Fall 1997/ Winter 1998

Issue 3

The History of EL Nino

The term "El Nino" was coined in 1891 when sailors off the coast of Peru noticed that a counter-current was flowing from north to south. This unusual ocean current was given the name "El Nino" ( the Child Jesus) because it had been observed to appear immediately after Christmas. These sailors had no idea that these unusual ocean currents extended to such great distances.

The unusual ocean current was given the name "El Nino" (the Child Jesus) because it had been observed to appear immediately after Christmas

The El Nino Phenomenon is a highly complex atmospheric and oceanic interaction. A simple explanation would be that for unknown reasons the pressure pattern shifts across the tropical Pacific, pushing warmer water toward South America. Dry conditions occur near the high pressure in Australia while wet weather occurs near the low pressure in parts of South America. This change in the atmospheric pressure pattern ends up having an impact across a large part of the globe.

It was not until the 1940s that scientists began to realize that the warm water near Peru actually extended far westward to the International Date Line. More detailed El Nino analysis occurred in the 1970s when scientists had more sophisticated tools available to study the phenomenon. Satellites were used more extensively to measure sea surface temperatures across remote areas. More reliable ship and buoy reports were also made available. The pool of warmer than normal water can be massive, stretching up to 5,000 miles long. In a strong El Nino period, such as 1982-83, the sea surface temperatures warmed as much as 16 degrees Fahrenheit in parts of the Pacific.

The combination of increasing public interest and more sophisticated research tools have led to a greater understanding of El Nino and its global impact. An El Nino event occurs every three to seven years, and is of varying degrees and duration. The El Nino of 1997-98 will likely turn out to the strongest this century.

The sea surface temperature anomalies during the first week in November. The darker areas along the equator and The Baja of California denote warmer than normal temperatures.

By: Ryan Sandler ILN Forecaster

Changes For Pagenet Customers

Many of the spotters have taken advantage of the severe weather information service offered through Pagenet or ARCH. If you currently have this service through Pagenet, than you may need to have your pager recoded.

Unfortunately, we recently discovered that some of the county groups were set up improperly. As a result, most of the group cap codes were changed. The following groups were not changed: Southwest Ohio and the Miami Valley Groups.

At the present time we are planning to make the official change sometime in January. When we have everything finalized, we will send a message over the pagers to let the affected people know when to have their pager re-coded. If you are one of the people affected, you will have the option of either mailing your pager to Pagenet or simply visiting them in person. I am truely sorry for the inconvenience. If you have any problem with the transition, feel free to call either Mary Jo Parker or myself, Diane Innes, at (937) 383-0031, and we will try to assist you.

By: Diane Innes

A Discussion About Freezing Rain

If you have lived in the Ohio Valley for a lifetime or even just a few years, you have learned that you must prepare for a variety of hazardous weather conditions each winter season. Of all the winter phenomena that occurs, freezing rain can be the most dangerous and destructive. Even light amounts of freezing rain can wreak an incredible amount of havoc, while heavy freezing rain can produce legendary damage.

Strictly speaking, freezing rain is defined as liquid drops of rain with a temperature of 0 Celsius or less, which freezes on surfaces and forms a layer of ice known as glaze. In reality, this clinical definition does not begin to illustrate the full impact of freezing rain. Glaze can render travel by vehicle or by foot difficult or impossible. Trees that have survived for a hundred years can splinter under the weight of ice. Entire electrical grids can be damage or destroyed, leaving thousands of customers without power for days.

Freezing rain is a significant issue for Wilmington Skywarn spotters. On an average, freezing rain occurs along and north of a Richmond-Dayton-Columbus line 8 to 12 days per year. Only a few other locations in the United States--in the upper Mississippi River Valley, near Lakes Superior and Michigan, and in the Adirondack Mountains of upstate New York--experience freezing rain more often. For areas such as Cincinnati, Portsmouth, Southeast Indiana, and Northern Kentucky--freezing rain typically occurs on 4 to 8 days a year.

How does freezing rain form? Consider a simplified version of a scenario that occurs often in the Ohio Valley. A cold front pushes through the region, and high pressure then ushers cold air into the area. However, within 24 hours, a low develops on the front over the Southern Plains and moves northeast toward the Ohio Valley. As the low treks our way, its counterclockwise circulations draws warm, moist air from the Gulf of Mexico northward into the area. Because the warm air is less dense than the cold air situated across the Ohio Valley, the warm air is forced up and over the cold air mass. As the warm air is lifted, it cools and condenses to form clouds and precipitation. In the winter across the Ohio Valley, all precipitation begins as snow about one to three miles above the earth. The type of precipitation you actually observe though depends on the temperature of the atmosphere between that level and the surface.

If the temperature remains below freezing from the snow formation altitude to the earth's surface, then you will observe snow. Often however, the temperature at one or more levels rises above freezing, causing the snowflakes to melt to some degree. If a sufficiently deep layer warms to above freezing, then the snowflakes melt and become raindrops.

In our simplified scenario, a deep, elevated layer of air warms to 4 C above zero, and the snowflakes melt. However, the cold, dense air mass that previously invaded the region remains at the surface where the temperature is

29 F or -2 C. As raindrops fall into this cold layer, the temperature of each drop falls below freezing. The drops do not freeze while airborne since, under proper conditions, liquid water can exist at temperatures as low as minus 40 C. However, once the drops encounter a surface which is below freezing these supercooled drops freeze on impact.

As often the case in Meteorology, real-life events are usually more complicated than our simplified case. There are many variables that dictate whether a given storm will produce no freezing rain, a brief period of light freezing rain or will become a headline-grabbing ice storm. It is impossible for the forecaster to directly measure these variables on a continuous basis; thus, forecasting freezing rain is very difficult. This fact renders the role of the Skywarn Spotter crucial during freezing rain events.

An element which affects the severity of the icing is the exact amount of precipitation that a given location will receive. For a typical storm, the forecaster may anticipate around one-quarter of an inch of rain in an area, but up to one-third of an inch of rain may fall in a few locations. While underforecasting rainfall amounts usually does not have significant effects during liquid events, it can make a large difference in a storm's total ice accumulation.

Other important variables which affect the severity of icing include the time of day and even the time of year. Since the temperature is usually colder at night, if the rain begins overnight, it is more likely to freeze to surfaces. Likewise, icing events tend to occur from December through February since the ground has had time to "freeze."

Another variable that is difficult to measure is the temperature difference between ground-based surfaces. Often, objects with most of their surfaces exposed to the air--such as tree branches, power lines and overpasses--are colder than objects firmly rooted in the ground--such as roads or buildings.

This is only a sample of the factors that we as meteorologists mush consider when forecasting freezing rain. Accurate, real-time spotter reports are a critical component of this dynamic process. Your reports help us to monitor and update the forecasts. Based on your calls, we may upgrade a Winter Weather Advisory to an Ice Storm Warning or even cancel a warning or advisory.

By: Steve Rowley, ILN Forecaster

El Nino's Potential Impact on the Ohio River Valley

During strong El Nino events, these cities (Cincinnati, Columbus, and Dayton) altogether average nearly ten fewer inches of snowfall while at the same time temperatures average 3.5 degrees warmer!

Temperatures (Degrees F) for December thru February

1957-58		31.1		28.9		30.0
1972-73		33.6		32.0		32.9
1982-83		36.6		34.4		34.8
1991-92		36.6		33.6		35.1
Average.	34.5		32.2		33.2
Average.	31.1		29.0		29.3

Snowfall (inches) for December thru February

1957-58		18.6		23.8		21.5
1972-73		17.7		21.7		24.5
1982-83		6.6		5.5		11.5
1991-92		13.8		17.0		18.9
Average		14.2		17.0		19.1
Average		23.4		27.7		27.8

The effects of El Nino are more visible in the Ohio Valley during the winter months when the jet stream (storm track) is more intense, and farther south. Large scale weather systems are typically well developed at this time of year, and there is a greater exchange of air between southern and northern areas.

The four strongest El Nino events since 1950 are listed in Tables 1 and 2. The winter months of December, January, and February clearly show the relationship with temperature and snowfall during a strong El Nino event compared with the typical 30 year averages for Cincinnati, Dayton, and Columbus. During strong El Nino events, these cities altogether average nearly ten fewer inches of snowfall while at the same time temperatures average 3.5 degrees warmer! This decrease in snowfall and increase in temperature during the winter months has the same effect as moving these cities nearly 80 miles south when compared to average conditions. In a sense, it would be as if Dayton and Columbus's winter climate became more like Dry Ridge or Maysville KY, and Cincinnati more like Louisville. Of course, if you like a milder, less snowy climate where you live then you probably welcome El Nino. However, if you area a snow lover and avid skier, El Nino may not be for you. Keep in mind that there were only four strong El Nino seasons available in the past, and that these different years had varying weather conditions.

Thus, although it is more likely that there will be less snowfall and warmer temperatures this winter, it is not a sure thing. It comes as no surprise that the 1998 Old Farmer's Almanac has November through March milder and drier than normal with snowfall below normal for the Ohio Valley.

By: Ryan Sandler, ILN Forecaster

Winter Weather Definitions

Since the winter season is now upon us, terms such as winter storm watch and winter storm warning have once again become apart of our vocabulary. So, the following is just a quick reminder of what these phrases represent.

A Winter Storm Outlook may be issued when there is a good chance of a major winter storm beyond 48 hours from the forecast time. These may be issued 2 to 5 days in advance of the storm and are use to give people considerable lead time to prepare for the effects of a possible winter storm.

A Winter Storm Watch is to alert people of the possible occurrence of a heavy snow, freezing rain or heavy sleet event or even a blizzard. The definition of heavy snow is 6+ inches in approximately 12 hours or less for West Central Ohio. For the remainder of Ohio and Southeastern Indiana as well as Northern Kentucky, heavy snow is categorized as 4+ inches of snow in approximately a 12 hour time period. Heavy snow can also be classified as 6+ inches of snow in 24 hours for all areas. A Winter Storm Watch will be issued for 36 to 48 hours before the event.

A Winter Storm Warning is issued when frozen precipitation such as sleet, or freezing rain/drizzle is expected to accumulate to 1/4 of an inch or more. This warning will also be issued when heavy snow is likely. This product is usually disseminated when the storm is expected within 12 hours or so.

A Blizzard Warning is issued when the following situation is forecasted: sustained winds or frequent gusts of 35 MPH or greater is expected in conjunction with heavy snowfall or blowing snow which reduces the visibility to less than a fourth of a mile. Another criteria is that the conditions persist for at least three hours.

A Wind Chill Warning is issued if wind chills of -35 degrees F or colder are anticipated within the next 12 hours.

A High Wind Warning is issued when sustained winds of 40 MPH or greater are expected or if wind gust of 58 MPH are anticipated. The duration of the event must be at least an hour.

A Winter Weather Advisory is to alert people of an event which will cause a significant inconvenience but does not meet the criteria for a winter storm warning. The criteria for a winter weather advisory can be any single event or a combination of the following:

  1. a snowfall accumulation of 1 to 3 inches
  2. wind chill readings ranging from -20 F to -34 F
  3. blowing and drifting snow with visibilities intermittently 1/4 of a mile or less
  4. freezing rain/drizzle which causes hazardous driving conditions and/ or up to 1/4 of an inch of freezing rain accumulation on tree branches and power lines.

An advisory will be issued when conditions are expected within 12 hours.

By: Diane Innes

Kudos To Spotters

Once again you as spotters did an outstanding job in supporting the NWSO ILN with verification information and rainfall reports this past summer and fall. Both members of Amateur Radio Originations as well as our individual spotters diligently relayed vital information to the Wilmington office. However, because of identification restrictions with information passed along via the HAM network, I will only be able to individually recognize the spotters who phoned in their reports and also gave either their name or Spotter ID.

Even though this severe weather season on a whole was unusually inactive, we did have a couple of very eventful days. One day, which spotters living in portions of Southwestern OH will likely remember well is on July 22nd. During the evening hours, nearly stationary thunderstorms dumped anywhere between 2 and 4 inches across portions of Butler, Warren, Hamilton, and Clermont counties. Localized extensive flooding occurred in these counties especially in sections of northeastern Cincinnati. Thanks to a rainfall report from Harry Epp of 1.5 inches of rain in the Oxford area within a 45 minute time period, we were able to better calibrate the radar to determine maximum rainfall amounts.

Another eventful day, once again in the Southwest Ohio, far Northern Kentucky, and Southeastern Indiana areas was on August 17th. On this day, supercell thunderstorms developed in Southeast Indiana and moved eastward. These storms caused extensive wind damage across much of the Cincinnati Tri-state area. The following spotters relayed damage reports to the Wilmington office, Dennis Simpson, Clarence Geoff, Jr., and Carolyn Apel. Also on that day, Dale Neiburg, a spotter in Putnam county relayed that a column of smoke looked very similar to a tornado. This was vital information, since the atmosphere conditions were prime for possible tornadic activity.

These were just a sample of the reports we received over the past few months. Just as a reminder, when you do phone in your report, please also give your Spotter ID number. I use the ID's to write this article; but, more importantly, the ID's assist during severe weather operations by helping to exactly pinpoint the of the report.

By: Diane Innes

The New NOAA Weather Radios Have Arrived

For those of you who are tired of waking up at 3 am to the friendly tone coming from your NOAA weather radio for a county that is other than your own, then I have great news for you. No, I am not suggesting that hide your NOAA weather radio in the garage. I have an even better suggestion, a radio that you can program the counties for which you would like to be alerted.

This new technologically advanced version of the NOAA weather radio has recently been released to consumers. Unfortunately though, I only have information on the Radio Shack style. If you prefer another brand, simply ask for the NOAA Weather Radio with SAME capabilities at your local gadgetry store such as Service Merchandise, Best Buy, or Circuit City.

Some of the features of the Radio Shack brand include NOAA seven channel reception, battery backup, and an internal antenna as well as an external antenna jack for a clearer signal in the "hard to reach" areas. At the present time the suggested retail price is $79.99.

Once you purchase a NWR-SAME system, you will need to code the radio with the counties for which you want the radio to be activated. Included in the package should be instructions of how to perform the coding procedures; however, it will not list the actual codes. Thus, Table 1 shows a list of the county codes for Wilmington's area. If you need any other counties, a toll free number is available. The number is 1-888-NWR-SAME (1-888-697-7263) . Also, additional counties are listed on the Wilmington Web page under the NOAA Weather Radio section.

By: Diane Innes

Improvements To The NOAA Weather Radio Program

NOAA Weather Radio broadcasts National Weather Service warnings, watches, forecasts and other hazard information 24 hours a day and is the public's primary source for weather information from the National Weather Service. In early 1998, the National Weather Service will begin a one-year process of implementing new equipment and procedures for automating NOAA Weather Radio broadcasts. A new, personal computer-based broadcasting console, known as the Console Replacement System, will automate the process of reading written information for broadcast on NOAA Weather Radio.

The new Console Replacement System will automatically translate written National Weather Service forecasts and warnings into synthesized-voice recordings and schedule them for broadcast on NOAA Weather Radio. The Console Replacement System will bring many benefits to the NOAA Weather Radio network. The new automated system will provide faster broadcasts of severe weather watches, warnings and emergency information over NOAA Weather Radio because multiple warnings can be both recorded and transmitted at once. This capability dramatically speeds up the broadcast of warnings during multiple severe weather events. The automated technology will also significantly reduce the time it takes National Weather Service staff to record NOAA Weather Radio broadcasts allowing them to devote more time to critical warning services and forecast duties.

The synthesized voice will be phased in over time. Eventually, all forecasts, warnings and weather information will be broadcast with the synthesized voice. A NOAA Weather Radio program will still be able to be interrupted with live broadcasts as needed. The National Weather Service is committed to making improvements to the system's voice quality as improvements become available. Console Replacement System technology will not require any changes to the receivers currently available at consumer electronics stores.

The Console Replacement System and the Specific Area Message Encoding (SAME) are two separate NOAA Weather Radio technological advances as part of the National Weather Service Modernization effort. Specific Area Message Encoding (SAME) is a feature on the newest generation of NOAA Weather Radios which lets listeners pre-select the National Weather Service alerts they want to receive based on the county where they live. The Console Replacement System automates the process of assigning SAME codes to watches and warnings.

By: Mary Jo Parker, Warning Coordination Meteorologist

Hazards Of Cold Weather

Most people are aware of the dangers associated with blizzards and ice storms. However, one winter weather condition which may be easily brushed off is the effect of subfreezing temperatures. While most deaths related to cold temperatures are due to severe cold weather outbreaks, a person can still die of exposure even if the temperatures are slightly below freezing. Everyone is potentially at risk to cold weather; however, the elderly and infants are the most susceptible. Recent winter death statistics indicate that 50 percent of deaths related to exposure to the cold are people who are over 60 years of age while over 75 percent of them are male. Also, about 20 percent of the deaths occur in the home. So, if you know of an elderly couple or a person living alone, try and check on them regularly during the winter months, especially during the extremely cold snaps.

Most cold related deaths are due to a condition called Hypothermia. This is when the body temperature drops below 95 F. Symptoms include slow or slurred speech, incoherence, memory loss, disorientation, uncontrollable shivering, drowsiness, repeated stumbling and apparent exhaustion.

The following are some suggestions as to what to do for a person who is suffering from Hypothermia. First, you should seek medical help immediately. If medical help is not available, then begin warming the person slowly. You always want to warm the body core first. If you warm the extremities first, the cold blood will be drawn toward the heart which could lead to heart failure. In order to warm the core of the victim, you want to first get that person into dry clothing. More than likely they will need assistance with this. You then want to wrap them in a warm blanket, being sure that both the head and neck are covered. You never want give the victim alcohol, drugs, coffee, or any hot beverage or food. One exception though would be warm broth.

Another condition which typically does not lead to death but can cause the loss of or permanent damage to limbs or extremities is frostbite. Technically, frostbite is damage which is done to the body tissue when the tissue freezes. Symptoms of frostbite include a loss of feeling and a white or pale appearance of the extremities. Extremities which are most susceptible to frostbite include fingers, toes, the nose and ear lobes.

Recent winter death statistics indicate that 50 percent of deaths related to exposure to the cold are people who are over 60 years of age and over 75 percent of them are male.

If you suspect signs of frostbite, you should obtain medical help immediately. If you must wait for help, slowly re-warm the affected area.

Some tips of what you can do to protect yourself and family from the cold weather include: 1) Wear loose fitting, lightweight, warm clothing, 2) Wear several layers since the trapped air will act as an insulation, 3) Wear outer garments that are tightly woven, water repellent and have hoods, 4) Always wear a hat since half of the body heat is lost though he top of the head, 5) Cover the mouth with scarves to protect the lungs from cold air, 6) Wear mittens that are snug at the wrist. Note: mittens area better than gloves since gloves allow you fingers to cool much faster than mittens, 7) Try to stay dry, and lastly 8) Do not remain outside for extended periods of time.

By: Al Randall, ILN Forecaster, and Diane Innes

Upcoming Spotter Talks

With the winter season now in full swing, spring is just around the corner. This means that everyone should be gearing up for the 1998 Spotter Talks. Just as a reminder, for those of you who did not attend a talk in 1997, we strongly recommend that you attend one this year. Ideally, each spotter should attend a talk once every two years.

For those of you who are unfamiliar with the Spotter training routine, the talks are generally conducted from February through mid May. We make an effort to do training in as many of our counties as possible each year. Typically, one talk is scheduled per county ; however, for some of the more densely populated areas, more than one talk may be scheduled. Also, the talks are generally arranged through the County Emergency Management Director.

Many spotters indicated on their questionnaires that they would have attended a meeting last year if they had know the time, date, and location of the one conducted in their area. Thus, the following are a couple of suggestions of where you can obtain information about the meetings. One of the easiest ways is through the Wilmington Web homepage. For those of you who do not know the address it is The information is posted under the Skywarn section. The talk calendar is updated whenever a course is added so you may want to check it regularly. If you do not have access to the internet, feel free to call us at (937) 383-0031. Another option is to call your local county EMA office or watch for an advertisement in your local newspaper. Lastly, if you are a member of an Amateur Radio Organization, watch for the listing of talks in your local newsletter or just ask other members of your Net.

If you know of any friends or family who are interested in the Skywarn program, please encourage them to attend a talk this year. We can always use more eyes on the skies!

By: Diane Innes

Tips For Measuring Snowfall

As some of you may remember from this past year's spotter talks, we have requested that you report every 2 inches of new snowfall and if an inch of snow falls in an hour time span. Unfortunately, though, we were unable to demonstrate how to accurately measure snow since by that time of year, snow was a little hard to come by. Thus, the following are a few pointers and hints for accurately measuring snowfall.

First, you will need a measuring device. A simple 12 inch plastic ruler is fine. (Hopefully, you will not need to use a yard stick this year!) The next step is to find a location in which the snow is least affected by drifting. A good place is the side of the house which is sheltered from the wind. The last step is to simply stick the stick in the ground and take a reading. Please measure the snow to the nearest quarter of an inch or if possible measure to the nearest tenth of an inch.

A couple of other suggestions are to take the average of a couple of readings since snowfall depths can very greatly. Also, it is best to measure snow on a flat surface such as a patio or a board rather than the grass. The grassy surface can yield inaccurate readings, since it can hinder the snow from actually settling to the ground, especially if the flakes are large.

By: Diane Innes