| Date Time MST |
Temp °F |
RH % |
DewPt °F |
Wind mph |
Dir ° |
Gust mph |
Dir ° |
Press in Hg |
Solar W/m^2 |
Prec in |
|---|---|---|---|---|---|---|---|---|---|---|
| 2019-09-16 14:30 | 89.2 | 12.1 | 30.1 | 5.1 | 150 | 8.7 | 149 | 24.728 | 725.2 | 0.00 |
| 2019-09-16 14:25 | 89.9 | 12.0 | 30.6 | 6.2 | 146 | 9.2 | 139 | 24.748 | 772.6 | 0.00 |
| 2019-09-16 14:20 | 89.8 | 12.1 | 30.6 | 7.0 | 122 | 11.3 | 134 | 24.740 | 770.1 | 0.00 |
| 2019-09-16 14:15 | 89.8 | 12.8 | 32.1 | 5.5 | 72 | 9.3 | 121 | 24.763 | 802.0 | 0.00 |
| 2019-09-16 14:10 | 90.7 | 12.3 | 31.7 | 7.0 | 109 | 11.9 | 118 | 24.757 | 857.0 | 0.00 |
| 2019-09-16 14:05 | 91.5 | 11.6 | 31.0 | 6.0 | 121 | 17.9 | 179 | 24.745 | 887.0 | 0.00 |
| 2019-09-16 14:00 | 89.5 | 11.8 | 29.8 | 2.4 | 176 | 6.1 | 230 | 24.738 | 905.0 | 0.00 |
| 2019-09-16 13:55 | 88.4 | 11.8 | 29.1 | 6.1 | 244 | 8.2 | 220 | 24.723 | 839.0 | 0.00 |
| 2019-09-16 13:50 | 87.9 | 12.5 | 30.1 | 6.8 | 264 | 10.4 | 233 | 24.750 | 679.2 | 0.00 |
| 2019-09-16 13:45 | 88.4 | 12.5 | 30.4 | 4.6 | 302 | 6.7 | 213 | 24.752 | 834.0 | 0.00 |
| 2019-09-16 13:40 | 88.1 | 12.5 | 30.1 | 4.7 | 241 | 8.3 | 191 | 24.760 | 847.0 | 0.00 |
| 2019-09-16 13:35 | 88.9 | 12.6 | 30.9 | 6.1 | 135 | 10.6 | 141 | 24.764 | 883.0 | 0.00 |
| 2019-09-16 13:30 | 88.8 | 12.6 | 30.9 | 5.5 | 235 | 9.6 | 202 | 24.766 | 906.0 | 0.00 |
| 2019-09-16 13:25 | 89.1 | 12.1 | 30.2 | 4.8 | 135 | 7.5 | 151 | 24.766 | 907.0 | 0.00 |
| 2019-09-16 13:20 | 87.3 | 12.7 | 29.9 | 3.4 | 151 | 8.1 | 136 | 24.767 | 790.1 | 0.00 |
| 2019-09-16 13:15 | 86.4 | 13.1 | 30.0 | 4.5 | 141 | 7.0 | 137 | 24.768 | 453.6 | 0.00 |
| 2019-09-16 13:10 | 85.9 | 14.2 | 31.5 | 3.4 | 144 | 7.7 | 116 | 24.769 | 385.8 | 0.00 |
| 2019-09-16 13:05 | 85.9 | 12.9 | 29.2 | 3.5 | 78 | 7.7 | 93 | 24.770 | 329.3 | 0.00 |
| 2019-09-16 13:00 | 86.2 | 13.4 | 30.5 | 5.3 | 93 | 8.7 | 125 | 24.771 | 325.0 | 0.00 |
| 2019-09-16 12:55 | 87.3 | 13.2 | 30.9 | 5.6 | 115 | 8.3 | 81 | 24.771 | 386.8 | 0.00 |
| 2019-09-16 12:50 | 88.0 | 12.9 | 30.8 | 4.9 | 82 | 7.3 | 82 | 24.773 | 818.0 | 0.00 |
| 2019-09-16 12:45 | 87.2 | 13.2 | 30.7 | 6.1 | 138 | 9.1 | 154 | 24.774 | 832.0 | 0.00 |
| 2019-09-16 12:40 | 86.2 | 13.6 | 30.8 | 6.2 | 92 | 10.0 | 142 | 24.775 | 556.3 | 0.00 |
| 2019-09-16 12:35 | 85.4 | 13.6 | 30.1 | 6.8 | 124 | 10.8 | 126 | 24.774 | 452.3 | 0.00 |
| 2019-09-16 12:30 | 85.4 | 14.5 | 31.7 | 7.3 | 141 | 12.1 | 133 | 24.773 | 431.1 | 0.00 |
| 2019-09-16 12:25 | 85.6 | 14.2 | 31.3 | 8.1 | 152 | 11.0 | 149 | 24.771 | 415.6 | 0.00 |
| 2019-09-16 12:20 | 85.7 | 13.1 | 29.3 | 5.8 | 119 | 9.6 | 127 | 24.771 | 494.2 | 0.00 |
| 2019-09-16 12:15 | 86.6 | 12.7 | 29.3 | 5.6 | 156 | 9.8 | 127 | 24.775 | 456.1 | 0.00 |
| 2019-09-16 12:10 | 87.6 | 12.9 | 30.6 | 7.2 | 131 | 10.6 | 130 | 24.776 | 888.0 | 0.00 |
| 2019-09-16 12:05 | 87.1 | 13.4 | 31.1 | 6.5 | 151 | 10.7 | 164 | 24.776 | 875.0 | 0.00 |
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John Knaff earned a B.S. in Meteorology (1989) from Texas A&M University, and a MS (1992) and PhD (1997) in Atmospheric Science from Colorado State University. He was briefly a post-doctoral researcher in the Department of Atmospheric Science at Colorado State University (1997). Following that appointment, he was a post-doctoral Fellow at the Cooperative Institute for Research in the Atmosphere at Colorado State University (1997-1999) where he was also employed as a Research Scientist position (1999-2006). He joined NOAA in 2006 as a Meteorologist in the NESDIS Regional and Mesoscale Meteorology Branch located in Fort Collins, Colorado.
As a student, he concentrated on topics related to tropical climate variability including El Nino/Southern Oscillation, monsoons, tropical cyclones and large-scale Atlantic climatology. The focus of his more recent studies, including his postdoctoral work, has been on observational aspects of hurricane structure and intensity variations and prediction. Much of that work has led to the development of forecast applications that have been transferred to operations at the NESDIS, the National Hurricane Center, the Joint Typhoon Warning Center, and tropical cyclone warning centers worldwide. These efforts have led to many awards. In 2004, he received the NOAA David Johnson Award for basic research for improving the understanding of tropical phenomenon and predicting tropical cyclone intensity, accompanied by exemplary transfer of the results into operational products. He has also been awarded Department of Commerce Bronze Medals in 2007, 2010, and 2012, was a member of a team that received the Colorado Governor’s Award for High Impact Research in 2012 and in 2014 was recognized for his support of JTWC operations.
Up-to-date publication information can be found at the following web locations:
Storm-centered infrared (IR) imagery of tropical cyclones (TCs) is related to the 850-hPa mean tangential wind at a radius of 500 km (V500) calculated from 6-hourly global numerical analyses for North Atlantic and eastern North Pacific TCs for 1995–2011. V500 estimates are scaled using the climatological vortex decay rate beyond 500 km to estimate the radius of 5 kt (1 kt = 0.514 m s−1) winds (R5) or TC size. A much larger historical record of TC-centered IR imagery (1978–2011) is then used to estimate TC sizes and form a global TC size climatology. The basin-specific distributions of TC size reveal that, among other things, the eastern North Pacific TC basins have the smallest while western North Pacific have the largest TC size distributions. The life cycle of TC sizes with respect to maximum intensity shows that TC growth characteristics are different among the individual TC basins, with the North Atlantic composites showing continued growth after maximum intensity. Small TCs are generally located at lower latitudes, westward steering, and preferred in seasons when environmental low-level vorticity is suppressed. Large TCs are generally located at higher latitudes, poleward steering, and preferred in enhanced low-level vorticity environments. Postmaximum intensity growth of TCs occurs in regions associated with enhanced baroclinicity and TC recurvature, while those that do not grow much are associated with west movement, erratic storm tracks, and landfall at or near the time of maximum intensity. With respect to climate change, no significant long-term trends are found in the dataset of TC size.
The National Hurricane Center (NHC) has a long history of forecasting the radial extent of gale force or 34-knot (kt; where 1 kt = 0.51 m s−1) winds for tropical cyclones in their area of responsibility. These are referred to collectively as gale force wind radii forecasts. These forecasts are generated as part of the 6-hourly advisory messages made available to the public. In 2004, NHC began a routine of postanalysis or “best tracking” of gale force wind radii that continues to this day. At approximately the same time, a statistical wind radii forecast, based solely on climatology and persistence, was implemented so that NHC all-wind radii forecasts could be evaluated for skill. This statistical wind radii baseline forecast is also currently used in several applications as a substitute for or to augment NHC wind radii forecasts. This investigation examines the performance of NHC gale force wind radii forecasts in the North Atlantic over the last decade. Results presented within indicate that NHC’s gale force wind radii forecasts have increased in skill relative to the best tracks by several measures, and now significantly outperform statistical wind radii baseline forecasts. These results indicate that it may be time to reinvestigate whether applications that depend on wind radii forecast information can be improved through better use of NHC wind radii forecast information.
