Moving from Deterministic to Probabilistic Methods for Forecasting Storm Surge Submitter: Dr. Rick Knabb, NOAA/NWS/National Hurricane Center
2 Jan 2013
INFORMATIONAL:Portions of the NWS tropical cyclone program continue to rely on deterministic methods, even though the AMS and National Academies recently endorsed greater use of probabilistic methods by the NWS to help users make decisions based on quantified uncertainties. The 2003 report entitled Fair Weather Partnerships in Weather and Climate Services, for example, includes the following recommendation from the National Academies: “As the organization responsible for setting the scientific standard for operational meteorology, the NWS should take the lead in adopting probabilistic forecasts. Doing so would require forecasters to become more familiar with user needs and expectations. It would also require NWS management to support the development and use of forecaster tools and systems that facilitate the generation of probabilistic information as a more integral part of the forecasting process. As experience in communicating the probability of precipitation in a particular area shows, the public can understand and use probabilistic forecasts.” The probabilistic storm surge (psurge) product was initially developed as a result of this report, but widespread adoption was initially hampered by an inability to integrate the data stream into the existing NWS operational paradigm. The NWS storm surge team, and the technical sub-team, has developed new tools and policies to allow for greater use of probabilistic storm surge information within NWS operational systems. The probabilistic storm surge information (psurge), for example, is now ingested within AWIPS and used to drive tropical cyclone impact graphics and storm surge wording in the Hurricane Local Statement. Furthermore, NHC and MDL have developed improved visualization (primarily Google Earth) mechanisms for online presentation, and NHC is increasingly using probabilistic information for the Public Advisory, media interviews, and emergency management briefings during landfalling tropical cyclone events. Finally, efforts are well underway at NHC/MDL to improve psurge (application of new basins, updated vertical datum, incorporation of tide, etc.) and to develop new storm surge products (i.e., high-resolution inundation graphic and a storm surge watch/warning) which will further expand the use of probabilistic information.
With the entire NWS storm surge product suite now making the transition to probabilistic approaches, the need for legacy deterministic SLOSH runs has been largely eliminated, at least for forecasting and evacuation decision-making applications. Continuing to disseminate deterministic storm surge guidance is harmful to effective and consistent communication of the storm surge hazard, especially since it causes conflicting information to come from the same source (i.e., NHC). In particular, the deterministic SLOSH runs have the potential to interfere with evacuation decision making by emergency managers, with Irene (2011) and Isaac (2012) being prominent, recent events during which a consistent message was especially critical. Deterministic/best track SLOSH simulations very near or after landfall are still needed to support response and recovery efforts, but this information should only be provided once evacuations and other preparations ahead of the storm have clearly been completed. The current NWS policy calls for creation and dissemination of deterministic SLOSH runs 36 hours prior to landfall, well within the critical time period for evacuation decision making and execution. During the past several years, NWS/NHC has used ftp, or other unofficial means, to disseminate SLOSH runs intended for specific users, but this policy has become increasingly difficult to maintain and justify. The SLOSH deterministic runs are not an official product, but this ad hoc dissemination method has allowed for widespread use of this information, leading to increased confusion since the deterministic information conflicts with the official NWS forecast for storm surge. In addition, the deterministic SLOSH runs require significant manual human intervention (constructing a wind field which is reasonably consistent with the official NHC forecast) by the NHC storm surge unit, taking those staff away from other critical operational duties including issuing new products (e.g., inundation graphic and storm surge watch/warning).
The NHC Director stated the continued provision of SLOSH deterministic runs is a resource issue and will impact planned improvements towards inundation graphics (a need voiced once again by the NWS Regions) and a potential storm surge warning.
The NWS Regions agree to “eliminate the NWS provision of deterministic SLOSH model output during tropical cyclones, except for simulations very near or after landfall that are needed to support response and recovery efforts, with the condition that Probabilistic Hurricane Inundation Surge Height (PHISH) 6 hourly cumulative and incremental probabilities (gridded and graphical) are provided on an experimental basis on the MDL web site, and for 2014 in AWIPS/SBN (delayed because of the NCEP data moratorium.) Based on the progress made in developing the PHISH outputs, a final decision on the SLOSH deterministic runs for 2013 will be made in time for the 2013 Interdepartmental Hurricane Conference (March 4). If the SLOSH deterministic runs will not be provided for 2013, then OS21 will transmit a national Public Information Statement immediately after the IHC. OS21 will disseminate a Public Information Statement to convey the elimination of SLOSH deterministic runs and the ftp dissemination mechanism. In addition, OS21 will send a national notification on the experimental PHISH 6 hourly cumulative and incremental probabilities.
OS21 will lead the effort to gather technical requirements from RFCs and develop a transition plan to move from the use of deterministic time series to a probabilistic time series.
Informational; brief members of the WG/HWSOR at annual meeting on 4 March 2013. Other recommendations?
2
Title Submitter Date Submitted Discussion
Recommendation
Action
Implementation of a Storm Surge Warning Rick Knabb, NOAA/NWS/National Hurricane Center
2 Jan 2013
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 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 national-scale 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 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) 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 real-time 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 post-tropical 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:
The NOAA Hurricane Conference agrees on implementation of an experimental, publically-available tropical cyclone storm surge watch and warning in 2015. This will be accompanied or preceded by a high resolution inundation graphic.
OS21, through the NWS Storm Surge Team, will work with Regions and NHC to identify the WFOs which will actively participate in 2013 real-time non-public testing for the storm surge watch/warning. Pacific Region will opt out at this time, but WFO Honolulu/CPHC will remain engaged.
OS21, through the NWS Storm Surge Team and the team’s Technical Working Group, will work to complete all administrative actions necessary to allow for operational implementation in 2015, e.g., CONOPS, OSIP, NWS Directives, policy on CFW/CFA, VTEC, WFO/NHC Watch/Warning issuance responsibilities and protocols.
Informational; brief members of the WG/HWSOR at annual meeting on 4 March 2013 and then Exec Sec forwards info to WMO RA-IV and RA-V committees for consideration. Other recommendations?
3
Title Submitter Date Submitted Discussion
Recommendation
Action
Breakpoint Correction Dan Brown, NOAA/NWS/National Hurricane Center
2 Jan 2013 NHC incorrectly lists the Aucilla River breakpoint as (30.04,-83.92). However, the coordinates they use are for the Ecofina River, which are the coordinates for the mouth of the Aucilla River. Their map is also incorrect.
The coordinates of the Aucilla River breakpoint will be changed to 30.09N 83.99W for 2013. OS21 will update NWS Directive 10-605.
Incorporate changes into the 2013 NHOP and then forwards info to WMO RA-IV Committee for consideration. (Note from Exec Sec, the NHOP no longer includes specific breakpoints. In place of this, a link to the NWS web page with this information is listed in Appendix B). Other recommendations?
4
Title Submitter Date Submitted Discussion
Recommendation
Action
Breakpoint Modification Dan Brown, NOAA/NWS/National Hurricane Center
2 Jan 2013
A change to the breakpoint county listing that fixed an error with Tarpon Springs caused an unintended error in Pasco County when a Tropical Storm Warning was issued for Isaac. The intention was to let the warning end in Pasco County and just include areas to the south. The error only occurs when the Advisory begins or ends at the Pasco/Pinellas County line and depends on which break point is used (e.g. Tarpon Springs vs Anclote Key) and which direction the watch/warning is extending.
For 2013, the Anclote Key and Tarpon Springs breakpoints will be dropped. A new breakpoint, Anclote River, 28.18N 82.80W will be added. (This breakpoint is essentially at the Pasco/Pinellas County Line.) OS21 will update NWS Directive 10-605.
Incorporate into the 2013 NHOP. IHC to forward to WMO RA-IV Committee. (Note from Exec Sec, the NHOP no longer includes specific breakpoints. In place of this, a link to the NWS web page with this information is listed in Appendix B). Other recommendations?
5
Title Submitter Date Submitted Discussion
Recommendation
Action
New Breakpoint Request for Ponte Vedra Beach, Florida Dan Brown, NOAA/NWS/National Hurricane Center
2 Jan 2013
The rationale for this breakpoint is to cover as much of the coast as possible in watches and warnings without including the Jacksonville Metropolitan Area, The Port of Jacksonville, the Port of Fernandina Beach and our major military installations (NAS Jacksonville, Naval Base Mayport, USMC Back River Transportation Command at Blount Island and the Navy Fuel Docks) in watches and warnings for peripheral/marginal events. We believe it would be desirable to have the option to include St Johns and Flagler Counties without including these facilities and population base.
For 2013, the NWS will add a new breakpoint for Ponte Vedra Beach, 30.24N and 81.38W.
OS21 will update NWS Directive 10-605.
Incorporate into the 2013 NHOP. IHC to forward to WMO RA-IV Committee. (Note from Exec Sec, the NHOP no longer includes specific breakpoints. In place of this, a link to the NWS web page with this information is listed Appendix B). Other recommendations?
6
Title Submitter Date Submitted Discussion
Recommendation
Action
Medium-Range Tropical Cyclone Genesis Probabilities Todd Kimberlain, NOAA/NWS/National Hurricane Center
2 Jan 2013
INFORMATIONAL: The NHC has been producing 1-5 day tropical cyclone genesis probabilities in-house 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). The NHC has developed prototype text and graphical products (see examples below), and tested their production during a two-week in-house exercise.
1. NHC 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 Central Pacific Hurricane Center would be necessary for systems that are forecast to cross 140°W and have a potential for development.
2. OS21 to complete Product Description Document, create feedback mechanism, issue Public Information Statement.
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 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.
$$
FORECASTER KIMBERLAIN
NNNN
Informational; brief members of the WG/HWSOR at annual meeting on 4 March 2013. Other recommendations?
7
Title Submitter Date Submitted Discussion
Recommendation
Action
Eliminate TCE text product James Franklin, NOAA/NWS/National Hurricane Center
2 Jan 2013
INFORMATIONAL: The Tropical Cyclone Position Estimate (TCE) is a short text product used to provide a continuous flow of information regarding the center location of a tropical cyclone when it nears the coast and the center can be easily tracked with land-based radar, for example:
HURRICANE IKE TROPICAL CYCLONE POSITION ESTIMATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008
900 PM CDT FRI SEP 12 2008
AT 9 PM CDT...0200Z...THE CENTER OF HURRICANE IKE WAS
ESTIMATED BY NOAA DOPPLER WEATHER RADARS...AND AIR FORCE RESERVE AND
NOAA RECONNAISSANCE AIRCRAFT...TO BE NEAR LATITUDE 28.5 NORTH...
LONGITUDE 94.3 WEST OR ABOUT 65 MILES...105 KM...SOUTH-SOUTHEAST OF
GALVESTON TEXAS AND ABOUT 90 MILES...140 KM...SOUTH-SOUTHWEST OF
BEAUMONT TEXAS.
$$
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
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1120 AM CDT TUE AUG 28 2012
... 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
$$
FORECASTER STEWART/BEVEN
Because the TCU’s summary block now contains all of the information previously conveyed in the TCE, we propose that the TCE product be eliminated. In those situations where a TCE would have been issued, NHC proposes to issue a TCU instead. Substituting the TCU for the TCE provides the same continuous flow of information, with the advantage of a fixed, easily decoded format within a single product. In addition, this format allows the NWS to provide the latest information on maximum winds, movement, and minimum pressure. An example of a TCU used in lieu of a TCE follows:
HURRICANE ISAAC TROPICAL CYCLONE UPDATE
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1100 AM CDT WED AUG 29 2012
...11 AM POSITION UPDATE...
A GUST TO 67 MPH WAS RECENTLY REPORTED AT SHELL BEACH LOUISIANA.
TROPICAL STORM CONDITIONS ARE CONTINUING ALONG THE MISSISSIPPI AND
ALABAMA COASTS.
SUMMARY OF 1100 AM CDT...1600 UTC...INFORMATION
PRESENT MOVEMENT...NW OR 310 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.70 INCHES
$$
FORECASTER STEWART
Discontinue the TCE product. Use the TCU in those situations previously calling for a TCE.
Eliminate section 1.5 of Directive 10-601 and update section 1.4 of Directive 10-601 as follows:
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.
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...”)
CPHC and NHC 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 cccc ddhhmm
TCUxxx
(TROPICAL CYCLONE TYPE) (NAME or NUMBER) UPDATE
