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 Ronald H. Kessel, SN
Stf/C Joan C. Croft, AP

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News

Launch of Wx2008

The Marine Environment Committee (MEnvCom) launched the new weather course with its completely rewritten manual at the beginning of 2009. During the first year over 1000 copies of the manual have been shipped. Wx2008 returns to a one-manual format, has four-color graphics, contains concise explanations of some of the more difficult topics in atmospheric dynamics, and includes Internet sources and content as an integral part of the curriculum. (12 Mar 10)

Instructor Manual and CD Revision

While there are no plans to revise the Student Manual, the Instructor Manual and PowerPoint Presentation were revised in March 2010. For a description of the improvements see Instructor Manual and PowerPoint Presentation below. The revised versions can be obtained by ordering a Weather Course Instructor Kit from the online catalog. (12 Mar 10)

Wx101 and Wx102 Exams

Wx08 is now the current edition of the USPS Weather Course. Wx101/102 materials and exams are no longer available as of 31 December 2009. (22 Jan 10)

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Weather 2008 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. Wx2008 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.

Wx2008 is designed to be conducted over ten classroom sessions, but each instructor will determine the pace of the course.

Wx2008 Manual – Refinements and Corrections

At the time of writing this appendix, the Wx2008 course had been taught for over a year so we now have the benefit of comments from instructors throughout the country. We leave typos and formatting corrections for the next printing. There are some substantive matters, however, that should be clarified, refined, or corrected. 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 student manuals. Instructors should check this Weather course web page for the latest information.

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.”

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.”

Instructor Manual and PowerPoint Presentation

All the predecessorWx2002 slides were included as part of the original Wx2008 PowerPoint presentation to give instructors maximum flexibility in customizing their classroom presentations.  Some instructors, however, would have preferred a smaller number of slides that tracked the manual contents more closely.

To capture the best of both worlds each chapter in the revised PowerPoint presentation begins with a set of slides designated Wx08 that includes all the graphics in the course manual plus other supplemental ones.  These Wx08 slides follow the manual’s order of topics fairly closely. The remaining Wx2002 slides from previous years have been designated Wx02 and follow the set of Wx08 slides.  In this way instructors still have the option of easily integrating their favorite Wx02 slides into each chapter presentation as they see fit.

Instructors can rely entirely on the slides designated Wx08 knowing that they are adequately covering the course material.  From a total of about 600 slides, roughly two-thirds have been designated Wx08 slides. Many of the slide notes for the Wx08 slides have been rewritten.  Slide notes for the Wx02 slides, however, have not been revised. The revised Instructor Manual does not include the Wx02 slides.

The Instructor Manual includes two new sections: clarifications and corrections to the Student Manual; and advice about the final exam (what is included and excluded as well as some tips).

Wx2008 – Final Exam

Examination Questions: The final examination will be 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 compound answers (e.g., “all of the above”, “none of the above”, “b and c”). 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.

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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.

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)

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Frequently Asked Questions

There are no Frequently Asked Questions for Wx 08 at this time.

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Regional Weather Guides

The MEnvCom is looking for your help with the Regional Weather Learning Guides Project.  We are soliciting contributions from all Members, Squadrons and Districts to complete this ambitious and worthwhile project.  Districts and individual Squadrons are encouraged to “adopt” one of the guides and contribute your local expertise to the rest of USPS.   We will also, of course, accept information from any individual contributors!

Introduction to Weather for Boaters, with examples from the Upper Mississippi River Basin (1936KB, PDF)—authored by Don Hansen, St Paul Squadron, D/10

Listed below are the 15 Regional Guides we would like to complete.  Following the list is a suggested outline for the guides we would like everyone to use for consistency.

1.      Northeast Atlantic Coast -  (New England – Long Island Sound)
2.      Northeast Interior (22KB, PDF) - (Lake Ontario, St. Lawrence River, Finger Lakes & Erie Canal)
Adopted by D/6--contact Harry Winberg, Utica Squadron, with comments and updates.
3.      Middle Atlantic Coast (11KB, PDF) - (Long Island South Shore, New York Harbor and Approaches, New Jersey and Delaware coasts and Bays)
Barnegat Bay from Barnegat Twp to the Metedeconk River, including Barnegat Inlet, adopted by D/4--contact Warren Timm, Barnegat Bay Squadron, with comments and updates.
4.      Chesapeake Bay
5.      Southeast Atlantic Coast - (including North Florida)
6.      South Florida and the Northern Bahamas - (east and west Florida coasts)
7.      Eastern Caribbean
8.      Gulf of Mexico
9.      Southern California and Baja
10.    Northwest Pacific Coast - (Northern California, Oregon/Washington and British Columbia)
Adopted by D/16—please contact Vern Redecker, Bellevue Squadron, with comments and updates.
11.     Great Lakes (9KB, PDF) - (lakes may be grouped or done individually as appropriate – note overlap with Northeast Interior)
Western Lake Erie adopted by D/7—please contact Doug Sewell, Berea Squadron, with comments and updates. Writeups are needed for Lakes  Huron, Michigan, and Superior.
12.     Mississippi River Basin Waterways (784KB, PDF)
Adopted by D/10--please contact Don Hansen, St Paul Squadron, with comments and updates.
13.     Inland Western Lakes
14.     Alaska
15.     Hawaii – South Pacific

Please contact the MEnvCom chair to get involved!
 

Regional Weather Learning Guide Suggested Outline

I.      Overview of local weather.
         A.      What seasons provide the best and/or worst boating?
II.     Where does the weather come from?
III.    What systems bring good and bad weather?
IV.     What conditions precede these systems?
V.      These systems bring what:
         A.      Winds
         B.      Precipitation
         C.      Visibilities
         D.      Clouds
         E.      Seas
VI.     Currents.
VII.    Tides.
VIII.    Where to seek shelter during a storm?
IX.     Sources of weather information.

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Weather Course Reference Material

Material of use to Weather course students is listed here.

• Weather symbols used on weather maps
• Suggested reference book list, May 2000 (PDF) (128KB)
• More suggested books, September 2000  (PDF) (137KB)

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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.

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