Post on 20-Jan-2021
Wind Speed Probabilities
A Local Perspective
Florida Governor Hurricane ConferenceMay 11-16
2014
Pablo Santos
Meteorologist In Charge
NWS Miami/South Florida Forecast Office
2014 – FLGHC
TS 22
Motivation
• What is there in it for me in this presentation?
– A better understanding of the wind speed probabilities available to you nationally and at the local level and:
• What they mean
• What questions you might have that THEY CAN answer
• How NWS can help you make better decisions using this data
• And potential advanced applications.
– Complements:• TS 23 presentation on Local Wind Forecast and its Uncertainty – Tue Morning
• TS 23 presentation on Local Application of Wind Speed Probabilities – Tue Morning
• TS 23 presentation on Local Wind Impact Recognition/Messaging – Tue Morning
• TS 24 Conveying Uncertainty to the Public – Wed Morning
D-Day Give me the Probabilities
1111
Wind Speed Probability Text Product(abbreviated)In addition to:
- Onset Probabilities: Text
- Cumulative Wind Speed Probability: Text/Graphic
11
Onset Period ProbabilitiesCumulative Probabilities
What Questions do They Answer?
• Cumulative (Available in NHC Graphic and PWSAT#; coarse time resolution) – What arethe chances that tropical storm or hurricane conditions will occur between hour 00 andXX out to 120 hours/5 days with this event at my location?
• Onset (Available in PWSAT#; coarse time resolution) – What are the chances thattropical storm or hurricane conditions will begin during a particular time period at mylocation? And given that, what is the most likely period of onset of these conditions?
• Incremental (Not available from NHC; but from NWS offices) – What are the chancesthat tropical storm or hurricane conditions will be experienced during a particularperiod at my location? How likely is the event to happen during that period? How likelyis it to last? At what values is the event becoming more plausible (likely) than justpossible?
We consider trend from advisory to advisory
Cumulative
Incremental – 12HR
Onset
Onset
Tropical
Storm
Conditions
Onset
Hurricane
Conditions
Threshold:
45%
Threshold:
35%
Threshold:
30%
Threshold:
25%
Threshold:
22.5%
Threshold:
20%
Threshold:
17.5%Incremental
Tropical
Storm
Threshold:
25%
Threshold:
20%
Threshold:
15%
Threshold:
12.5%
Threshold:
10%
Threshold:
8%
Threshold:
7%Incremental
Hurricane
What are the critical values to look for that make the event more likely than possible?
Incremental Wind Speed Probabilities
Period 2014
PWS64 PWS34
00-12 hr 25% 45%
13-24 hr 20% 35%
25-36 hr 15% 30%
37-48 hr 12.5% 25%
49-60 hr 10% 22.5%
61-72 hr 8% 20%
73-84 hr 7% 17.5%
85-96 hr 6% 15%
97-108 hr 5% 12.5%
109-120 hr 4% 10%
Local ScaleWind Speed Probabilities
Consider Trend From Advisory to
Advisory
Applications
• Communicate Risk.
• Provide objective measure of uncertainty that can be used to create new targeted products.
– Threat/Potential Impact Graphics• Briefings
• Can be used as decision making aid by planners (example follows).
• Communicate to the public graphically the threat and degree of preparation needed.
• Can be used by EM and Media along with NWS to help communicate the bottom line message to the public.
– Expressions of Uncertainty• Used to enhance forecast information during tropical cyclones (Expressions of Uncertainty).
• Can be used as decision making aid by planners.
• Trend analysis from advisory to advisory for proper risk assessment.
Cumulative: Note that
chances of hurricane-
force winds at Tampa
Bay and Port Charlotte
are both around 30%!
Tampa
Port Charlotte
IncrementalNotice: highest right
up Port Charlotte
Communicate RISK
Example: Forecast Applications: Expressions of UncertaintyAdvisory Time: 20040902_1500 (25-36 Hours – Third Period)
FRANCES (ZFP) FRANCES (Click Point)
Official in 2014
Threat/Potential Impact Graphics
Forecast Actual Threat/Potential Impact
Example: Approaching major hurricane at the onset
of the warning period (~ 36 hours).
QUESTION: When advocating the measure of protective
actions according to wind impacts, which is better?
http://www.weather.gov/tcig
Storm Intensity
Cat 3(96-113 Kt)
Threat?
OR
FORECAST VALID XX/XX00Z 31.4N 77.5W
MAX WIND XXX KT...GUSTS XXX KT.
Neal Batista
Decision Making Guide
Clearance Times
Forecast impact ≤33hrs?
FORECAST VALID XX/XX00Z 31.4N 77.5W
MAX WIND XXX KT...GUSTS XXX KT.
Available 2012 season
Neal Batista
Wind Probabilities
64KtIncremental wind
prob ≥25%?
Neal Batista
More on Trend –Wilma Example
Impact Graphics use
implicitly probabilistic
guidance. What about
their trend from
advisory to advisory
also?
• Advisory 30• Advisory 30
• Advisory 31
• Advisory 32
• Advisory 35
Take Away
• More detailed in space and time wind speed probabilities are available to and from your local NWS office:
– NWS local offices can help sort through it and target your needs with their proper application.
• Be aware of the limitations of deterministic only based information.
– And making decisions solely based on deterministic or even “alternate scenarios” only.
• Be aware of all probabilistic data available to you including
– Cumulative, Onset, Incremental
– Questions they answer
– Their temporal resolution
– Be knowledgeable of their significance and trend behavior.
– Again your local NWS office can help you sort through this
• Be aware of the potential applications of using combined deterministic/probability data and their utility in communicating the message and making decisions.
– Again, your local NWS office can help you with this
Questions…Pablo Santos
Meteorologist In ChargeNWS Miami/South Florida Forecast Office
305-220-4500pablo.santos@noaa.gov