[nws-changes] 20111003: comments on enhanced GFS- Fwd: ADMIN NOTICE NOUS41 KWBC

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-------- Original Message --------

040
NOUS41 KWBC 131639
PNSWSH

Public Information Statement, Comment Request
National Weather Service Headquarters Washington, DC
1238 AM EDT Thu Oct 13 2011

To:      Subscribers:
         -Family of Services
         -NOAA Weather Wire Service
         -Emergency Managers Weather Information Network
         -NOAAPORT
         Other NWS Partners and NWS Employees

From:    Kathryn Gilbert
         Chief, Statistical Modeling Branch
         Meteorological Development Laboratory

Subject: Soliciting Comments on Proposed Enhancements to the
         Global Forecast System (GFS)-Based Gridded MOS Product
         Through November 30, 2011

The NWS is soliciting public comments by November 30, 2011, on
the proposed increase in horizontal resolution over the CONUS
from 5 km to 2.5 km and the future addition of several weather
elements to the GFS-Based Gridded Model Output Statistics (MOS)
Guidance.  We will continue to provide the GFS-based gridded MOS
guidance at a horizontal resolution of 5 km to allow sufficient
time for necessary software or hardware upgrades.

1. Proposed increase in horizontal resolution

The current GFS-based gridded MOS guidance over the CONUS is
available on a Lambert Conformal grid at a horizontal resolution
of 5 km. The resolution of the gridded MOS guidance over the
CONUS will be increased from 5 km to 2.5 km to support the
planned 2.5 km National Digital Forecast Database (NDFD) and
provide greater spatial detail in areas of complex terrain.

Customers can expect the characteristics of the temperature,
dewpoint temperature, daytime maximum/nighttime minimum
temperature, relative humidity, sky cover, probability of
thunderstorms, wind speed, wind direction, wind gusts, and 24-hr
snowfall amount to remain very similar to the current
operational 5 km products with more detail noticeable in and
around complex terrain. The enhanced resolution grids will be
made available in grib2 format in the experimental area of the
National Digital Guidance Database (NDGD) on a date to be
advertised in an upcoming Technical Implementation Notice.
Currently the grids are available at the link provided below.

  http://www.mdl.nws.noaa.gov/~mos/gmos/conus25

Table 1 below lists representations of the WMO headers for each
2.5 km gridded MOS element.

Table 1: Communication Identifiers for the Experimental 2.5-km
GFS-based Gridded MOS Grib2 Products for the CONUS

    WMO HEADING         ELEMENT

    YAUXXX KWBQ   Total Sky Cover
    YBUXXX KWBQ   Wind Direction
    YCUXXX KWBQ   Wind Speed
    YDUXXX KWBQ   12-Hour Probability of Precipitation
    YEUXXX KWBQ   2-Meter Temperature
    YFUXXX KWBQ   2-Meter Dew Point Temperature
    YGUXXX KWBQ   Daytime Maximum Temperature
    YHUXXX KWBQ   Nighttime Minimum Temperature
    YIUXXX KWBQ   6-h Quantitative Precipitation Amount
    YJUXXX KWBQ   6-h Probability of a Thunderstorm
    YRUXXX KWBQ   Relative Humidity
    YSUXXX KWBQ   24-h Snowfall Amount
    YUUXXX KWBQ   6-Hour Probability of Precipitation
    YVUXXX KWBQ   12-h Quantitative Precipitation Amount
    YWUXXX KWBQ   Wind Gusts
    YXUXXX KWBQ   12-h Probability of a Thunderstorm
    YYUXXX KWBQ   3-h Probability of a Thunderstorm

2. Proposed removal of some stations from gridded MOS analysis

An additional proposed change is the removal of some Cooperative
Observer Program (Coop) stations from the analysis of MOS
daytime maximum and nighttime minimum temperature guidance.
Forecasts for Coop sites within 10 km of a METAR station will no
longer influence the temperature analysis.  This is in response
to complaints from users concerning discrepancies between the
max/min MOS grids and the MOS point values at nearby locations.
Coop sites contribute a large amount of detail to gridded MOS
max/min forecasts, especially in data-sparse regions; however,
the local 24-hour reporting period valid for Coop observations
can be difficult to match with the appropriate daytime maximum
and nighttime minimum forecast periods.  A list of Coop sites
proposed for removal and images from several case studies can be
found at the following site:

   http://www.nws.noaa.gov/mdl/synop/gmos/coopremove.php

3. Proposed enhancement of PoP and QPF forecasts

The experimental 2.5 km gridded MOS suite will include enhanced-
resolution, GFS-based MOS probability of precipitation (PoP) and
quantitative precipitation forecasts (HRMOS QPF).  The improved
QPF forecasts are developed from archived stage IV national
mosaic precipitation data that defines the precipitation
predict.  In addition, high resolution topographic and
climatological interactive predictors are incorporated into the
equations to enhance resolution of the PoPs and QPFs.  See the
following link for more details:

   http://www.nws.noaa.gov/mdl/hrqpf/publications.php

4. Proposed future additions to gridded MOS

Future additions to the 2.5 km gridded MOS suite will include
GFS-based precipitation type and MOS predominant weather.  The
precipitation type guidance will include best category and
probabilities of freezing, frozen and liquid precipitation types
out to 192 hours in advance. Gridded precipitation type is
produced differently from other gridded MOS elements.
Generalized operator equations are used to generate forecasts
directly at each 2.5 km gridpoint while incorporating gridded
climatologies and logit 50 percent values as predictors, which
help to capture localized effects and produce enhanced terrain
detail.

The experimental 2.5 km MOS weather grid is the predominant
weather valid at the indicated hour, generated from a collection
of other gridded MOS elements.  The gridded MOS weather element
provides type, probability, and intensity information valid
every 3 hours out to 192 hours in advance.

At this time, all of the above proposed enhancements are an
addition to the gridded MOS suite, not a replacement for the
current 5 km gridded MOS guidance.  Customers who use the 5 km
guidance over the CONUS can continue to use these products
without disruption until all customers and systems are able to
use the higher resolution guidance.

Graphics, links to GRIB2 data for download, and more details on
these experimental products can be found at:

   http://www.mdl.nws.noaa.gov/~mos/gmos/conus25

General information on the gridded MOS file structure and
additional references is available at:

   http://www.weather.gov/mdl/synop/gmos.php

Submit comments and questions regarding the proposed
enhancements to the GFS-Based Gridded MOS products to:

  Kathryn Gilbert
  NWS Meteorological Development Laboratory
  301 713-0023 x130
  Kathryn.Gilbert@xxxxxxxx

National Public Information Statements are online at:

   http://www.weather.gov/os/notif.htm

$$
NNNN




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