ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
HURRICANE JOAQUIN DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015
1100 PM EDT WED SEP 30 2015
Joaquin has rapidly intensified during the past 24 hours with the
satellite presentation continuing to improve this evening. The eye
has recently become apparent near the center of the very symmetric
central dense overcast. An Air Force Reserve Hurricane Hunter
aircraft that has been investigating the hurricane this evening has
measured peak 700 mb flight-level winds of 113 kt and 102 kt surface
winds from the SFMR. These data support an initial intensity of
100 kt, making Joaquin the second major hurricane of the 2015
Atlantic hurricane season. NOTE: Communications problems have
delayed the public release of the Air Force reconnaissance data.
Joaquin continues to move slowly southwestward with an initial
motion estimate of 220/5 kt. The hurricane is forecast to move
slowly southwestward or west-southwestward for another 24 hours or
so while it remains to the south of a narrow northeast to southwest
oriented ridge. This ridge is expected to weaken by Friday as a
trough deepens and cuts off over the southeastern United States.
This should cause Joaquin to turn northward within 48 hours. The 18Z
runs of the GFS and HWRF remain in general agreement with the 12Z
UKMET and Canadian models moving Joaquin around the northeastern
portion of the cut-off low and bring the hurricane inland over the
Carolinas or mid-Atlantic states. The 12Z ECMWF remains the outlier
by showing a track toward the northeast out to sea. The NHC
forecast continues to follow the trend of the bulk of the guidance
and takes Joaquin toward the U.S east coast. The NHC track is
similar to the previous advisory and is once again east of the
multi-model consensus. The NOAA G-IV aircraft has recently
completed its synoptic surveillance flight, and data collected
during this mission should be assimilated into the 0000 UTC models,
hopefully reducing the spread of the track guidance.
The upper-level wind pattern over the hurricane is forecast by the
global models to become even more conducive during the next couple
of days. This favors additional intensification, with the only
possible limiting factors being upwelling of cool SSTs beneath the
slow-moving hurricane and eyewall cycles which could cause some
fluctuations in intensity. By 72 hours, increasing southwesterly
shear, dry air intrusion, and lower SSTs are expected to cause
gradual weakening. The updated NHC intensity forecast has been
significantly increased from the previous advisory primarily due to
the higher initial intensity. The official forecast is between the
lower statistical guidance and the higher HWRF during the first
36-48 hours, and is near the SHIPS/LGEM guidance after that time.
1. Preparations to protect life and property within the warning
areas in the Central Bahamas should be completed now.
2. Confidence in the details of the forecast after 72 hours remains
low, since we have one normally excellent model that keeps Joaquin
far away from the United States east coast. The range of possible
outcomes is still large, and includes the possibility of a major
hurricane landfall in the Carolinas.
3. Every effort is being made to provide the forecast models with
as much data as possible. The NOAA G-IV jet has begun a series of
missions in the storm environment, and the National Weather Service
has begun launching extra balloon soundings.
4. Because landfall, if it occurs, is still more than three days
away, it's too early to talk about specific wind, rain, or surge
impacts from Joaquin in the United States. Regardless of Joaquin's
track, strong onshore winds will create minor to moderate coastal
flooding along the coasts of the mid-Atlantic and northeastern
states through the weekend.
5. A hurricane watch for a portion of the U.S. coast could be
required as early as Thursday evening.
6. Many portions of the eastern U.S. are currently experiencing
heavy rains and gusty winds associated with a frontal system. These
heavy rains are likely to continue for the next few days, even if
the center of Joaquin stays offshore. The resulting inland flood
potential could complicate preparations for Joaquin should it head
toward the coast, and even more substantial inland flooding is
possible if Joaquin later passes near or over these same areas.
FORECAST POSITIONS AND MAX WINDS
INIT 01/0300Z 23.8N 73.1W 100 KT 115 MPH
12H 01/1200Z 23.5N 73.8W 110 KT 125 MPH
24H 02/0000Z 23.6N 74.5W 120 KT 140 MPH
36H 02/1200Z 24.7N 74.8W 120 KT 140 MPH
48H 03/0000Z 26.6N 74.7W 110 KT 125 MPH
72H 04/0000Z 31.6N 74.7W 95 KT 110 MPH
96H 05/0000Z 36.2N 75.6W 85 KT 100 MPH
120H 06/0000Z 38.5N 76.5W 55 KT 65 MPH