1. An Update to the Convective Wind Climatology of
Kennedy Space Center and Cape Canaveral Air Force Station
Kevin Lupo, Plymouth State University, Plymouth, NH
Background
The convective wind climatology of Kennedy Space Center/Cape Canaveral Air Force Station (KSC/CCAFS) documents eighteen years ( ) of warm-season (May-September) convective wind events over a 30 km x 40 km region on and around KSC/CCAFS. Issued by the Air Force 45th Weather Squadron, warnings for strong convective winds account for the second greatest number of weather warnings issued at KSC/CCAFS, behind only lightning.
Sanger (1999) developed the original convective wind climatology, including warning level convective wind events for The climatology was further updated by Loconto, et al. (2006) to include warning level events through 2003, and then by Cummings et al. (2007), adding all warning and non-warning level convective wind events through 2005 to the climatology.
Dinon et al. (2008) developed a radar climatology studying cell and group motion, boundary interactions, cell strength, and the relative location of the maximum recorded wind gust. Ander et al. (2009) added data for 2006 and 2007, and updated the radar climatology to include both warning and non-warning level events. Laro (2011) and Laro (2012) added data for to the convective wind climatology.
This update to the convective wind climatology of KSC/CCAFS added data for 2012 warm-season convective wind events to the KSC/CCAFS convective wind climatology. This study also reviewed all previously identified convective events using base reflectivity data from the Weather Surveillance Radar in Melbourne, Florida (KMLB). A threshold of ≥40 dBZ base reflectivity over the KSC/CCAFS area was used to identify convective periods. This review modified the listed start and end times of many convective events, and led to the removal of 72 events from the convective wind climatology.
Additional information about the KSC/CCAFS convective wind climatology measures is available online at:
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Climatological Results
Figure 13 shows the direction of motion of the individual cell responsible for producing the MPW for all convective event. Figure 14 shows the direction of motion of the group of cells containing the cell responsible for the MPW. These figures show that the both cell motion categories have similar results, and that storm cells and groups that are moving toward the east are the most likely to produce warning level wind events, while those storms with variable motion are least likely to produce warning level wind events.
Location
Criteria
Desired Lead Time
KSC (surface-300 ft)
>= 35 kt
30 min
>= 50 kt
60 min
CCAFS (surface-200 ft)
Figure 13.
Figure 3. Distribution of warm-season convective versus non-convective days by year for KSC/CCAFS during for the 18-year climatology.
Figure 8. Frequency of occurrence of all synoptic scale flow regimes for convective days for all years.
Figure 8 shows that southwesterly flow regimes were most commonly associated with convective activity during the 18-year climatology, while northerly flow regimes were the least associated with convective activity.
Figure 9 shows the diurnal cycle of convective activity during the Florida warm-season, with the maximum number of convective wind observations occurring in the middle-late afternoon hours.
Figure 1. Specific convective wind warning criteria and lead time for the 45th Weather Squadron at KSC/CCAFS.
Figure 14.
Figure 9. Diurnal distribution of total wind observations over the 18-year climatology
Radar Climatology
Figure 4. Distribution of maximum peak winds (MPW) by warning criteria by year for KSC/CCAFS during the 18-year climatology.
Cell Initiation
Cell Structure
Cell Strength
Group Movement
Individual Cell Movement
Location of MPW
Sea Breeze Front (SBF)
Linear
Weak/Broken (<45 dBz)
16 Cardinal wind directions
Behind
Outflow Boundary (OFB)
Individual Cell
Moderate
(45-55 dBz)
Variable/
Stationary
Overhead
SBF & OFB
Cluster
Strong
(>55 dBz)
Ahead
No SBF or OFB
Figure 3 shows the distribution of convective and non-convective days by year during the warm-season at KSC/CCAFS was the only year in the climatology where more convective than non-convective days occurred during the warm-season, which included a total of 86 convective events. On average, 38.5% of all days during the warm-season are classified as convective days. Figure 4 breaks out all individual convective events by warning criteria of the MPW. Ob average, 61.5% of all events did not exceed the warning criteria of 35 kt, while only 7.4% of all events exceeded the 50 kt warning threshold.
Figure 15 shows the distribution of flow regime classification with respect to warning and non-warning level convective wind events. This figures shows that southwesterly flow regimes are most commonly associated with warning level convective wind events, and that northerly flow regimes are associated with fewer convective events overall. Figure 16 shows storm strength from base reflectivity in reference to warning and non-warning level events. Strong cells were associated with the highest ratio of warning to non-warning level convective wind events.
FLOW REGIME
SUBTROPICAL RIDGE POSITION
SW-1
Subtropical ridge south of Miami
SW-2
Subtropical ridge between Miami and Tampa
SE-1
Subtropical ridge between Tampa and Jacksonville
SE-2
Subtropical ridge north of Jacksonville NW
Subtropical ridge far to south and extending far into Gulf of Mexico and stronger than normal NE
Subtropical ridge far to north and extending into SE US and much stronger than normal
Other
Subtropical ridge position not defined
Missing
Missing synoptic data to determine flow regime
Figure 5 shows the eight synoptic scale flow regime classifications established by Lericos, et al. (2002) and updated by Lambert (2007).
Figure 10. Developed by Dinon et al. (2008), convective events over KSC/CCAFS were categorized by six characteristics observed in KMLB or KTBW radar data.
Figure 15.
Figure 11 shows the sources of cell initiation responsible for the MPW recorded during a convective period. Thunderstorms initiated by a mesoscale boundary interaction (SBF, OFB, SBF & OFB) constituted a majority (54%) of the warning level events from It is also shown that the majority of non-warning level events resulted from thunderstorms that were initiated without boundary interaction.
KSC/CCAFS Wind Tower Network
Figure 5.
Figure 11.
Figure 12 shows the 0354Z 31 July 2006 base reflectivity image from the KMLB radar overlaid with wind barbs from wind tower observations. This event was responsible for the strongest wind speed recorded in the climatology, 74 kts. Based on the classifications from Dinon et al. (2008):
Cell Initiation: OFB
Cell Structure: Individual
Cell Strength: Strong
Group Movement: East
Cell Movement: Northeast
Location of MPW: Behind
Figure 16.
References
Figure 6. Monthly distribution of convective and non-convective days.
Figure 7. Flow regimes for convective and non-convective days for the least active year (2006, 34 events) and most active (2009, 86 events) in the 18-year climatology.
Dinon, H. A., M. J. Morin, J. P. Koermer, and W. P. Roeder, Convective winds at the Florida Spaceport: year-3 of Plymouth State research. 13th Conf. on Aviation, Range, and Aerospace Meteorology, January, New Orleans, LA.
Lambert, W. C., Objective Lightning Probability Forecasting for Kennedy Space Center and Cape Canaveral Air Force Station, Phase II. NASA Contractor Report CR pp.
Lericos, T. P., H. E. Fuelburg, A. I. Watson, and R. I. Holle, Warm season lightning distributions over the Florida Peninsula as related to synoptic patterns. Weather and Forecasting, 17,
Tower 0300:
Height: 54 ft
Wind: 74 kt
Direction: 289°
Figure 6 shows the frequency of occurrence for convective and non-convective days by month over the 18-year warm–season convective wind climatology. On average, July tends to be the peak of warm-season convective days (52.5%), joined by only the month of August (50.5%) as months with more convective days than non-convective days. Figure 7 breaks the year of maximum activity (2009) and the year of minimum activity (2006) into flow regime classifications by convective and non-convective day. Figure 7 shows that southwesterly flow regime were most associated with convective days during the 2009 warm-season.
Figure 2. Map of 36 wind towers used in the KSC/CCAFS convective wind climatology. 82 anemometers are distributed across the 36 towers at 8 heights ranging from ft. Only towers labeled with black text were used in this study.
Figure 12.