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TOPIC 1: Why are we seeing differences between operational
and experimental versions of Selected Cities Weather Summary and
TOPIC #2 :What changes do the eXtensible Markup Language
(XML) products have over their legacy text counterparts?
- Q: Why do the observed data differ?
A: The algorithm used to determine the previous
day's high and low temperatures is different from the algorithm
used to create the legacy/operational SCS. The old method
used only the 6-hourly synoptic high/low temperature reports
from the METAR observations. The TPEX method uses hourly
METAR temperatures in addition to those values. This allows
the TPEX software to more frequently sample the daytime and nighttime
periods for each city in the SCS.
- Q: Why do the forecast high and low temperatures differ?
A: The data that feed the legacy/operational
SCS can be up to 6 hours older than the data that feed the Tabular
Product Evolution in eXtensible Markup Language (TPEX) SCS. In
rapidly changing forecast scenarios, a Weather Forecast Office’s
(WFO's) forecast can change quite a bit during this timeframe. For
this reason, the TPEX SCS may contain some last minute updates
that are not found in the official SCS products.
See Table 1 for details.
||Legacy SCS forecast data cutoff
||TPEX SCS forecast data cutoff
||Improvement in forecast recency.
Table 1. Comparison of forecast data cutoff
times used in creating the legacy and TPEX versions of the SCS.
- Q: Why does the predominant weather forecast differ?
A: There are two primary answers to this question.
First, similar to the answer given above regarding temperature
differences, the forecast data used to determine the TPEX predominant
weather may be up to 6.5 hours fresher than the data in the legacy/operational
SCS. See Table 1 for details.
Second, the forecast data that feed the legacy/operational SCS
originate from over 100 WFOs. Many of those WFOs have tailored
the way their forecast data are input into the legacy/operational
SCS. In order to provide a more consistent method of presenting
the forecast data in the SCS, TPEX uses a single set of algorithms
when determining the predominant weather. These algorithms
are designed to closely mimic other digital forecast algorithms
used within the NWS and also to comply with the NWS Policy.
TOPIC #3: What are the TPEX Product Sizes and how can we
- Data Format
- Logical separation of Forecast and Observation products.
- Introduction of new product information
- As a part of the Observations in XML (ObX) product, users
and partners have access to the High and Low Temperatures “so
- The Forecasts in XML (FoX3 and FoX7) forecast products contain
both daytime and nighttime weather summaries out to 3 and 7
days, respectively. This differs from the legacy SCS
text product, which only included daytime weather summaries
and forecast projections for just 2 days.
- The FoX3 and FoX7 forecast products also contain a link to
the associated weather summary icons.
- XML makes it easier for our users and partners to choose
the output and amount of data they want. Extensible Stylesheet
Language (XSLT) style sheets can be used as starting points
to tailor the exact output of desired products.
- New cities, weather elements, and times can be added to National
Weather Service (NWS) products with little impact to our users
and partners software. This is the beauty of moving to
- XML products will be issued more frequently. They will
be more in tune with today’s 24x7 news cycle.
- This increased temporal frequency allows us to addresses
the “West Coast” observation timing issue for reporting
of High and Low Temperatures. The “west coast” issue
arises because the issuance times of the current operational
SCS products (0035Z and 1235Z) do not correlate well with the
natural timing of the high and low temperature of the day for
West Coast cities.
||Daily Total (approx)
||WMO Heading/AWIPS ID
|7-day FoX (FOX7)
||24x / day
||RXUS30 KWBN / XF07DY
|3-day FoX (FOX3)
||24x / day
||RXUS30 KWBN / XF03DY
||24x / day
||RXUS30 KWNO / XOBUS
||4x / day
||RXUS30 KWNH / XTEUS
||2x / day
||FPUS20 KWBN / SCS01
FPUS20 KWBN / SCS02
FPUS20 KWBN / SCS03
FPUS20 KWBN / SCS04
* Assumes 163 stations in the FoX and ObX