1. Gridded MOS – A Prototype System
J. Paul Dallavalle
NWS/OST/MDL
, x135
Ninth Annual Great Divide Workshop
Great Falls, MT
October 26, 2005

2. (Webster’s Dictionary, 1974)
Revolution
DEFINITION:
A radical change of circumstances in a scientific, social, or industrial system
(Webster’s Dictionary, 1974)

3. NWS Revolution

4. Traditional Short-Range MOS Guidance
KGTF GFS MOS GUIDANCE 10/21/ UTC
DT /OCT /OCT /OCT / HR
X/N
TMP
DPT
CLD OV OV OV SC CL CL SC SC SC SC SC CL SC SC SC CL CL CL CL CL CL
WDR
WSP P P Q Q
T / 1 0/ 0 0/ 2 0/ 0 0/ 0 0/ 0 0/ 0 0/ 0 0/ 0 1/ 0
T / / / / / 0
POZ
POS
TYP R R R R R R R R R R R R R R R R R R R R R
SNW
CIG
VIS
OBV N N N N N N N N N N N N N N N N N N N N N

5. Traditional Extended-Range MOS Guidance
KGTF GFSX MOS GUIDANCE 10/21/ UTC
FHR 24| | | | | | |
FRI 21| SAT 22| SUN 23| MON 24| TUE 25| WED 26| THU 27| FRI 28 CLIMO
X/N 56| | | | | | |
TMP 51| | | | | | |
DPT 33| | | | | | |
CLD PC| PC PC| CL CL| CL CL| CL CL| PC OV| OV OV| PC OV
WND 7| | | | | | |
P12 4| | | | | | |
P24 | | | | | | |
Q12 0| | | | | | |
Q24 | | | | | | |
T12 0| | | | | | |
T24 | | | | | | | 2
PZP 1| | | | | | |
PSN 26| | | | | | |
PRS 16| | | | | | |
TYP R| R R| R R| R R| R R| R RS| RS RS| RS S
SNW | | | | | | |

6. Traditional MOS Graphics

7. Objectives of Gridded MOS Project
Produce MOS guidance on high-resolution grid (2.5 to 5 km spacing)
Generate guidance with sufficient detail for forecast initialization at WFOs
Generate guidance with a level of accuracy comparable to that of the station-oriented guidance

8. Max Temperature – Cool Season (0000 UTC Cycle)

9. MDL Approach to Downscaling
High-resolution geoclimatic variables
Diverse observational networks
Appropriate MOS equation development (single station, regional, or generalized operator)
Analysis on high-resolution grid

10. High-Resolution Terrain

11. High-Resolution Geophysical Data

12. High-Resolution Geophysical Data

13. High-Resolution Geophysical Data

14. High-Resolution Geoclimatic Data

15. Remotely-sensed Precipitation Data

16. Satellite-based Effective Cloud Amount

17. CONUS – Western Tile Prototype

18. Prototype Weather Elements
00Z/12Z cycles
Temperature, every 3 h to 192-h projection
Dewpoint, every 3 h to 192-h projection
Max temperature, day 1 through day 8
Min temperature, day 1 through day 8

19. Diverse Observational Systems
METAR
Buoys/C-MAN locations
Mesowest sites (RAWS/SNOTEL primarily)
NOAA cooperative observer network
RFC-supplied sites

20. CONUS MOS Sites
CONUS grid – with 5-km terrain as background; note station density – standard METAR sites in black; mesowest sites in yellow, co-op sites in red and rfc sites (i.e., data provided by RFC’s) in purple; buoys and C-MAN sites are not shown, though they are in the MOS system

21. Western CONUS
When all was said and done, this is what we had – approximately 300 METAR/marine sites, 1175 mesowest sites, 1325 cooperative observer sites and 80 RFC-supplied sites. This gave us a nominal resolution of about 30 km – if every station reported every observation, and if sites were uniformly distributed. Both assumptions are false, of course.

22. Method of successive corrections
BCDG Analysis
Method of successive corrections
Land/water gridpoints treated separately
Elevation (“lapse rate”) adjustment

23. Goodness of Fit by Using Terrain
VARIABLE
NO. STA.
MAE (°F) (ALL)
MAE (°F) (WITHHELD)
TMRW’S MAX (terr.)
2621
1.11
3.00
TMRW’S MAX (w.o.)
1.38
4.08
27-H TMP (terr.)
1406
0.98
2.92
27-H TMP (w.o.)
1.34
4.29
This table shows the results of using the BCDG analysis on a case from July 15, The leftmost column shows the variable, the next column shows the number of stations that influenced the analysis. The third column shows the error of fit for all stations when the terrain correction is used (in yellow) or when the terrain correction is not used (in white). You can see that using the terrain correction improved the analysis fit – by.27 deg F for the max, and by .36 deg F for the spot temperature. The last column represents what happens at randomly withheld sites with and without the terrain correction. This column represents the mean absolute error, when 48 different analyses were done, and 10 randomly selected points were withheld from each analysis. Note the large improvement when the terrain correction is applied.

24. MOS Temperature Analysis (w. terrain)
Here’s an example of the MOS temperature forecast when the terrain correction is applied. Note the Nevada border and the detail near Death Valley, and along the CO River.

25. MOS Temperature Analysis (no terrain)
Contrast this with the no terrain elevation correction analysis.

26. NDFD Min Temperature Forecast

27. MOS Min Temperature Forecast

28. NDFD Max Temperature Forecast

29. MOS Max Temperature Forecast

30. NDFD PoP Forecast

31. MOS PoP Forecast

32. General information and documentation
Gridded MOS Products
General information and documentation
Sample graphics (from gempak)
NDGD Web Page (graphics ala NDFD)
NWS ftp server (grib2)

33. Evaluation (objective & subjective)
Future of Gridded MOS
Evaluation (objective & subjective)
Expansion (area & elements)
Improvement
Use of remote-sensing observations
Dissemination on SBN

34. Retrospective sample: December 2004 – September 2005
Objective Evaluation
Retrospective sample: December 2004 – September 2005
Western CONUS only
Comparison between NDFD, HPC, and MOS grids
Max/min temperature and dew point only
Selected sites – generally RAWS

35. Western CONUS Verification Sites
When all was said and done, this is what we had – approximately 300 METAR/marine sites, 1175 mesowest sites, 1325 cooperative observer sites and 80 RFC-supplied sites. This gave us a nominal resolution of about 30 km – if every station reported every observation, and if sites were uniformly distributed. Both assumptions are false, of course.

36. Schedule
November 30, 2005 – wind dir. & speed, relative humidity, PoPs, tstm prob., and snowfall added to NDGD web site (as of 12/13/05, winds and snowfall have been delayed)
January 31, 2006 – grib2 products sent on SBN (pending resolution of TOC moratorium)
June 30, 2006 – CONUS grid completely populated
September 30, 2006 – sky cover, precip. type, qpf, and wind gusts added to product suite
September 30, 2007 – Alaska grids available

37. Issues Quality of observations Inversions Winds Quality Assurance
Site representativeness
Sampling
Skewed samples
Instrumentation bias
Small sample, inconsistent in time
Inversions
Winds
Quality Assurance