American Meteorological Society Wright Memorial Chapter

OCTOBER 2008 VOLUME 4, NUMBER 1

In this newsletter:

• Note from our President

• Minutes from 27 October 2008 Meeting

• From the National AMS

• Picture of the Month

Note from our President

Thanks for all those who participated in the Wright Memorial Chapter's first full meeting of Fall 2008.   Professor Hobgood's talk resonated well with the AMS  group  and with  the  interests  of  the  local  area‐‐as  evidenced  by  the media presence.    It's  likely Dr Hobgood's presentation will bring additional positive attention to our chapter from the national AMS.  Upcoming meeting speakers  and  continued  participation  in  Dayton  area  science  events  like TechFest  (in  Feb  09)  should  reinforce  our  standing  as  a  local  chapter  of significance.    Local  chapters  are  as  vibrant  as  the  local  participants make them, and right now our  funding  is good  (please remember your dues) and interest  in  the chapter  is  rising.   Thanks again  to all  those who have made that happen.  Some of the news from the chapter is unfortunately sad.  Recently we've lost two members  or  former members,  Ron  Rodney  and  Patrick  Hayes.    Paul Gehred's moving memorial of Ron recently appeared in the September 2008 issue of the Bulletin of the AMS.  Pat Hayes no longer lived and worked in the Miami  Valley,  but  had  been  working  diligently  on  his  Doctorate  in Engineering  Management  Systems  Engineering  (EMSE)  from  The  George Washington University  as well  as holding  a  full  time  job.   Because he was very close in completing his degree, the Dean of the EMSE School requested and  was  granted  permission  to  confer  the  Doctorate  to  Patrick posthumously.   The Dean of EMSE conducted an eloquent ceremony on 25 Oct 2008, where he presented  the Doctoral of  Science Degree  to Patrick's wife.   The Hayes family, collegiate friends and fellow coworkers attended  in what was a very moving time for all to share the common remembrance of a great person.  (Thanks to Ron Meris for the news on Pat Hayes' Doctorate).  Steve Fiorino AMS Wright Memorial Chapter President 

Minutes from 27 October 2008 Meeting AMS Wright Memorial Chapter meeting of 27 October 2008 Meeting of Chapter at Fox and Hound, Beavercreek, OH Before the meeting began, Ms Kimberly Thomson of WHIO-TV 7 weather interviewed Dr Hobgood and Paul Gehred, Chapter Secretary.

Mr. Paul Gehred, Secretary, introduces the evening’s speaker, Dr. Jay Hobgood.

Figure 1 - Ike began as a small cyclonic convergence region associated with a tropical wave off Cape Verde as seen in this 18Z August 29, 2008 satellite image.

Ms Thomson was a former student of Dr Hobgood’s at OSU. A short segment of her work was shown at the 11 PM edition of the nightly news broadcast on October 27th.

Meteorological Analysis of Hurricane Ike's Effects in Ohio by Dr. Jay Hobgood, (Ohio State University): Tropical Storm Ike

and the Windstorm in Ohio After welcomes and introductions, Dr Hobgood began by reviewing some of the damages in Ohio, $131k insurance claims; $533M in damages for insured; estimates of total damage are ~$1 Billion in Ohio.

Almost a million (Duke, Dayton Power and Light, AEP, etc.) lost power for a few hours to two weeks, some schools have used up all 5

calamity days for the year – by law have to make up missed time after that so they may be in school until late June – TBD What made Ike different? Why did we have the windstorm in Ohio? Not an easy problem. Ike began as a small cyclonic convergence region associated with a tropical wave off Cape Verde (Figure 1), it

later grew into an above average sized hurricane with a double eye wall (Figure 2) – the inner wall collapsed and the outer eye wall took over just prior to landfall on September 13th, a Saturday. Ike’s wind field was very extensive. Wilma of 2005 was the only other time he saw something like this double eyewall that persisted for a such a long period of time after a hurricane made landfall (Ike in Cuba and Wilma over Yucatan). Also of note is a large region of much drier air entraining into the system from the west which tends to hurt development. Meanwhile, excellent outflow is evidenced by the radial

Figure 2 – Four different views of Hurricane Ike from 7 September 2008. Note the double eye wall structure. Even early on in the cyclone history, entrainment of dry air into the west side of the system can be seen. Upper left: IR image, upper right: IR image with BD enhancement, lower left: 85GHz H image, lower right: color composite.

Figure 3 – GOES-12 visible satellite image of Ike from 2315Z 12 September 2008. Note the spoke like clouds, which are indicative of strong upper level outflow.

spokes of cirrus aloft which did help to intensify this storm prior to landfall – see satellite image Sept 11th for evidence of good out flow more on the east side.

Dr Hobgood then quoted James Franklin’s discussion no. 42, released at 11am Sept 11th … “ Ike is maintaining an atypical wind structure…characterized by a very broad wind field with multiple wind maxima and relatively little transport of winds aloft down to the surface.” Why the de-coupling of surface

You may also be interested in visiting the NWS Wilmington Office site for some thoughts about the windstorm at: http://www.erh.noaa.gov/er/iln/sept14_2008/sept14wind.html

Figure 4 – 850 mb Chart from 00Z 13 September 2008.

Figure 5 – 850 mb chart from 00Z 14 September 2008.

winds and winds at 3000-4000ft? Normally, thunderstorm downdrafts act to bring upper level winds down to the surface, yet this was not the case for Ike. Perhaps the entraining dry western air was decreasing thunderstorm development on the south and east sides of the storm? James Franklin continued… “The NOAA aircraft reported maximum flight-level winds[~10 kft] of 103 kt at 100 nmi north-northeast of the center…but SMFR and dropsonde data indicate that the surface winds were only around 65 kt.” The stepped frequency microwave radiometer, SFMR, is a multi-frequency C-band remote sensing instrument that is routinely flown into hurricanes by NOAA to measure surface wind speed and rain rate. So the winds were 40kts slower at the surface compared to those winds at 10 kft. Further evidence of vertical shear in the flow came from Auger Garden Banks off-shore oil platform [27.5° N, 92.5° W] where winds spiked to 109 kts at 400ft height before the anemometer quit reporting.

The satellite image on 1800Z, Sept 12th shows great spoke-like filaments of cirrus indicating excellent upper level outflow (Figure 3). So as the storm barreled into SE Texas coast, it was actually spinning up a little bit more. On Saturday morning, the weather map had a weak low pressure system in the South Dakota with a trailing cold front thru the OK

panhandle into west Texas. Ahead of the front was a significant low level jet with 40 kts or better from Ike north along the Mississippi Valley into central Illinois. Dr Hobgood pointed out that Lake Charles, LA had an amazing 90 kts at 850 mb (Figure 4)! Between the western trough and a very persistent ridge in SE US was a moderately

Figure 6 – 00 Z 14 September 2008 Sounding (black dots) and 12 Z 14 September (red dots) for Wilmington, OH

strong mid-level jet stream oriented SW-NE from the Mexico’s Sierra Madre all the way northward to Lake Erie.

Again, the winds aloft are slower at 500 mb than at 850 mb for many of the soundings. Even in Louisiana, there is little rain to bring the winds down to the surface for the dissipation of wind energy. The 14/00Z 850 mb map (Figure 5) puts the low near Dallas-Ft Worth-Red

River area and 80 kts were recorded at 850 mb [60 kts at 700mb] in northwestern Louisiana. Still, the Wilmington sounding was fairly benign on 00z on 14 Sep 08. Evening forecasters noting Ike’s track put it in northwestern Indiana, were

anticipating plenty of rain in swath of about 100 mi east of this track, and perhaps convective gusts to 35-50kts. Forecasters saw Sunday morning’s sounding where Nashville had 60kts at 850 mb and Wilmington had 40 kts at 850mb. The surface low [Ike dominated] was in SE Missouri while the 700 mb low [trough dominated] was in southern Illinois, so this is a relatively atypical “forward leaning” low. The surface weather depiction at 10 AM did not show too much of interest, however, 925 mb winds are ~ 40 kts. The winds at 925 mb were twice as fast as in the previous 00Z sounding. Did this indicate that the mechanical mixing was already underway? If so, the mixing started before the thermal heating got going. Looking at the 1215 L satellite, Dr Hobgood showed the cumulus cloud streets indicated gravity waves around 850 mb to 700 mb (Figure 7). These waves play a role in transferring momentum downward as well. What about the inversion capping the planetary boundary layer? Was this inversion due to the upper level ridge off to the southeast? The approaching cold front? Something else? This inversion stands out in the Wilmington 18Z sounding (Figure 7), and the gravity waves show up in the circled area. Did the mechanical mixing come from the increased friction of the hills of southeast Ohio? It may be more due to the gravity waves, the stability set up the gravity waves, so this is consistent – and soon the cold front caught up with the leading edge of the storm. By 2000L the low was in Ontario and the winds were dying down – it was over. Pennsylvania never did get the strong winds. This is not a synoptically driven situation.

Figure 7 – 1615Z Visible GOES-12 satellite image. Note the telltale signs of gravity waves over eastern Indiana.

So why in OH?

1. Ike was a large intensifying hurricane when it made landfall near Houston, on Saturday morning, 13 Sep.

2. Ike contained a decoupled upper layer with 30-40 kt faster winds above the sfc

3. Limited rainfall didn’t produce downdrafts that would have damped the winds at 850-700 mb and brought them to the surface.

4. Mechanical mixing really fired up over the Ohio River valley

5. The inversion at 750 mb confined the mixing to the lower trope

6. Gravity waves may have contributed too, we need baragraph traces or METARs to see if there looks like there may have been fluctuations caused by gravity waves.

Figure 8 – 18 Z 14 September 2008 Sounding from Wilmington, OH.

Questions from the Meeting What about the role of surface heating? We may not have gotten to the convective temperature at the dry adiabatic lapse rate replied Dr Hobgood. Did the warming do it

or was it the mechanical mixing that drove the winds downward? The sounding looks very much like a subsidence driven inversion. Does anyone know why Wilmington took the afternoon sounding? According to the forecaster on duty, they were still very concerned about explosive severe thunderstorm development ahead of the cold front. With the 2 PM sounding, they saw the strength of the capping inversion and the very strong winds from the surface to 20 kft they knew it wasn’t going to be a thunderstorm day. How did the Hurricane Forecast Center do? Well they nailed the track of the storm, they suggested it would redevelop into a tropical storm when it synched up with the mid-latitude low, and they even called its speed. They deserve high marks. The synoptic models showed the vertical placement of the

Highest Measured Wind Gusts (Official Observations)

75 m.p.h. – Port Columbus International74 m.p.h. – Cincinnati-Northern KY Airport74 m.p.h. – Airborne Airpark, Wilmington68 m.p.h. – Dayton-Wright Brothers Airport63 m.p.h. – Don Scott Field60 m.p.h. – Dayton International Airport59 m.p.h. – Wright-Patterson Air Force Base

According to: http://www.spc.noaa.gov/misc/AbtDerechos/derechofacts.htm#definition a derecho is a widespread and long lived windstorm that is associated with a band of rapidly moving showers or thunderstorms.

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Information about the entire 89th Annual AMS Meeting can be found at: http://www.ametsoc.org/meet/annual/ Hotel information can be found at: http://www.ametsoc.org/meet/annual/hotel.html

lows at 500 mb, and the strong steering flow of 50 kts from Little Rock to Toronto. This helped usher the system rapidly northeastward and it was squeezed between the ridge and the cold front coming into synch in NW Indiana. The NAM saw a large rain event in NW Ohio with typical gusty winds associated with convection so they really didn’t provide much help on forecasting this very rare windstorm. Was it a “derecho”? I haven’t heard it called that yet except by a few old schoolers.

Treasurers Report

We have $499.90 in the treasury.

Dues were collected from members.

From the National AMS

AMS Benefits of Membership

The American Meteorological Society, founded in 1919, is the preeminent scientific and professional organization for scientists and practitioners in the atmospheric sciences and related oceanic and hydrologic sciences. With a membership of more than 12,000 professionals, students, and weather enthusiasts, the AMS publishes nine atmospheric and related oceanic and hydrologic journals, sponsors more than 12 conferences annually, and offers numerous programs and services.

The AMS offers several membership classifications to meet the needs of all individuals. Specific benefits for members include significant discounts on AMS periodicals and other publications, access to online resources available to members only, and savings on meeting and workshop registrations.

89th Annual AMS Meeting AMS 89th Annual Meeting, 11–15 January 2009, Phoenix Civic Plaza Convention Center, Phoenix, Arizona The theme for the 2009 AMS Annual Meeting is “Urban Weather and Climate: Now and the Future.” The relevance and timeliness of the urban theme cannot be overemphasized. Recent events – Hurricane Katrina; urban floods in Europe and China; heat waves in London, Paris and Chicago; homeland security concerns and industrial chemical accidents; to name a few – point out the vulnerability of urban populations to high-impact weather of all types. In the U.S. today, approximately two-thirds of the population live in cities that occupy less than two percent of the U.S. land mass. This past year, the global population may have reached a tipping point with the world’s urban population equaling its rural population; by 2030, the urban population fraction is predicted to surpass 60% globally and exceed 82% in the more developed countries. Most of the urban population growth results from migration from the rural areas as birth rates tend to decline in the urban areas. The nexus of urbanization and population growth, coupled with anthropogenic urban weather influences and global climate changes, portend an impending ‘perfect storm’ for the urban environment. The 2009 Annual Meeting aims to highlight advances and challenges in

Preliminary programs, registration, and general information will be posted on the AMS Web site later this year

Shutterbugs – Submit your latest and greatest weather shots to our newsletter! Send them via e-mail to: mary.bedrick@wpafb.af.mil

AMS – Wright Memorial Chapter President: Steve Fiorino Steven.fiorino@afit.edu Vice President: Allison Schauer aschauer2008@hotmail.com Secretary: Paul Gehred Paul.gehred2@wpafb.af.mil Treasurer: Karen Kowalewsky kjkowal@verizon.net Web Master: John Turnbull John.turnbull@wpafb.af.mil Newsletter Editor Mary Bedrick Mary.bedrick@wpafb.af.mil

We’re on the Web!

www.ametsoc.org/chapters/wrightmem/index.html

urban-related science, applications, observations, modeling and operations. The specialty conferences, symposia and special sessions that comprise the annual meeting will focus attention on six cross-cutting urban themes: (a) measurement systems and networks; (b) modeling and forecasting; (c) observations and studies of high-impact weather; (d) geographic influences on urban weather and climate; (e) human and environmental impacts; and (f) implications of climate change and population growth. “High-impact” weather is considered in its broadest sense, and includes severe weather, high wind events, precipitation, floods, icing, lightning, poor visibility, adverse air quality, and temperature extremes. The meeting will also feature workshops and short courses, numerous town hall meetings, the Sunday WeatherFest, a Monday Presidential Policy Forum on the role of weather and climate in urban affairs, and two special named symposia honoring Prof. Timothy Oke and the late Dr. Tony Hollingsworth. Calls for Papers follow for the various specialty conferences, symposia and special sessions. For additional information on the organization of the 89th AMS Annual Meeting, please contact meeting co-chairpersons Sue Grimmond, King’s College London (Sue.Grimmond@kcl.ac.uk) or Rita Roberts, National Center for Atmospheric Research (rroberts@ucar.edu).

Picture of the Month Photograph by Harleth Herremans. Roll cloud viewed from Manistee, MI looking over Lake Michigan, July 2008.