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Hurricane Laura Discussion Number  23
NWS National Hurricane Center Miami FL       AL132020
1000 AM CDT Tue Aug 25 2020

Satellite imagery shows that Laura has become a little better 
organized since it crossed western Cuba, and it now has a central 
dense overcast and some outer banding in the southern quadrant.  
Reports from Air Force Reserve and NOAA Hurricane Hunter aircraft 
included SFMR winds of near 65 kt, 700-mb flight-level winds as high 
as 77 kt, and a central pressure near 990 mb.  Based on these data, 
Laura has been upgraded to a hurricane with an initial intensity of 
65 kt.

The initial motion is west-northwestward or 290/14 kt.  The 
hurricane is currently on the south side of a large-deep layer ridge 
over the southeastern United States, and it is moving toward a break 
in the ridge caused by mid- to -upper-level troughing over Texas and 
the southern Great Plains.  The current and forecast synoptic 
pattern should steer Laura west-northwestward today followed by a 
turn toward the northwest tonight and toward the north by Wednesday 
night and Thursday.  This will result in the hurricane making 
landfall in the area of southwestern Louisiana or the upper Texas 
coast late Wednesday night or Thursday morning.  The new forecast 
track before landfall has been nudged a little to the west of the 
previous track in response to a westward nudge in the guidance.  
However, it still lies a little east of the consensus models at the 
time of landfall.  After landfall, Laura is expected to recurve into 
the westerlies and move eastward through the Tennessee Valley and 
the mid-Atlantic States.

The hurricane currently looks a little ragged, with little or no 
convection outside of the central dense overcast and the southern 
quadrant banding.  This may be due to dry air in the vicinity and 
some light northerly shear.  Conditions appear generally favorable 
for strengthening during the next 36 h, and the new intensity 
forecast calls for Laura to become a major hurricane during this 
time.  The global model are in good agreement that the hurricane 
should encounter increasing shear in the last 12 h before landfall, 
although the potential impacts on the landfall intensity are 
unclear.  After landfall, Laura should weaken through the 96 h 
point.  After that, some re-intensification is expected as the 
storm becomes extratropical.
 
Users are again reminded not to focus on the exact details of the
track or intensity forecasts as the average NHC track error at 48 h
is around 80 miles and the average intensity error is close to 15
mph. In addition, wind, storm surge, and rainfall hazards will
extend far from the center.
 
Key Messages:
 
1. Laura is forecast to reach the northwestern Gulf Coast at or 
near major hurricane intensity Wednesday night. Do not focus on the 
details of the official forecast given the typical uncertainty in 
NHC's track and intensity predictions. Storm surge, wind, and 
rainfall hazards will extend well away from Laura's center along the 
Gulf Coast.

2. There is the danger of life-threatening storm surge accompanied 
by large and dangerous waves from San Luis Pass, Texas, to the Mouth 
of the Mississippi River, including areas inside the Port Arthur 
Hurricane Flood Protection system. A Storm Surge Warning is in 
effect and residents should follow any advice given by local 
officials. Actions to protect life and property should be rushed to 
completion today, as water levels will begin to rise Wednesday. 

3. Hurricane conditions are expected by Wednesday evening in the 
area from San Luis Pass, Texas, to west of Morgan City, Louisiana, 
and a Hurricane Warning is in effect. Tropical storm conditions are 
expected to begin in the warning area Wednesday afternoon. 

4. The threat of widespread flash and urban flooding along with 
small streams overflowing their banks will be increasing Wednesday 
night into Thursday from far eastern Texas, across Louisiana, and 
Arkansas. This will also lead to minor to isolated moderate river 
flooding.  The heavy rainfall threat will spread northeastward into 
the middle-Mississippi, lower Ohio, and Tennessee Valleys Friday and 
Saturday.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  25/1500Z 23.7N  87.0W   65 KT  75 MPH
 12H  26/0000Z 24.6N  89.2W   75 KT  85 MPH
 24H  26/1200Z 26.0N  91.5W   90 KT 105 MPH
 36H  27/0000Z 28.0N  93.3W  100 KT 115 MPH
 48H  27/1200Z 30.5N  93.9W   80 KT  90 MPH...INLAND
 60H  28/0000Z 33.1N  93.6W   45 KT  50 MPH...INLAND
 72H  28/1200Z 35.2N  92.1W   30 KT  35 MPH...INLAND
 96H  29/1200Z 37.5N  83.5W   25 KT  30 MPH...INLAND
120H  30/1200Z 40.5N  69.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Beven
 
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