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Posted: Mon, Jun 28, 1993 5:17 PM EDT Msg: IGJD-5772-5705
Subj: METAR and TAF code changes on 7/1/93
In case you haven't heard about this in another way, here's a message I sent
out today on AFOS only about changes in the surface observation code used
internationally (METAR) and the international terminal forecast code (TAFs),
which will take place on Thursday 7/1/93. I hope you already know about this
- I haven't been involved in this at all, so I'm not sure how the notification
has been done.
By the way, I did get a message from you about 2 weeks ago asking about WMO
headers, but I haven't had time to check into it yet for you. Let me know if
there's some urgency - otherwise, it might be a while before I get to it.
Hope you're enjoying your summer - Chris
-----------------------------------------------------------------------------
WSHADAWSH
TTAA00 KWSH 281921
ADMINISTRATIVE MESSAGE
NATIONAL WEATHER SERVICE HEADQUARTERS
330 PM EDT MON JUN 28 1993
TO: All NWS Offices
FROM: Charlie Sprinkle,
Chief, Aviation Services Branch
SUBJECT: Reminder concerning the new METAR and TAF code
TAFs should be prepared in the new code beginning with the 0000
UTC issuance for July 1, 1993. (METARs are being converted by
computer and are being sent to the Federal Aviation
Administration's Weather Message Switching Center for
distribution to airlines.)
BACKGROUND INFORMATION:
A worldwide changeover to the new METAR and TAF code will occur
July 1, 1993 -- the first major change since 1968.
The last major "North American" SA and FT change was essentially
from cloud cover symbols to abbreviations and who can remember
before that.
IMPLEMENTATION INFORMATION:
Mexico, Canada and the U.S. will also begin to implement the new
code for international-designated airports and complete the
changeover January 1, 1996. The implementation schedule will
vary. Mexico plans to phase out, in increments of about 25
observations at a time, its Spanish version of the "North
American" SA and FT code by the end of 1994. Canada plans to
convert observations for 28 locations and also continue the SAs
as well as prepare TAFs in the new code.
IN THE U.S. BETWEEN JULY 1, 1993 AND JANUARY 1, 1996:
(1) observations from about 250 "landing rights" airports will
be converted from the SA to the new METAR by a computer
software program at the National Weather Service
Telecommunications Gateway;
(2) forecasts for about 80 international airports will be
prepared in the new TAF code by National Weather Service
Forecast Offices (also, international area forecasts for
parts of the North Atlantic and for the Gulf of Mexico and
Caribbean will be prepared with the new code's terminology);
(3) all existing U.S. SAs and FTs will continue until 1996.
IN THE U.S. AFTER JANUARY 1, 1996:
(1) All existing U.S. aviation observations and forecasts will
be prepared in the new METAR and TAF code -- unique North
American observation and forecast codes end.
(2) Other U.S. domestic aviation forecasts will be converted to
the new METAR and TAF code form, i.e., weather abbreviations
and contractions.
If you have any questions, call Jerry Uecker of my staff at
(301)-713-1726.
END
>From /PN=LINDA.MILLER/O=OMNET/ADMD=TELEMAIL/C=US/@sprint.com Tue Jul 6
>15:37:43 1993
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Status: RO
Forwarded message:
Posted: Wed, Jun 30, 1993 3:33 PM EDT Msg: DGJD-5776-7358
K.MIELKE(REC),
J.PARTAIN(REC), G.HUFFORD(REC), J.SCHAEFER(REC)
CC: L.MILLER.UCAR(REC)
Subj: NTIM ON MRF MOS CHANGES
I SENT THE FOLLOWING NTIM ON AFOS, ETC. TODAY.
------------------------------------------------------------------------
WSHPNSNMC
NOUS41 KWBC 301813
NATIONAL TECHNICAL INFORMATION MESSAGE 93-28
NATIONAL WEATHER SERVICE HEADQUARTERS
200 PM EDT WED JUN 30 1993
TO: ALL NWS OFFICES, DOMESTIC DATA SERVICE SUBSCRIBERS
FROM: MARY M. GLACKIN
CHIEF, SERVICES DEVELOPMENT BRANCH
SUBJECT: IMPLEMENTATION OF UPDATED MAX/MIN TEMPERATURE NORMALS
IN THE MRF-BASED STATISTICAL GUIDANCE FORECASTS
(THE FOLLOWING INFORMATION WAS PROVIDED BY JOHN JENSENIUS OF THE
TECHNIQUES DEVELOPMENT LABORATORY.)
On or about July 8, 1993, the maximum and minimum temperature
normals (identified as CLIMO) that appear in the MRF-based
statistical forecast messages will be switched from the 1951-80
normals to the 1961-90 normals. Although the differences between
the two sets of normals are generally small, the temperature
normals for some stations may change by as much as 2 to 3 degrees
Fahrenheit for certain days. If you notice a sudden change in
the temperature normals in the message for a particular station
on or about July 8, 1993, it is likely due to the period used to
calculate the normals.
Note that the MRF-based statistical forecast messages are
distributed on AFOS under the FMR category and disseminated to
external users as the FOXCxx, FOXExx, FOXSxx, FOXWxx, and FOUS20
KWBC messages, where xx is a two digit number identifying each
message.
Users should refer to the yellow card mailed with a "Dear
Colleague" cover memo (dated November 20, 1992) for the exact
format of the message.
A Technical Procedures Bulletin (TPB) which describes the MRF-
based statistical forecast message is nearing the final stages of
publication now, and will be distributed to TPB subscribers
shortly. If you are not on the mailing list for TPBs and would
like to receive a copy of this TPB (or you would like to be added
to the mailing list), call (301)-713-0462, or write to:
NOAA/National Weather Service
Office of Meteorology
Services Development Branch, W/OM23
1325 East West Highway, Rm. 13466
Silver Spring, MD 20910
Yellow reference cards are also available from the above address.
If you need further information about the change in temperature
normals or about the medium-range statistical forecast messages,
please call John Jensenius of the Techniques Development
Laboratory at (301)-763-8151.
END - SENT - W/OM23
>From /PN=LINDA.MILLER/O=OMNET/ADMD=TELEMAIL/C=US/@sprint.com Tue Jul 6
>15:37:44 1993
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Status: RO
Forwarded message:
Posted: Tue, Jun 29, 1993 3:21 PM EDT Msg: BGJD-5774-5022
k.mielke(rec),
g.hufford(rec), j.partain(rec), j.schaefer(rec)
CC: l.miller.ucar(rec)
Subj: 2 NTIMs on changes to FWC/FOUS14
I sent the following NTIMs on AFOS this afternoon:
_________________________________________________________________________
WSHPNSNMC
NOUS41 KWBC 291803
NATIONAL TECHNICAL INFORMATION MESSAGE 93-26
NATIONAL WEATHER SERVICE HEADQUARTERS
200 PM EDT TUE JUN 29 1993
TO: ALL NWS OFFICES, DOMESTIC DATA SERVICE SUBSCRIBERS
FROM: MARY M. GLACKIN
CHIEF, SERVICES DEVELOPMENT BRANCH
SUBJECT: IMPLEMENTATION OF NGM-BASED MOS VISIBILITY AND
OBSTRUCTION TO VISION FORECASTS (TWO NEW LINES)
(THE FOLLOWING INFORMATION WAS PROVIDED BY PAUL DALLAVALLE OF THE
TECHNIQUES DEVELOPMENT LABORATORY.)
Effective with the 1200 UTC cycle on or about July 7, 1993,
Nested Grid Model (NGM)-based Model Output Statistics (MOS)
visibility and obstruction to vision guidance will be added to
the NGM MOS forecast bulletin. The NGM MOS guidance is
distributed under the WMO header of FOUS14 KWBC and under the
AFOS category of FWC. Users are referred to Technical Procedures
Bulletin (TPB) 408 for a description of the complete FOUS14/FWC
message, including the visibility and obstruction to vision
forecasts.
Two lines are being added to the NGM MOS message. The first of
these, starting with the characters "VIS," provides forecasts of
five categories of visibility valid at specific times. The
forecast projections are for 6, 9, 12, 15, 18, 21, 24, 27, 30,
33, 36, 42, and 48 hours after either 0000 or 1200 UTC. The
categories of visibility are indicated by numbers ranging from
1 through 5. These values are as follows: 1 = < 1/2 mile;
2 = 1/2 - 7/8 miles; 3 = 1 - 2 3/4 miles; 4 = 3 - 5 miles; and
5 = > 5 miles. Note that missing values for visibility are
indicated by the character 9.
The second additional line, labeled as "OBVIS," provides
forecasts of 3 categories of obstruction to vision. The
categories of obstruction to vision are indicated by the
following plain language identifiers: H = haze, F = fog, and
N = neither haze nor fog. The forecast projections are identical
to those for visibility. In the NGM MOS message, the visibility
and obstruction to vision forecasts are displayed beneath the
time of the day for which they are valid. Note that missing
values for obstruction to vision are indicated by an X.
The categorical forecasts described above are prepared
objectively from MOS probabilistic forecasts of the same
categories. The probabilities are not, however, available in
the NGM MOS message. Equations that produce the probability
forecasts were developed for each forecast projection, both
forecast cycles (0000 and 1200 UTC), a number of regions in the
contiguous United States, and two seasons (cool: October -
March; warm: April - September). The algorithm that selects
the categorical forecasts from the probabilities was designed to
maximize the threat score while not excessively under- or
over-forecasting individual categories. The categorical forecast
is determined by comparing the forecast probabilities to a set of
pre-determined "threshold" probabilities. Threshold
probabilities were derived for each forecast projection, cycle,
region, and season. In tests on independent data, the NGM MOS
guidance was found to be generally more skillful than the LFM MOS
guidance (available under AFOS category FPC; WMO header FOUS12
KWBC), particularly in predicting the visibility categories.
A TPB which specifically describes the new NGM MOS visibility and
obstruction to vision guidance is being prepared and will be
distributed to TPB subscribers when it becomes available. If you
have any questions concerning this new guidance or the message
format, call Major David Miller at 301-713-1065 or Paul
Dallavalle at 301-763-8151.
NOTE: Another National Technical Information Message regarding
changes to the NGM MOS-based cloud equations will be transmitted
shortly. We recommend AFOS users store 3 versions of WSHPNSNMC
in their databases, since up to 3 messages may be transmitted per
day in this PIL.
END - SENT - W/OM23
------------------------------------------------------------------
******************************************************************
WSHPNSNMC
NOUS41 KWBC 291805
NATIONAL TECHNICAL INFORMATION MESSAGE 93-27
NATIONAL WEATHER SERVICE HEADQUARTERS
200 PM EDT TUE JUN 29 1993
TO: ALL NWS OFFICES, DOMESTIC DATA SERVICE SUBSCRIBERS
FROM: MARY M. GLACKIN
CHIEF, SERVICES DEVELOPMENT BRANCH
SUBJECT: IMPLEMENTATION OF NEW NGM-BASED MOS CLOUD FORECASTS
(THE FOLLOWING INFORMATION WAS PROVIDED BY MARY ERICKSON OF THE
TECHNIQUES DEVELOPMENT LABORATORY.)
Effective with the 1200 UTC cycle on July 7, 1993, the equations
used to generate the Nested Grid Model (NGM)-based Model Output
Statistics (MOS) cloud forecasts will be changed. New equations
have been developed with more dependent data and new predictors.
In addition, to better serve aviation forecasting, equations are
now available to produce forecasts valid every 3 hours, rather
than every 6 hours, from 6 to 60 hours after both 0000 and
1200 UTC. The NGM MOS guidance for the contiguous United States
is distributed under the WMO header of FOUS14 KWBC and under the
AFOS category of FWC. This change will affect the forecasts on
the CLD line of the NGM MOS message. Users are referred to
Technical Procedures Bulletin (TPB) 408 for a description of the
complete FOUS14/FWC message, including the cloud forecasts.
As with the prior cloud system, separate equations were developed
for each projection, the 0000 and 1200 UTC forecast cycles, and
two seasons (cool: October to March; warm: April to
September). Separate equations were also developed for
individual regions, which are the same as those used in the
original NGM MOS cloud development. The equations produce
probability forecasts of clear, scattered, broken, and overcast
opaque cloudiness. The probabilities are then compared to
threshold values and a categorical forecast is selected. The
threshold values are determined in a way that assures unit bias
on the dependent sample. In other words, the number of forecasts
of a category and the number of observations of that category are
approximately equal. Only the categorical forecasts are included
in the NGM MOS message. The categories of clouds are indicated
as follows: CL (clear) - 0 tenths, SC (scattered) - 1 to
5 tenths, BK (broken) - 6 to 9 tenths, and OV (overcast) -
10 tenths.
For the warm season, verification results on independent data
show that the new NGM MOS forecasts were more skillful than
either the currently operational NGM MOS or the LFM MOS forecasts
(available under AFOS category FPC; WMO header FOUS12 KWBC).
Users should also be aware that while the operational
NGM MOS tended to underforecast the broken and overcast
categories, the new NGM MOS cloud forecasts are much closer to
unit bias. For the cool season, verification results on
independent data show that the new and operational NGM MOS cloud
forecasts are approximately equal in skill and bias
characteristics.
A Technical Procedures Bulletin (TPB) describing the new
NGM-based MOS cloud system is being prepared and will be
distributed to TPB subscribers when it becomes available. If you
have any questions concerning this change in the guidance or the
message format, call Mary Erickson or Paul Dallavalle at
(301)-763-8151.
END - SENT - W/OM23
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