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Objective Techniques In
Analog Seasonal Forecasts
•Analog Forecasting•Objectively Picking Analogs•Tools for Interpretation•The Forecast•Future Developments
Analog Seasonal Forecasting
• Look at this year so far…
Analog Seasonal Forecasting
• Look at this year so far…• Look for past years that are similar to
this year …
Analog Seasonal Forecasting
• Look at this year so far…• Look for past years that are similar to
this year …• Use what subsequently happened in
those past years as a forecast for what will happen this year.
Analog Seasonal Forecasting
• Look at this year so far…• Look for past years that are similar to
this year …• Use what subsequently happened in
those past years as a forecast for what will happen this year.
Southern Oscillation Index
Pacific Decadal Oscillation
Pacific Decadal OscillationMultivariate ENSO IndexMultivariate ENSO Index
PNANino 3.4
Sahel Rainfall
Climate IndicesPNA (Pacific North American Index)
NAO (North Atlantic Oscillation)
Jones NAO
EPO (Eastern Pacific Oscillation)
TNH
ONI
NTA (North Tropical Atlantic Index)
CAR (Caribbean Index)
MEI
BEST
Nino 3
Nino 1+2
Nino 3+4
Nino 4
Pacific Warm Pool
Tropical Pacific SST EOF
TNA
TSA
WHWP WP (West Pacific Index)
QBO (Quasi-Biennial Oscillation)
PDO (Pacific Decadal Oscillation)
PMM (Pacific Meridional Mode)
NP (North Pacific Index)
NOI (Northern Oscillation Index) AO (Arctic Oscillation) AAO TNI Atlantic Tripole SST EOF AMO AMM (Atlantic Meridional Mode) ACE (Atlantic Accumulated Cyclone
Intensities) Solar Cycle (Flux) Monthly Hurricane Total MDR Hurricanes SST Anomaly MDR - Tropics SST Anomaly Central India Monsoon Precipitation Sahel Rainfall Brazil Rainfall SW USA Monsoon Global Mean Temperature ESPI Globally integrated angular
momentum
Not just the index…But sensible weather…IE Warm/Cool… Wet/Dry
Automate the Process
• Compare each previous year to this year…
• Compute a “Goodness of Fit” number…
• Sort “Goodness of Fit”…• Print/Save results…• Do this for multiple indices…• Find “Consensus” analog years
Objective Forecast
The Indices:MEI CPC SOI BOM SOIONININO3 TEMPS
NINO4 TEMPSPNAPDOWP
Objective Forecast
Analog Composites
November Temperature Precipitation
December Temperature Precipitation
January Temperature Precipitation
February Temperature Precipitation
March Temperature Precipitation
April Temperature Precipitation
Highs
Lows
Period of Record Average
Analog Average
32F = 273.15K
Wind storm 9th, 10th or 11th? … Mild Thanksgiving
30dm 500H anomaly over Pacific Northwest
Flirt w/cold air ~12th-14th Cold 20th-29th…Possible Arctic Event(s)?
Positive 500H anomaly ~ 800 west of Oregon
Warm 2nd -8th (Early “January Thaw”?) Arctic event toward end of month? 500H/850T significant negative anomaly
Cool MonthValentine’s Day Snow?
30dm 500H negative anomaly
Wind Event 17th, 18th or 19th?
500H anomaly positive/850T anomaly negative
Active month.Wide swings in temperatures but averages out cool.
Government Camp Snow
•2008: 4th and 5th 16 inches total…gone by 11th.
•2000: Snow on 6th, snow again on 8th and continuous snow cover through the end of the month.
•1999: 21st and 22nd eight inches total…all melted by 27th.
•1989: Six inches on 13th… 24th-27th twenty-eight inches.
•1974: 18th through 27th seventeen inches total.
•1971: Twenty-one inches on ground to start month… snowed fourty-seven inches during month.
Government Camp SnowNovember
Good
Great!
•2008: 4th and 5th 16 inches total…gone by 11th.
•2000: Snow on 6th, snow again on 8th and continuous snow cover through the end of the month.
•1999: 21st and 22nd eight inches total…all melted by 27th.
•1989: Six inches on 13th… 24th-27th twenty-eight inches.
•1974: 18th through 27th seventeen inches total.
•1971: Twenty-one inches on ground to start month… snowed fourty-seven inches during month.
Bad
Marginal
Good
Good
Government Camp SnowNovember
23d 24th 25th 26th 27th 28th 29th 30th 31st
2008 63 61 72 72 71 69 59 61 55
2000 44 44 48 48 44 42 40 40 36
1999 10 9 8 8 8 8 8 8 8
1989 1 1 T 0 0 1 T T 0
1974 27 27 27 27 28 30 30 35 34
1971 69 73 68 68 66 64 68 74 72
Government Camp SnowDecember
Snow Depth in Inches
23d 24th 25th 26th 27th 28th 29th 30th 31st
2008 63 61 72 72 71 69 59 61 55
2000 44 44 48 48 44 42 40 40 36
1999 10 9 8 8 8 8 8 8 8
1989 1 1 T 0 0 1 T T 0
1974 27 27 27 27 28 30 30 35 34
1971 69 73 68 68 66 64 68 74 72
Government Camp SnowDecember
Snow Depth in Inches
23d 24th 25th 26th 27th 28th 29th 30th 31st
2008 63 61 72 72 71 69 59 61 55
2000 44 44 48 48 44 42 40 40 36
1999 10 9 8 8 8 8 8 8 8
1989 1 1 T 0 0 1 T T 0
1974 27 27 27 27 28 30 30 35 34
1971 69 73 68 68 66 64 68 74 72
Government Camp SnowDecember
Snow Depth in Inches
OK
OK
Bumm
er
Dude
Further Development
Further Development
More indices
Further Development
More indices
Write routine(s) to produce and verify historical forecasts
Further Development
More indices
Write routine(s) to produce and verify historical forecasts
Index/time period weighting
Forecast Summary/Questions
Climate Division 2 – Willamette Valley
Nov Dec Jan Feb Mar Apr
Temp:
Precip:
Above Near Near Below Near Below Near Near Above Near Below Near