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Tropical Storm Beta Discussion Number   6
NWS National Hurricane Center Miami FL       AL222020
1000 PM CDT Fri Sep 18 2020
 
An Air Force Reserve Hurricane Hunter aircraft investigating Beta
this evening found that the center has re-formed or been tugged
northeastward by bursts of strong convection.  While flying through
that convection, the plane measured a peak flight-level wind of 57
kt at 10,000 feet before descending to 2500 feet.  To the northwest
of the center, the SFMR instrument on the plane measured a solid
area of 46-48 kt, and there have been multiple ship reports in the
region of 40-45 kt.  Based on all these data, Beta's initial
intensity is estimated to be 50 kt.  The plane reported an 
extrapolated minimum pressure of 996 mb on the last pass through 
the center, which also corresponds to a typical 50-kt tropical 
storm.
 
The aircraft fixes indicate that Beta is moving north-northeastward,
or 030/10 kt.  This motion is expected to continue for the next 12
hours or so, but as mid-level ridging develops over the Southern
Plains on Saturday, Beta should begin to slow down and turn
westward.  A slow motion in the direction of the Texas coast should
continue through day 3, with a shortwave trough possibly causing the
cyclone to recurve and move northeastward near or along the Texas
coast on days 4 and 5.  While there remains a large amount of spread
among the track models, they all agree on this general scenario and
indicate that Beta is likely to move very slowly as it makes its
closest approach to the Texas coast.  The initial position fixed by
the plane necessitated a northward shift in the NHC official
forecast compared to the previous forecast for the first 3 days, but
it comes back in line with the previous prediction on days 4 and 5.
 
Beta has been able to strengthen despite being affected by strong
southwesterly shear.  The shear could begin to relax over the next
few days, particularly by day 2 and 3, which could allow for some
further strengthening.  The SHIPS guidance remains the most
aggressive of the intensity models, and the NHC intensity forecast
leans heavily toward those solutions given Beta's recent
intensification trend (which SHIPS seemed to handle better).  Beta
is forecast to steadily strengthen and become a hurricane in a
couple of days as it approaches the Texas coast.  Some weakening is
forecast on days 4 and 5 due to another increase in southwesterly
shear and possible land interaction.
 
 
Key Messages:
 
1. There is an increasing risk of heavy rainfall and flooding along
the northwest Gulf Coast Sunday through at least the middle of next
week as Beta is forecast to move slowly toward and along or offshore
of the coast through that time. For additional information, see
products from your local National Weather Service office.
 
2. Life-threatening storm surge and hurricane-force winds are
possible along portions of the Texas coast early next week, with
tropical storm conditions possible by late this weekend. Storm Surge
and Hurricane watches are in effect, and residents in these areas
should ensure they have their hurricane plan in place and follow
advice given by local officials.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/0300Z 25.5N  92.3W   50 KT  60 MPH
 12H  19/1200Z 26.3N  92.2W   55 KT  65 MPH
 24H  20/0000Z 26.8N  92.8W   60 KT  70 MPH
 36H  20/1200Z 26.8N  93.7W   65 KT  75 MPH
 48H  21/0000Z 27.0N  94.6W   70 KT  80 MPH
 60H  21/1200Z 27.4N  95.5W   70 KT  80 MPH
 72H  22/0000Z 27.8N  96.0W   70 KT  80 MPH
 96H  23/0000Z 28.4N  95.8W   65 KT  75 MPH
120H  24/0000Z 29.4N  94.1W   55 KT  65 MPH
 
$$
Forecaster Berg
 
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