Image of Diamondhead Crater Department of Meterology: Aloha! Meteorology Logo
Meterology Home Weather Server News/Seminars
Academics Application Contact Us

Department Objectives
Academic Programs
Department Facilities
Research Projects
Application Information
Links to other Meteorolgy Sites
Frequently Asked Questions about the Server Space holder
Weather Server
University of Hawaii Home

Here is a List of Questions with links to the section with the answer:

USE OF DATA at this web is discussed in the Unidata document which covers the guidelines; specifies rules and provides the rationale

1. How can I get climatological data for the State of Hawaii?
2. What do the weather symbols on the hourly weather maps represent?
3. Where could a person learn about meteorology and weather forecasting through the web?
4. What are some useful books to study and learn meteorology?
5. What do the colors represent on the satellite IR images?
6. What are the frequently asked satellite meteorology questions?
7. What are the frequent questions on hurricanes, typhoons and tropical cyclones?
8. What are the frequently questions on where to locate weather data? [  current weather, research data, CD-ROM discs and web sources].
9. What causes a blank map?
10. Why doesn't my browser show the most recent image?
11. What are the time zones that are used on maps you plot and what do the UTC, GMT and Z time references mean?
12. What time is it (Hawaiian Standard Time & UTC)?
13. How do you get your data and what software do you use to create the weather maps, satellite images and the text files of weather forecasts and bulletins? And why are text files in upper case characters?
14. Please define your abbreviations.

1. How can I get climatological data for the State of Hawaii?

NOAA's Western Regional Climate Center (WRCC) has a web accessible narrative description of the Climate of Hawaii and in addition they have long-term climate data for many locations at

Hardcopy climatological data are maintained by NOAA and their National Climatic Data Center (NCDC) offices. Within six months after the observations, the following documents become available:

  1. Local Climatological Data (LCD) (for NWS airport stations);
  2. Climatological Data; Hawaii and Pacific (CD); and
  3. Hourly Precipitation Data; Hawaii and Pacific (HPD).
LCDs have information on temperature, dewpoint, precipitation, wind, sunshine and sky cover for Lihue, Honolulu, Kahului and Hilo airports. CDs have temperature and precipitation from cooperative observers on most islands. HPD have the rainfall information (hourly & monthly) for many island sites. These products are avaiable from the NCDC web site at

And a useful reference on the climate (plus the natural, cultural and Local environment) of Hawaii is the Atlas of Hawaii, 3ED from the University of Hawaii at Hilo Department of Geography (1998), University of Hawaii Press (ISBN 0-8248-2125-4/paperback or ISBN 0-8248-1745-1/cloth cover).

Return to the top of this page.

2. What do the weather symbols used on your station plots and hourly weather maps represent?

The station circle represents the cloud cover; open circle means clear; and a completely covered circle means 100% cloud cover (or fog). The line extending outward from the station circle is called a wind barb and represents the wind flow; where the wind is blowing from the direction of the barb (north is towards the top of the map and east is towards the viewer's right). The line(s) extending from the end of the barb are called feathers and represent the windspeed. There are three types of feathers; a normal length represents a wind of 10 knots; a half-length one represents 5 knots and a triangular shaped one is 50 knots: So a 25 knot wind would have two full and one half-length feathers. The various symbols to the left of the circle represent the weather phenomenon. There are different symbols for rain, drizzle, fog, thunderstorms and other weather.

Here is a gif plotted legend which depicts the symbols and explains the numeric values that are plotted about the station circle. This WXP map legend shows the various symbols plotted by our imaging software, which are called GEMPAK (aka N-AWIPS) and WXP.

Return to the top of this page.

3. Where could a person learn more about meteorology and weather forecasting through the web?

The University of Illinois at Urbana-Champaign has a comprehensive web based learning system; please check their index web page for topics you are interested in studying. And the National Weather Service (NWS) San Francisco Bay Area server has an Area Forecast Discussion Glossary and a Guide to Weather and to the NWS, with information on decoding products and learning terminology.

Then there is NWS tutorial material for weather forecasting professionals and college-level students, where the UCAR COMET program maintains links to Web-based educational/training material. COMET is the Cooperative Program for Operational Meteorology, Education and Training, where NWS weather forecasters study improved forecasting techniques.

Return to the top of this page.

4. What are some useful books to study and learn meteorology?

Book for general meteorology; a college freshman level text:

  • Essentials of Meteorology by C. Donald Ahren (Modesto Junior College) West Publishing Company (ISBN 0-314-01245-1 for paperback edition)

Books for weather in Hawaii:
  • Prevailing Trade Winds; Weather and Climate in Hawaii edited by Marie Sandersen; University of Hawaii Press (ISBN 0-8248-1491-6)
  • Weather in Hawaiian Waters by Paul Haraguchi (written for local fishing enthusiasts and no longer in print; loan copies are in the Hawaii State Libraries--go to the Hawaiian Section).

Atlases with basic climatological information on Hawaii:

  • Atlas of Hawaii; Third Edition (1998) from the University of Hawaii at Hilo, Department of Geography; University of Hawaii Press (ISBN 0-8248-2125-4 for paperback and ISBN 0-8248-1745-1 for cloth cover). And both the 1973 first and the 1983 second editions also have information on the weather of Hawaii.
  • Hawaii; A Unique Geography by Joseph R. Morgan; Bess Press (ISBN 1-57306-021-6)

Manual on Tropical Meteorology for Weather Forecasting Professionals:
  • Forecaster's Guide to Tropical Meteorology; AWS TR 240 Updated; August 1995 by Colin S. Ramage (University of Hawaii); United States Air Force/Air Weather Service Technical Report 95/001 (AWS/TR-95/001); Approved for Public Release by the Defense Technical Information Center (DTIC) to the National Technical Information Service (NTIS)

Return to the top of this page.

5. Infrared Satellite Image Enhancement Key: what do IR satellite colors represent?
Color enhancements are often added to Infrared Satellite images to more clearly distinguish temperatures of various features. While the colors, and intervals of the enhancements may vary, the temperature values of each color may be determined from the registration bar included with the images.

Below is a Color Bar Temperature key for GOES-12 or GOES-10 Satellite IR images:
(the bar will be presented vertically on actual images):

IR Image color key--GOES-12 or GOES-10

Below is a Color Bar Temperature key for GMS/GOES-10 Satellite IR images:
(the bar will be presented vertically on actual images):

IR Image color key-- GMS/GOES-10

Satellites also detect water vapor in the atmosphere.

Below is a Water Vapor key for GOES-12 or GOES-10 Satellite WV images:
(the bar will be presented vertically on actual images):

IR Image color key--GOES-12 or GOES-10

Below is a Water Vapor key for GMS/GOES-10 Satellite WV images:
(the bar will be presented vertically on actual images):

IR Image color key-- GMS/GOES-10

Return to the top of this page.

6. What are the frequently asked questions on satellite meteorology?

Return to the top of this page.

7. What are the frequently asked questions on hurricanes, typhoons and tropical cyclones?

For hurricane and tropical cyclone meteorology, check NOAA's Atlantic Oceanographic and Meteorological Laboratory Hurricane Research Division FAQ (or use anonymous ftp to:

(Jan99) Where is the JTWC located? The Joint Typhoon Warning Center which forecasts tropical cyclones in the Western Pacific and Indian oceans was moved in January 1999 from their long-time home at Nimitz Hill, Guam to the US Naval Base at Pearl Harbor in Honolulu, Hawaii. JTWC continues to forecast tropical cyclones for the their forecast areas from Pearl Harbor. Note that JTWC is not directly part of the World Meteorological Organization (WMO) forecasting agreement, but they were formed by the US military to monitor destructive cyclones near US ships and bases in overseas locations.

Return to the top of this page.

8. What are the frequently asked questions on weather data sources for current weather, for research meteorology datasets, for CD ROM discs and web/internet accessible resources?

For sources of weather data, check UCAR's Data Support Section
Other Resources Page, where there are separate postings for current data, research data, CD rom data and internet resources (or use anonymous ftp to; cd pub/usenet/news.answers/meteorology or use this link to that ftp location).

NOTE: That internet resource points to the USENET news groups (e.g., sci.geo.meteorology) as well as mailing lists on weather topics.

Return to the top of this page.

9. What causes a blank map?

Blank maps occur when data files are not available when map generation time arrives. Typically this means that the network connection has been down for some period of time. Some products such as station report maps are generated on a fixed schedule when data is expected to arrive by specific times, while other maps such as tropical storm locations are generated only when new data is received. Occasionally, the schedule for receiving products changes, and the schedule for producing WWW images must be adjusted.

In most cases, the situation is temporary; however, you should always check the time printed on the image to ensure the map is recent.

Return to the top of this page.

10. Why doesn't my browser show the most recent image?

Many browsers have a feature which caches images to your own computer system and your browser uses that image rather than a newer one that is on our server's disk. To ensure that you receive the most recent image posted at all times, check the cache setting of your browser or use its "refresh" or "reload" function/button/menu.

Return to the top of this page.

11. Reading Times on Maps

Weather maps often cover large regions, and may span multiple time zones. Similarly, people access this WWW server from many locations around the world. To standardize map times, most follow the convention of using Greenwich Mean Time (GMT) or Coordinated Universal time (UTC) to denote the time for which the map is valid. Additionally, time is always reported using a 24 hour clock frequently referred to as military time, or Zulu time, which is often denoted using the letter "Z". Midnight Greenwich time would be denoted as 0000Z and noon would be 1200Z, while times after noon are added to 1200, so 6:00 PM is 1800Z (note that the colon is not used).

Weather maps generated from observed data are valid at the time of the observations. Forecast maps are valid at some time from the observations from which the forecast is generated. The initial time of the forecast is often referred to as either the 0 (zero) hour forecast or the analysis. The zero hour forecast is used to initialize forecast models. Since the basis for all forecasts depends on how well the initial field represents the actual state of the atmosphere, careful consideration must be given access the representativeness of this field.

On the weather charts and satellite images in our web pages, if the time reference is not specified, then it is based on Universal time.

When forecast maps have time stamps in the form shown below:
970131/0000V024 --or-- 970228/1200V072
The first map is a forecast for 1997 January 31 at 0000UTC and is a 24hour forecast product; and the second one is for 1997 February 28 at 1200UTC and is a 72hour forecast product.

Return to the top of this page.

12. What Time is it?

exec cmd="cgi-bin/date.csh GMT"
exec cmd="/cgi-bin/date.csh HST"

Hawaii is in the Hawaiian Standard Time (HST) zone which is 10 hours behind Greenwich time. GMT = HST + 10 hours. Hawaii does not change to daylight savings time. UTC is the abbreviation for Coordinated Universal Time and it is the same as GMT. In recent years, UTC is being used more frequently as the reference time at the prime meridian at 0 degrees East, which is the longitude of Greenwich, England.

Return to the top of this page.

13. How do you get your data and what software do you use to create the weather maps, satellite images and the text files of weather forecasts and bulletins? And why are text files in upper case characters?

We participate in the National Science Foundation program called Unidata. The Unidata Program Center (UPC) is located in Boulder, Colorado. The UPC oversees the transmission of data from the National Weather Service and National Environmental Satellite, Data, and Information Service to our university (and many others throughout North America) using the computer system called the Internet Data Distribution (IDD). Unidata is a program of the National Science Foundation to support the study of meteorology.

The University of Hawaii Department of Meteorology maintains a current weather database from our offices in Honolulu located in the Hawaii Institute for Geophysics building on the Manoa Campus of the university. Weather maps for the WWW are regularly updated to allow interested users to actively participate in studying the many aspects of weather phenomenon.

Data are continually received by our computer systems. Selected data are then automatically sent to programs that use them to generate 1) maps of the hourly weather observations, 2) maps of the forecasted wind, temperature and pressure patterns for various periods up to 10 days, 3) satellite images, 4) text files with forecasts of SEVERE WEATHER/surf conditions/local weather and 5) coded airport weather observations (international weather code). All data files are erased or overwritten when a newer web product is produced; although the original data are saved nightly in their raw (undecoded formats) for use by students and professors in their research work.

The computer software programs we use are GEMPAK, MCIDAS and WXP. The GEMPAK programs are our primary display software. This software was developed by NASA and is now maintained by NOAA/National Center for Environmental Prediction (NCEP) and Unidata. The MCIDAS software formats the satellite products and comes from the University of Wisconsin-Space Science and Engineering Center (SSEC). WXP (version 4) display software was provided by Purdue University through Unidata: WXP has been transferred to the Unisys Corp. which is the new location for Dan Vietor, developer of WXP (versions 4, 5 and previous). It and GEMPAK are used to create the weather maps and satellite images.

About upper case text files: Text files are presented as they are transmitted by the forecasting office. These will be in upper case characters as these data flow through international communications circuits which in some locations involve teletype equipment which generally can only handle upper case letters. The forecast office within the United States (USA), is the National Weather Service (NWS) and although current USA communications are with computer circuits, the NWS conforms to the international agreements and prepare their bulletins with upper case characters.

Many members of the Unidata community actively share ideas and scripts used in campus weather displays around the country, as well as help provide support to their fellow meteorologists. Please acknowledge their hard work by visiting those Webs.

Return to the top of this page.

14. Please define your abbreviations.
Here are abbreviations listed into three groups: 1) University of Hawaii; 2) Weather Satellites; and 3) Research Groups and Other Terms

Abbreviations for the University of Hawaii (UHawaii/UH/UHManoa):

  • SOEST=School of Ocean and Earth Science and Technology
  • IPRC=International Pacific Research Center
  • HIG=Hawaii Institute of Geophysics (building used by UH Meteorology Department and the WSFO/Honolulu Forecasters)
  • HIGP=Hawaii Institute of Geophysics and Planetology
  • OCEAN=Department of Oceanography
  • IFA=Institute for Astronomy

Weather Satellites Abbreviations (also some definitions):

  • GMS=Japan geostationary satellite at 140deg-east
  • GOES=US geostationary satellites, GOES-West/G10 at 135deg-west & GOES-East/G12 at 75deg-west
  • METEOSAT=European geostationary satellite at 0deg-east
  • FY-2=China geostationary satellite at 104deg-east
  • DMSP=US polar orbiting satellite
  • NOAA(polar)=US polar orbiting satellite
  • Sat.=satellites observing earth weather from geostationary orbit or from polar orbit recording reflected light or infrared energy
  • geostationary satellite=object that maintains same position over earth equator (night and day) at 30,000 km above the surface
  • polar (or polar orbiting) satellite=object traveling pole to pole generally making 14 orbits per day from about 800-1000km over the earth's surface
  • reflected light=sunlight/moonlight reflected from clouds--the whiter objects (the clouds) reflect the most light and darker objects (such as ocean surface or forested land) reflect less and are dark
  • infrared energy=energy measured by weather satellites which is computed into the infrared temperature of the cloud tops or the earth's surface layer, which could be ocean-lake-land-snow-or-ice and, generally, the whiter objects are the colder clouds. However, a false color pattern is also used to represent the different temperatures. (See question on satellite IR colors.)

Abbreviations for Research Groups and Other Terms

  • NOAA=US National Oceanic and Atmospheric Administration
  • NWS=NOAA National Weather Service
  • NHC=NWS National Hurricane Center in Miami, Florida
  • CPHC=NWS Central Pacific Hurricane Center in Honolulu, Hawaii
  • WSFO=NWS Weather Service Forecast Office (generally with NEXRAD)
  • NBDC=NWS National Buoy Data Center
  • NEXRAD=US Doppler Radar system used by civilian and military weather offices.
  • UCAR=University Corporation for Atmospheric Research at Boulder, Colorado. A consortium of universities with doctoral programs in atmospheric and related sciences plus many U.S. and international affiliate institutions. UCAR runs NCAR and also the UCAR Office of Programs which includes Unidata.
  • NCAR=UCAR National Center for Atmospheric Research
  • Unidata=UCAR project to support meteorology at universities
  • COLA=U. Maryland Center for Ocean-Land-Atmosphere Studies
  • NPMOC=US Navy Pacific Meteorological and Oceanographic Center at Pearl Harbor in Hawaii
  • JTWC=US Navy and US Air Force Joint Typhoon Warning Center co-located with NPMOC
  • NASA=US National Air and Space Administration