losses from 1997-98 el nino
DESCRIPTION
Losses From 1997-98 El Nino. Deadliest Tornado Outbreak in Florida History - Most Damaging Tornado Outbreak in South Florida History - Most Strong and Violent Tornadoes in Florida Since 1983 Extensive Flooding Rains. Decadal Trend in Florida Population Growth. - PowerPoint PPT PresentationTRANSCRIPT
Forecasting Florida Dry Season Storminess From the ENSOSignal and Communicating Likelihood of Impacts to
Decision Makers
Bart Hagemeyer and Jacklyn R. AlmeidaNational Weather Service
Melbourne, Florida
Losses From 1997-98 El NinoLosses From 1997-98 El Nino-Deadliest Tornado Outbreak in Florida History
- Most Damaging Tornado Outbreak in South Florida History
- Most Strong and Violent Tornadoes in Florida Since 1983-Extensive Flooding Rains
Decadal Trend in Florida Population GrowthDecadal Trend in Florida Population Growth
Seasonal Storminess - The Accumulated Passage of Significant Extratropical Cyclones
Goal: Predict Dry Season Storminess Over Florida as Far in Advance as Possible From Observed and Predicted Pacific SST’s and other
Telleconnections and Exploit the Results
Conceptual Model of a Significant Extratropical Cyclone inthe Florida Dry Season:
996
1000
1004
1008
1012
1016
1020
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6Storm-Relative Days
Daily MSLP (mb)
Conceptual Model of Significant Extratropical Cyclone or“Storm” Passage Through the Florida Grid -
Daily MSLP Minima 1012.5 From 1 November - 30 April
>Tornadoes – Hailstorms – Damaging Wind – Flooding Rain- Coastal Flooding – Gradient Winds – Marine Hazards>Beneficial Rain>Lack of Storms - Drought - Wildfire
ImprovedImproved StorminessStorminess ClimatologyClimatology
Individual Inspection of “Statistical Storms” 1948-2002 Individual Inspection of “Statistical Storms” 1948-2002 for Validity, Track, and Jet Track – Left 329 Storms for Validity, Track, and Jet Track – Left 329 Storms
Average of 6 Per Dry Season – Mode/Median 5Average of 6 Per Dry Season – Mode/Median 5
Significant Interseasonal Variability
1948 - 2002
Is Seasonal Variability Related to ENSO?
CoolSeasonForecast
-6
-4
-2
0
2
4
6
jan97mar
mayjul
sepnov
jan 98mar
mayjul
sepnov
jan 99mar
may
Monthly NINO 3.4 3-Month Moving Average MSLP Anomaly
Monthly Nino 3.4 PredictorsMonthly Nino 3.4 Predictors
Storms
Nino SSTSSTs3.4
Seasonal Forecast Methodology - Find Best Combinationof May to April SST Predictor Variables to Predict
November to April (Seasonal) Storminess Over Florida
Lesson Learned: Limited to Two Variables Due to Multicolinearity
BEST
Many predictor combinations gave similar results Strong relationship between ENSO and above/below normal storminess – Especially extreme phases which generally have most significant impact
11
02-03
Taylor Russell Diagram of Predicted Versus Observed Storminess
83-84
01-02
Scatter Plot of Nino 3.0 and Florida Dry Season Storms (1950-2002)
Updated Historical Conditional Probabilities In Progress
Synthesis of “ensemble” MLR,Conditional historical Probabilities, Recent trends, and Forecaster experience and Judgment.
Monthly Dry Season Nino 3.0 for 2001-02 and 1983-04 Very Similar83-84 4th Stormiest Ever – 2001-02 Tied For Least Stormiest Ever!
The ENSO Neutral Forecast Challenge
Some Issues
PNA Appears to be the Dominant Seasonal Telleconnecton
2001-02
1983-84
PNA
NAO
2001-02 Season – 1 Storm in Neutral ENSO – Near Record Dryness
Our Forecast is Dependent on Other ForecastsOur Forecast is Dependent on Other Forecasts
Accurate ENSO Forecast as far in advance as Accurate ENSO Forecast as far in advance as possible.possible.
Seasonal Outlooks of PNA, NAO etc.Seasonal Outlooks of PNA, NAO etc. Expand MLR to include PNA/NAO with ENSO Expand MLR to include PNA/NAO with ENSO
Stratified by phase.Stratified by phase.
Gulf Low with Gulf Jet or “Florida Cyclone”Gulf Low with Gulf Jet or “Florida Cyclone”
Improved Florida Storm Impact Climatology is UnderwayNot all Storms are Created Equal – Some Don’t Reach Their Potential
Many are purely beneficial
Two Types With Greatest Potential Negative Impact:
Strong Gulf Jet Crossing Strong Trailing Cold FrontStrong Gulf Jet Crossing Strong Trailing Cold Front
There is strong evidence that while these two types of storms are not exclusive to El Nino Seasons
They are more likely in them!
Impacts Can Be Quite Localized – 2002/03 Moderate El Nino – Record DecemberStorminess and Rainfall Across Central Florida (Volusia County Flooding)
Strong El Nino’s Appear More Likely to Impact More Areas…However Ability To Forecast Which Area of State Might Bear the Brunt is Problematic.
Are We In A “Stormier” Period – and Will it Continue?
Questions?