The Weather Bureau (forerunner to the National Weather Service) began launching weather balloons routinely in the late 1930s. Today, over 90 stations are part of the upper-air network in the United States, with over 800 stations worldwide. Your NOAA/Florida Keys National Weather Service office in Key West is one of these stations! Our meteorologists launch weather balloons twice daily, at approximately 6:00 a.m. and 6:00 p.m. Eastern Standard Time (EST), and 7:00 a.m. and 7:00 p.m. Eastern Daylight Time (EDT). Occasionally, balloons will be released four times daily, usually when severe weather threatens (e.g., a hurricane). The payload tethered to the balloon is called a “radiosonde”, a small expendable instrument package containing sensors that measure pressure, temperature, humidity, and GPS position. These sensors are linked to a battery powered, 300 milliwatt or less radio transmitter that sends the sensor measurements to a sensitive ground tracking antenna (the ground tracking antenna is located inside the “white ball” behind the National Weather Service facility on White Street in Key West). Wind velocity data are obtained by tracking the radiosonde position in flight. The radio signals received by the tracking antenna are converted automatically to meteorological values, from which coded data are assembled for multiple elevations, and immediately transmitted to data users. All data are archived and available at the NOAA/National Centers for Environmental Information.

A typical National Weather Service weather balloon ascent will last about two hours. During that time, the radiosonde usually reaches an altitude of around 100,000 feet above ground. Horizontal distance traveled from the release point may vary from a mile or less to nearly 200 miles, depending on the winds aloft. During a typical flight over the Florida Keys, the radiosonde will reach subfreezing temperatures within 15 to 20 minutes after the release time! When released, the balloon is about five feet in diameter. It gradually will expand as it rises due to decreasing atmospheric pressure with increasing height. When the giant balloon (up to 25 feet in diameter) bursts in the bitter cold, rarefied air above the troposphere, about 99% of the mass of the atmosphere lies below. At this point, a small, orange-colored, biodegradable parachute will slow the descent of the radiosonde. Presently, data is not collected while the radiosonde descends. Eventually, the radiosonde will return to Earth. If you happen to find one, it is safe to handle. Please find the postage-paid mailbag (as noted in the instructions printed on the instrument), and send it back to the National Weather Service where it may be refurbished and flown again, lowering the cost of the weather balloon program.

If you catch sight of a rising balloon during the early morning or evening hours around Mid Town Key West, know that this old-fashioned, yet very effective data gathering operation remains essential for providing you with accurate marine weather warnings, advisories, and forecasts throughout the year. Indeed, these balloon observations will help you become marine weather-ready and stay safe!

Rain is necessary, but too much of a good thing can be a bad thing on the water, from both a comfort and safety perspective. The details matter (rainfall rate, intensity, duration, presence of lightning or wind) when considering the impacts on a voyage (planning, navigation, vessel maneuvering, passenger safety and comfort, etc.). However, these specific attributes of “rain” are not only difficult and often impossible to predict, but also are not explicitly forecast by your local weather people. In fact, even when asked the simple question, “Is it going to rain?”, the meteorologist often directs their perplexed gaze toward the sky--a “rainy daze”, perhaps. The answer often is, “It depends”. Since the mid-1960s, the National Weather Service has been preparing “probability of precipitation” (POP) forecasts. At the Florida Keys National Weather Service, our POP is defined as the probability of at least 0.01 inch of rainfall at a point in a particular forecast zone during a 12-hour period (6:00 a.m. to 6:00 p.m. or 6:00 p.m. to 6:00 a.m.). The POP (chance of rain) is just a number, and says nothing about many of the characteristics of rainfall that matter. In addition, the POP gives you no information about the prospects for flooding rain or wind-driven rain, and it will not tell you if it is going to rain once, twice, or thrice during the day or night.

Meteorology is a science that always has evolved with technology, and there are some very promising applications of weather prediction modeling and telecommunications technology in the works. These advances may one day soon improve our forecasts of rain and its impacts. In the interim, we do offer a few ways beyond the POP for you to obtain additional information about the prospect for a rainy day. The “Area Forecast Discussion” is a prognostic narrative written by the forecaster on duty, which gives one a glimpse of the forecast challenge of the day, the scientific uncertainty and associated confidence level in a forecast, and even some additional details regarding actual impacts. With rain, that may be information on rainfall intensity and associated reductions in horizontal visibility. Visibility is important for watercraft, aircraft, and land-based vehicles alike. The Area Forecast Discussion also may provide additional details on expected rain rates and potential for street flooding, or whether multiple episodes of rainfall are expected at a particular location during a given time frame. Another helpful and freely available product is the “Short Term Forecast” or “Nowcast”. This product is a very effective addendum to a radar animation, focusing on the next one to three hours, and providing information pertaining to the location, movement, and impacts from rain showers, squalls, and thunderstorms. It helps answer the question, “Will this affect me, and, if so, how?”.

You may access both the Florida Keys “Area Forecast Discussion” and “Short Term Forecast” at the following websites:

Area Forecast Discussion:https://forecast-v3.weather.gov/products/locations/KEY/AFD/1

Short Term Forecast:https://forecast-v3.weather.gov/products/locations/KEY/NOW/1

Bookmark these links, and place them next to your Doppler radar link/app, and you will be on your way to going “beyond the POP”. Finally, you may access the Short Term Forecast and all available marine weather observations, forecasts, warnings, and advisories via the NOAA All Hazards Weather Radio broadcasts on marine VHF Channels 2 (lower/middle Keys), 5 (middle/upper Keys), and 4 (North Key Largo/Ocean Reef).

Please be marine weather-ready, and stay safe in 2018!

Hurricane season is upon us once again. The time between about Memorial Day and Thanksgiving includes many holidays, festivals, birthdays, and vacations. People from all walks of life will visit the Florida Keys, and make lifetime memories, while people residing in the Keys will help visitors make those memories fondly and safely. Safety is important, is it not? Every day, we consider our personal safety, family safety, customer safety, safety on the job, fire safety, and safety of life at sea. We wear seat belts, life jackets, and safety gear at work. We develop safety policies, plans, and procedures, and then we train, exercise, and execute those plans, policies, and procedures. We do this because research, experience, and common sense tell us it works, and, in many cases, the law requires it. We should treat the hurricane and its multiple hazards with the same level of attention to detail. It could save your life.

Hurricanes are rare. Only about 50 develop each year across the planet. In the Atlantic Basin, spanning from the coast of Africa to North America, only about six hurricanes develop in an “average” year. Of those, perhaps a few will make landfall somewhere in the basin. The area within the broad storm system we call a “hurricane” which actually will experience sustained hurricane-force winds is quite small. Most people who claim to have experienced a “hurricane” have experienced only the relatively benign outer periphery. True hurricane conditions are loud, violent, and unsettling, and this is with a category one hurricane. The destructive power of the hurricane wind increases dramatically between a category one storm and a category five storm. This is because the force of the wind increases exponentially with wind speed. Catastrophic damage is always reported in association with category four and five hurricanes. However, the primary cause of death in hurricanes is drowning. Storm surge is by far the most potentially lethal hurricane hazard in the Florida Keys. Storm surge is why Monroe County issues evacuation orders. Storm surge is why the Monroe County (Florida Keys) Tourist Development Council (TDC) has a formal communications program that is tightly coordinated with local emergency management officials to provide crucial information to help visitors safely exit the Florida Keys in the event a hurricane threatens the region. 

During the 2017 hurricane season, and for the first time, the National Weather Service will issue Storm Surge Watches and Warnings. The Storm Surge Watch will be issued for the possibility of life-threatening inundation from rising water moving inland from the shoreline somewhere within the specified area, generally within 48 hours, in association with an ongoing or potential tropical cyclone, a subtropical cyclone, or a post-tropical cyclone. The Storm Surge Warning will be issued for the danger of life-threatening inundation from rising water moving inland from the shoreline somewhere within the specified area, generally within 36 hours, in association with an ongoing or potential tropical cyclone, a subtropical cyclone, or a post-tropical cyclone.

Of course, in the Florida Keys, many of us cannot afford to wait to act until 48 or 36 hours prior to tropical storm or hurricane conditions. The Florida Keys have complex social, economic, and transportation networks that require early action in order for people to stay safe. Effective evasive action requires preparation, and proper preparation requires thoughtful planning. Do you have a hurricane plan for yourself, your family, or your business? If not, it is time to get a plan. Some things to consider:

• Determine your risk

• Develop an evacuation plan

• Secure an insurance checkup

• Assemble disaster supplies

• Strengthen your home

• Identify your trusted sources for information during a hurricane event

• Complete your written hurricane plan

For more information on hurricane planning and preparation, visit www.weather.gov/hurricanesafety.

As a boater, the most effective strategy is avoidance, meaning getting your boat out of the Florida Keys via sortie, haul-out, or trailering. Sheltering in a hurricane hole or haven, or securing a vessel in dry storage are strategies with only limited effectiveness, while adding extra lines or doing nothing is least effective. A marina in the Florida Keys simply is not a viable sanctuary for a vessel of any type during a direct hurricane threat. Be proactive. Move your boat out of the path of the storm, and do it early on.

If you plan to trailer your boat out of the Keys, the Overseas Highway can wreak havoc on worn trailers. Now is a good time to carefully assess the condition of your trailer (air in tires, tire cracks or rot, wheel bearings/lube, leaf springs, tie-down straps). 

Boaters should have a boater hurricane preparedness plan. Include steps to be taken to prepare the physical environment of the boat itself. Review any pre-arranged agreements with storage facilities or property owners. Develop a list of tasks and time required to complete them. How many total daylight hours do you need?

Finally, if you live aboard, do not stay on your boat. A BOAT IS NO PLACE TO BE IN A HURRICANE!

Develop a hurricane plan now for yourself, your family, and/or your business. Doing so is time well spent. The men and women of the Florida Keys National Weather Service maintain a continuous surveillance of potential hazardous weather threats across the Florida Keys and adjacent coastal waters 24 hours per day, seven days a week, year-round. If you have any questions regarding tropical storm or hurricane impacts in the Florida Keys this season, please give us a call at (305) 295-1316, visit us online at weather.gov/key, or follow us on Facebook or Twitter (NWSKeyWest).

Hurricane Season is here – remember to be weather-ready, and stay safe!

Weather-related marine incidents associated with this “March squall” included the following:

• Several boats throughout the Florida Keys went adrift after their mooring lines snapped.
• A 21-foot sailboat with four people aboard began taking on water near Summerland Key.
• A drifting sailboat struck power lines near the Channel Five Bridge.
• Two boats lost power near Little Palm Island.
• A boat capsized in Florida Bay, and two people were pulled from the water.
• A 40-foot catamaran ran aground, and took on water near Cottrell Key.  All persons subsequently were evacuated by the U.S. Coast Guard. 
• Four parachutists from Sugarloaf Airport landed in shallow water after being blown off course.

Your Florida Keys National Weather Service predicted thunderstorms along a cold front for several days prior to this strong squall event.  However, squall line intensity, coverage, and movement usually are very difficult to predict with any accuracy until the event is only 6–12 hours away.  The National Weather Service issues location-specific Special Marine Warnings for strong to severe thunderstorms and squalls with a typical lead time of 10 to 60 minutes.  This certainly is an improvement from 10 or 20 years ago, but if you are 90 minutes from a safe harbor, then this is a problem!  This is where awareness and preparedness are important, and potentially life-saving.  The United States Coast Guard motto is Semper Paratus, meaning “always ready”--good advice for any mariner.  Moreover, the primary vision of the National Weather Service is a “Weather-Ready Nation”.  Readiness is the “state of being fully prepared for something”, and this means deliberate actions toward maintaining high levels of awareness and preparedness.  Accessing quality marine weather information from your local National Weather Service forecast office is only one part of competent voyage planning and execution.

To avoid being a “search and rescue case”, please:

• Stay Informed.  Check the current and expected weather and water conditions before heading out (weather.gov), and be aware that weather conditions can change quickly.
• Wear life jackets while on the water.
• File a float plan with friends, family members, and local marinas before heading out.  The list should include the number of passengers aboard the vessel, destination and expected time of return.
• Always have a working marine-band radio on board.
• Carry marine flares on board the vessel.
• Ensure bilge pumps are operational and vessels are secure for heavy winds and rain.  Have a manual pump on hand as a backup.

Squall season is here.  Please be marine weather-ready, and stay safe!

The difference between weather and climate has been explained by various sources in the following simple quote: “Climate is what you expect, and weather is what you get”. At NOAA/National Weather Service, an observational record of 30 years is used to represent the climate “normal” for a given weather element. Actually, these “normals” are more accurately described as statistical averages. These averages are updated every 10 years, so the numbers one may view in today’s daily climate report are based on the most recent 30-year observational record, which is the period 1981–2010.

One of the great things about winter weather in the Florida Keys is the temperature-humidity combination (usually!). For most of December, January, and February (a period known as “meteorological winter”), one can expect the air mass in the Florida Keys to be “mild”, sometimes warm, and occasionally cool, but rarely hot, and almost never cold; okay for shorts or a long-sleeved shirt, but rarely requiring a jacket. This is because the cold, polar or arctic air rushing southward off the North American continent will usually modify and warm quickly over the Gulf of Mexico and Atlantic Ocean before reaching the subtropical Florida Keys. At the same time, the sultry maritime tropical air will be pushed to the south, and relegated usually to the Caribbean basin. Using the Key West International Airport data record, the average daily high temperatures for the months of December, January, and February are 76.0°, 74.3°, and 76.0° (Fahrenheit), respectively. The average daily low temperatures for December, January, and February are 67.0°, 64.8°, and 65.8° (Fahrenheit), respectively.

While wintertime temperature and humidity in the Florida Keys go down, the winds come up. In fact, winter is the “windiest” season in the Florida Keys, on average. Using data from the Florida Keys Coastal-Marine Automated Network (C-MAN) stations, the average sustained (2-minute average) wind for the December–February period is 12–14 knots (gusts 14–17 knots). Contrast this with the June–August average of 8–10 knots (gusts 10–14 knots).

The winter is also the “dry season” in the Florida Keys. Any user of weather forecasts is very familiar with the issuance of “precipitation probabilities” (or, “rain chances”). In the National Weather Service, this number represents the 12-hour probability of “measurable” rain (0.01 inch or greater) falling within a given forecast zone. During the peak rainy season months of August and September, the forecast rain chances typically fall in the range of 30–40 percent. However, during the winter months of December, January, and February, the forecast rain chances typically drop closer to 10 percent. Wintertime rain in the Keys usually occurs along an approaching cold front.

For more information on winter weather and climate in the Florida Keys, please visit the NOAA/Florida Keys National Weather Service web site at weather.gov/key, or find us on Facebook and Twitter (“NWSKeyWest”).

Remember to check the winter weather before heading out on the water, and as always, be weather-ready, and stay safe!

Weather researchers, forecasters, and communicators are thrilled about the impending flood of new data which will pour forth from GOES-16 in (hopefully) less than a year. This is a BIG deal for weather forecasting. Here’s why. The GOES-16 satellite is NOAA’s most advanced geostationary satellite to date. It will be capable of scanning the sky five times faster, with four times the image resolution, and three times the number of spectral channels than current GOES satellites. In addition, GOES-16 is flying six new instruments, including the first operational lightning mapper in geostationary orbit. The increase in data variety, frequency, and resolution will provide more, and better, satellite images, helping weather forecasters more accurately assess developing severe storms in real time, which will result in more accurate and timely hazardous weather warnings and forecasts. The robust increase in satellite data will bolster research efforts in the satellite meteorology community. Finally, the sharper and more frequent satellite images will help weather communicators tailor more effective hazardous weather messages to vulnerable communities and decision makers, in person, on television and across social media.

For a place like the Florida Keys, where weather and ocean observations are scarce, the bevy of new data which GOES-16 will provide will be a boon to local meteorologists at the NOAA/Florida Keys National Weather Service. Moreover, beyond weather forecasting, GOES-16 will be a part of SARSAT, an international, satellite-based search and rescue network. The satellite is carrying a special transponder that can detect distress signals from emergency beacons.

The successful launch of GOES-R was the result of an effective large-scale collaboration among multiple government and private-sector entities. NOAA manages the GOES-R Series Program through an integrated NOAA-NASA office. NASA’s Goddard Space Flight Center oversees the acquisition of the GOES-R series spacecraft and instruments. Lockheed Martin is responsible for the design, creation and testing of the satellites and for spacecraft processing, along with developing the Geostationary Lightning Mapper and Solar Ultraviolet Imager instruments. Harris Corp. provided GOES-R’s main instrument payload, the Advanced Baseline Imager, the antenna system for data receipt and the ground segment. The Laboratory for Atmospheric and Space Physics provided the Extreme Ultraviolet and X-Ray Irradiance Sensor, and Assurance Technology Corporation provided the Space Environment In-Situ Suite.

Once data from the GOES-16 satellite starts arriving online, look for a future article to go into more detail about products and images directly of relevance for the Florida Keys marine community. In the interim, check out www.noaa.gov/satellites for latest information about the NOAA satellite program and www.goes-r.gov for the latest on GOES-16.

Remember to always check the weather before heading out on the water, and as always, be weather-ready, and stay safe!

Another complicating factor in Florida Keys rainy-season weather forecasting is the absence of the sea breezes which modulate daily rainfall patterns over much of the Florida Peninsula.  The accompanying graph illustrates the influence that Florida Peninsular sea breezes have on the daily rainfall patterns at mainland South Florida locations versus Key West.  Note that at Fort Myers, Miami, and Fort Lauderdale, rain chances spike during the afternoon hours as sea breezes develop at the coast, and help initiate showers and thunderstorms through lifting of the hot, moist air at the surface.  Sea breezes of such intensity do not occur in the Florida Keys where surrounding waters keep the island air slightly cooler than over mainland South Florida.  In fact, the hourly relative frequencies of rain, or “rain chances” at Key West show little or no pattern during the 24-hour day, with rain about as likely to occur during the dark of night as it is during the middle of the afternoon.

Despite the “unpredictability” of rain in the Keys, the climate statistics do offer some useful insight, mainly related to the “steering” winds of the lower atmosphere (surface to about 10,000 feet elevation).  The most common steering wind regimes are when winds are blowing out of the east and southeast (not surprising given the Keys’ location at the northern fringe of the tropical trade-wind belt).  However, the “wettest” wind regime is when winds are blowing from the northeast.  In this regime, sea-breeze thunderstorms move southwestward off the Everglades toward the Keys; in addition, lines of cumulus clouds, showers, and thunderstorms can develop along or parallel to the Keys archipelago which runs east-northeast to west-southwest.  The least common and driest rainy-season wind regime is when winds are blowing out of the northwest. 

The most effective means by which forecasters have come up with to communicate the likelihood for “measurable” rain (0.01 inch) are probabilities.  The daily forecast communicates the chance of rain for a 12-hour period (6:00 a.m. to 6:00 p.m. or 6:00 p.m. to 6:00 a.m.) at any point in the forecast area.  In marine and aviation products, “coverage” terms typically have been used due to the transient nature of these users.  Examples include:  “numerous showers”, “scattered showers”, or “isolated thunderstorms”.  Here, these coverage terms are equated to ranges of probabilities (“isolated” = less than 25 percent; “scattered” = 25–54%; “numerous” = 55–79%; and categorical (e.g., “showers”) = 80% or greater).

For more immediate decision making, the “Short Term Forecast” is available, usually once per hour, offering an assessment of location, timing, and impacts of rain and storm areas based on Doppler radar interpretation.  Of course, the National Weather Service Doppler Radar images are available in near real time for any and all to see as well.  These sources are available online here:

Short Term Forecast:
http://forecast.weather.gov/product.php?site=NWS&product=NOW&issuedby=KEY

National Weather Service Key West
Doppler Radar Data:
http://radar.weather.gov/radar.php?rid=byx
Remember to check the radar and the forecast before heading out on the water, and as always, be weather-ready, and stay safe!

The “weather enterprise” (including government, academia, and private sector weather research, data, and forecasting organizations) has produced a plethora of smartphone applications and widgets during the last few years.  Many users consult a variety of weather information sources to support their daily, weather-sensitive decision making.  The mission of the National Weather Service, under NOAA, is to provide weather, water, and climate data, forecasts, and warnings for the protection of life and property and enhancement of the national economy.  To this end, the 146-year-old National Weather Service supports the broader weather enterprise with data, information, and knowledge concerning weather, water, and climate warnings, forecasts, and observations.  Such information is delivered to local communities by the meteorologists of 122 Weather Forecast Offices across the nation, among which 47 serve coastal communities, including the one in Key West, serving the Florida Keys and the adjoining busy waterways.  Recently, the National Weather Service has developed an experimental “adaptive forecast page”, or smartphone widget.  It works like an app on your smartphone, and provides direct access to the National Weather Service (NWS) digital forecast database and derived products, including hazardous weather watches, warnings, and advisories.  The information comes directly from local NWS meteorologists 24/7/365, and is updated several times per day.  Landlubbers may simply type in a zip code or city, state to access the latest seven-day forecast, radar, satellite, forecast discussions, and more.  A mariner may use the map to select the latest marine forecast for a location of his or her choice.  Key Westers should use “33041” for the zip code.

This smartphone widget can be accessed by simply pointing your smartphone browser to “weather.gov/key”, then clicking on “Smartphone Widget” at the top of the page (under “Top News of the Day”, in pink).  Then, just add to your home screen, and you will be all set.  We are interested in your feedback, so if you have any, please e-mail kennard.kasper@noaa.gov.

Remember to check the weather before heading out on the water, and as always, be weather-ready, and stay safe!

In fact, scale may help explain why the wind, waves, and weather differ greatly between the Islamorada Humps and the Cay Sal Bank, or even between Western Dry Rocks and Eastern Dry Rocks in any given day. Why is scale so important then for interpreting weather forecasts?  First, weather systems important to everyday life vary significantly across space and time.  

In meteorology, four fundamental scales are considered, encompassing diverse weather phenomena:  (1) planetary scale; (2) synoptic scale; (3) mesoscale; and (4) microscale.  Planetary-scale phenomena cover thousands of miles over time periods of a week or more.  Examples include the polar jet stream and the trade winds.  Synoptic-scale phenomena cover distances of a few hundred to a few thousand miles over time periods of about 1–7 days.  Examples include upper-level troughs, tropical waves, and hurricanes.  Mesoscale phenomena cover distances of a few miles to a few hundred miles, usually over a period of about 1–24 hours.  Examples include thunderstorms and sea breezes.  Finally, microscale phenomena operate over distances less than a mile, and time periods under an hour.  Examples include waterspouts and turbulence.  If a region is primarily influenced by mesoscale weather systems (as the Florida Keys often are during the summer), then this would help explain why it may be cloudy and raining in Key Largo, but sunny and dry in Key West, or why winds may suddenly surge to 25 knots at Cosgrove Shoal, but remain nearly calm at Carysfort Reef.  If, on the other hand, a region is primarily influenced by synoptic-scale weather systems (as the Florida Keys often are during the winter), then this would help explain why northeast winds may blow 15 to 20 knots for days on end, uniformly, from Fowey Rocks all the way past the Dry Tortugas.  Second, weather systems of different scales interact in complex, often nonlinear ways, posing a limit to predictability.  Dr. Edward Lorenz, a meteorologist and mathematician, was an early pioneer of the mathematical field of study called “chaos theory”.  Lorenz defined chaos as “when the present determines the future, but the approximate present does not approximately determine the future”.  This is one of the reasons why weather forecasts fail – we can only approximately define the present (initial conditions), and our models also are only approximate.  Lorenz famously posed the question in a 1972 paper, “Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas?”  This concept became known as “the butterfly effect”, highlighting the importance of both scale interactions and initial conditions in modern numerical weather prediction.  Many of the routine information products from your NOAA/ Florida Keys National Weather Service provide numbers, graphics, and automated phrases derived from a digital forecast database created locally by the duty forecaster, based on his or her diagnosis of the weather situation, analysis of weather prediction model output, and experience.  If you wish to gain further insight into the forecast process, predictability, potential scenarios, and confidence that a duty forecaster possesses in a given forecast situation, then you may consult a little-known product called the “Area Forecast Discussion” (available online at http://forecast.weather.gov/product.php?site=NWS&issuedby =KEY&product=AFD). Remember to always check the weather before heading out on the water, and as always, be weather-ready, and stay safe!