**National Climatic Data Center**

**DATA DOCUMENTATION**

**FOR**

**DATA SET 3901 (DSI-3901)**

## NOAA Surface & Upper Air Weather Charts

**March 24, 2003**

National Climatic Data Center

151 Patton Ave.

Asheville, NC 28801-5001 USA

**Table of Contents**

[Topic Page Number]{.underline}

1\.
Abstract\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...
3

2\. Element Names and Definitions**:**
\...\...\...\...\...\...\...\...\.... 4

3\. Start
Date\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...\.... 4

4\. Stop
Date\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...\..... 4

5\.
Coverage\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...
4

6\. How to order
data\...\...\...\...\...\...\...\...\...\...\...\...\...\... 5

7\. Archiving Data Center.
\...\...\...\...\...\...\...\...\...\...\...\... 5

8\. Technical
Contact\...\...\...\...\...\...\...\...\...\...\...\...\...\... 5

9\. Known Uncorrected
Problems\...\...\...\...\...\...\...\...\...\...\... 5

10\. Quality
Statement\...\...\...\...\...\...\...\...\...\...\...\...\...\... 6

11\. Essential Companion Data
Sets\...\...\...\...\...\...\...\...\...\... 6

12\.
References\...\...\...\...\...\...\...\...\...\...\...\...\...\...\...\....
6

Appendix A, Chart Series A: Surface and UA Weather Charts\...\... 7

Appendix B, Chart Series B: Initial Anal and Forecast Charts.. 10

Appendix C, Chart Series C: Tropical Strip/Precipitation and

Observed Weather Charts\...\...\...\...\...\...\... 14

**1. [Abstract]{.underline}:** The National Climatic Data Center\'s
three-disc set of NOAA

weather charts contains the charts most commonly used by researchers and
the general public. This set is the first National Climatic Data Center
(NCDC) CD-ROM product available on a monthly subscription basis and will
serve as a continuation of the microfilm archive.

The NCDC Weather Chart Archive

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

In addition to providing a quick historical reference about weather
conditions on selected dates, weather charts can be used to quickly
geographically locate and date a series of similar weather phenomena and
events. Using such charts saves researchers tremendous amounts of time
in studying and isolating the dates of weather phenomena. Because of
these uses, the NCDC has long maintained an archive of the weather
charts and analyses produced by the U.S. [National Centers for
Environmental Prediction](http://wwwt.ncep.noaa.gov/) (NCEP),

formerly the National Meteorological Center (NMC).

NCDC Microfilm Archive

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

NCDC\'s archive for weather charts extends back as early as 1899 for the
U.S. Daily Weather Map series. The archive for Constant Pressure (Upper
Air) and North American Surface charts begins in March 1942. Subsequent
charts have been added or deleted since then. The original archive
consisted of paper charts which were later placed on microfilm. This was
the official archive media through September 1994. Specific details
about the microfilm archive for each chart are provided under the
heading \"Microfilm Archive File Structure\" in the chart description
files provided on each CD-ROM. (See files: A-SFC&UA.TXT, B-FORCST.TXT,
and C-PRCWX.TXT)

NCDC CD-ROM Set

\-\-\-\-\-\-\-\-\-\-\-\-\-\--

NCDC\'s NOAA Weather Charts CD-ROM set consists of three closely-related
series of charts. These charts are but a subset of all the charts
produced by NCEP. However, all the charts in NCDC\'s microfilm archive
(which are current NOAA charts) are included, as well as the NOAA
forecast charts. Some charts which were dropped from the microfilm
archive have been reintroduced.

All charts on the three CD-ROM set are officially archived in a digital
database, from which NCDC has the capacity to produce paper copies. NCDC
acquires the charts from NCEP and ingests the data. The digital database
contains the same charts as those on the CD-ROM set, though in a
different format. The use of CD-ROM media allows NCDC to present data on
a media that is being increasingly used by the public, libraries, and
researchers.

The chart series names and lists of charts on each CD-ROM are provided
below. For more information about the directory tree structure and
naming conventions for files, please consult the READ_1ST.TXT file.
Included in this file are hardware/software requirements and suggestions
for viewing and printing charts. For detailed information about
particular charts in each chart series, consult the corresponding files.
These files provide general information about the production of the
charts and present a list of each chart name plus a narrative
description of each chart, the CD-ROM directory, names of the charts,
time period covered by the NCDC archive, geographic coverage, format,
and microfilm archive file structure.

> 1\) Chart Series A: Surface and Upper Air Weather Charts
>
> Description File: A-SFC&UA.TXT
>
> A\) North America: Constant Pressure
>
> B\) N. Hemisphere: Constant Pressure
>
> C\) North America: Surface
>
> D\) N. Hemisphere: Surface
>
> E\) S. Hemisphere: Constant Pressure
>
> 2\) Chart Series B: Initial Analysis and Forecast Charts
>
> Description File: B-FORCST.TXT
>
> A\) North America: 500 mb Heights/Vorticity
>
> B\) N. Hemisphere: 500 mb Heights/Vorticity
>
> C\) N. Hemisphere: Mean Relative Humidity/Vertical Velocity
>
> D\) N. Hemisphere: Surface Analysis/1000-500 mb Thickness
>
> E\) S. Hemisphere: Surface Analysis/1000-500 mb Thickness
>
> 3\) Chart Series C: Tropical Strip/Precipitation and Observed Weather
> Charts
>
> Description File: C-PRCWX.TXT
>
> A\) Tropical Strip: Constant Pressure
>
> B\) Tropical Strip: Surface
>
> C\) Composite Moisture Index
>
> D\) Observed Precipitation, Snowfall, and Temperature
>
> E\) Radar Summary
>
> F\) Weather Depiction
>
> G\) Winds Aloft

Viewing and Printing the Charts

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

NOTE: These instructions are intended for Microsoft Windows users. Other
systems, such as the MacIntosh, will have a slightly different method
for viewing/printing these chart images.

To view these PCX files, double-click on the file icon in File Manager
and Paintbrush will automatically be loaded with the image. You can
scroll and zoom as well as cut and paste into other documents using the
Clipboard. In addition, the images can be printed at different sizes
using the tools in Paintbrush.

If another graphics program is launched when you double click in File
Manager, then another program has been \"associated\" with PCX files. To
create an association in File Manager for a preferred graphics program,
consult your Windows documentation.

If you need the files in other graphic formats (ie., \*.bmp, \*.tif,
etc.) or somehow altered, excellent conversion utilities exist as
shareware products.

**2. [Element Names and Definitions]{.underline}:** Please see
Appendices A, B, and C

**3. [Start Date]{.underline}:** Please see Appendices A, B, and C

**4. [Stop Date]{.underline}:** Please see Appendices A, B, and C

**5. [Coverage]{.underline}:** Please see Appendices A, B, and C

**6. [How to Order Data]{.underline}:**

Ask NCDC's Climate Services about the cost of obtaining this data set.

Phone: 828-271-4800

FAX: 828-271-4876

E-mail: [**NCDC.Orders@noaa.gov**](mailto:NCDC.Orders@noaa.gov)

**7. [Archiving Data Center]{.underline}:**

National Climatic Data Center

Federal Building

151 Patton Avenue

Asheville, NC 28801-5001

Phone: (828) 271-4800**.**

**8. [Technical Contact]{.underline}:**

National Climatic Data Center

Federal Building

151 Patton Avenue

Asheville, NC 28801-5001

Phone: (828) 271-4800**.**

**9. [Known Uncorrected Problems]{.underline}:**

PROBLEM: When the image is displayed in Paintbrush, it comes up as all
black.

SOLUTION: What you are actually seeing is a black image on a black
background. Some applications alter the color palette when they are
started and do not reset it back when exited. This is only a problem for
PC systems with an SVGA driver with 256 colors selected. Under such
conditions, the color palette remains altered for the entire Windows
session. Solutions include exiting and restarting Windows (making sure
the offending application(s) do not automatically restart), using
another graphics program instead of Paintbrush or changing video driver
and/or color palette combinations.

PROBLEM: When the image is displayed, it appears as all white.

SOLUTION: The problem here is that a few of the charts have a large
amount of white space along some of the edges. This is true only for the
following charts:

Series C: Tropical Strip /Precipitation and Observed Weather Charts

\* Tropical Strip Constant Pressure (trop_str.con), all descriptions
(250mb, 500mb, and 700mb), and all UTC times (00z and 12z). These charts
all have a large margin along the top edge.

\* Winds Aloft (winds.aft), Second Standard Level 14k, 24k, 34k ft.
(14_24_34.2sl) for 00 UTC (00z). This chart has a large top and left
edge margin.

The solution to this problem for viewing is to maximize the viewing
window and/or scroll the view area to the desired portion of the chart.
See the descriptions for these charts in their respective \"readme\"
files for more information.

PROBLEM: The image appears with \"noise\" (ie, unexpected vertical lines
running through the chart), oriented upside-down or sideways, and/or
truncated.

SOLUTION: These are all symptoms of a scanned image. While certain
measures have been used to catch corrupt images, some charts will escape
notice. For those that are caught, we have indicated that these are the
\"Best Copy Available.\" In either case, this represents the most
complete image available for that chart.

**10. Quality Statement:** None available.

**11. [Essential Companion Datasets]{.underline}:**

The other files stored in the README.DIR directory are provided for
additional help in understanding and using this CD product. All these
files are best viewed and printed with 1 inch margin settings. Here is a
listing of these files and a brief explanation of each:

\*\* A-SFC&UA.TXT gives detailed information about the weather charts
included in the Surface and Upper Air Weather Charts series.

\* ABBREV.TXT is a listing of the abbreviations used in the naming of
the directories. It is designed to serve as a \"cheat sheet\" that
expands the directory names to their original titles.

\*\* B-FORCST.TXT gives detailed information about the weather charts
included in the Initial Analysis and Forecast series.

\*\* C-PRCWX.TXT gives detailed information about the weather charts
included in the Tropical Strip/Precipitation and Observed Weather Charts
series.

INTRO.TXT is a description of the NCDC weather charts archive.

\* SUBSET.TXT contains a listing of all the charts available on CD-ROM
and is grouped by their respective series\' and subset numbers. Each
series is available on a separate CD.

\* Although all the above text files can be printed, it is especially
recommended that these two files be printed and made available for easy
access while the user is navigating the CD.

\*\* These files are included only on the appropriate CD. Therefore, if
you have the Surface and Upper Air series, you should only have the
A-SFC&UA.TXT file.

**12. [References]{.underline}:** No information provided with original
documentation.

**Appendix A**

Chart Series A: Surface and Upper Air Weather Charts

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Note: The NCDC CD-ROM archive will ultimately begin with October 1994
data.

Introduction

\-\-\-\-\-\-\-\-\-\-\--

Current weather and analyses products are produced from a global
observing and telecommunications network which funnels observations to
the NCEP. In earlier years, the primary function of the NCEP\'s
operational analyses programs was to provide information from which
initial atmospheric conditions for numerical forecast models could be
derived. The charts in this

series document the basic weather data that enter into forecasts and
present the surface and upper air weather conditions up to eight times
per day in chart form.

In some cases, an element of human interpretation is used by
meteorologists at the NCEP to make both objective and subjective
adjustments. Both the North American and Northern Hemisphere surface
charts on the CD-ROM set prior to October 1995 do NOT contain the human
interpretations, but they are available on the microfilm archive through
that date.

Description of NOAA Charts

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

**(A&B) CHART NAMES: NORTH AMERICAN CONSTANT PRESSURE CHARTS.**

**NORTHERN HEMISPHERE CONSTANT PRESSURE CHARTS.**

DIRECTORY NAMES: N America: n_amerca.con

N Hemisphere: n_hemis.con

Levels:

hite_tmp.xxx where N Amer xxx = 850, 700, 500

N Hem xxx = 850, 700, 500, 100, 50, 30, 10

hite_iso.jjj where N Amer jjj = 300, 250, 200, 100

N Hem jjj = 300, 250, 200

> Tropopause: trpopaus.anl (N Hemisphere)

TIME PERIOD: January 1, 1946 through the present.

GEOGRAPHIC COVERAGE: North American Continent or Northern Hemisphere.

FORMAT: Twice daily analyzed constant pressure charts

> 1\. January 1, 1946 through December 31, 1949 for 0400 and 1600 UTC
> for 1000-, 850-, 700-, 500-, 300-, and 200-millibars,

2\. January 1, 1950 through May 31, 1957 for 0300 and 1500 UTC for
1000-, 850-, 700-, 500-, 300-, 200-, and 150-millibars,

3\. June 1, 1957 through December 31, 1966 for 0000 and 1200 UTC for
850-, 700-, 500-, 300-, 200-, and 150- millibars. For 1200 UTC only,
100-millibars.

4\. January 1, 1967 through the present for 0000 and 1200 UTC for 850-,
700-, 500-, 300-, and 200-millibars. For 1200 UTC only: 100-, 50-, 30-,
and 10-millibars

(plus 4- and 1-millibars on a sporadic basis).

All levels 100-mb and above end January 13, 1997, 1200 UTC.

CONTENTS: Analyzed heights (decameters) for each constant pressure chart
are drawn as solid lines at 60-meter intervals. Isotachs at 20-knot
intervals are drawn as dashed lines. High and low pressure centers,
troughs, ridges, and jet streams (sometimes) are depicted. Station
observational data with wind-barbs are also plotted.

**(C) CHART NAME: NORTH AMERICAN SURFACE CHARTS.**

DIRECTORY NAME: n_amerca.sfc

TIME PERIOD: March 1, 1942 through the present.

GEOGRAPHIC COVERAGE: North America; 20 degrees North to 70 degrees North
latitude.

FORMAT: Analyzed surface weather charts as follows:

1\. 0000, 0600, 1200, and 1800 UTC from

March 1, 1942 through September 30, 1953,

2\. 0000, 0300, 0600, 0900, 1200, 1500, 1800, and 2100 UTC from October
1, 1953 through the present.

CONTENTS: These surface weather charts contain isobaric analyses at
4-millibar intervals. They also depict high and low pressure areas,
tropical cyclones, and the various types of fronts (cold, warm, etc.)
Surface land and surface marine observational data are plotted. Some of
the charts from 1942 through 1953 are analyses of the United States
only.

**(D) CHART NAME NORTHERN HEMISPHERE SURFACE CHARTS.**

**MODIFIED NORTHERN HEMISPHERE SURFACE CHARTS.**

DIRECTORY NAME: n_hemis.sfc

n_hemis.sfm

TIME PERIOD: May 1, 1954 through the present.

GEOGRAPHIC COVERAGE: Northern Hemisphere : pole to approximately 10
degrees North latitude.

FORMAT: Surface weather charts as follows:

1\. Analyzed 0000, 0600, 1200, and 1800 UTC from May,

1954 through May 1989;

2\. Analyzed 0000 and 1200 UTC from June 1989 through January 1994 and
October 1995 through January 7, 1997

3\. Modified (Unanalyzed) Northern Hemisphere Surface

charts for 0000, 0600, 1200, and 1800 UTC from

> February 1994 through September 1995 and January 17 1997 to the
> present (Note: Charts for July through September 1995 are missing on
> the CD-ROM set. Contact the NCDC for details about obtaining them).
> These charts are operational NCEP charts and rarely contain isobaric
> analyses, frontal positions, or pressure centers

MICROFILM ARCHIVE Chart Series: MF-917

FILE STRUCTURE: This file of surface weather charts is stored on 4 reels
of 35-millimeter microfilm each year through September 1995. Charts
available on microfilm after

> January 1994 usually do not contain frontal analyses and pressure
> centers. In addition, isobaric analyses may be incomplete. The film is
> filed in the NCDC archives and is available for purchase.

CONTENTS: These surface weather charts contain isobaric analyses at
4-millibar intervals. The analyzed Northern Hemisphere charts also
depict high and low pressure areas, tropical cyclones, and the various
types of fronts (cold, warm, etc.) Surface land and surface marine
observational data are plotted.

**(E) CHART NAME: SOUTHERN HEMISPHERE CONSTANT PRESSURE**

**CHARTS.**

DIRECTORY NAMES: s_hemis.con, hite_isoxxx where xxx =

250, 300, 500

TIME PERIOD: November 1, 1975 through the present.

GEOGRAPHIC COVERAGE: Southern Hemisphere; pole to 10 degrees

South latitude.

FORMAT: Twice daily, 0000 and 1200 UTC, computer

plotted and analyzed charts for constant

pressure levels of 500-, 300-, and

250-millibars.

CONTENTS: Analyzed heights (decameters) for each pressure chart are
drawn as solid lines at 60-meter intervals. Isotachs at 20-knot
intervals are drawn as dashed

> lines. High and low pressure centers are depicted and the station
> observational data with wind-barbs are plotted.

**Appendix B**

Chart Series B: Initial Analysis and Forecast Charts

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Note: The NCDC CD-ROM archive will ultimately begin with October 1994
data.

A Note about Directory Times

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

North American and Northern Hemisphere charts on the Chart Series B
(Initial Analysis and Forecast Charts) CD-ROM represent initial
analyses, plus 12-, 24-, 36-, and 48-hour forecasts for each twelve hour
period. The directory tree for this CD-ROM lists the dates and times
when charts are ISSUED by NCEP. The times in this directory are NOT the
times for which the charts are VALID. On Chart Series A and C CD-ROM\'s,
the issued and valid times for charts are the same.

Example: \\n_hemis.mrh\\36hr\\01\\00z\\ is the directory listing

for a Northern Hemisphere Relative Humidity/Vertical

Velocity 36-hour Forecast Chart ISSUED at 00 UTC on the

first day of the month, and is VALID at 12 UTC on the second

day of the month (36 hours after the issue time). The

directory for this chart lists the ISSUED time; the chart is

labelled with the VALID time.

Introduction

\-\-\-\-\-\-\-\-\-\-\--

The NCEP has long produced several series of forecast charts, dependent
upon the area covered and their use. The NCDC microfilm archive includes
only a limited number of such charts and these were primarily from the
production run that is now known as the Aviation Run. The charts
presented on this CD-ROM are all derived from the Aviation Run.

Forecast charts are products of the various computer models operated by
the Environmental Modeling Center (EMC) for weather prediction at the
NCEP. In general, analysis programs assign values of meteorological
parameters to grid points using spatially interpolated available
observations. In addition, first

guess fields, usually in the form of a numerical forecast made from a
previous analysis and valid at the time of the current analysis, were
also used to make the initial analysis. Once the analysis was complete,
the process moved to the forecast model in use.

In some cases, human interpretation is introduced into the forecasts by
meteorologists at the NCEP. These meteorologists make both objective and
subjective adjustments. These adjustments improve the forecasts based
upon the knowledge of tendencies and systematic errors known to exist in
the forecast models.

History of the Aviation Run

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

The basic primitive equation model used at the NCEP was implemented
operationally in June 1966. This model was the ancestor of the Limited
Fine Mesh (LFM) and of the 7-layer Primitive Equations (7L PE) model.
The LFM model was introduced into routine operations in 1971. After
changes in the grid spacing and an additional forecast layer was added
in the stratosphere, the new model was designated the 7L PE in January,
1978. On August 12, 1980, NCEP\'s Global Spectral Model replaced the 7L
PE coarse mesh as NCEP\'s primary operational hemispheric/global model.
This Spectral Model had 12 layers and used a finite differencing scheme
to formulate the model in the vertical. Up to 30 waves or modes could be
incorporated. Whenever the 30 mode resolution for the Spectral Model was
used, it approached that of the 7L PE that it replaced.

The status of the NCEP model runs continues to evolve. The most recently
introduced model is the Eta Model (Eta), which is unique in its
treatment of orography as a set of steps, each of which corresponds to a
level of the model\'s vertical coordinate, which is referred to as Eta.

The NCEP now runs four different models to service the five standard
production runs. The runs and the currently used models to produce them
are: 1) Early Look (ERL) Run using the LFM and Eta Models; 2) Regional
Run (RGL) using the Nested Grid Model (NGM); and 3) The Aviation Run
(AVN); Medium Range Forecast Run (MRF), and the Final (FNL), all run
under the Global Spectral Model (GSM).

Global Spectral Model/Aviation Run

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

The wind and mass variables in the current Global Spectral Model are
represented by triangularly truncated series of surface spherical
harmonics on each of 28 vertical layers defined in sigma coordinates.
The series are truncated at wave number 126 (T126), equivalent to a
globally homogeneous grid resolution of 105-km. The AVN model forecasts
are issued twice per day and are initiated approximately three hours
after the principal synoptic hours 0000 and 1200 UTC.

Additional information about NCEP modeling can be obtained by accessing
the Internet homepage of the Global Modeling Branch of NCEP\'s
Environmental Modeling Center. The URL is:

http://nic.fb4.noaa.gov:8000/research/global2.html

To obtain information about the model status, access \"Model Status as
of October 25, 1995\" whose URL is:

http://nic.fb4.noaa.gov:8000/research/mrf.html

(URL\'s current as of March 1997.)

Description of NOAA Charts

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

**(A&B) CHART NAMES: NORTH AMERICAN 500 mb HEIGHTS/VORTICITY CHARTS.
NORTHERN HEMISPHERE 500 mb HEIGHTS/VORTICITY CHARTS.**

DIRECTORY NAMES: n_amerca.500 and n_hemis.500, xxhr where

xx = 12, 24, 36, 48; analysis

TIME PERIOD: May 1, 1961 through the present.

GEOGRAPHIC COVERAGE: Northern Hemisphere/North America.

FORMAT: Twice daily, 0000 and 1200 UTC, computer-produced initial
analysis and 12-, 24-, 36-, and 48-hour prognoses.

CONTENTS: The basis for these computer-produced charts is the numerical
prediction model being used at the time. The 500-millibar contours are
depicted as dashed lines at 60 meter intervals and are labeled by

> three-digit white numbers on a black background. Circulation centers
> are indicated by \"H\" for high and \"L\" for low. Centers are located
> by an X within
>
> a circle and labeled by three-digit hollow numbers in decameters. The
> location points of 500-millibar absolute vorticity isopleths are drawn
> as solid
>
> lines at intervals of 2 x 10-5sec-1. Absolute vorticity isopleths are
> labeled 2, 4, 6, etc., in multiples of 10-5sec-1. Centers of positive
> absolute vorticity are indicated by an \"x\" and negative
>
> absolute vorticity by an \"N\". Both Northern Hemisphere and North
> American charts are on the CD-ROM.

**(C) CHART NAME: NORTHERN HEMISPHERE MEAN RELATIVE**

**HUMIDITY/VERTICAL-VELOCITY CHARTS.**

DIRECTORY NAMES: n_hemis.mrh, xxhr where xx = 12, 24, 36, 48; analysis

TIME PERIOD: May 1, 1961 through the present.

GEOGRAPHIC COVERAGE: Northern Hemisphere/North America.

FORMAT: Twice daily, 0000 and 1200 UTC,computer-produced initial
analysis and 12-, 24-, 36-, and 48-hour prognoses.

CONTENTS: The mean relative humidity is defined for a column through the
lower layers of the numerical prediction model being used at the time.
This has varied from

the surface or 1000-mb to approximately 450- to 500-millibars. The ratio
of precipitable water in a column to that which would exist if the water
vapor was at its saturation level is a measure of the mean relative
humidity. Mean relative humidity isopleths are drawn as solid lines for
10, 30, 50, 70 and 90%

> and are labeled with one-digit hollow numbers. Centers of maximum and
> minimum relative humidity are depicted by an x within a circle with
> two-digit hollow numbers. The areas with relative humidity above 70%
> are hatched.

Vertical velocity isopleths are depicted as solid lines with labels at
intervals of 1-microbar per second (1-microbar = .001 millibars). These
values may be converted approximately to centimeters per second at 700
mb by multiplying by 1.12. Centers of maximum upward and downward motion
are interpolated and printed as + or -, respectively. Vertical velocity
values are at the 700-millibar level. Only Northern Hemisphere charts
are on the CD-ROM.

**(D) CHART NAME: NORTHERN HEMISPHERE SURFACE ANALYSIS/1000-500 mb
THICKNESS CHARTS**

DIRECTORY NAMES: n_hm1000.500, xxhr where xx = 12, 24, 36, 48; analysis

TIME PERIOD: February 1, 1983 through the present.(with breaks)

GEOGRAPHIC COVERAGE: Northern Hemisphere.

FORMAT: Twice daily, 0000 and 1200 UTC, computer-produced initial
analysis and 12-, 24-, 36-, and 48-hour prognoses.

CONTENTS: The basis for these computer-generated charts is the NCEP
numerical prediction model being used at the time. Isobaric analyses at
4-millibar intervals of the mean sea level pressure are shown in solid
lines. Pressure centers are labeled with their respective values. One
thousand to 500 mb thickness analyses in 60 decameter intervals are
depicted as dashed lines. There are no plotted station data.

**(E) CHART NAME: SOUTHERN HEMISPHERE SURFACE ANALYSIS/1000-500 mb
THICKNESS CHARTS.**

DIRECTORY NAME: s_hm1000.500

TIME PERIOD: January 1, 1966 through June 30, 1971 and November 1, 1975
through the present.

GEOGRAPHIC COVERAGE: Southern Hemisphere; pole to 20 degrees South
latitude.

FORMAT: Computer analyzed charts for 0000 and 1200 UTC.

CONTENTS: These computer-analyzed charts depict isobaric analyses at
4-millibar intervals and thickness analyses in decameters. High and low
pressure areas

are also depicted. There are no plotted station data.

**Appendix C**

Chart Series C: Tropical Strip/Precipitation and Observed Weather Charts

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Note: The NCDC CD-ROM archive will ultimately begin with October 1994
data.

Introduction

\-\-\-\-\-\-\-\-\-\-\--

The ingest of data by NCEP for the production of these charts is similar
to that described for the surface and upper air charts; i.e., a global
observing and telecommunications network funnels observations to the
NCEP. This series contains charts providing information about tropical
strip surface and upper air data, daily recorded precipitation,
temperatures, and snowfall; current observed weather conditions (radar
summary and weather depiction charts); and forecast moisture conditions
and winds (composite moisture and winds aloft) charts.

Description of NOAA Charts

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

**(A) CHART NAME: TROPICAL STRIP CONSTANT PRESSURE CHARTS.**

DIRECTORY NAMES: trop_str.con, xxxmb where xxx = 250, 500, 700

TIME PERIOD: August 1, 1975 through the present.

GEOGRAPHIC COVERAGE: Global; 60 degrees North to 50 degrees S. latitude.

FORMAT: Analyzed constant pressure charts for 0000 and 1200 UTC for the
700-, 500-, and 250-millibar levels. The 850- and 150-millibar levels
were added 1 Jan, 1985.

CONTENTS: Analyzed flow fields for each constant pressure level are
depicted by solid streamlines drawn to show the direction of flow.
Isotachs are drawn as dashed

lines at 20 knot intervals. Grid point winds from the analyzed field and
station observational winds are plotted in wind-barb form.

Note: Due to constraints on the files as received from NCEP, these
charts will appear with significant blank space at the top.

**(B) CHART NAME: TROPICAL STRIP SURFACE CHARTS.**

DIRECTORY NAME: trop_str.sfc

TIME PERIOD: March 1, 1969 through the present.

GEOGRAPHIC COVERAGE: Global; 30 degrees North to 50 degrees S. latitude.

FORMAT: These charts are analyzed in two sections, one for the Western
Hemisphere and one for the Eastern Hemisphere. They include 0000 and
1200 UTC charts

from March 1, 1969 through December 31, 1978 and 0000, 0600, 1200, and
1800 UTC charts from January 1, 1979 through the present.

CONTENTS: The Western and Eastern Hemisphere charts depict wind flow
patterns by solid streamlines, fronts, troughs,

ridges, and high and low pressure areas. Plotted data include surface
land and surface marine stations and satellite winds from low cloud
motions. Extra surface marine data are plotted at the bottom of each
chart.

**(C) CHART NAME: COMPOSITE MOISTURE INDEX CHARTS.**

DIRECTORY NAMES: [Dataset]{.underline} [cmpmoist.ndx]{.underline}

1\. Average Relative avg_sfc.500

Humidity

2\. Freezing Level freezing.lev

3\. Lifted Index/K Index lifted_k.ndx

4\. Precipitable Water pre_h20

TIME PERIOD: January 1, 1962 through the present.

GEOGRAPHIC COVERAGE: Conterminous United States, Southern Canada, and
Northern Mexico.

FORMAT: Twice daily (0000 and 1200 UTC) computer plotted and hand
analyzed four panel charts.

CONTENTS: 1. Lifted Index/K Index (Upper-Left Panel); Isopleths of
lifted index are drawn for intervals of 4 units for index values of +4
and lower. Areas of index values

less than +4 are labeled unstable (u) - areas of high index values above
+4 are labeled stable (s). The zero isopleth is drawn as a heavier solid
line. Station circles are blacked-in for index values of zero or less.
Values of K will be plotted below the values of lifted index for each
raob (upper air)

station. High K unstable, low values of K (or negative) are stable. No
analyses of the K-index are made.

2\. Precipitable Water (Upper-Right Panel). The precipitable water is
analyzed for intervals of .50 inch with .25 inch (dashed isopleths) used
to define the pattern when necessary. Station circles are blacked-in for
values of 1.00 inch or greater.

3\. Freezing Level (Lower-Left Panel). Several freezing levels may occur
on an upper air sounding, but only the lowest 3 levels are plotted. The
lowest level

is plotted below the station circle and the others above. Only the
lowest freezing level is analyzed. The surface intersection (32 Deg F)
is a dashed line

and the free-air contours are drawn as solid lines for 4000-feet
intervals. The free-air contours are shown as discontinuous where they
intersect smoothed terrain contours in the western United States.

4\. Average Relative Humidity (Lower-Right Panel). The average relative
humidity (surface to 500-millibars) is analyzed for intervals of 10% for
humidities 50%

and higher. Station circles are blacked-in for humidities of 50% and
higher with the average relative humidity (%) plotted above the station

circle.

**(D1) CHART NAME: OBSERVED 24-HOUR PRECIPITATION CHARTS.**

DIRECTORY NAMES: pr_sn_tm.obs, 24h_prec.obs

TIME PERIOD: January 1, 1962 through the present (updated annually).

GEOGRAPHIC COVERAGE: Conterminous United States, Southern Canada, and
Northern Mexico.

FORMAT: Computer plotted chart for 1200 UTC daily.

CONTENTS: These charts present plotted 24-hour precipitation amounts to
one-hundredth inch and traces (less than one-hundredth inch). When a
station reported no

24-hour precipitation, the 1200 UTC 6-hour accumulated precipitation
amount is plotted instead. This substitution is denoted by the symbol,
\"A\" in place of the decimal point. Additional reports, for which there
is no space at station location, are listed in a column along right edge
of the chart and are identified by station number, call letters, or
name.

**(D2) CHART NAME: OBSERVED SNOW COVER CHARTS.**

DIRECTORY NAMES: pr_sn_tm.obs, sno_covr.obs

TIME PERIOD: March 1, 1966 through the present.

GEOGRAPHIC COVERAGE: Conterminous United States and Southern Canada.

FORMAT: Computer plotted chart for 1200 UTC daily.

CONTENTS: The major parameters plotted on these charts are total snow
depth and 6-hour increase of snow to the nearest whole inch. Trace
amounts are also plotted.

Total snow depth is plotted to the right of a blacked-in station circle.
When there has been snow in the last six hours, this amount is plotted
centered on the station circle using white numbers on a black
background. Additional reports, for which there is no space at the
station location, are

listed in a column along the right edge of the chart and are identified
by station number, call letter, or name. These computer-plotted charts
are from the automatically processed data sets which have as their
source the 1200 UTC observations of the National Weather Service. These
charts are prepared only

for those days that snow cover exists, normally October through April.

**(D3) CHART NAME: MAXIMUM AND MINIMUM TEMPERATURE CHART (12-Hour).**

DIRECTORY NAMES: pr_sn_tm.obs, 12hr_max.tmp, 12hr_min.tmp

TIME PERIOD: April 1, 1966 through the present.

GEOGRAPHIC COVERAGE: United States, except Alaska and Hawaii,and
Southern Canada.

FORMAT: Computer plotted charts of observed temperatures, one for
maximum and one for minimum, during the 12 hours ending at 0000 and 1200
UTC, respectively.

CONTENTS: The data plotted on these charts are from the automatically
processed surface data sets from the National Weather Service. The
maximum or minimum

temperatures (Deg. F) are plotted above the station circles. When both a
city office and an airport office send temperatures, the city office
temperature is plotted on-station and the airport temperature is in the
printed box, labeled AIRPORT TEMP, on the right edge of the chart. The
RECORD TEMPS box printed in the Gulf of Mexico is filled in from the
fifth group of the SM (Hi-Lo report) for all records

reported on each set of data:

> Contraction Type of Temperature Record
>
> \-\-\-\-\-\-\-\-\-\--
> \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--
>
> HIXFM HIghest eXceeded For the Month
>
> LOXFM LOwest eXceeded For the Month
>
> Spring temperatures (March, April, May)
>
> HIXSE HIghest eXceeded So Early
>
> LOXSL LOwest eXceeded So Late
>
> HIESE HIghest Equaled So Early
>
> LOESL LOwest Equaled So Late
>
> Autumn Temperatures (September, October, November)
>
> HIXSL HIghest eXceeded So Late
>
> LOXSE LOwest eXceeded So Early
>
> HIESL HIghest Equaled So Late
>
> LOESE LOwest Equaled So Early
>
> All time records (since observations began)
>
> HIXAT HIghest eXceeded for All Time
>
> LOXAT LOwest eXceeded for All Time
>
> HIEAT HIghest Equaled for All Time
>
> LOEAT LOwest Equaled for All Time

**(E) CHART NAME: RADAR SUMMARY CHARTS.**

DIRECTORY NAME: radar.sum

TIME PERIOD: March 1, 1957 through the present.

GEOGRAPHIC COVERAGE: United States, except Alaska and Hawaii.

FORMAT: Hourly analyzed charts.

CONTENTS: These charts present analyzed areas, lines, and cells of
precipitation formations. The speed and direction of cell movement
and/or line echoes, tops and bases of clouds, precipitation type, any
watch/warning boxes, and status of radar at each station are included.
Shaded areas give an indication of areal

coverage and contours are used to depict each of the Digital Video
Integrator Processor (DVIP) levels (1 and 2; 3 and 4; 5 and 6). Echo
heights are in hundreds of feet above to mean sea level as a three digit
number and echo movements are indicted by arrows. Precipitation types
and change of intensity (+ is new or increasing, - is decreasing) are
also plotted as one entry close to the activity to which

they apply (see chart below). Severe weather watch boxes with labels
indicating the type and time of

expiration are also included. The time of these charts are 35 minutes
past the hour for all 24 hours (UTC) of the day. The NCDC rounds up the
time to the next hour (e.g., 1635 UTC is the 17 UTC Chart).

> PRECIPITATION TYPE CONTRACTION
>
> \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\--
>
> Thunderstorm (with rain shower) TRW
>
> Thunderstorm (with snow shower) TSW
>
> Thunderstorm (with freezing rain shower) TZRW
>
> Thunderstorm (with ice pellet shower) TIPW
>
> Rain R
>
> Rain Shower RW
>
> Freezing Rain ZR
>
> Freezing Rain Shower ZRW
>
> Snow S
>
> Snow Shower SW
>
> Drizzle L
>
> Freezing Drizzle ZL
>
> Ice Pellet IP
>
> Ice Pellet Shower IPW

**(F)** CHART NAME: WEATHER DEPICTION ANALYSIS CHARTS.

DIRECTORY NAME: weather.dep

TIME PERIOD: January 1, 1976 through the present.

GEOGRAPHIC COVERAGE: Conterminous United States, Southern Canada, and
Northern Mexico.

FORMAT: Computer plotted and manually analyzed air terminal weather
conditions on charts for 0100, 0400, 0700, 1000, 1300, 1600, 1900, and
2200 UTC daily.

CONTENTS: The data plotted on these charts are from the automatically
processed surface data set of the National Weather Service. The plotting
model on each

station circle is an abbreviated version of the complete aviation
observation and includes significant weather, visibility, total sky
cover, and ceiling height. When the total sky cover is 5/10

or less, the height of the lowest scattered layer is plotted.
Visibilities over 6 miles are not plotted. Areas with IFR conditions
(ceiling below 1000 feet

and/or visibility less than 3 miles) are enclosed by solid lines and are
shaded. Areas with MVFR conditions (ceiling 1000 feet to 3000 feet
inclusive and visibility 3 miles to 5 miles inclusive) are enclosed by
scalloped lines without shading. All other areas on the chart are VFR
conditions (ceiling greater than 3000 feet and visibility more than 5

miles). High and low pressure centers, fronts, troughs, and squall lines
from the previous hour are also depicted.

**(G) CHART NAME: WINDS ALOFT CHARTS.**

DIRECTORY NAMES: winds.aft, 14_24_34.251

TIME PERIOD: March 1, 1942 through the present.

GEOGRAPHIC COVERAGE: United States, except Alaska and Hawaii.

FORMAT: Plotted 6-hourly, or 12-hourly, United States charts. The charts
were plotted for 0300 and 1500 UTC (some years had additional 0900 and
2100 UTC) from March 1942 through May 1957. From June 1957 through the
present, charts were plotted for 0000 and 1200 UTC (some years had
additional 0600 and 1800 UTC). The altitude of the plotted winds vary,
almost year to year.

CONTENTS: These charts present plotted stations wind direction speed
(knots) as wind-barbs for various altitudes from 3,000 feet to 47,000
feet. Currently, the altitudes are for the second standard level,
14,000, 24,000, and 34,000 feet.

Note: Due to constraints on the files as received NCEP, the 0000 UTC
charts appear in the lower right corner.