Hurricane Ophelia Advisory Number 20
Statement as of 5:00 am EDT on September 11, 2005
...Ophelia slightly stronger but remains stationary...
...Little movement expected today...
At 5 am EDT...0900z...a portion of the Hurricane Watch area from
Savannah River South Carolina northeastward to Edisto Beach South
Carolina has been discontinued.
A Hurricane Watch remains in effect for the southeast coast of the
United States from north of Edisto Beach South Carolina
northeastward to Cape Lookout North Carolina. The Hurricane Watch
may have to be shifted northward later today. A Hurricane Watch
means that hurricane conditions are possible within the watch
area...generally within 36 hours.
Interests elsewhere in the southeastern United States coastal region
should monitor the progress of Ophelia.
For storm information specific to your area...including possible
inland watches and warnings...please monitor products issued
by your local weather office.
At 5 am EDT...0900z...the center of Hurricane Ophelia was located
near latitude 31.7 north... longitude 75.9 west or about 250
miles... 405 km... east-southeast of Charleston South Carolina and
about 245 miles... 390 km...south of Cape Hatteras North Carolina.
Ophelia is stationary and is expected to remain nearly stationary
today.
Maximum sustained winds are near 85 mph... with higher gusts.
Ophelia is a category one hurricane on the Saffir-Simpson scale.
Little change in strength is forecast during the next 24 hours.
Hurricane force winds extend outward up to 30 miles from the
center...and tropical storm force winds extend outward up
to 150 miles.
Estimated minimum central pressure is 978 mb...28.88 inches.
Repeating the 5 am EDT position...31.7 N... 75.9 W. Movement
...Stationary. Maximum sustained winds... 85 mph. Minimum central
pressure... 978 mb.
An intermediate advisory will be issued by the National Hurricane
Center at 8 am EDT followed by the next complete advisory at 11 am
EDT.
Forecaster Knabb
Hurricane Ophelia Discussion Number 20
Statement as of 5:00 am EDT on September 11, 2005
Air Force recon measured a peak 700 mb flight level wind of 85 kt
about 25 N mi west of the center as they departed from their last
fix at around 06z. This is the strongest flight level wind
reported to date in Ophelia and supports increasing the intensity
to 75 kt. The most recent central pressure measured by dropsonde
was 978 mb...basically unchanged during the past several hours. The
75 kt intensity is also consistent with the latest Dvorak
estimates... although the data T numbers are only 4.0 due to the
slight degradation of the satellite appearance since coming out of
the GOES-12 eclipse period... so it is possible that Ophelia is
again a little weaker than 75 kt. While Ophelia might be within an
environment more conducive for strengthening once the upper level
ridge reaches the East Coast and the longitude of the hurricane in
a couple of days... the slow motion of Ophelia could cause ocean
upwelling and provide a counteracting limitation on the intensity.
Given this reasoning and that none of the intensity guidance
forecasts significant changes... the official forecast maintains 75
kt through 72 hours...followed by weakening due to increasing shear
and cooler waters ahead of the next midlatitude trough.
Ophelia remains stationary and sandwiched between strong and deep
high pressure centers over the western half of the Atlantic and
over the east half of the United States. Lacking a substantial
change in this pattern during the next couple of days...very slow
motion is expected. The midlatitude pattern is forecast by the
dynamical models to become more progressive and move the U.S. Ridge
offshore in about 3 days...followed by the next trough which should
then finally get Ophelia moving northeastward. Perhaps due in part
to the synoptic surveillance mission by the NOAA G-IV jet last
night... some of the dynamical models have come into better
agreement on the forecast track. The 00z GFS has shifted more than
100 miles westward and now forecasts landfall over the North
Carolina Outer Banks in three to four days. This shift brings the
GFS into remarkably good agreement with the 00z runs of the NOGAPS
and UKMET. The new official forecast is adjusted somewhat to the
east at 72 hours...and is a little faster therafter... to conform
with this guidance...but is essentially unchanged during the period
of slow motion through day two.
The new forecast implies a lesser possibility of Ophelia directly
impacting the extreme southern end of the Hurricane Watch area...
so a small portion of the watch has been discontinued...from Edisto
Beach southward. However... throughout the remainder of the
Hurricane Watch area... since Ophelia is not yet moving... it is
still much too early to rule out the possibility of hurricane
conditions.
Forecaster Knabb
forecast positions and Max winds
initial 11/0900z 31.7n 75.9w 75 kt
12hr VT 11/1800z 31.6n 76.0w 75 kt
24hr VT 12/0600z 31.6n 76.2w 75 kt
36hr VT 12/1800z 32.0n 76.5w 75 kt
48hr VT 13/0600z 32.6n 76.7w 75 kt
72hr VT 14/0600z 34.0n 76.5w 75 kt
96hr VT 15/0600z 36.5n 75.0w 50 kt
120hr VT 16/0600z 39.5n 71.0w 40 kt