severe weather operations

Severe Weather Severe Weather OperationsOperations

Severe Weather StaffingSevere Weather Staffing(Positions in orange are minimum needed)(Positions in orange are minimum needed)

Severe Weather Coordinator – oversees the Severe Weather Coordinator – oversees the operations of the office during severe weather. operations of the office during severe weather. Sometimes combined with the Public Sometimes combined with the Public ForecasterForecaster

Public Forecaster – issues the public forecasts, Public Forecaster – issues the public forecasts, and long term watches / advisories / warningsand long term watches / advisories / warnings

Aviation forecasterAviation forecaster Public service – handles routine public service Public service – handles routine public service

duties including upper air balloons, phone duties including upper air balloons, phone calls (media included), climate products, and calls (media included), climate products, and NWRNWR

Warning meteorologist(s) – issues convective Warning meteorologist(s) – issues convective warningswarnings

Severe Weather StaffingSevere Weather StaffingOptional extra positions that may be staffedOptional extra positions that may be staffed

Short term forecaster – writes the Short Short term forecaster – writes the Short Term ForecastsTerm Forecasts

Communications coordinator – handles Communications coordinator – handles phone calls, notification of warnings via phone calls, notification of warnings via phone / NAWAS / radios, gathers and phone / NAWAS / radios, gathers and issues storm reports, handles media issues storm reports, handles media requestsrequests

More recently - someone to manage our More recently - someone to manage our NWS Shreveport web homepage, NWS Shreveport web homepage, including graphical depictions of the including graphical depictions of the weather and headlines displayed on our weather and headlines displayed on our homepagehomepage

Severe Weather StaffingSevere Weather Staffing Clear assignment of job tasks during severe weather Clear assignment of job tasks during severe weather

will (all have occurred at this office):will (all have occurred at this office): Avoid two warnings being issued for the same county Avoid two warnings being issued for the same county

or parish at the same time by different people.or parish at the same time by different people. Avoid two short term forecasts being issued at the Avoid two short term forecasts being issued at the

same time by different people.same time by different people. Avoid NO short term forecast being issued at all Avoid NO short term forecast being issued at all

because it was not clear who was suppose to issue because it was not clear who was suppose to issue them.them.

Avoidance of “What we have here is, failure to Avoidance of “What we have here is, failure to communicate” between NWS staff members. communicate” between NWS staff members.

Provide clear communication between the NWS and Provide clear communication between the NWS and our outside users, including the media, Emergency our outside users, including the media, Emergency Managers, and first responders!Managers, and first responders!

Tornado Warning Tornado Warning CriteriaCriteria

Tornado Warning CriteriaTornado Warning Criteria

In the late 1990s, Lee Harrison and I In the late 1990s, Lee Harrison and I conducted a study to derive a list of factors conducted a study to derive a list of factors that comprise a tornadic mesocyclone.that comprise a tornadic mesocyclone.

It concentrated on about 50 tornadic and It concentrated on about 50 tornadic and non-tornadic mesocyclones in the four state non-tornadic mesocyclones in the four state area.area.

Since then, additional mesocyclone cases Since then, additional mesocyclone cases have been examined (about 80) to fine tune have been examined (about 80) to fine tune our suggested tornado warning criteria.our suggested tornado warning criteria.


The results of one of the earlier The results of one of the earlier studies were presented at the 1998 studies were presented at the 1998 AMS Severe Storms Conference by AMS Severe Storms Conference by Bill Parker and myself.Bill Parker and myself.

This study produced a nomogram of This study produced a nomogram of rotational mesocyclone shear values rotational mesocyclone shear values (calculated using AWIPS VR-Shear (calculated using AWIPS VR-Shear tool) associated with tornadoes in tool) associated with tornadoes in the four state area.the four state area.


We also incorporated rotational We also incorporated rotational velocity from a modified version of a velocity from a modified version of a previously developed nomogram.previously developed nomogram.


We came up with the current Tornado We came up with the current Tornado Warning criteria (on the next slide).Warning criteria (on the next slide).

These criteria are used as guidelines for These criteria are used as guidelines for Tornado Warnings. They are not strict Tornado Warnings. They are not strict criteria that have to be precisely met criteria that have to be precisely met for a Tornado Warning to be issued. for a Tornado Warning to be issued. The staff have flexibility of when they The staff have flexibility of when they feel a Tornado Warning is needed.feel a Tornado Warning is needed.


A cyclonic rotational coupletA cyclonic rotational couplet in the lower in the lower levels of the storm (approx. 1000 - 10,000 ft levels of the storm (approx. 1000 - 10,000 ft AGL). A AGL). A gate to gate signaturegate to gate signature of of maximum inbound and outbound wind is maximum inbound and outbound wind is particularly dangerous, but particularly dangerous, but notnot required. required.

A A SRM velocitySRM velocity in either the inbound or in either the inbound or outbound wind of the mesocyclone couplet of outbound wind of the mesocyclone couplet of >40 kt at any distance from the radar. >40 kt at any distance from the radar.

A A VR shearVR shear rotational velocityrotational velocity of >30 kt at of >30 kt at any distance from the radar.any distance from the radar.

A A VR shearVR shear rotational shear rotational shear of .008 withing of .008 withing 60 miles, or .006 beyond 60 miles. 60 miles, or .006 beyond 60 miles.

Microburst Warning Microburst Warning CriteriaCriteria


A local study was conducted on A local study was conducted on microburst warning criteria and microburst warning criteria and published a SR Technical published a SR Technical Attachment in 1997.Attachment in 1997.

The study developed a conceptual The study developed a conceptual model of a microburst, and radar model of a microburst, and radar “proof” of this model.“proof” of this model.


High reflectivity core of 50 dBz to High reflectivity core of 50 dBz to heights of 25,000 ft AGL.heights of 25,000 ft AGL.

Storm core velocity convergence of Storm core velocity convergence of >50 kt somewhere in the layer 5000 - >50 kt somewhere in the layer 5000 - 11,000 AGL in or near the high 11,000 AGL in or near the high reflectivity core.reflectivity core.

Severe thunderstorm warnings based Severe thunderstorm warnings based on these guidelines should contain on these guidelines should contain wording about strong damaging winds.wording about strong damaging winds.

Severe Weather BriefingSevere Weather Briefing

NWS provides weekly weather briefings on Thursday mornings to media and emergency managers. Prior to severe weather or winter weather event, NWS may provide a special briefing.

Severe Weather BriefingSevere Weather Briefing

Severe Weather Severe Weather OperationsOperations

Questions / Comments

Dual Polarization RadarDual Polarization RadarMedia TrainingMedia Training

Dual Polarization is expected to be Dual Polarization is expected to be installed in the NWS Doppler Radar in installed in the NWS Doppler Radar in January, 2013.January, 2013.

Training for our media partners is Training for our media partners is provided by the Warning Decision provided by the Warning Decision Training Branch (WDTB) in Norman, OK.Training Branch (WDTB) in Norman, OK.

Training consists of going through 13 Training consists of going through 13 modules on a web site provided to you. modules on a web site provided to you. The 13 modules cover the 6 new products The 13 modules cover the 6 new products that Dual Polarization Radar provides.that Dual Polarization Radar provides.


The training should be completed about The training should be completed about 1 month prior to the installation of Dual 1 month prior to the installation of Dual Polarization at NWS Shreveport Doppler Polarization at NWS Shreveport Doppler Radar.Radar.

The web site for the training modules is:The web site for the training modules is: http://www.wdtb.noaa.gov/courses/dualp

ol/ outreach/ outreach/


The six new products the Dual The six new products the Dual Polarization Radar provides are:Polarization Radar provides are:

Correlation Coefficient (CC)Correlation Coefficient (CC) Differential Reflectivity (ZDR)Differential Reflectivity (ZDR) Specific Differential Phase (KDP)Specific Differential Phase (KDP) Hydrometeor Classification (HC)Hydrometeor Classification (HC) Melting Layer (ML)Melting Layer (ML) Quantitative Precipitation Estimation Quantitative Precipitation Estimation

(QPE)(QPE)

Dual Polarization Dual Polarization TornadoTornado

Dual Polarization Winter Dual Polarization Winter WeatherWeather

severe weather operations

Documents

tornado warning criteriawe

tornado warning criteriamic

tornado warnings

vr shear rotational

vr shear rotational

mesocyclone couplet

phone calls media

staffedshort term forecaster