WORLD METEOROLOGICAL ORGANIZATION
___________________________
RA IV HURRICANE COMMITTEE
RA IV/HC-35/Doc. 6, ADD. 1, REV.
(05.IV.2013)
________
THIRTY-FIFTH SESSION
ITEM 6
WILLEMSTAD, CURACAO
ENGLISH ONLY
8 TO 12 APRIL 2013
REVIEW OF THE RA IV HURRICANE OPERATIONAL PLAN
(Submitted by the RSMC Miami – Hurricane Center, USA)
Summary and Purpose of Document
Information and proposals are provided in this document to assist the
Committee in its review of the RA IV Hurricane Operational Plan.
ACTION PROPOSED
The Hurricane Committee is invited to take into consideration the actions and
recommendations proposed in the Appendix in its review of RA IV Hurricane Operational
Plan.
__________________
Appendix:
Proposed changes in the RSMC products
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX
PROPOSED ACTION ITEMS by RSMC Miami (2013)
1
Title
Implementation of a Storm Surge Warningin the United States ( informational item)
Submitter
RSMC Miami
Date Submitted
April 2013
Discussion
INFORMATIONAL: Tropical cyclones have killed more than 25,000 people in the United States since its
founding, with a majority of those deaths attributable to storm surge. At least one storm in each decade
from the 1890s through the 1960s claimed hundreds or even thousands of lives due to surge. The problem
continues to this day, with hundreds more lives lost in the decade just concluded.
Given this history, it is remarkable that the U.S. NWS does not issue warnings for the phenomenon that
presents the greatest weather-related threat for a massive loss of life in a single day. Other tropical cyclone
hazards, such as tornadoes and rain-induced floods, have specific associated warnings, while historically
the surge threat has been implicitly contained in the coastal “Hurricane Warning” — a warning that simply
means that hurricane conditions are expected within the warned area within the next 36 hours. While
forecasters can consider storm surge in their hurricane warning issuances, in practice the warning best
reflects the timing and extent of the wind field. The visibility of surge was further diminished when the
NWS eliminated the distinction between the coastal and inland hurricane warnings at the 2010 NOAA
Hurricane Conference.
The NWS and its partners in emergency management have long (and rightly so) advocated different
responses to the wind and surge threats posed by hurricanes (e.g., “hide from the wind, run from the
water”). Unfortunately, the current paradigm of burying the surge hazard within the hurricane warning has
proven ineffective in helping the public differentiate between these two threats.
The need for an improved warning paradigm was first informally discussed between NHC and coastal
WFOs in 2002. In the years that followed, several noteworthy storm surge events occurred (e.g., Isabel,
Ivan, Katrina, Rita, Gustav, and Ike), and in 2008 NHC prepared a white paper that formally endorsed the
concept of a storm surge warning. The white paper led to the establishment of an NWS Storm Surge
Team, which was charged with exploring new ways to communicate the storm surge hazard, including the
possibility of a storm surge warning. Based on input received during the 2009 NOAA Hurricane
Conference and the resulting action items, the NWS began to work with the social science community to
assess users’ needs regarding storm surge information.
Multiple studies indicated significant confusion on the part of the public regarding storm surge risk, and
highlighted the need for improved products and graphics to communicate storm surge forecast information.
The studies also showed overwhelming support for an explicit storm surge warning among emergency
managers and broadcast meteorologists, along with a desire for better visualizations of NWS storm surge
forecasts. Other federal agencies and private weather vendors have also expressed the need for nationalscale storm surge information. By establishing a storm surge warning, the NWS will be taking an
important step forward to join and become consistent with a number of other countries that have already
introduced such warnings into their repertoire.
The 2010 NOAA Hurricane Conference endorsed continued development and testing of a storm surge
warning in conjunction with the development of a high-resolution inundation graphic. Based on the action
items from that Conference, the NWS Storm Surge Team developed an initial concept of operations
(CONOPS), which was subsequently tested with WFO Morehead City in 2011 during Hurricane Irene.
Results from this test were presented to the 2011 NOAA Hurricane Conference and received positive
feedback. However, the initial tests were conducted with non-NWS software, and the 2011 NOAA
Hurricane Conference requested more formal testing within the existing NWS IT infrastructure. As a
result, a new technical team was formed and tasked with developing an AWIPS/GFE collaborative
watch/warning tool. The initial AWIPS/GFE tool was developed and operationally tested with WFO
Tampa Bay, Slidell, and Miami during the 2012 hurricane season in Tropical Storm Debby and Hurricane
Isaac. Efforts are now underway to transition the existing GFE tool to AWIPS2.
NHC intends to continue working toward operational implementation of a U.S. storm surge warning at the
earliest possible date. Based on the experiences gained in 2011 and 2012, NHC has refined the original
CONOPS (detailed below) and plans to conduct a more extensive test with additional WFOs during the
2013 hurricane season. It is expected that additional modifications of the CONOPS will occur during the
experimental period.
Current Storm Surge Watch/Warning CONOPS
Warning name:
Storm surge warning (watch)
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX, p. 2
Definition:
A significant risk of life-threatening flooding from rising water moving inland from the
shoreline. The warning (watch) is generally issued within 36 hours (48 hours) of the arrival of tropical
cyclone conditions that would hinder evacuation or other surge preparedness actions.
Operational criteria:
Subject to the additional guidance below, the warning or watch shall be
issued for those locations assessed to meet at least one of the following criteria:
•
•
At least a 20% chance of surge-related inundation of 4 feet or more.
At least a 5% chance of surge-related inundation of 8 feet or more.
Additional guidance:
•
Issue the warning (watch) 36 h (48 h) in advance of the arrival of any tropical cyclone hazard
that is expected to hinder evacuations or other surge preparedness actions.
•
The primary guidance for the assessments will be probabilistic exceedance and P-surge
products, based on historical tropical cyclone forecast errors.
•
Where practical, inundation assessments should consider the combined effects of storm surge,
astronomical tide, and waves.
•
Subjective factors (such as continuity, or situation-dependent assessments of the uncertainty in
the track, intensity, or structure forecasts for the tropical cyclone) may also be used to inform the
probabilistic assessment of risk and specify the area to be warned.
•
To enhance continuity, P-surge risk assessments should be based on an appropriate time horizon
beyond the nominal 36 h (48 h) period of the surge warning (watch). For example, an approach
normal to the coastline could consider the cumulative inundation risk through 72 h or even
longer, while a 48-h cumulative risk might be more appropriate for an approach oblique or
parallel to the coastline.






Storm Surge Watch/Warning will use SS.A for and SS.W for event codes.
NHC would initiate the collaboration process as demonstrated and tested during the 2011 realtime tests with pilot offices.
When the collaboration process is finalized, a national TCV-like product for storm surge
watch/warning would be issued by NHC. Along with the TCV-like product, a graphical
depiction of the final coordinated storm surge W/W would be issued by NHC.
After merging of the SSA/SSW into the WFO Hazard grid, information will provide headline
information for WFO products most notably the HLS.
This assumes that even after NHC is no longer issuing advisories on a storm (extratropical
transition), NHC will continue the TCV-like product as long as there is a remnant surge threat
as needed and that the WFOs can continue to use their HLS to address the hazard. This would
prevent switching gears in the middle of an event. Note this only applies to storm surge
warnings which were initiated for a tropical event. Storm surge warnings arising from posttropical events, assuming warnings were not initiated during the tropical phase, will be handled
using the ET storm surge warning CONOPs.
For extratropical storm systems, the WFO will be able to use the same event code to issue storm
surge watches and warnings using the CFW.
Call to action:
This is a life-threatening situation. Persons located within the warning areas should
take all necessary actions to protect life and property, including evacuation if instructed by local officials.
Actions underway by the NOAA/NWS:
1)
Recommendation
The NOAA Hurricane Conference agrees on implementation of an experimental, publically-available
U.S. tropical cyclone storm surge watch and warning in 2015. This will be accompanied or preceded
by a high resolution inundation graphic.
Informational; brief members WMO RA-IV and RA-V.
Action
2
Title
Medium-Range Tropical Cyclone Genesis Probabilities
Submitter
RSMC Miami
Date Submitted
April 2013
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX, p. 3
Discussion
INFORMATIONAL: RSMC Miami has been producing 1-5 day tropical cyclone genesis probabilities inhouse for four hurricane seasons (2009-2012). Verification results show that the 1-5 day genesis
probabilities have similar reliability as the 1-2 day probabilities currently featured in the Tropical Weather
Outlook (TWO). RSMC Miami has developed prototype text and graphical products (see examples
below), and tested their production during a two-week in-house exercise.
1.
RSMC Miami will issue an experimental 1-5 day tropical cyclone formation probability as part of
the current Atlantic TWO beginning sometime between 15 July and 1 September, pending an in-house trial
period during the first part of the season and the completion of the necessary technical development.
Assuming additional technical development, also depict the probabilities graphically. Issues to be resolved
include determining whether systems that have a 0% chance of tropical cyclone formation during the first
48 h would be included in the 1-5 day TWO only if they meet a specific probability threshold. Also,
coordination with the RSMC Honolulu would be necessary for systems that are forecast to cross 140°W
and have a potential for development.
2.
Public Information Statement will be issued by NWS Headquarters.
Sample text and graphical depiction of 1-5 day genesis probabilities.
ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE OCT 23 2012
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH AN AREA OF LOW PRESSURE
LOCATED ABOUT 1175 MILES EAST-NORTHEAST OF THE NORTHERN LEEWARD ISLANDS
HAVE BECOME A LITTLE BETTER ORGANIZED.
ALTHOUGH UPPER-LEVELS WINDS
ARE ONLY MARGINALLY FAVORABLE FOR DEVELOPMENT...THEY ARE EXPECTED TO
BECOME MORE FAVORABLE DURING THE NEXT DAY OR TWO. THIS SYSTEM HAS A
MEDIUM CHANCE...40 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD AT 10 MPH. AFTER THAT
TIME...THE SYSTEM IS EXPECTED TO MOVE GENERALLY NORTHWESTWARD AND HAS A
HIGH CHANCE...80 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 5 DAYS.
A BROAD LOW PRESSURE AREA ASSOCIATED WITH A TROPICAL WAVE IS LOCATED
ABOUT 450 MILES SOUTHWEST OF THE CAPE VERDE ISLANDS. WHILE THIS SYSTEM
IS PRODUCING A LARGE AREA OF CLOUDINESS AND SCATTERED
SHOWERS...ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY FAVORABLE FOR
DEVELOPMENT.
THIS SYSTEM HAS A MEDIUM CHANCE...40 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
GENERALLY WESTWARD AT 10 TO 15 MPH. ENVIRONMENTAL CONDITIONS ARE THEN
FORECAST TO BECOME MORE CONDUCIVE FOR DEVELOPMENT AS THE WAVE CONTINUES
WESTWARD. THIS SYSTEM HAS A HIGH CHANCE...80 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS.
AN AREA OF DISTURBED WEATHER HAS FORMED IN ASSOCIATION WITH A BROAD LOW
PRESSURE AREA ABOUT 700 MILES NORTHEAST OF THE NORTHERN LEEWARD
ISLANDS. SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE DURING THE NEXT
SEVERAL DAYS AS THE LOW MOVES GENERALLY WESTWARD AT ABOUT 10 MPH. THIS
SYSTEM HAS A LOW CHANCE...NEAR 20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE 48 HOURS.
BY SUNDAY THE DISTURBANCE IS EXPECTED TO
TURN NORTHWARD AND THE ENVIRONMENT SHOULD REMAIN MARGINALLY FAVORABLE
FOR DEVELOPMENT. THIS SYSTEM HAS A MEDIUM CHANCE...30 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.
OTHER SYSTEMS WITH FORMATION POTENTIAL BEYOND 48 HOURS...
THE REMANT CIRCULATION OF HURRICANE ISAAC IS LOCATED OVER THE OHIO
VALLEY. THIS SYSTEM IS FORECAST TO DRIFT SOUTHWARD AND REACH THE
WATERS OF THE NORTH-CENTRAL GULF OF MEXICO IN A FEW DAYS.
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE FAVORABLE IN THE GULF OF
MEXICO FOR SOME SLOW DEVELOPMENT. THERE IS A LOW CHANCE...NEAR 0
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE AGAIN DURING THE
NEXT 48 HOURS AND A MEDIUM CHANCE...40 PERCENT...DURING THE NEXT 5 DAYS
ONCE IT REACHES THE GULF OF MEXICO.
AN AREA OF LOW PRESSURE IS EXPECTED TO FORM IN THE NORTHWESTERN
CARIBBEAN SEA IN 3 TO 5 DAYS...AND ENVIRONMENTAL CONDITONS APPEAR
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX, p. 4
CONDUCIVE FOR DEVELOPMENT DURING THAT TIME. THERE IS A LOW
CHANCE...NEAR 0 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS BUT A HIGH CHANCE...NEAR 60 PERCENT...DURING
THE NEXT 5 DAYS.
&&
FIVE-DAY FORMATION PROBABILITIES ARE EXPERIMENTAL IN 2013.
$$
FORECASTER KIMBERLAIN
NNNN
Recommendation
Informational; brief members of the RA-IV HC
Action
3
Title
Eliminate TCE text product
Submitter
RSMC Miami
Date Submitted
April 2013
Discussion
INFORMATIONAL: The Tropical Cyclone Position Estimate (TCE) is a short text product used to
provide a continuous flow of information regarding the center location of a tropical cyclone when it nears
the coast and the center can be easily tracked with land-based radar, for example:
HURRICANE IKE TROPICAL CYCLONE POSITION ESTIMATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
AL092008
900 PM CDT FRI SEP 12 2008
AT 9 PM CDT...0200Z...THE CENTER OF HURRICANE IKE WAS
ESTIMATED BY NOAA DOPPLER WEATHER RADARS...AND AIR FORCE RESERVE AND
NOAA RECONNAISSANCE AIRCRAFT...TO BE NEAR LATITUDE 28.5 NORTH...
LONGITUDE 94.3 WEST OR ABOUT 65 MILES...105 KM...SOUTH-SOUTHEAST OF
GALVESTON TEXAS AND ABOUT 90 MILES...140 KM...SOUTH-SOUTHWEST OF
BEAUMONT TEXAS.
$$
FORECASTER STEWART
In recent years, the Tropical Cyclone Update (TCU) was modified and now can include a summary block
that conveys not only the storm’s center location but other key parameters in a fixed format that is easily
decoded by software, as shown below:
HURRICANE ISAAC TROPICAL CYCLONE UPDATE
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX, p. 5
NWS NATIONAL HURRICANE CENTER MIAMI FL
1120 AM CDT TUE AUG 28 2012
AL092012
... ISAAC ACHIEVES HURRICANE STATUS...
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
INDICATE THAT MAXIMUM WINDS ASSOCIATED WITH ISAAC HAVE INCREASED
TO 75 MPH...120 KM/H. ON THIS BASIS...ISAAC IS BEING UPGRADED TO
A HURRICANE.
SUMMARY OF 1120 AM CDT...1620 UTC...INFORMATION
----------------------------------------------LOCATION...28.1N 88.6W
ABOUT 75 MI...115 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 160 MI...250 KM SE OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES
$$
FORECASTER STEWART/BEVEN
Because the TCU’s summary block now contains all of the information previously conveyed in the TCE,
we propose that the TCE product be eliminated. In those situations where a TCE would have been issued,
NHC proposes to issue a TCU instead. Substituting the TCU for the TCE provides the same continuous
flow of information, with the advantage of a fixed, easily decoded format within a single product. In
addition, this format allows RSMC Miami to provide the latest information on maximum winds,
movement, and minimum pressure. An example of a TCU used in lieu of a TCE follows:
HURRICANE ISAAC TROPICAL CYCLONE UPDATE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1100 AM CDT WED AUG 29 2012
AL092012
...11 AM POSITION UPDATE...
A GUST TO 67 MPH WAS RECENTLY REPORTED AT SHELL BEACH LOUISIANA.
TROPICAL STORM CONDITIONS ARE CONTINUING ALONG THE MISSISSIPPI AND
ALABAMA COASTS.
SUMMARY OF 1100 AM CDT...1600 UTC...INFORMATION
-------------------------------------------------LOCATION...29.6N 90.7W
ABOUT 1 MI...2 KM W OF HOUMA LOUISIANA
ABOUT 45 MI...75 KM SW OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.70 INCHES
$$
FORECASTER STEWART
Discontinue the TCE product. Use the TCU in those situations previously calling for a TCE.
Change the operational Plan
1.4
Tropical Cyclone Updates (TCU).
1.4.1
Mission Connection. The TCU provides users with timely, succinct information on significant
changes to tropical cyclones.
1.4.2
Issuance Guidelines.
1.4.2.1
Creation Software. ATCF system.
1.4.2.2 Issuance Criteria. TCUs are issued to inform users of significant changes in a tropical cyclone in
between regularly scheduled public advisories. Such uses include, but are not limited to the following:
-
-
To provide timely information of an unusual nature, such as the time and location of landfall, or
to announce an expected change in intensity that results in an upgrade or downgrade of
status (e.g., from a tropical storm to a hurricane).
To provide a continuous flow of information regarding the center location of a tropical cyclone
when watches or warnings are in effect and the center can be easily tracked with land-based
radar.
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX, p. 6
-
To provide advance notice that significant changes to storm information will be conveyed
shortly, either through a subsequent TCU or through a Special Advisory.
To announce changes to international watches or warnings made by other countries, or to cancel
U.S. watches or warnings.
To issue a U.S. watch or warning, but only if the TCU precedes a special advisory that will
contain the same watch/warning information, and indicates the special advisory will be
issued shortly.
1.4.2.3 Issuance Times. TCUs issued to provide updated center position information when
watches/warnings are in effect are issued in between scheduled TCPs near the beginning of each hour. All
other TCUs are issued on an event-driven basis.
1.4.2.4 Valid Time. TCUs are valid at time of issuance until a subsequent TCU is issued or until the
next scheduled or special TCP.
1.4.2.5
Product Expiration Time. Not applicable.
1.4.3
Technical Description. TCUs will follow the format and content described in this section.
1.4.3.1
UGC Type. Not applicable.
1.4.3.2 Mass News Disseminator Header. The TCU MND header block product type line is
“(TROPICAL CYCLONE TYPE) (NAME or NUMBER) UPDATE”
1.4.3.3 Content. The TCU is a brief alphanumeric text product containing either block paragraph text, a
formatted storm summary section, or both.
The storm summary section is identical in format to the storm summary section found in the TCP. The
storm summary section is required whenever the TCU is issued to update storm intensity, location, or
motion information. The storm summary section is not required for TCUs issued to provide advance notice
that significant changes to storm information will be conveyed shortly, or for those issued to convey
changes to watches or warnings.
TCUs issued to provide hourly storm location information will contain a headline indicating the purpose of
the TCU (e.g., “...11 AM POSITION UPDATE...”)
RSMC Honolulu and Miami base the information contained within the TCU on latest available data from
all sources with special reliance on aircraft reconnaissance and satellite data. Local weather offices will use
this information in all official statements.
1.4.3.4 Format. This product is available in industry standard encoding and languages, and may include,
but not limited to, ASCII, XML, WML and HTML.
WTaa6i ccccddhhmm
TCUxxx
(TROPICAL CYCLONE TYPE) (NAME or NUMBER) UPDATE
(ISSUING OFFICE CITY STATE)
BBCCYYYY
time am/pm time_zone day of week monddyyyy
TEXT
Recommendation
Action
The NOAA Hurricane Conference agrees to the recommendations. NWS Pacific Region Headquarters to
obtain TCU product headers for WFO Guam. OS21 to modify directive and disseminate appropriate
notifications.
Forward to WMO RA-IV HC Committee for consideration.
4. Title:
This item has been withdrawn and this change will not be implemented by RSMC Miami during the
2013 hurricane season.
Submitter:
The use of mixed case text in the RSMC Tropical Cyclone Discussion
RSMC Miami
Date Submitted:
April 2013
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX, p. 7
Discussion:
The U.S. National Weather Service and RSMC Miami have long used all capital letters and limited
punctuation for its text products, initially for dissemination via teletype machines. This format is difficult
to read and likely leads to lack of clarity and less effective communication. Beginning in the 2013
hurricane season, RSMC Miami is expected to experiment with the use of mixed case text (upper and lower
case text) in the Tropical Cyclone Discussion (TCD). A survey of RA-IV member countries conducted in
early 2013 indicate that mix case text would not interfere with receipt of the TCD.
Action
5.
Title:
Information item for RA-IV.
Recommend retirement of tropical cyclone name Sandy
RSMC Miami
Submitter:
April 2013
Date Submitted:
Given the devastating impact caused by Hurricane Sandy in the United States, RSMC Miami recommends
the retirement of the name Sandy and be replaced with Sara, Sheri or Susan.
Discussion:
Forward to Forward to WMO RA-IV HC Committee for consideration.
Action
6. Title:
Best product and warning practices for storms transforming from tropical to non-tropical upon approach to
land
Submitter:
RSMC Miami
Date Submitted:
April 2013
Discussion:
Among Hurricane Sandy's unprecedented aspects was the strategy adopted by
the U.S. NWS to handle two issues associated with the storm's potential transformation from a
tropical cyclone to a non-tropical cyclone before it made landfall: (1) the type (tropical or nontropical) of watch/warning and product suite to issue; (2) which National Center(s) would be
responsible for national-level products, and what those products should be and contain when
Sandy became post-tropical prior to making landfall.
Sandy was forecast to make its transformation to post-tropical "shortly" (~12 hours) before its
center made landfall. More than two days before that, conference calls about how to handle this
situation began between the U.S. NWS Eastern Region and those National Centers with potential
operational involvement. The U.S. NWS Eastern Region made a strong statement there that the
watch/warning and product type should not change during the course of the storm. It voiced
concerns about (a) the mechanics for such a change by the U.S. WFOs; (b) confusion that could occur
for the public if the warning type was changed not long before landfall; and, (c) problems that
emergency managers have said they would incur if they had to accommodate a change in the
warning type, product type, product name, and product provider (i.e., National Center vs. WFOs)
close to landfall.
The U.S. NWS received some criticism from the media and questions from emergency managers for
opting not to issue a Hurricane Watch or Warning. Detractors have said a Hurricane Watch or
Warning could or would have been more effective than non-tropical watches/warnings, although
it cannot be known whether that is truly the case. Indeed, well in advance, the U.S. NWS identified
benefits and drawbacks associated with each possible watch/warning approach. It isn't clear that
the detractors realize, fully understand, or maybe appreciate the potential ramifications, some
negative, of issuing hurricane watches/warnings in this case. In particular, if hurricane watches
and warnings had been issued on the Friday or Saturday before landfall, there was a significant
risk of having to discontinue those watches/warnings if Sandy had become post-tropical sooner,
on Sunday or early Monday, which was quite possible as viewed from Friday and Saturday.
(That would have left us with the same warnings as we chose for Sandy, but with far less time
before impact to provide the rationale, and little time to clear up any confusion caused by
changing the warning and product type.) In that case, the only ways to preserve those
watches/warnings would have been:
- NHC dishonestly write advisories using the header for a hurricane, that actually was not a
hurricane, for an entire day or more until landfall, or
- NHC continue issuing advisories and keeping the hurricane warning up, but using a posttropical cyclone header, risking product and warning dissemination problems.
RA IV/HC-35/Doc. 6, ADD. 1, REV., APPENDIX, p. 8
Neither of those options would have been received very well, in the middle of evacuation
decision-making and other preparations. The U.S. NWS handled this event in such a way to avoid all
of those potential problems, using what it believed would be a balanced approach providing the
most effective service. Still, these potential problems were caused by limitations in the U.S. NWS
product/warning suite, and the NHC felt the hurricane program was hamstrung by not at least
having the option to use hurricane/tropical storm watches/warnings while Sandy was a posttropical cyclone, for reasons given by members of the media and some emergency managers. It
is important that the hurricane program have greater flexibility in its application of
watches/warnings when cases like Sandy occur. The Actions below provide such an
approach.
Action:
1. Modify the definitions of the coastal hurricane and tropical storm watches and warnings to
allow them to be issued or remain in effect after a tropical cyclone becomes post-tropical. The
new definitions would be:
Hurricane Warning: An announcement that sustained winds of 64 knots (74 mph or
119 km/hr) or higher are expected somewhere within the specified area in association with a
tropical, subtropical, or post-tropical cyclone. Because hurricane preparedness activities
become difficult once winds reach tropical storm force, the warning is issued 36 hours in
advance of the anticipated onset of tropical-storm-force winds (24 hours for the Western North
Pacific). The warning can remain in effect when dangerously high water or a combination of
dangerously high water and waves continue, even though winds may be less than hurricane
force.
Hurricane Watch: An announcement that sustained winds of 64 knots (74 mph or 119 km/hr) or
higher are possible within the specified area in association with a tropical, subtropical, or posttropical cyclone. Because hurricane preparedness activities become difficult once winds reach
tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of
tropical storm force winds.
Tropical Storm Warning: An announcement that sustained winds of 34 to 63 knots (39 to 73
mph or 63 to 118 km/hr) are expected somewhere within the specified area within 36 hours (24
hours for the Western North Pacific) in association with a tropical, subtropical, or post-tropical
cyclone.
Tropical Storm Watch: An announcement that sustained winds of 34 to 63 knots (39 to 73 mph
or 63 to 118 km/hr) are possible within the specified area within 48 hours in association with a
tropical, subtropical, or post-tropical cyclone.
2. Allow RSMC Miami to continue issuing advisory products after a tropical cyclone becomes
post-tropical, in those cases when the system continues to pose a significant threat to life and
property, and when the transfer of responsibility to another U.S. NWS office would result in an
unacceptable discontinuity in service. RSMC Miami text advisory products would continue to be issued
under the POST-TROPICAL CYCLONE XXXXX header, and be accompanied by the full suite of
standard tropical cyclone graphical products.
3. Modify the operational plan as appropriate if agreed upon by RAIV member countries.