MDL Probabilistic Forecast Guidance

1

• MDL Probabilistic Forecast Guidance
• NFUSE Presentation
• Bob Glahn (MDL)
• Kathryn Gilbert (MDL/MOS)
• Judy E. Ghirardelli (MDL/LAMP)
• National Weather Service
• Meteorological Development Laboratory
• July 11, 2007

2
MOS Probability Post-Processing

• MOS provides objective forecast guidance for
  sensible weather elements
• Products may be deterministic or probabilistic
• Probability forecasts are transformed to a best
  category by applying a threshold value to the
  probability
• Categorization is often done at the request of
  the users
• decisions are made before dissemination
• Thresholds are determined to maximize some
  characteristic of performance, i.e. threat score,
  or in our case, usually unit bias
• events are forecast with the same frequency they
  are observed
• provide a desired balance between the threat
  score, the bias, the POD and the FAR

3
MOS Sample Text Message

• KPHL GFS MOS GUIDANCE 2/14/2007 0000 UTC
  
• DT /FEB 14 /FEB 15
  /FEB 16 /
• HR 06 09 12 15 18 21 00 03 06 09 12 15 18 21
  00 03 06 09 12 18 00
• X/N 32 15
  26 13 29
• TMP 23 24 25 29 29 28 26 22 18 17 16 19 24 25
  23 19 17 16 15 27 25
• DPT 20 23 25 29 28 23 16 8 6 4 3 2 0 0
  0 2 3 4 4 5 5
• CLD OV OV OV OV OV OV OV OV FW CL SC SC SC BK
  BK BK SC SC SC BK CL
• WDR 06 06 05 02 34 31 30 30 29 29 28 29 29 28
  28 28 27 27 27 28 27
• WSP 15 16 19 17 19 24 25 24 21 18 15 19 20 20
  14 13 13 13 13 20 15
• P06 100 84 32 0 0 0
  0 0 0 0 0
• P12 85 2
  0 0 0
• Q06 5 5 1 0 0 0
  0 0 0 0 0
• Q12 4 0
  0 0 0
• T06 3/ 0 1/24 2/ 0 0/ 0 1/ 1 1/19 0/
  6 0/ 3 0/ 0 0/ 0
• T12 3/24 2/26 1/19
  1/23 0/21
• POZ 69 61 50 36 19 20 20 7 1 1 0 0 0 3
  0 0 0 0 0 3 0
• POS 16 12 10 25 30 45 64 76 84 99 85 97 97 86
  88 85 81100 93 91 94
• TYP Z Z Z Z S S S S S S S S S S
  S S S S S S S
• SNW 1
  0

4
MOS Sample Text Message

• KPHL GFS MOS GUIDANCE 2/14/2007 0000 UTC
  
• DT /FEB 14 /FEB 15
  /FEB 16 /
• HR 06 09 12 15 18 21 00 03 06 09 12 15 18 21
  00 03 06 09 12 18 00
• X/N 32 15
  26 13 29
• TMP 23 24 25 29 29 28 26 22 18 17 16 19 24 25
  23 19 17 16 15 27 25
• DPT 20 23 25 29 28 23 16 8 6 4 3 2 0 0
  0 2 3 4 4 5 5
• CLD OV OV OV OV OV OV OV OV FW CL SC SC SC BK
  BK BK SC SC SC BK CL
• WDR 06 06 05 02 34 31 30 30 29 29 28 29 29 28
  28 28 27 27 27 28 27
• WSP 15 16 19 17 19 24 25 24 21 18 15 19 20 20
  14 13 13 13 13 20 15
• P06 100 84 32 0 0 0
  0 0 0 0 0
• P12 85 2
  0 0 0
• Q06 5 5 1 0 0 0
  0 0 0 0 0
• Q12 4 0
  0 0 0
• T06 3/ 0 1/24 2/ 0 0/ 0 1/ 1 1/19 0/
  6 0/ 3 0/ 0 0/ 0
• T12 3/24 2/26 1/19
  1/23 0/21
• POZ 69 61 50 36 19 20 20 7 1 1 0 0 0 3
  0 0 0 0 0 3 0
• POS 16 12 10 25 30 45 64 76 84 99 85 97 97 86
  88 85 81100 93 91 94
• TYP Z Z Z Z S S S S S S S S S S
  S S S S S S S
• SNW 1
  0

5
40-km contoured 10
20-km contoured 10
Probability of 1 or more cloud-to-ground
lightning strikes in a grid box over a 3-h
period Identical techniques, different horizontal
resolutions
6
40-km contoured 10
20-km contoured 5
Magnitude of the probabilities is proportional to
the grid spacing, similar behavior with length of
time periods
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Gridded MOS Prob. Of Precip
NDGD Products are available in GRIB2
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Available MOS Probability Guidance
Probability Event
6-, 12-, 24-h Prob. Of Precipitation Liquid equiv. 0.01 Yes/No
3-h 20-km Thunderstorm 1 or more CG lightning strikes in grid box Yes/No
3-, 6-, 12-, 24-h 40-km Thunderstorm 1 or more CG lightning strikes in grid box Yes/No
6-, 12-, 24-h 40-km Severe Thunderstorm (conditional on thunderstorms) (hail, damaging winds, tornado) Yes/No
6-, 12-, 24-h 40-km Severe Thunderstorm (unconditional tstmcsvr) (hail, damaging winds, tornado) Yes/No
12
Available MOS Probability Guidance
Probability Event
6-h Quantitative Precipitation Forecast 0.01, 0.1, 0.25, 0.5, 1
12-, 24-h Quantitative Precipitation Forecast 0.01, 0.1, 0.25, 0.5, 1, 2
1-, 3-h Precipitation occurring on the hour Yes/No
Precipitation type (Conditional on Precipitation) Freezing, Frozen, Liquid
Precipitation Characteristics (Conditional on Precipitation) Drizzle, Continuous, Showers
13
Available MOS Probability Guidance
Probability Event
Ceiling (feet) lt200, 200-400, 500-900, 1000-1900, 2000-3000, 3100-6500, 6600-12000, gt12000 or unlimited)
Visibility (mi) lt ½, lt1, lt2, lt3, 5, 6, gt6
Obstruction to Vision None, Haze/Smoke, Mist, Fog, Blowing Phenomena
24-h Snow Amount gtT, 2, 4, 6, 8
Total Sky Cover (Octets) Clear 0/8, Few 1/8-2/8, Sct 3/8-4/8, Bkn 5/8-7/8, Ovc 8/8
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12-H Probability of Precipitation Warm
SeasonBrier Score
Brier Score
Forecast Projection (hr)
15
12-H Probability of Precipitation Cool Season
All Stations
24-h Reliability
16
Probability of Quantitative Precip .25
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MOS Products

• Alphanumeric Bulletins
• Precipitation, Thunderstorm, SevereTstm, Snow,
  Freezing, Rain/Snow
• Station guidance in BUFR format
• Contains all MOS probabilities
• Gridded MOS guidance in GRIB2 format (NDGD)
• 3-, 6- and 12-h thunderstorm probabilities
• 6- and 12-h probability of precipitation
• Web graphics of most MOS probability products
• http//www.nws.noaa.gov/mdl/synop/products.shtml

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LAMP Background

• LAMP
• is a system of objective analyses, simple models,
  regression equations, and related thresholds
  which together provide guidance for sensible
  weather forecasts
• LAMP guidance is both probabilistic and
  deterministic
• bridges the gap between the observations and the
  MOS forecast
• acts as an update to MOS guidance
• provides guidance for aviation elements
• is useful to WFO forecasters in making the TAFs
  and to AWC forecasters in making the convective
  products
• provides guidance for CONUS, Alaska, Hawaii, and
  Puerto Rico

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LAMP Probabilities
Probability of Event
Liquid Equivalent Precip. 0.01 inch during past 6 hours/12 hours Yes/No
Precipitation occurring on the hour Yes/No
Precipitation type (Conditional on Precipitation) Freezing Frozen Liquid
Precipitation Characteristics (Conditional on Precipitation) Drizzle Continuous Showers
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LAMP Probabilities
Probability of Event
Thunderstorms during 2 hr period in 20km box Yes/No
Total Sky Cover 0/8 (Clear) 1/8 2/8 (Few) 3/8 4/8 (Sct) 5/8 7/8 (Bkn) 8/8 (Ovc)
Obstruction to Vision No obstruction to vision Haze/Smoke Mist Fog Blowing Phenomena
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LAMP Probabilities
Probability of Event
Ceiling Height lt 200 feet 200 400 feet 500 900 feet 1000 1900 feet 2000 3000 feet 3100 6500 feet 6600 12,000 feet gt 12,000 feet
Ceiling Height (Conditional on Precipitation) Same as above
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LAMP Probabilities
Probability of Event
Visibility lt ½ mile lt 1 mile lt 2 miles lt 3 miles 5 miles 6 miles
Conditional Visibility (Conditional on Precipitation) Same as above
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LAMP Probabilistic Products

• SBN/NOAAPort/NWS FTP server products
• Alphanumeric bulletin guidance
• Probs of precipitation occurrence, POP6, 2hr
  thunderstorm, freezing precipitation, frozen
  precipitation
• Station guidance in BUFR format
• Contains all probabilities made by LAMP
• Gridded thunderstorm guidance in GRIB2 format
• 2hr thunderstorm probabilities
• Graphical products on weather.gov
• Gridded thunderstorm images, including
  probabilities
• Station plots of POPO
• Meteograms, including probabilities found in
  bulletin

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GFS LAMP Status

• Operational Status
• 0300, 0900, 1500, and 2100 UTC - operational July
  2006
• 0000, 0600, 1200, and 1800 UTC - operational May
  2007
• 4 more cycles planned to be operational September
  2007
• In Stage 5 (Deploy, Maintain, and Assess) of OSIP
• Data being sent out to
• SBN/NOAAPort
• AWIPS depictables in OB7.2
• NWS FTP server
• NDGD
• NWS Web Farm

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LAMP Meteogram Products
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LAMP Thunderstorm Probabilities and Best
Category (Y/N) Projection 1, Hrs 1-3
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LAMP Thunderstorm Probabilities and Best
Category (Y/N) All Projections
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POP6 Reliability Cool Season
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1694
1288
1598
1778
2032
2507
3196
4419
6695
13383
24899
37203
30
1270
1348
1549
1787
2006
2454
3148
4279
7154
14665
21013
40861
31
889
1128
1467
1843
1936
2430
3230
4259
6904
14148
30190
32798
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Ceiling lt 1000 feet Reliability Warm and Cool
Seasons
33
827
2642
4348
5189
4171
3625
3684
5574
14848
56727
165669
145522
34
543
1504
2749
3876
5170
6247
8882
14551
32718
84430
142072
108049
35
111
486
1264
2676
4627
8028
13531
22439
40353
84219
145324
104261
36
Visibility lt 3 miles Reliability Warm and Cool
Seasons
37
127
350
1268
2145
3175
3815
3233
7822
15090
48684
167357
161115
38
83
147
373
1010
2290
4197
7716
13759
29062
86103
147979
119527
39
43
18
141
560
1563
3724
7585
15591
33554
86219
153950
125758
40
Thunderstorm Reliability Warm Season
41
974
1117
1805
2839
4501
6956
11427
19702
40770
150318
1418921
1515938
42
10
296
166
80
1551
6394
28542
204603
1306667
1626959
43
512
13277
7
179071
1163074
1819327
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Thunderstorm Brier Score Improvement on
Climatology Spring Season
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MDL MOS and LAMP Products on the Web

• MOS Products
• http//www.nws.noaa.gov/mdl/synop/products.shtml
• LAMP Products

http//www.weather.gov/mdl/lamp/