Hurricane Laura, Category 4, Nears Landfall In Louisiana - Could Affect The Region This Weekend

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WTNT43 KNHC 270255

TCDAT3

Hurricane Laura Discussion Number  29

NWS National Hurricane Center Miami FL       AL132020

1000 PM CDT Wed Aug 26 2020

Extremely dangerous Laura has the signature of a classic hurricane

on satellite images, with a well-defined eye surrounded by very

deep convection.  There is little evidence of shear, and the

upper-level outflow pattern is extremely well defined, while the

cyclone is over sea surface temperatures near 30 deg C.

Observations from both NOAA and Air Force Hurricane Hunter

aircraft show that Laura continued to strengthen during the

evening.  Using a blend of adjusted flight-level and SFMR-observed 

surface winds, the intensity estimate is 130 kt for this advisory.  

Since there is now little time remaining for the system over water, 

no significant change in intensity is anticipated until the center 

crosses the coastline.  Laura will weaken rapidly after it begins 

to move over land, but destructive winds should spread well inland, 

more than 100 miles, along its path.  Later in the forecast period, 

the ECMWF and U.K. Met. Office global models indicate some 

baroclinic re-intensification as the remnants of Laura move off the 

U.S. East coast, and this is reflected in the NHC forecast.

Laura has begun to turn northward as it moves around the western

side of a subtropical high pressure area, and the initial motion is

about 340/13 kt.  The track forecast is essentially unchanged

from the previous advisories.  The cyclone should move through a

weakness in the ridge and turn to the northeast over the next day

or two.  Then the system should accelerate toward the

east-northeast while embedded in the westerlies.  The official 

track forecast remains close to both the simple and the corrected 

dynamical model consensus predictions, TVCA and HCCA.

Laura is a large hurricane, and users are reminded to not focus on

the precise track forecast since wind, storm surge, and rainfall

hazards extend far from the center.

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 40 miles inland from the immediate

coastline, and flood waters will not fully recede for several days

after the storm.

2. Hurricane-force winds are expected tonight in portions of the

hurricane warning area, with catastrophic wind damage expected

where Laura's eyewall moves onshore. Hurricane-force winds and

widespread damaging wind gusts will spread well inland into portions

of extreme eastern Texas and western Louisiana early Thursday.

3. Widespread flash flooding along small streams, urban areas, and

roadways is expected to begin overnight tonight into Thursday from

far eastern Texas into Louisiana and Arkansas. This will also lead

to minor to moderate freshwater river flooding. The heavy rainfall

threat and flash and urban flooding potential will spread

northeastward into the middle-Mississippi, lower Ohio, and Tennessee

Valleys Friday night and Saturday.

FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 29.0N  93.2W  130 KT 150 MPH

 12H  27/1200Z 31.0N  93.7W   95 KT 110 MPH...INLAND

 24H  28/0000Z 33.8N  92.9W   50 KT  60 MPH...INLAND

 36H  28/1200Z 35.6N  91.5W   35 KT  40 MPH...INLAND

 48H  29/0000Z 36.8N  88.2W   25 KT  30 MPH...INLAND

 60H  29/1200Z 37.5N  82.7W   25 KT  30 MPH...POST-TROP/INLAND

 72H  30/0000Z 38.5N  75.5W   30 KT  35 MPH...POST-TROP/EXTRATROP

 96H  31/0000Z 45.0N  60.0W   45 KT  50 MPH...POST-TROP/EXTRATROP

120H  01/0000Z 52.0N  46.0W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$

Forecaster Pasch