POST-TROPICAL CYCLONE HERMINE ADVISORY NUMBER 28
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016
500 AM EDT SUN SEP 04 2016
...HERMINE EXPECTED TO SLOW DOWN AND TURN NORTHWARD LATER TODAY...
...DANGEROUS STORM SURGE TO CONTINUE ALONG THE COAST FROM VIRGINIA
TO NEW JERSEY...
SUMMARY OF 500 AM EDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...36.8N 70.8W
ABOUT 305 MI...485 KM SSE OF THE EASTERN TIP OF LONG ISLAND
ABOUT 255 MI...415 KM ESE OF OCEAN CITY MARYLAND
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...ENE OR 65 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning has been discontinued south of Duck,
North Carolina.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for...
* Duck to west of Watch Hill
* Chesapeake Bay from Smith Point southward
* Delaware Bay
A Tropical Storm Watch is in effect for...
* Watch Hill to Sagamore Beach
* Block Island
* Martha's Vineyard
* Nantucket
For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.
DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 500 AM EDT (0900 UTC), the center of Post-Tropical Cyclone
Hermine was located near latitude 36.8 North, longitude 70.8 West.
The post-tropical cyclone is moving toward the east-northeast near
12 mph (19 km/h). A turn toward the northeast and the north with a
decrease in forward speed is expected later today, followed by a
slow northward to northwestward motion through Monday. On the
forecast track, the center of Hermine will meander slowly offshore
of the mid-Atlantic coast for the next couple of days.
Maximum sustained winds are near 65 mph (100 km/h) with higher
gusts. Little change in strength is expected today. After that, the
cyclone is forecast to intensify to hurricane force late tonight and
on Monday.
Hermine has a large wind field. Tropical-storm-force winds extend
outward up to 205 miles (335 km) from the center.
The minimum central pressure based on recent reports from an Air
Force Reserve reconnaissance aircraft is 998 mb (29.47 inches).
HAZARDS AFFECTING LAND
----------------------
WIND: Tropical storm conditions will continue to spread northward
within the warning area along the Atlantic coast through Monday,
and there may be multiple occurrences of tropical storm conditions
along portions of the mid-Atlantic coast in the warning area during
the next couple of days. Tropical storm conditions are possible in
the watch area by Monday.
STORM SURGE: The combination of a storm surge and the tide will
cause normally dry areas near the coast to be flooded by rising
waters moving inland from the shoreline. Along the immediate
coastline, the surge will be accompanied by large and dangerous
waves. There is a danger of life-threatening inundation through
tonight in the Hampton Roads area, and in the next 36 hours from
Chincoteague, Virginia, to Sandy Hook, New Jersey. Persons within
these areas should take all necessary actions to protect life and
property from rising water. Promptly follow all instructions,
including evacuation orders, from local officials. There is also
the possibility of life-threatening inundation during the next 48
hours at many coastal locations between Sandy Hook, New Jersey, and
Bridgeport, Connecticut.
For a depiction of areas at risk, please see the Prototype Storm
Surge Watch/Warning graphic, which displays areas that would qualify
for inclusion under a storm surge watch or warning currently under
development by the National Weather Service and planned for
operational use in 2017. The Prototype Graphic is available at
www.hurricanes.gov/graphics_at4.shtml?wsurge
The water could reach the following heights above ground if the
peak surge occurs at the time of high tide...
North Carolina sounds...1 to 3 feet
Hampton Roads area...2 to 4 feet
Chincoteague, VA to Sandy Hook, NJ...3 to 5 feet
Sandy Hook, NJ to Bridgeport, CT...2 to 4 feet
RAINFALL: Heavy rainfall associated with Hermine will remain
offshore through Monday/Labor Day. Hermine will produce rainfall
amounts of 1 to 2 inches over southern New England from Long Island
to eastern Massachusetts, and additional rainfall of one inch or
less along the coastline of the mid-Atlantic states.
SURF: Large waves generated by Hermine will affect the U.S. east
coast from the mid-Atlantic states and expand northward along the
coast of southern New England through Monday. These waves are
likely to cause life-threatening surf and rip current conditions,
and significant beach erosion. Please consult products from your
local weather office.
NEXT ADVISORY
-------------
Next intermediate advisory at 800 AM EDT.
Next complete advisory at 1100 AM EDT.
$$
Forecaster Stewart
POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER 28
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016
500 AM EDT SUN SEP 04 2016
The overall structure of Hermine has changed little during the past
6 hours. A ring of shallow convection has developed within 60-100
n mi northwest through northeast of the center, possibly due to that
portion of the circulation passing over the Gulf Stream, where water
temperatures are 29-30C. An earlier ASCAT-B pass indicated that
winds had decreased to 50-55 kt, and recent data from an Air Force
Reserve reconnaissance aircraft confirms that Hermine has peak
winds of 55 kt.
The initial motion estimate is 065/10 kt. Hermine is expected to
move slowly northward and perhaps erratically during the next 36
hours as the post-tropical cyclone begins to interact with an
approaching strong mid-/upper-level shortwave trough that is
gradually becoming more negatively tilted based on water vapor
imagery. By 36-48 hours, Hermine is expected to become vertically
stacked beneath a cut-off low, which could result in the cyclone
briefly stalling south of southern New England before lifting out to
the northeast by 72 hours. The models are in fairly good agreement
on this developing track scenario through about 36 hours, but then
diverge significantly after that with the UKMET model turning
Hermine farther west closer to the New Jersey coast while the ECMWF
lifts out Hermine more quickly. The GFS solution lies between these
two extremes, and the new forecast track closely follows that model.
However, there remains low confidence in any particular model.
Little change in strength is likely today. However, by late tonight
and on Monday, the models indicate that at least 6 deg C of cooling
in the mid-/upper-levels will occur when Hermine's low-level
circulation moves underneath the cut-off low. The combination of the
much cooler air aloft over SSTs of at least 27-28C should generate
strong instability and some inner-core convection, possibly
resulting in a Hermine making the transition to a subtropical
cyclone and strengthening back to hurricane force. The guidance is
in good agreement that the system should slowly weaken after 48
hours when the system will be moving over much cooler water north
of the Gulf Stream. The intensity forecast closely follows a blend
of the GFS-ECMWF model solutions.
KEY MESSAGES:
1. The slow motion and large wind field associated with Hermine will
result in a long duration of hazardous conditions along much of the
mid-Atlantic coast extending into southern New England through the
holiday weekend and into midweek.
2. Small changes in the meandering track of Hermine could result in
large differences in the impacts along the mid-Atlantic coast during
the next several days. In addition, there could be multiple
occurrences of tropical storm conditions in some locations within
the warning area during this time.
3. Although Hermine has become a post-tropical cyclone, NHC will
continue to issue its full suite of advisory and warning products as
long as the system remains a significant threat to land areas.
4. P-surge, the model that drives the Potential Storm Surge Flooding
Graphic, is designed for a wind field typical of a tropical cyclone.
The wind field of Hermine is very poorly represented by the P-surge
model and as a result, Flooding Graphics prior to today's 11 am
EDT advisory understated the inundation risk from the Carolinas
northward. The NWS is using the GFS ensemble system instead of
P-surge for ongoing issuances of the Potential Storm Surge Flooding
Graphic to provide a more realistic depiction of the threat.
5. The Prototype Storm Surge Watch/Warning Graphic accounts for
the current wind structure of Hermine, and therefore accurately
identifies those areas at risk for life-threatening storm surge.
This graphic will also continue to be produced for Hermine.
FORECAST POSITIONS AND MAX WINDS
INIT 04/0900Z 36.8N 70.8W 55 KT 65 MPH
12H 04/1800Z 37.2N 70.3W 55 KT 65 MPH...POST-TROPICAL
24H 05/0600Z 37.7N 70.6W 60 KT 70 MPH...POST-TROPICAL
36H 05/1800Z 38.0N 71.0W 65 KT 75 MPH...POST-TROPICAL
48H 06/0600Z 38.5N 70.8W 65 KT 75 MPH...POST-TROPICAL
72H 07/0600Z 39.2N 70.0W 60 KT 70 MPH...POST-TROPICAL
96H 08/0600Z 40.3N 68.0W 55 KT 65 MPH...POST-TROPICAL
120H 09/0600Z 41.5N 63.5W 50 KT 60 MPH...POST-TROPICAL
$$
Forecaster Stewart