Weather

This site is provided as a means of communications with the USPS National Marine Environment Committee (MEnvCom). We welcome your questions and comments on our courses, seminars and associated materials.

R/C Charles J. Wells, SN
Stf/C Robert F. Anderson, AP

Topics

News

New Seminar Under Development

As boaters, we are exposed to the elements from the moment we set foot on our boats. In most cases, we can anticipate and forecast inclement weather and avoid the worst. However, certain weather and oceanographic events can affect us on short notice. Our new seminar, Severe Marine Weather, attempts to identify these phenomenon to help the on the water boater to understand the event and take the appropriate action. This seminar coupled with the related Boat Handling seminars should help all boaters facing impending severe weather. Look for the new seminar later this year. (30 Jan 13)

Smartphone/Tablet Applications

There are a large number of applications available for smartphones and tablets related to weather. Some of these are excellent tools for on-board weather forecasting. We are creating an application list to help you determine which are useful and others that may be less so. For this we solicit your help. As you find new weather-related applications that are useful, let us know about them. We can share this information with other members. Here are some Wx apps for iOS devices and here are some Wx apps for Android devices. (30 Jan 13)

Erratum for the Basic Weather and Forecasting Seminar

Please delete bullet number four on page 3 under slide 8. This will eliminate the confusion between the rays angle and the angle of incidence. Also, the first three bullets adequately describe the concept. (22 Apr 12)

Weather Course 2012 Revised Edition

The student and instructor kits for the revised edition of the USPS weather course began shipping in the latter part of January 2012. The new materials include a revised course manual, a new instructor manual, and an updated PowerPoint presentation. Over 2,500 copies of the Wx2008 manual have been shipped. Anticipating the need for more manuals, the course materials were revised and updated before the new Wx 2012 print run. (27 Jan 12)

Marine Weather Forecasting Webinar

A new seminar—Marine Weather Forecasting—was offered via the Internet as a webinar in June 2011. The webinar—a USPS Educational Department first—with its emphasis on the 500 mb chart and NWS sources of coastal and offshore forecasts particularly appealed to blue water cruisers. Stf/C Robert Anderson, AP, MEnvCom Assistant Chair, was the main contributor and one of the two presenters. (27 Jan 12)

New Basic Weather and Forecasting Seminar

A new weather seminar—Basic Weather and Forecasting—has replaced the Onboard Weather Forecasting seminar. The new seminar is more comprehensive than the superseded one (94 slides versus 63 in the old one). In addition to the Onboard Weather Forecasting QuickGuide, participants receive a full color Seminar Guide complete with notes—a major upgrade from the previous guide. There is no separate printed Instructor Guide. The notes in the Seminar Guide also serve as instructor notes. The Instructor’s CD, however, in addition to the PowerPoint presentation has a file with an Instructor’s Guide that contains suggestions and tips for instructors. (29 Apr 11)

Return to Top

Weather Course Description

The safety and comfort of those who venture out-on-the water have always been weather dependent. In this course students will become keener observers of the weather, but weather observations only have meaning in the context of the basic principles of meteorology — the science of the atmosphere.
The course focuses on how weather systems form, behave, move, and interact with one another and reflects the availability of all sorts of weather reports and forecasts on the Internet. Wx2012 is a general weather course benefiting those sitting in their living rooms, as much as those standing behind the helm. Each student receives:

• a Weather Manual - USPS Weather - an explanatory text with full color photographs and drawings covering weather in the United States and its coastal and inland waters;
• a set of three Daily Weather Maps - learning aids with a compete explanation of map symbols designed to develop weather map reading and analysis skills; and
• NOAA’s Sky Watcher Chart - a reference to assist in identifying cloud types – helpful indicators of approaching weather.

The Weather Course is designed to be conducted over ten two-hour sessions including time for review and the multiple choice closed book exam, but each instructor will determine the pace of the course.

Weather Course Manual, etc.

The Weather course manual and other materials build on a long USPS tradition of presenting a comprehensive meteorologically (scientifically) oriented course designed for recreational boaters. The 2012 Revised Edition of the course manual has both text and graphic additions and enhancements, but its basic structure and contents remain the same as the Wx2008 course.

• The Weather Course can be taught with a mix of the original Wx2008 and the revised edition Wx2012 Course Manuals.
• The old paragraph numbers have been carried over to the revised edition, but many page references are different. New material in the Wx2012 manual is contained in additional paragraphs that are indicated by an “a” or a “b” following the paragraph that has been carried over.
• The final closed-book examination remains the same.

Instructor Manual

This Instructor Manual is not the traditional black & white hard copy with all the thumbnail slide images. Instead it is a part of the instructor CD that contains the PowerPoint Presentation with slides and complete notes. Anecdotal evidence indicates that more and more instructors are not using the hard copy thumbnail images, but rather review the slides and notes using PowerPoint. The idea is to reduce costs by not printing a hard copy version. If after trying this approach, instructors still prefer a hard b/w copy with the thumbnail images, we will format and print some. Please let us know what you think after teaching the course.

Three Appendices are a part of this manual. Two of them deal respectively with Upper-Air Charts and Sounding Analysis Diagrams.  Instructors should read them.  They are designed to provide instructors with additional background information to increase their comfort level in teaching various topics relating to atmospheric dynamics. The third relates to Clarifications and Corrections that pertain to the original Wx2008 Course Manual, but not to the revised edition Wx2012 one. It is provided in case some students are using the Wx2008 manual. These Wx 2008 – Clarifications and Corrections also are included below on this webpage.

Instructor PowerPoint Presentation

In connection with the publication of the revised course manual, the PowerPoint presentation also has been updated with the addition of new slides and some minor changes in sequence. The revised presentation can be used with both the original and the revised course manuals.

There is an introductory set of five slides designed for use at the beginning of the first class.  All the remaining slides are organized into the eight chapters of the manual.  Within each chapter the slides are divided into two groups.

• Wx08 /Wx12 Slide Group:  The slides in the first group are designated “Wx08” or “Wx12” to indicate which slides have been added with the revised edition of the course manual.  This group of integrated slides is a complete presentation of the material covered (and closely follows the organization of topics) in the chapter.  The group includes figures in the manual as well as some supplemental slides. The slides begin each chapter with a title slide and a class activities/demonstrations slide—the latter being mainly for the benefit of the instructor. Most instructors will probably hide it. Each chapter presentation ends with a chapter summary.

• Wx02 Slide Group:  After the Wx08/Wx12 slides there is another group of slides that is designated Wx02.  These “hidden” slides are legacy slides from the predecessor Wx2002 course that did not make the cut for this course.  They are included only as an additional convenient resource for instructors.  Unlike the Wx08/Wx12 slides, the slide notes have not been edited.

Final Exam

Except for some minor updating, the final examination is the same examination used with the Wx2008 Course Manual. In fact, going forward the same examination will be given to students regardless of which course manual they use. The new manual, however, contains a section of practice questions about weather scenarios. The new section comes after the Chapter 7 homework questions. Instructor’s should duplicate the Weather Scenarios section and give it to those students using the Wx2008 manual as a handout so they are not disadvantaged.

• Examination Questions: The final examination is a typical 100-question USPS multiple-choice, closed-book test.  About 80% of the exam questions will be based on homework questions.  Unlike some of the homework questions, there will be no test questions that have the compound answers “all of the above”. The final examination will only include questions on the material in the first seven chapters. The material covered in Chapter 8 is reinforced through map drawing and analysis exercises.

• Tips for the Examination:  While the test will only cover the material in the first seven chapters, there is obviously some overlap in the topics dealt with in these chapters and Chapter 8 – Forecasting. If a topic is covered in one of the first seven chapters it may be on the exam even though it is also dealt with in Chapter 8. What follows are some points of clarification and some guidance for instructors and students.

• Temperature Conversions: There will be no exam questions that require students to convert Fahrenheit degrees to Celsius degrees or vice versa (i.e., no questions like Chapter 1 homework questions 10 and 11 will be on the exam).

• Station Models: Unlike exams for previous weather courses, station model questions will deal only with temperature, dew point, pressure, pressure tendency and wind speed and direction. There will be no questions about other symbols such as precipitation, cloud type or cloud cover. These additional station model elements are covered in Chapter 8 but only in connection with the use of the Daily Weather Maps.

• Mid-Latitude Storm: Continuing a USPS weather course tradition, every exam will include verbatim the ten questions in the Chapter 6 homework based on a frontal mid-latitude storm figure (questions 20 – 29).

• Scenarios: While there will be two of the customary “forecasting” scenarios on the exam (e.g., “Your cruiser is 50 miles east of….”), the analysis required to answer the three questions based on each scenario will not require any of the additional information contained in Chapter 8.  Each scenario will be based upon one of the following weather events or patterns: warm front; cold front; thunderstorm squall line; advection fog; or waterspout.
  A significant number of students are missing questions based on a scenario that involves a warm front pattern in the winter assuming that winter precipitation must involve a cold front. Some others are confusing an approaching warm front (indicated by a darkening sky with lowering layered–stratus-type clouds) and an approaching cold front or squall line (indicated by a line or wall of dark clouds and static or lightning).

Wx2008 Manual – Clarifications and Corrections

Note that these corrections do not apply to the Revised Edition 2012 course manual. The Wx2008 course had been taught for over three years so we have the benefit of comments from instructors throughout the country. There are some substantive matters that should be clarified, refined, or corrected in the Wx2008 manual.  For the most part, they are fairly technical and tangential to the main principles that are the course’s focus.  Instructors should deal with them as they see fit. An errata sheet has not been included with the Wx2008 Course Manuals.  Instructors should copy the corrections and clarifications that follow and give them to any students who are using the original Wx2008 course manuals rather than the new 2012 Revised Edition ones.

Chapter 1:

• Lapse Rate
  Lapse rates are changes in temperature with altitude.
  Page 18 Ques 20: To accurately reflect this definition, replace the question with the following: “On average, the temperature in the lower atmosphere:” Make the same change on page 216.

Chapter 2:

• ITCZ
  Textbook figures illustrating global scale pressure and wind patterns (like the ones on pages 20 and 21 of the manual) typically show the ITCZ and the Doldrums as a broad band centered on the equator. While these simplified versions are quite useful for illustrative purposes, the varying widths and locations of the ITCZ and the Doldrums are actually much more complex.
  Page 20 Par 11: to eliminate text inaccuracies about the width and locations of the ITCZ and the Doldrums, in the first sentence replace “roughly within 100 north and south “ with the phrase “in the general vicinity”.
  
  
• Semi-permanent Highs and Lows
  The major semi-permanent highs and lows that affect weather in the continental United States are:

  • the Aleutian Low that disappears in the summer;
  • the Icelandic Low;
  • the Pacific High;
  • the Bermuda High;
  • a high over the continent in the winter; and
  • a low over the southwest in the summer.

  
  Page 22 Par 20: Replace the list in this paragraph with the above list.

Chapter 3:

• Dew Point and Persistence
  When the air temperature falls below the dew point, the dew point normally is lowered.
  Page 50 Par 26: The last sentence does not take into account the above relationship between air temperature and dew point. Replace this sentence with the following: “The dew point does not change during the day in the way that relative humidity does. Meteorologists say that dew point is more “persistent” than relative humidity. This “persistence” makes dew point a far more useful humidity measurement than relative humidity in describing air masses.”

• Supersaturation and Humidity
  When supersaturation occurs the relative humidity can be higher than 100% and the dew point can be higher than the air temperature. The text does not deal with supersaturation and these consequences.
  Page 51 Par 30: to cover supersaturation and its relationship to humidity replace the entire paragraph with the following two paragraphs:
  “For water vapor to become water droplets (condensation) or ice crystals (deposition), there must be some kind of surface on which the water vapor molecules can stick. On the Earth’s surface there are all sorts of such surfaces (e.g. lakes, oceans, the ground, plant leaves). In mid-air the necessary platforms for condensation, freezing or deposition to occur are tiny nuclei. Typical condensation nuclei, for example, are sea salt, and particles of sand, dust or smoke. In the absence of these nuclei, supersaturation can occur. When the air is supersaturated, the relative humidity is higher than 100% and the dew point is higher than the air temperature.
  The regular relationships among air temperature, dew point and relative humidity in the absence of supersaturation are:

• the dew point is lower than or equal to (but not higher than) the air temperature;
• the dew point spread is the difference between the air temperature and the dew point;
• the smaller the dew point spread – the higher the relative humidity; and
• when the dew point spread is zero (the dew point = the air temperature), the relative humidity is 100%.”

Page 57 Par 64: to take into account the possibility of supersaturation with the relative humidity being higher than 100%, in the 6th bullet delete the phrase “or is below”.

• Fog and Wind Speed
  The wind speeds most favorable to the development of fog are 2 to 3 knots for radiation fog and 5 to 15 knots for advection fog.
  Page 61 Ques 19 & 20: to clarify the ambiguous reference to speed in these questions insert “wind” before “speed”; make same changes on page 221.

Chapter 5:

• Sun Pillars
  Sun Pillars are caused by ice crystal reflection. – not refraction.
  Page101 Par 74: to eliminate the reference to refraction, replace the last sentence with the following: “They, however, are caused by ice crystal reflection – not refraction.”

Chapter 7:

• Tropical and Subtropical Storms
  While storms in the tropics and subtropics are typically single air-mass without fronts, there are also hybrid-storms (now called “Subtropical Storms – see page 138 par 42) that have fronts. Also some “subtropical” regions experience mid-latitude weather with frontal storms during parts of the year (e.g. Florida in the Winter).
  Page 131 Par 10: to eliminate the unqualified generalization that storms in the tropics and subtropics are single air-mass without fronts, eliminate the last sentence

• Intertropical Convergence Zone (ITCZ)
  Accurately defining and describing the locations of the ITCZ is a fairly complicated matter. The actual front where the Northeasterly and Southeasterly trade winds converge is much narrower (up to only 300 miles) than the 200 width for the ITCZ stated in the text.
  Page 132 Par 12: to eliminate inaccuracies in the description of the ITCZ, replace the 2nd and 3rd sentences with the following: “In the Atlantic Ocean, for example, the ITCZ can migrate northward as far as 15 degrees North in the Northern Hemisphere’s Summer and southward to just north of the Equator in the Northern Hemisphere’s Winter.”
  
  
• Hurricane Watches and Warnings
  While the NOAA/NWS web pages are not consistent, the National Hurricane Center now issues Hurricane Watches 48 hours before landfall and Hurricane Warnings 36 hours before landfall.
  Page 143 Par 67: change "24 to 36 hours." to "48 hours." and change "24 hours or less." to  "36 hours."
  Page 148 Ques 16: in answer b) change "24" to "36" and in answer c) change "36" to "48"  Make same changes on page 232. 
  Page 148 Ques 17: in answer b) change "24 to 36" to "48". Make same change on page 232.

Chapter 8:

• Ensemble Forecasts and Spaghetti Plots
  The text should (i) explain the relationship between the Spaghetti Plot figures and Ensemble Forecasts, and (ii) make it clear that different forecasting computer runs may use not only different initial data but also different models.
  Page 154 Par 26: replace the last two sentences with the following:
  “Sometimes different models also are used. If the results of multiple runs (so-called “Spaghetti Plots” when graphically depicted) are quite different or disorganized the forecast is not considered reliable. If there is a uniform pattern to the results the forecast is considered more reliable. See Spaghetti Plot figures showing hypothetical plots of the Polar Jet Stream.”

• Canada Weather Radio
  All the Canadian Weather channels can be received using the same radios that receive NOAA Weather Radio broadcasts.
  Page 162 Par 69: Replace the 1st sentence with the following sentence: “Canada has it own “Weather Radio” that uses seven VHF channels with the same operating frequencies as NOAA, and so the same VHF receiver can be used to receive both Canadian and NOAA weather forecasts.”
  

Return to Top

Downloadable Material

See the Educational Department Help page to obtain any needed free viewers or shareware zip programs for these files. See the PowerPoint Help page for information on how to replace slides.

Regional Weather

Appendix A of the Wx2008 Manual has a description of weather for selected regions of the United States. This Appendix is not in the new Wx2012 Manual, but it can be downloaded as an additional resource (489KB, PDF). (30 Jan 12)

Weather Log

The following Weather Logs are for use in both the Cruise Planning and Weather courses.

• Weather Log in Acrobat format (PDF, 13KB)
• Weather Log in MS Excel format (XLS, 26KB)

Weather PowerPoint Slides

Slide shows of various weather phenomena for use by Weather course instructors and students. You will need Microsoft PowerPoint or its free viewer to view or print these slides.  To download into a directory on your hard drive, right click on the file link and be sure to change the file name to something meaningful for you. 

• Clouds ( 727KB)
• Floods (609KB)
• Hail (201KB)
• Miscellaneous (104KB)
• Thunderstorms and Tornados (1110KB)
• Weather Instruments (1475KB)

Return to Top

Frequently Asked Questions

QUESTION: Where do I find any corrections or revisions to the Wx08 manuals?

ANSWER:  Look into the Wx2008 Manual – Clarifications and Corrections section of this page, above.

Return to Top

Questions or Comments?

If you have any questions or comments about the Weather course, please contact the National Marine Environment Committee chairman by e-mail, phone or postal service mail.  Please be sure to keep your SEO and/or DEO advised of any correspondence you may have with the National committee. Addresses for the National MEnvCom chairman are listed in The ENSIGN and on the Committee Chairpersons page.

We will try to answer your questions as soon as possible, but please allow 5 working days for an answer.

Return to Top