NWS MelbourneTotal Lightning Information (TLI) Initiative

Purpose: To evaluate the utility of Total Lightning Information (TLI) for the potential improvement in weather products & services for the people of East Central Florida.

 NWS Melbourne has access to 4 lightning workstations. Two of the workstations [National Lightning Data Network (NLDN); Warning Decision Support System (WDSS)] display "traditional" cloud-to-ground lightning information, while the remaining workstations [Lightning Detection And Ranging (LDAR); Lightning Imaging Sensor Data Application Demonstration (LISDAD)] are unique to NWS Melbourne and display TOTAL lightning information (in-cloud as well as cloud-to-ground). Using these sources of new technology collectively, NWSO Melbourne has begun to apply them toward improved public service and education efforts.

Additional information on each of the lightning workstations can be found below:
LISDAD/TLI - Marshall Space Flight Center (MSFC)
Melbourne Integrated Lightning Detection Systems

Local efforts will be focused in three areas: Severe Storm Discernment, Improved Aviation Forecasts, Improved Public Forecasts.

 


 

 

Severe Storm Discernment - to consider the utility of TLI in the proper discernment of severe vs non-severe thunderstorms.

 Local intentions will be centered around:

 a) Pulse Storms...(warm season/weak vertical shear)

b) Storms within Tropical Cyclone Rainbands...(TC tornadic threat)
 
 ACTION:

      For Pulse Severe vs non-Severe Storms - AMU meteorologist will monitor select thunderstorms within MLB's county warning area which have the potential to become severe (pulse severe - large hail and/or damaging wind) during the warm/wet season. TLI flash rates (as viewed on LISDAD) will be assessed through pop-up boxes to make application of a pre-defined flash rate threshold. Thunderstorms with associated flash rates which exceed (in particular...those which well-exceed) 120 LDAR flashes per minute should be regarded suspect as "severe" (current NWS definition...expect large hail & damaging wind), especially if the flash rate has experienced a recent significant trend increase. Information will be passed along to the warning meteorologist to be factored into the warning decision (thus contrasted against traditional radar signatures for pulse-severe thunderstorm identification).

      Remember, the refresh rate for LDAR data is every "one" minute where as the WSR-88D data refresh rate is every "five" minutes.

      (Be sure to make the proper flash rate determination...check the multiplication factor to the left of the scale/y-axis (FPM/xx) on the pop-up box. See example below.)

      LISDAD example

      Flashes per Minute (FPM) Factor

      Note to the left of the Y axis...the number "2" next to the "FPM". This means that the operator must multiply the LDAR values on the graph by 2. In this example, 140 LDAR flashes (2 x 70) were occurring around the "0-minute" time. Sometimes the multiplication factor will be as high as 3 or 4 (we have seen it as high as 5!). Always be alert to the digit next to the FPM.

For Tropical Cyclone Rainband Tornadic vs non-Tornadic Storms - AMU meteorologist will monitor convective rainbands (both inner-band/eyewall & outer-band) which are in proximity of central Florida for the existance of electrical activity.

      1. Inner-bands / eyewall...when any electrical activity (TLI) is observed within these bands, the tropical cyclone should be examined for signs of strengthening. Information should be passed along to the Tropical Prediction Center.
      2. Outer-bands...when any electrical activity (TLI) is observed within these bands, individual convective cells should be closely monitored on radar for signs of tornadogenesis.

 


 

Improved Aviation Forecast Products

Statement of purpose

In accordance with the NWS mission of mitigating costs to interstate commerce through accurate and timely weather forecasts and warnings, and as part of it's total lightning information initiative, NWS MLB will exploit all available lightning detection systems - Lightning Imaging Sensor Data Application Demonstration display system (LISDAD), Lightning Detection and Ranging (LDAR), Lightning Position and Tracking System (LPATS), as well as the lightning alert in the Integrated Terminal Weather System (ITWS) to improve it's Terminal Aerodrome Forecasts.
 

Background

Since April of 1996, the National Weather Service (NWS) Office in Melbourne, Florida (MLB) has routinely issued Terminal Aerodrome Forecasts (TAFs) four times daily for the following four sites: Daytona Beach International Airport (DAB), Orlando International Airport (MCO), Melbourne International Airport (MLB), and Vero Beach Municipal Airport (VRB). During the convective season (generally late May through September) the MLB aviation forecaster routinely issues TAFs which include forecasts of afternoon thunderstorms (TS) for a period of between three [3] and six [6] hours, with four [4] hours being the most common time span specified.
 

NWS Melbourne forecasters are well aware of the importance of balancing airlines' needs for both cost-effectiveness and safety when it comes to composing TAFs. The inclusion of TS and accompanying IFR ceilings/visibilities in either the prevailing or TEMPO group of a TAF has significant consequences with respect to airport operations particularly if it is a major hub (Ott and Ladd, 1994).
 

For instance, not only are the number of arrivals/departures reduced during TS/IFR conditions, but any aircraft whose destination airport contains a forecast of prevailing or TEMPO TS must carry additional fuel so that it may reach a designated alternate destination airport should the weather not permit a landing at the planned destination airport. Carrying this extra fuel costs the commercial carriers more money, and if TS are inaccurately (excessively) forecast, the cost incurred by a commercial airline can become exorbitant.
 

Climatological study

An initial study will be undertaken by the aviation focal point to ascertain the time of both onset and dissipation, as well as the duration of thunder (lightning) events at the four airport terminals for which MLB is responsible, during the convective season. This will be done using locally archived SAO and METAR data from 1994-97. These events will then be stratified according to regime by correlation to morning soundings (10-15Z) from the Cape Canaveral Air Force Station (CCAFS), after which mean start, stop and duration times will be compiled.
 

Sub-Initiative Goals for Exploitation of TLI  as a complement to WSR-88D, ITWS, etc.

Without a compromise to safety...

1) Minimize/optimize the usage of thunderstorms (TS), convective wind gusts (GxxKT) and associated IFR ceilings/visibilities in both the prevailing and TEMPO groups of the TAFs in the 0 to 4 hour time frame, with emphasis placed on the 0 to 2 hour time period.  See example below: 

The following are two examples which shows how TLI is routinely used to accurately update terminal aerodrome forecasts within NWSO Melbourne's area of aviation responsibility. On this day, TLI was exploited by both the AMU and the duty forecasters during the composition of three TAF amendments (AMD) - two were issued for the Orlando International Airport (KMCO) and one was issued for Daytona Beach Airport (KDAB).
 

September 23, 1997

    At 18Z, the TAF for KMCO forecast southeast winds from 130 degrees at 8 knots, prevailing visibility greater than 6 statute miles, and scattered clouds at 3,500 feet. Between 18Z and 21Z,  moderate rain showers were forecast to temporarily (TEMPO) reduce visibility to 4 statute miles, accompanied by broken clouds at 2,500 feet. Examination of the LISDAD at 1833Z showed a line of heavy rain showers approximately 15-20 east to northeast of the airport, with the southernmost cell (5) beginning show electrical activity, yet to be detected by NLDN (see trend table). Due to both the northwestward movement of the cells and their westward propagation, a TAF amendment was issued at 1841Z, forecasting thunderstorms to temporarily reduce visibility to 3 statute mile between 19Z and 21Z, accompanied by a broken cumulonimbus cloud deck at 2,500 feet.

    The subsequent SPECI observation from 2017Z showed that a thunderstorm began at 2016Z.

    Continued examination of radar and lightning data showed additional thunderstorms had developed and were increasing in coverage and intensity between 5 and 10 miles to the west and southwest of KMCO by 2035Z. Based on this, the TAF was immediately updated to show prevailing weather of: winds out of the east 100 degrees at 12 knots, visibility of 5 statue miles from thunderstorms with moderate rain, few clouds at 1,000 feet and broken cumulonimbus clouds at 4,500 feet, with the following temporary condtions until 22Z: wind out of the SE, 150 degrees at 15 gusting to 20 knots,  visibility 1 statute mile in a thunderstorm with heavy rain, and broken cumulonimbus clouds at 1,500 feet.

    The METAR from 2053Z showed conditions had deteriorated to: winds 130 at 14 gusting to 22 knots, visibility 3 statue miles in a thunderstorm with heavy rain, few clouds 8 hundered feet, scattered clouds at 2,800 feet and broken cumulonimbus clouds at 5,000 feet. A SPECI was taken at 2122Z  to end the thunderstorm at that time. 
   

TAF
KMCO 237120Z 231818 13008KT P6SM FEW035 TEMPO 1821 4SM SHRA BKN025
             FM0000....

TAF
KMCO 231841Z  231918 13008KT P6SM FEW040 TEMPO 1921 3SM TSRA BKN025CB
             FM0000....

TAF
KMCO 232034Z 232118 10012KT 5SM TSRA FEW010 BKN045CB TEMPO 2122
               15015G20KT 1SM +TSRA BKN015CB
             FM0000....
 

2) Narrow the time frame in which "extreme" thunderstorm related aviation weather - defined here as LIFR ceilings/visibilities, wind gusts in excess of 30KT - to one hour or less within the 0 to 2 hour time frame, when warranted.  example
 

3) Decrease usage of TS in the TEMPO groups of the TAFs in the 6 to 24 hour time frame as appropriate. Emphasize/encourage the use of PROB30 and PROB40 within this time period when appropriate.
 

4) Establish that the use of "TS VCSH" as a prevailing weather group is preferable over the use of "VCTS". 
 

Operational Methodology

1) *TENTATIVE* The plan view of the LDAR display system will be modified with the placement of 20nm diameter circles around each (DAB, MCO, MLB, VRB) of the four TAF locations. LDAR will visually alert the aviation or AMU forecaster to the presence of lightning within either 20nm (yellow) or 10nm (red). LISDAD will also have a variation of this functionality.

Currently, both LDAR & LISDAD are being reprogrammed to accommodate these requirements. (SOO, 07/97)

2) As part of his/her duties, the AMU forecaster will monitor all available lightning information systems and routinely coordinate with the Aviation/Short term forecaster regarding the presence (or lack thereof) and trend of lightning activity in the proximity of the aforementioned TAF sites.

3) The 88D, LISDAD and ITWS will continue to be monitored for the presence and movement of boundaries which may initiate electrified convection near the TAF sites.
 

* Obviously, workload and staffing during the remainder of Stage 1 will need to be considered, since the sub-initiative goals will likely increase the number of TAF amendments issued for each terminal location.

 


Improved Public Forecast Products

The inclusion of TLI into items 1) and 2) above will be for the most part transparent to users. However, the goal of item 3) is to include additive, descriptive lightning information to public products. This "improved lightning service" should assist users in planning outdoor activities within the 0-12 hour time-frame, and improve lightning safety by describing specific times and areas at risk from potentially deadly lightning. In order to gain maximum benefit from this information it must reach as large of an audience as possible. Therefore, in addition to being broadcast on NOAA Weather Radio and on the local forecast segment of The Weather Channel, it is hoped that local broadcast media will use the information to pass on to their viewers/listeners as well. 

 

Concerning the "direct effects" of the various meteorological phenomena which occur in central Florida, lightning causes more deaths and injuries than any other weather hazard (see Florida Weather History...July & August) . This is especially true during the summer months. It also accounts for millions and millions of dollars of property damage. By combining local lightning research with the next generation of lightning sensors and workstations currently in place at NWSO Melbourne, we expect to be able to provide an improved public service and education campaign to the people of east central Florida.

Specific intentions of the TLI include:

a) Recognizing "lightning" as a legitimate hazard and increasing public education (new and enhanced terminology)

Relative Frequency of Strikes

The use of enhanced terminology within forecast products may help emphasize the lightning danger. For example, when other threats associated with thunderstorms (tornadoes, damaging winds, large hail, flooding) are expected to be minimal, the term  "LIGHTNING STORMS" should be used rather than "THUNDERSTORMS" to highlight the main threat. Here's an example from a Hazardous Weather Outlook.

The threat for injuries/deaths and property damage likely increases as the amount of cloud-to-ground strikes increase.  For this  reason, it is suggested that quantitative terms are used to indicate the expected frequency or current frequency of strikes. This will also ensure that our lightning terminology is consistent from one forecast shift to the next. ***Preliminary research*** indicates that the following thresholds should be used:

OCCASIONAL:     1-2    CG strikes per minute
FREQUENT:         3-11  CG strikes per minute
EXCESSIVE:        12+    CG strikes per minute

Rather than using "instantaneous" 1-minute rates however, it is better to use the above frequencies averaged over a 7-minute period to confirm persistence (note: the NLDN PC will default to a 7-minute display cycle). You may use the NLDN PC to zoom down to storm scale and observe the number of CG strikes during the last 7 minutes. If the rates reach the following  preliminary thresholds, you should include the appropriate wording in short-term forecasts or severe weather statements.

OCCASIONAL:     1-20    CG strikes per 7-minutes
FREQUENT:         21-83  CG strikes per 7-minutes
EXCESSIVE:         84+     CG strikes per 7-minutes

***As we gain further knowledge regarding flash rates, these thresholds may be adjusted.***


 

In order to avoid confusion between anvil lightning and "bolts from the blue", note the following local definitions:

Anvil Lightning: Any bolt which develops in the ANVIL and travels generally straight down to strike the ground.

"Bolt from the blue": A bolt which originates within the UPDRAFT of the storm, typically 2/3rds of the way up, travels HORIZONTALLY for many miles, then strikes the ground. Here's a great example of a "bolt from the blue" and the locally written Severe Storm Conference preprint which inititially defined the "bolt from the blue".

Both types are cloud-to-ground lightning and are very dangerous. The basic difference between the two is that ANVIL lightning is discharged from the ANVIL portion of the storm, while a "bolt from the blue" is discharged from the UPDRAFT portion (side) of the storm. A person alert to his environment will see clouds above him/her with anvil lightning while a bolt from the blue will "appear" to originate from "clear air". It is the "bolts from the blue" and anvil lightning which likely kill people locally, as both typically occur far from the cell core (rain area).


b) Providing pertinent lightning information in the HAZARDOUS WEATHER OUTLOOK (MIASPSMLB)

ACTION:

Hazardous Weather Outlook (HWO) - The AMU Meteorologist should make proper use of the latest lightning flash density climatologies, lightning statistics, thunderstorm probability forecasts, and sea breeze regime studies. Pertinent information should be added to the HWO for public & interagency preparation and planning purposes.

The Lightning & Electrification Focal Point will also provide a series of "Lightning Facts" which may be used within the HWO. (i.e. "Lightning-related deaths typically occur just before the heavy rain arrives or soon after the storm appears to be over...").


c) Providing pertinent lightning information in the AREA FORECAST DISCUSSION (MIAAFDMLB) 

ACTION:

Area Forecast Discussion (AFD) - The AFD is the product most used by local media, who in-turn use much of  the content to inform the public about the threats of the day. Therefore, expectations regarding the extent and location of future lightning activity should be included in the AFD.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
230 PM EDT THU JUL 24 1997

ACTIVITY SLOW TO FIRE TODAY. SEVERAL AREAS OF CONVERGENCE NOTED ON
LATEST SATELLITE AND RADAR IMAGERY...THEREFORE EXPECT COVERAGE OF
STORMS TO INCREASE THROUGH EARLY EVENING...ESPECIALLY INLAND.
OVERNIGHT POPS NOT LIKELY ALONG THE COAST AS THE FLOW COMPONENT
REMAINS ALONG SHORE TO SLIGHTLY OFFSHORE.

WITH LOW LEVEL RIDGE AXIS CONTINUING TO DROP SLOWLY SOUTH
FRIDAY...AFTERNOON CONVECTION WILL FAVOR THE EAST COASTAL ZONES FROM
INDIAN RIVER COUNTY NORTHWARD...AND INTERIOR COUNTIES TO THE SOUTH.
SCATTERED POPS LIKELY INLAND...AS MOST ACTIVITY ADVECTS NE DURING THE
DAY. EXPECT EAST COAST SEA BREEZE TO FORM...POSSIBLY LEADING TO A FEW
STRONG STORMS AND EXCESSIVE LIGHTNING OVER VOLUSIA AND BREVARD
COUNTIES DURING THE LATE AFTERNOON. TEMPS ALOFT REMAIN WARM
HOWEVER...AND UPPER DIVERGENCE MAY NOT BE AS PRONOUNCED AS DEPICTED
BY EARLIER MODEL RUNS...SO MESOSCALE INFLUENCES WILL LIKELY RULE...AS
USUAL FOR MID SUMMER.

SPRATT 


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
320 AM EDT TUE APR 22 1997

MODEL OUTPUT SLOW TO ARRIVE HENCE A COMPOSITE OF THINKING.   IN THE
NEAR TERM...INTERESTING SITUATION OVER BREVARD COUNTY LAST HOUR HAS
ADDED WEIGHT TO A CERTAIN WAY OF THINKING...LOW-TOPPED THUNDERSTORM
DEVELOPED WITH TOTAL LIGHTNING INFORMATION EXCESSIVE RELATED TO
STORM IMPLYING A VIGOR TO THE UPDRAFT IN THE PRESENCE OF COLD TEMPS
(ABOUT -13C 500 MB) ALOFT AND A RETURN OF LIMITED MOISTURE IN THE
LOW-LEVELS.  VWP WINDS SHOW 30 TO 40 KTS JUST OFF THE SURFACE WITH
POTENTIAL TO BE DOWNWARD ADVECTED IN STORM COLLAPSE.  THIS POTENTIAL
SHOULD BE KEPT IN MIND UNTIL GULF TROF AXIS CLEARS WHICH IS STILL WEST
OF CURRENT CLOUD SHIELD (AND LATER THIS MORNING) AS IT EJECTS MINOR
WAVES EAST.  AFTERWARDS...REMAINDER OF DAY REASONABLE WITH MAIN
LOOK FORWARD TO DEVELOPMENT OF SURFACE LOW ALONG FRONT OVER
ALABAMA THAT DEEPENS TONIGHT.  THIS WILL BRING A THREAT OF STRONG
STORMS TO CENTRAL FLORIDA FOR WEDNESDAY.

SHARP 
  

d) Providing pertinent lightning information in the NOWCAST (MIANOWMLB)...most important!!!

 

ACTION:

Nowcast (NOW) - The AMU Meteorologist should make proper use of real-time TLI for use in the NOW.

1. Storm-specific information - Individual lightning storms should be examined for their respective NLDN-CG flash rates. Attempts should be made to quantify such terms as "EXCESSIVE", "FREQUENT", and "OCCASIONAL" according to actual flash rates. Potential impacts should be mentioned in the NOW.

 

SHORT TERM FORECAST
NATIONAL WEATHER SERVICE MELBOURNE FL
617 PM EDT FRI JUL 25 1997

FLZ041-044>047-053-054-058-059-064-501-260000-
VOLUSIA-LAKE-ORANGE-SEMINOLE-BREVARD-OSCEOLA-INDIAN RIVER-OKEECHOBEE-
ST. LUCIE-MARTIN-COASTAL WATERS VOLUSIA TO MARTIN COUNTY-

.NOW...
...STRONG STORMS TO DEVELOP FROM KISSIMMEE/ST CLOUD NORTHWARD...
THROUGH 800 PM...LIGHTNING STORMS WILL BE SCATTERED FROM LAKE GEORGE AND LAKE
HELEN...TO LISBON...TO APOPKA AND THE CENTRAL FLORIDA ATTRACTIONS AREA. THEY WILL
MOVE SLOWLY AND STRENGTHEN AS THEY COLLIDE WITH THE EAST COAST SEA BREEZE.
STORMS PRODUCING EXCESSIVE LIGHTNING WILL BE POSSIBLE FROM KISSIMMEE/ST CLOUD...
TO ORLANDO AND SANFORD...NORTHWARD INTO VOLUSIA COUNTY FROM DELAND TO THE
COAST FROM DAYTONA BEACH NORTHWARD. AN ISOLATED LIGHTNING STORM
WILL ALSO MOVE NORTH ALONG THE OSCEOLA/INDIAN RIVER COUNTY LINE BETWEEN
BLUE CYPRESS LAKE AND YEEHAW JUNCTION.
CRISTALDI

$$

SHORT TERM FORECAST
NATIONAL WEATHER SERVICE MELBOURNE FL
743 PM EDT FRI JUL 25 1997

FLZ041-044>046-260145-
VOLUSIA-LAKE-ORANGE-SEMINOLE-

.NOW...
...STORMS WITH EXCESSIVE LIGHTNING OVER SEMINOLE & VOLUSIA COUNTIES...
THROUGH 900 PM...STORMS WITH EXCESSIVE CLOUD TO GROUND LIGHTNING
...SMALL HAIL...GUSTY WINDS...AND HEAVY RAIN WILL OCCUR FROM LAKE MONROE
NORTH TO DELTONA AND DELAND. OTHER STORMS WILL DEVELOP ACROSS SEMINOLE
COUNTY FROM SANFORD TO LAKE JESSUP AND OVIEDO. THESE STORMS SHOULD
BEGIN TO WEAKEN BY 900 PM.
CRISTALDI

$$ 


METAR KDAB 252353Z 28004KT 10SM TS FEW010 BKN032CB OVC055 28/21
 A3004 RMK A02 SLP172 CONS LTGICCCCG SW-W TS SW-NW MOV SLOLY N DARK
 SW-W T02830211 10339 20278 53009

 

2. Location-specific information - When possible, statements should be made regarding the electrical character of the atmosphere over ECFL. This may be further broken down into sub-areas or counties (when feasible). Particular attention should be given to the beginning and ending of lightning as seen by LDAR and mentioned in the NOW.

 

Any statements which quantify or detail the electrical character of the atmosphere over ECFL can be useful to NOWCAST readers.  Pertinent information which can be added to a NOW include:

 

CG Lightning Onset time/location:  Using satellite, radar, and LDAR signatures, forecasters should attempt to issue a NOW each day in advance of the initial CG strikes. Unique methods to convey this information should be explored. For example, a NOW could be issued for Indian River, St. Lucie, and Martin counties at 10 AM with a headline stating "...CLOUD TO GROUND LIGHTNING WILL BEGIN BY 11 AM..."
 
CG Lightning occurring far from the cell core:  LDAR signatures of anvil lightning can be especially useful since a majority of lightning deaths occur from strikes away from the cell core. If the upper level flow is favorable for an anvil to travel far downstream from the reflectivity core and TLI data supports elevated electrification, a NOW could be issued to supply this important information. For example, a 2 PM NOW could state: "...CLOUD TO GROUND LIGHTNING DANGER ACROSS MARTIN COUNTY... THROUGH 4 PM...MOST RAINFALL WILL REMAIN TO THE SOUTH OVER PALM BEACH COUNTY HOWEVER OCCASIONAL LIGHTNING STRIKES TO THE GROUND WILL LIKELY OCCUR ACROSS PORTIONS OF MARTIN COUNTY FAR FROM THE STORMS. FAR REACHING LIGHTNING STRIKES OCCUR WITH LITTLE ADVANCE WARNING...AND THEREFORE CAN BE ESPECIALLY DANGEROUS."

CG Lightning End time/location:  Specifying lightning end times can be more arduous than determining start times. Although determining an end time for ALL CG strikes associated with particular cells is unlikely at this point, the lightning workstations can help forecasters identify a decreasing potential for ground strikes. If the anvil has advected away from the area, re-development is not expected, and TLI displays confirm an end to electrification, useful information can be supplied in a NOWCAST.  For example, a NOW could be written for Lake, Orange, and Seminole counties at 6 PM, such as "...CLOUD TO GROUND LIGHTNING DECREASING...  THROUGH 8 PM...THE THREAT OF CLOUD TO GROUND LIGHTNING STRIKES WILL DECREASE SIGNIFICANTLY AS STORMS MOVE INTO THE COASTAL COUNTIES AND THE ATMOSPHERE BECOMES STABLE ACROSS THE METRO ORLANDO VICINITY."

The NOWCAST segments cited above were created to illustrate how TLI can potentially be used to increase public awareness and hopefully improve reactions. Forecasters are urged to experiment with unique wording to convey the lightning threat, as portrayed by TLI workstations, to the ECFL NOW customers. Examples taken from actual NOW's will be collected and displayed on LANTERN and on the USER.COM bulletin board as appropriate. The TLI initiative is just beginning, and will evolve as we learn additional ways to convey information from the lightning sensors to the public.

 

SHORT TERM FORECAST
NATIONAL WEATHER SERVICE MELBOURNE FL
617 PM EDT FRI JUL 25 1997

FLZ041-044>047-053-054-058-059-064-501-260000-
VOLUSIA-LAKE-ORANGE-SEMINOLE-BREVARD-OSCEOLA-INDIAN RIVER-OKEECHOBEE-
ST. LUCIE-MARTIN-COASTAL WATERS VOLUSIA TO MARTIN COUNTY-

.NOW...
...STRONG STORMS TO DEVELOP FROM KISSIMMEE/ST CLOUD NORTHWARD...
THROUGH 800 PM...LIGHTNING STORMS WILL BE SCATTERED FROM LAKE GEORGE AND LAKE
HELEN...TO LISBON...TO APOPKA AND THE CENTRAL FLORIDA ATTRACTIONS AREA. THEY WILL
MOVE SLOWLY AND STRENGTHEN AS THEY COLLIDE WITH THE EAST COAST SEA BREEZE.
STORMS PRODUCING EXCESSIVE LIGHTNING WILL BE POSSIBLE FROM KISSIMMEE/ST CLOUD...
TO ORLANDO AND SANFORD...NORTHWARD INTO VOLUSIA COUNTY FROM DELAND TO THE
COAST FROM DAYTONA BEACH NORTHWARD. AN ISOLATED LIGHTNING STORM
WILL ALSO MOVE NORTH ALONG THE OSCEOLA/INDIAN RIVER COUNTY LINE BETWEEN
BLUE CYPRESS LAKE AND YEEHAW JUNCTION.
CRISTALDI

$$

SHORT TERM FORECAST
NATIONAL WEATHER SERVICE MELBOURNE FL
743 PM EDT FRI JUL 25 1997

FLZ041-044>046-260145-
VOLUSIA-LAKE-ORANGE-SEMINOLE-

.NOW...
...STORMS WITH EXCESSIVE LIGHTNING OVER SEMINOLE & VOLUSIA COUNTIES...
THROUGH 900 PM...STORMS WITH EXCESSIVE CLOUD TO GROUND LIGHTNING
...SMALL HAIL...GUSTY WINDS...AND HEAVY RAIN WILL OCCUR FROM LAKE MONROE
NORTH TO DELTONA AND DELAND. OTHER STORMS WILL DEVELOP ACROSS SEMINOLE
COUNTY FROM SANFORD TO LAKE JESSUP AND OVIEDO. THESE STORMS SHOULD
BEGIN TO WEAKEN BY 900 PM.
CRISTALDI

$$ 

METAR KDAB 252353Z 28004KT 10SM TS FEW010 BKN032CB OVC055 28/21
 A3004 RMK A02 SLP172 CONS LTGICCCCG SW-W TS SW-NW MOV SLOLY N DARK
 SW-W T02830211 10339 20278 53009

 3. User-specific information - At this time, the AMU will consider all interests in ECFL as the "user-community".  The Lightning & Electrification Focal Point, along with the Warning Coordination Meteorologist, will also provide a series of lightning-related "Calls-to-Action" which may be used within the NOW.

At this time, the only "user community" which has been defined is the "beach/coastal recreation community". A large number of lightning fatalities result from individuals taking part in beach & coastal recreation. Any useful lightning information we can provide to this segment of the population (including mariners) will be an added benefit. For example, forecasters should be especially wary of the potential for anvil lightning approaching the beaches. Also, notification of  lightning storms which will rapidly approach the coastline, or result in strong/severe weather, should be made as early as possible (within HWO's and NOW's).

 


     

    "EXAMPLES" (products issued by NWS Melbourne):


    July 25, 1997: Transition of "excessive lightning" statements

    AREA FORECAST DISCUSSION
    NATIONAL WEATHER SERVICE MELBOURNE FL
    230 PM EDT THU JUL 24 1997

    ACTIVITY SLOW TO FIRE TODAY. SEVERAL AREAS OF CONVERGENCE NOTED ON LATEST SATELLITE AND RADAR IMAGERY...THEREFORE EXPECT COVERAGE OF STORMS TO INCREASE THROUGH EARLY EVENING...ESPECIALLY INLAND. OVERNIGHT POPS NOT LIKELY ALONG THE COAST AS THE FLOW COMPONENT REMAINS ALONG SHORE TO SLIGHTLY OFFSHORE.

    WITH LOW LEVEL RIDGE AXIS CONTINUING TO DROP SLOWLY SOUTH FRIDAY...AFTERNOON CONVECTION WILL FAVOR THE EAST COASTAL ZONES FROM INDIAN RIVER COUNTY NORTHWARD...AND INTERIOR COUNTIES TO THE SOUTH. SCATTERED POPS LIKELY INLAND...AS MOST ACTIVITY ADVECTS NE DURING THE DAY. EXPECT EAST COAST SEA BREEZE TO FORM...POSSIBLY LEADING TO A FEW STRONG STORMS AND EXCESSIVE LIGHTNING OVER VOLUSIA AND BREVARD
    COUNTIES DURING THE LATE AFTERNOON. TEMPS ALOFT REMAIN WARM HOWEVER...AND UPPER DIVERGENCE MAY NOT BE AS PRONOUNCED AS DEPICTED BY EARLIER MODEL RUNS...SO MESOSCALE INFLUENCES WILL LIKELY RULE...AS USUAL FOR MID SUMMER.

    SPRATT

     


    SHORT TERM FORECAST
    NATIONAL WEATHER SERVICE MELBOURNE FL
    617 PM EDT FRI JUL 25 1997

    FLZ041-044>047-053-054-058-059-064-501-260000-
    VOLUSIA-LAKE-ORANGE-SEMINOLE-BREVARD-OSCEOLA-INDIAN RIVER-OKEECHOBEE-
    ST. LUCIE-MARTIN-COASTAL WATERS VOLUSIA TO MARTIN COUNTY-

    .NOW...
    ...STRONG STORMS TO DEVELOP FROM KISSIMMEE/ST CLOUD NORTHWARD...
    THROUGH 800 PM...LIGHTNING STORMS WILL BE SCATTERED FROM LAKE GEORGE AND LAKE HELEN...TO LISBON...TO APOPKA AND THE CENTRAL FLORIDA ATTRACTIONS AREA. THEY WILL
    MOVE SLOWLY AND STRENGTHEN AS THEY COLLIDE WITH THE EAST COAST SEA BREEZE. STORMS PRODUCING EXCESSIVE LIGHTNING WILL BE POSSIBLE FROM KISSIMMEE/ST CLOUD...TO ORLANDO AND SANFORD...NORTHWARD INTO VOLUSIA COUNTY FROM DELAND TO THE COAST FROM DAYTONA BEACH NORTHWARD. AN ISOLATED LIGHTNING STORM WILL ALSO MOVE NORTH ALONG THE OSCEOLA/INDIAN RIVER COUNTY LINE BETWEEN BLUE CYPRESS LAKE AND YEEHAW JUNCTION.
    CRISTALDI
    $$

     


    BULLETIN - IMMEDIATE BROADCAST REQUESTED
    SEVERE THUNDERSTORM WARNING
    NATIONAL WEATHER SERVICE MELBOURNE FL
    703 PM EDT FRI JUL 25 1997

    THE NATIONAL WEATHER SERVICE IN MELBOURNE FL HAS ISSUED A
    SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 750 PM EDT
    FOR PEOPLE IN THE FOLLOWING LOCATION...

    IN EAST CENTRAL FLORIDA
    ...VOLUSIA COUNTY

    AT 700 PM...MELBOURNE DOPPLER RADAR SHOWED A SEVERE THUNDERSTORM DEVELOPING ALONG I-4 JUST WEST OF DELTONA. OTHER STORMS WILL QUICKLY DEVELOP SOUTHWARD ALONG S.R. 11 TOWARDS DELAND AND LAKE HELEN. SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 58 MPH...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A STRONG BUILDING. HEAVY RAINS FLOOD ROADS QUICKLY SO DON'T DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

    CRISTALDI

     


    SHORT TERM FORECAST
    NATIONAL WEATHER SERVICE MELBOURNE FL
    743 PM EDT FRI JUL 25 1997

    FLZ041-044>046-260145-
    VOLUSIA-LAKE-ORANGE-SEMINOLE-

    .NOW...
    ...STORMS WITH EXCESSIVE LIGHTNING OVER SEMINOLE & VOLUSIA COUNTIES...
    THROUGH 900 PM...STORMS WITH EXCESSIVE CLOUD TO GROUND LIGHTNING...SMALL HAIL...GUSTY WINDS...AND HEAVY RAIN WILL OCCUR FROM LAKE MONROE NORTH TO DELTONA AND DELAND. OTHER STORMS WILL DEVELOP ACROSS SEMINOLE COUNTY FROM SANFORD TO LAKE JESSUP AND OVIEDO. THESE STORMS SHOULD BEGIN TO WEAKEN BY 900 PM.
    CRISTALDI
    $$

     


    METAR KDAB 252353Z 28004KT 10SM TS FEW010 BKN032CB OVC055 28/21
     A3004 RMK A02 SLP172 CONS LTGICCCCG SW-W TS SW-NW MOV SLOLY N DARK
     SW-W T02830211 10339 20278 53009

     


    EVENT SYNOPSIS:

    THE AREA FORECAST DISCUSSION WRITTEN ON THURSDAY AFTERNOON...ACCURATELY DEFINED THE POTENTIAL FOR EXCESSIVE LIGHTNING ACROSS VOLUSIA COUNTY OVER 24 HOURS AHEAD OF TIME BASED ON EXPECTED BOUNDARY INTERACTIONS. THE FOLLOWING AFTERNOON...NOWCASTS WERE ISSUED TO EMPHASIZE THE LIGHTNING DANGER BASED ON TLI OBSERVATIONS. NOTE THE DAB OBSERVATION OF CONTINUOUS CG LIGHTNING TO THE SW THROUGH W. SEVERE WEATHER IN THE FORM OF WIND DAMAGE ALSO OCCURRED IN VOLUSIA COUNTY...SEE LISDAD DATA.

     

    July 29, 1997: "Extreme lightning event" near Disney; severe storm winds

    SHORT TERM FORECAST
    NATIONAL WEATHER SERVICE MELBOURNE FL
    436 PM EDT TUE JUL 29 1997

    ORANGE-OSCEOLA-

    .NOW...
    ...STRONG THUNDERSTORMS LIKELY ACROSS NORTHERN OSCEOLA AND SOUTHERN ORANGE COUNTIES THROUGH 530 PM...COLLIDING OUTFLOW BOUNDARIES OVER NORTHERN OSCEOLA AND SOUTHERN ORANGE COUNTIES WILL ALLOW FOR STRONG TO SEVERE THUNDERSTORMS TO DEVELOP FROM THE ORLANDO INTERNATIONAL AIRPORT SOUTH ACROSS THE GREATER KISSIMMEE/ST CLOUD AREA. STORMS WILL BE CAPABLE OF PRODUCING NEARLY CONTINUOUS CLOUD TO GROUND LIGHTNING...LOCALLY DAMAGING WINDS AND HAIL. RAINFALL RATES OF 2 TO 3 INCHES PER HOUR WILL ALSO BE POSSIBLE. SEEK A SAFE LOCATION AS THESE STORMS MOVE ACROSS THE REGION.
    $$
    HODANISH

     


    BULLETIN - IMMEDIATE BROADCAST REQUESTED
    SEVERE THUNDERSTORM WARNING
    NATIONAL WEATHER SERVICE MELBOURNE FL
    514 PM EDT TUE JUL 29 1997

    THE NATIONAL WEATHER SERVICE IN MELBOURNE FL HAS ISSUED A
    SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 615 PM EDT
    FOR PEOPLE IN THE FOLLOWING LOCATION...

    IN EAST CENTRAL FLORIDA
    ...ORANGE COUNTY

    AT 514 PM EDT...A LINE OF STRONG TO SEVERE THUNDERSTORMS EXTENDED FROM NEAR THE DISNEY COMPLEX...TO NEAR THE INTERNATIONAL AIRPORT. THE STORMS WERE MOVING SLOWLY NORTH. A WIND GUST NEAR 50 MPH HAS ALREADY BEEN RECORDED AT THE INTERNATIONAL AIRPORT.

    SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 58 MPH...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A STRONG BUILDING. HEAVY RAINS FLOOD ROADS QUICKLY SO DON'T DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

     


    BULLETIN - IMMEDIATE BROADCAST REQUESTED
    SEVERE THUNDERSTORM WARNING
    NATIONAL WEATHER SERVICE MELBOURNE FL
    524 PM EDT TUE JUL 29 1997

    THE NATIONAL WEATHER SERVICE IN MELBOURNE FL HAS ISSUED A
    SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 625 PM EDT
    FOR PEOPLE IN THE FOLLOWING LOCATION...

    IN EAST CENTRAL FLORIDA
    ...OSCEOLA COUNTY

    AT 522 PM EDT...WEATHER RADAR INDICATED SEVERE THUNDERSTORMS DEVELOPING FROM NEAR THE TOLL BOOTH IN EAST ORANGE COUNTY...SOUTH TO NEAR HOLOPAW IN OSCEOLA COUNTY...TO 5 MILES WEST OF KENANSVILLE. OTHERS WERE FORMING NEAR KISSIMMEE/ST CLOUD. THESE STORMS WERE MOVING SLOWLY NORTH.

    THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH YOU SHOULD PREPARE FOR DAMAGING WIND IN EXCESS OF 58 MPH...LARGE HAIL...AND DEADLY LIGHTNING. PEOPLE OUTSIDE OR IN MOBILE HOMES SHOULD MOVE INSIDE A STRONG BUILDING AND STAY AWAY FROM WINDOWS.

    SHARP

     


    SEVERE WEATHER STATEMENT
    NATIONAL WEATHER SERVICE MELBOURNE FL
    532 PM EDT TUE JUL 29 1997

    ...SEVERE THUNDERSTORM WARNING FOR ORANGE COUNTY UNTIL 615 PM...
    ...SEVERE THUNDERSTORM WARNING FOR OSCEOLA COUNTY UNTIL 625 PM...

    AT 529 PM DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 5 MILES EAST OF THE DISNEY COMPLEX. THIS STORM WILL BE CAPABLE OF PRODUCING DAMAGING WINDS...LARGE HAIL AND RAINFALL ACCUMULATIONS IN EXCESS OF 2 INCHES PER HOUR. IN ADDITION...LIGHTNING DETECTION EQUIPMENT WAS INDICATING EXCESSIVE FLASH RATES OF 20 FLASHES PER MINUTE. OTHER STRONG TO SEVERE STORMS WERE LOCATED IN EASTERN OSCEOLA COUNTY 10 MILES WEST OF THE ST JOHNS RIVER. THE STORMS WERE SHOWING VERY LITTLE MOVEMENT.

     


    SHORT TERM FORECAST
    NATIONAL WEATHER SERVICE MELBOURNE FL
    542 PM EDT TUE JUL 29 1997

    VOLUSIA-ORANGE-SEMINOLE-BREVARD-OSCEOLA-

    .NOW...
    ...STRONG TO SEVERE THUNDERSTORMS WITH EXCESSIVE CLOUD TO GROUND LIGHTNING OCCURRING ACROSS THE REGION...
    STRONG THUNDERSTORMS WILL CONTINUE TO AFFECT AREAS FROM EDGEWATER TO MIMS TO THE EASTERN ORLANDO AREA TO KISSIMMEE/ST CLOUD. THE STRONGEST STORMS AND HEAVIEST RAIN WILL OCCUR FROM SCOTTSMOOR TO BITHLO/CHRISTMAS SOUTH TO HOLOPAW. THESE STORMS WILL PRODUCE RAINFALL ACCUMULATIONS OF 1 TO 3 INCHES...STRONG WINDS AND EXCESSIVE CLOUD TO GROUND LIGHTNING. THE STORMS WILL MOVE TO THE NORTHEAST AT 10 MPH.
    $$
    HODANISH

     


    SEVERE WEATHER STATEMENT
    NATIONAL WEATHER SERVICE MELBOURNE FL
    600 PM EDT TUE JUL 29 1997

    ...SEVERE THUNDERSTORM WARNINGS FOR ORANGE AND OSCEOLA COUNTIES CANCELLED...
    THE SEVERE THUNDERSTORM WARNINGS FOR ORANGE AND OSCEOLA COUNTIES HAS BEEN CANCELLED. THE STORMS WHICH PROMPTED THE WARNINGS HAVE WEAKENED AND NO LONGER SEVERE. SCATTERED THUNDERSTORMS WITH OCCASIONAL CLOUD TO GROUND LIGHTNING WILL CONTINUE OVER THE GREATER ORLANDO AREA THROUGH 7 PM THIS EVENING...HOWEVER THESE STORMS SHOULD REMAIN BELOW SEVERE LIMITS.

     


    SHORT TERM FORECAST
    NATIONAL WEATHER SERVICE MELBOURNE FL
    718 PM EDT TUE JUL 29 1997

    VOLUSIA-LAKE-ORANGE-SEMINOLE-BREVARD-OSCEOLA-INDIAN RIVER-OKEECHOBEE-ST. LUCIE-MARTIN-COASTAL WATERS VOLUSIA TO MARTIN COUNTY-

    .NOW...
    THROUGH 930 PM...SCATTERED AREAS OF LIGHT RAIN WITH A FEW EMBEDDED LIGHTNING STORMS EXTENDING FROM NEAR DAYTONA BEACH SOUTH TO THE SPACE CENTER AND SOUTHWEST ACROSS THE SOUTHERN ORLANDO METRO AREA TO SOUTH LAKE COUNTY WILL CONTINUE TO MOVE NORTHEAST AT 10 MPH AND SLOWLY DIMINISH THROUGH THE EVENING HOURS. ALTHOUGH THE STORMS WERE PRODUCING VERY LITTLE CLOUD TO GROUND LIGHTNING...LIGHTNING DETECTION EQUIPMENT WAS INDICATING THE FLASHES WERE DEPOSITING POSITIVE ELECTRICAL CHARGE TO GROUND...WHICH IS UP TO 10 TIMES MORE POWERFUL THAN A NORMAL LIGHTNING FLASH.
    &&
    OVER THE REMAINDER OF EAST CENTRAL FLORIDA...SCATTERED TO NUMEROUS HIGH CLOUDS WILL PREVAIL.
    $$
    HODANISH

     


    EVENT SYNOPSIS:

    THE CLOUD TO GROUND FLASH RATE WITH ONE STORM EAST OF DISNEY REACHED 220+ FLASHES PER 7 MINUTES...OR ABOUT 30 CG FLASHES PER MINUTE...OR A FLASH HITTING THE GROUND EVERY 2 SECONDS. TOTAL LIGHTNING (CG+CC+IC) PEAKED NEAR 120 FLASHES PER MINUTE. THIS ENORMOUS AMOUNT OF LIGHTNING OCCURRED DUE TO A COLLISION BETWEEN THE WEST COAST SEA BREEZE AND AN OUTFLOW BOUNDARY.

    THE NOWCASTS SET THE STAGE BY DEFINING THE LOCATION AND TIME FRAME OF EXPECTED INTENSE CONVECTION AND EXCESSIVE LIGHTNING WELL AHEAD OF TIME. LATER SEVERE WEATHER STATEMENTS EMPHASIZED THE ONGOING LIGHTNING THREAT.

    SEVERE WEATHER IN THE FORM OF HAIL UP TO GOLFBALL SIZE HAIL AND WIND DAMAGE WAS CONFIRMED. AT ORLANDO INTERNATIONAL AIRPORT (MCO)...A WIND GUST TO 44 KT...AND FREQUENT CG LIGHTNING WAS OBSERVED FOR OVER 45 MINUTES.

     

    July 30, 1997: "Bolt from the blue"

    SHORT TERM FORECAST
    NATIONAL WEATHER SERVICE MELBOURNE FL
    406 PM EDT WED JUL 30 1997

    FLZ041-044>046-053-058-302200-
    VOLUSIA-LAKE-ORANGE-SEMINOLE-OSCEOLA-OKEECHOBEE-

    .NOW...
    THROUGH 600 PM...THE EAST AND WEST COAST SEA BREEZES WILL COLLIDE OVER THE INTERIOR. AS A RESULT...SHOWERS AND LIGHTNING STORMS WILL RAPIDLY DEVELOP OVER THE CORRIDOR FROM LAKE GEORGE TO DELAND...DELTONA AND SANFORD...AND CONTINUING SOUTH TO METRO ORLANDO...KISSIMMEE/ST CLOUD...HOLOPAW AND KENANSVILLE. SOME STORMS WILL PRODUCE FREQUENT TO EXCESSIVE CLOUD TO GROUND LIGHTNING STRIKES...SOME POSSIBLY 5 TO 10 MILES AWAY FORM THE CORE OF THE STORM. THESE "BOLTS FROM THE BLUE" HAVE ALREADY OCCURRED WITH STORMS AROUND CAPE CANAVERAL. TORRENTIAL RAINS OF BETWEEN 2 AND 3 INCHES AND GUSTY WINDS MAY ALSO OCCUR.
    CRISTALDI
    $$ 

     

     

     

     


 


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