is possible within the area from Morgan City, Louisiana, to the Mouth of the Mississippi River. Interests throughout the warning area should follow any advice given by local officials.
  3. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area.
  4. Ida is likely to produce heavy rainfall later Sunday into Monday across the central Gulf Coast from southeast Louisiana to coastal Mississippi resulting in significant flash and riverine flooding impacts. As Ida moves inland, flooding impacts are possible across portions of the Lower Mississippi and Tennessee Valleys.


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Brief Discussion

At 700 AM CDT (1200 UTC), the center of Hurricane Ida was located near latitude 24.4 North, longitude 85.7 West. Ida is moving toward the northwest near 16 mph (26 km/h) and this general motion should continue through late Sunday or early Monday, followed by a slower northward motion on Monday. On the forecast track, the center of Ida will move over the southeastern Gulf of Mexico today and move over the central Gulf of Mexico tonight and early Sunday. Ida is then expected to make landfall along the U.S. northern Gulf coast within the hurricane warning area on Sunday, and then move inland over portions of Louisiana or western Mississippi later on Monday.

Maximum sustained winds have increased to near 85 mph (140 km/h) with higher gusts. Rapid strengthening is forecast during the next 24 to 36 hours and Ida is expected to be an extremely dangerous major hurricane when it approaches the northern Gulf coast on Sunday. Weakening is expected after Ida makes landfall.

Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 115 miles (185 km).

The latest minimum central pressure estimated from NOAA reconnaissance aircraft data is 985 mb (29.09 inches).



Anticipated Impacts

STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide…

Morgan City, LA to Mouth of the Mississippi River…10-15 ft
Mouth of the Mississippi River to Ocean Springs, MS including Lake Borgne…7-11 ft
Intracoastal City, LA to Morgan City, LA including Vermilion Bay…6-9 ft
Ocean Springs, MS to MS/AL border…4-7 ft
Lake Pontchartrain…4-7 ft
Lake Maurepas…3-5 ft
Pecan Island, LA to Intracoastal City, LA…3-5 ft
MS/AL border to AL/FL border including Mobile Bay…2-4 ft
Sabine Pass to Pecan Island, LA…2-4 ft

Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher than those shown above.

The deepest water will occur along the immediate coast near and to the east of the landfall location, where the surge will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.

WIND: Hurricane conditions are expected in the hurricane warning area along the northern Gulf coast beginning Sunday with tropical storm conditions expected to begin by late Saturday night or early Sunday morning. These conditions will spread inland over portions of Louisiana and Mississippi Sunday night and Monday. Gusty winds are possible over portions of western Cuba and the Florida Keys this morning.

RAINFALL: Ida will bring an additional 2 to 4 inches of rain with isolated maximum amounts of 6 inches across western Cuba today. These rainfall amounts may produce flash floods and mudslides.

As Ida moves into the Louisiana coast late Sunday, total rainfall accumulations of 8 to 16 inches with isolated maximum amounts of 20 inches are possible across southeast Louisiana and southern Mississippi through Monday. This rainfall is likely to result in significant flash and riverine flooding impacts.

Ida is forecast to turn northeast as it moves inland later Monday, with rainfall totals of 4 to 8 inches possible from northeastern Louisiana and central Mississippi into the Tennessee Valley. This is likely to result in considerable flash and riverine flooding impacts.

TORNADOES: A few tornadoes will be possible Sunday through early Monday across southeast Louisiana and southern Mississippi.

SURF: Swells generated by Ida will continue to affect western Cuba through today. Swells will begin reaching portions of the northern Gulf coast later today and continue through Monday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.



Watches & Warnings

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for…

  • East of Rockefeller Wildlife Refuge Louisiana to the Mississippi/Alabama border
  • Vermilion Bay, Lake Borgne, Lake Pontchartrain, and Lake Maurepas

A Hurricane Warning is in effect for…

  • Intracoastal City Louisiana to the Mouth of the Pearl River
  • Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans

A Storm Surge Watch is in effect for…

  • Sabine Pass to Rockefeller Wildlife Refuge Louisiana
  • Mobile Bay

A Hurricane Watch is in effect for…

  • Cameron Louisiana to west of Intracoastal City Louisiana
  • Mouth of the Pearl River to the Mississippi/Alabama border

A Tropical Storm Warning is in effect for…

  • Cameron Louisiana to west of Intracoastal City Louisiana
  • Mouth of the Pearl River to the Mississippi/Alabama border

A Tropical Storm Watch is in effect for…

  • Mississippi/Alabama border to the Alabama/Florida border

A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

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.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.



Technical Discussion

Just after the last advisory, the convective structure of Ida got a bit ragged, probably due to the residual effects of land interaction with Cuba and a tongue of dry air that wrapped into the eastern side of the circulation. However, latest radar images from Cuba show that the eye is becoming better defined, and satellite imagery shows cooling of the cloud tops in the eyewall.

The initial intensity has been held at 70 kt based on the latest trends and earlier Hurricane Hunter aircraft data. NOAA and Air Force reserve Hurricane Hunter aircraft are scheduled to investigate Ida again starting around 12Z.

The initial motion remains northwestward or 315/14. A subtropical ridge centered off the southeast U.S. coast is expected to shift westward through the weekend, and this feature should continue to provide a steering flow that will take Ida steadily northwestward across the Gulf of Mexico during the next 36-48 h. The track guidance remains in good agreement that Ida will make landfall on the coast of southeastern or central Louisiana late Sunday or early Monday morning.

After landfall, Ida is expected to turn northward through Louisiana and western Mississippi at a slower forward speed as it moves around the western end of the ridge. Recurvature into the westerlies and an east-northeastward motion are expected by the end of the forecast period. The new forecast track is nudged slightly to the west after 36 h to keep it near the various consensus models, but this is not a significant change from the previous forecast.

Users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center.

Ida is expected to remain in a favorable environment of light vertical shear and very warm sea-surface temperatures until it makes landfall. The only negative factor is the possibility that dry air may try to entrain into the system and slow the expected intensification.

The SHIPS and LGEM models are showing a little less strengthening than previously. However, the HWRF and HMON models continue to forecast Ida to reach Category 4 intensity before landfall. The new intensity forecast will forecast a peak intensity of 120 kt in best agreement with the HWRF and HMON, and the pre-landfall part of the forecast is little changed from the previous forecast. After landfall, rapid weakening is expected due to land interaction, drier air, and an increase in shear, and Ida is expected to become a post-tropical cyclone as it moves through the Tennessee Valley.

As Ida continues to intensify over the Gulf of Mexico, an expansion of its wind field is predicted. The NHC wind radii forecast is largely based on the radii consensus, and winds of at least tropical storm force are likely to reach the coast Sunday morning.

Therefore, all preparations to protect life and property for this dangerous event need to be made today.



Author of the article:


Nick Lilja

Nick is former television meteorologist with stints in Amarillo and Hattiesburg. During his time in Hattiesburg, he was also an adjunct professor at the University of Southern Mississippi. He is a graduate of both Oregon State and Syracuse University that now calls Houston home. Now that he is retired from TV, he maintains this blog in his spare time.