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Hurricane Harvey Discussion Number 25
NWS National Hurricane Center Miami FL AL092017
1000 AM CDT Sat Aug 26 2017
Harvey has been inland for about 12 hours and weakening is under
way. Doppler radar data indicate that winds have decreased to 65 kt,
and that is the intensity used in this advisory. Since Harvey is
over land, a continued weakening is anticipated, and the NHC
forecast uses the trend provided by the SHIPS decay model. However,
if a portion of Harvey's circulation remains over the Gulf of
Mexico, the cyclone could weaken at a slower rate than shown here.
The hurricane is moving very slowly toward the north at about 2 kt.
Harvey is embedded within very light steering currents, and global
models keep this weak flow in place for the next several days. Based
on this pattern, Harvey could easily meander for the next 4 to 5
days over southeast Texas as indicated in the NHC forecast. The only
agreement among the track guidance is that Harvey is certainly not
going anywhere fast.
This slow motion of the cyclone is expected to exacerbate the
potential for catastrophic flooding from heavy rainfall at least
through the middle of next week.
Please note that hourly Tropical Cyclone Updates (TCUs) have been
discontinued due to the degradation of Harvey's center on radar.
1. While Harvey's winds have begun to weaken, life-threatening
hazards will continue from heavy rainfall over much of southeastern
Texas and from storm surge along portions of the Texas coast.
2. Catastrophic and life-threatening flooding is expected across the
middle and upper Texas coast from heavy rainfall of 15 to 30 inches,
with isolated amounts as high as 40 inches, through Thursday.
Please heed the advice of local officials and do not drive into
flooded roadways. Refer to products from your local National
Weather Service office and the NOAA Weather Prediction Center for
more information on the flooding hazard. A summary of rainfall
totals compiled by the Weather Prediction Center can be found at:
3. A Storm Surge Warning remains in effect for portions of the
Texas. Life-threatening storm surge flooding will be slow to recede
due to the slow motion of Harvey and a prolonged period of onshore
flow. For a depiction of areas at risk, see the Storm Surge
Watch/Warning Graphic at hurricanes.gov.
FORECAST POSITIONS AND MAX WINDS
INIT 26/1500Z 28.9N 97.3W 65 KT 75 MPH...INLAND
12H 27/0000Z 29.1N 97.4W 45 KT 50 MPH...INLAND
24H 27/1200Z 29.2N 97.5W 40 KT 45 MPH...INLAND
36H 28/0000Z 29.0N 97.5W 35 KT 40 MPH...INLAND
48H 28/1200Z 28.7N 97.0W 30 KT 35 MPH...INLAND
72H 29/1200Z 28.7N 96.7W 30 KT 35 MPH...INLAND
96H 30/1200Z 29.5N 96.7W 30 KT 35 MPH...INLAND
120H 31/1200Z 30.5N 96.5W 30 KT 35 MPH...INLAND