The National Hurricane Conference ’08 in Orlando adjourned at noon Fri. Some highlights from the last couple of days:
Thursday was a day of simultaneous workshops. The only problem with this format is that you can’t get in on every workshop that might be interesting and/or helpful. I began the day with specialists/forecaster from the Nat. Hurr. Center. Lightning research has been increasing regarding tropical systems. While not all tropical cyclones behave in the exact same way, there are some indications that an increase in lightning (mainly outer bands & the eye wall) correlates well with an increase and/or peak in intensity of the system. As far as forecast models, the UKMET has had a couple of stellar yrs. going from worst to first. The NOGAPS (Navy) model has been in serious decline & in last place 9 out of the last 10 yrs. Intensity forecasts remain a bugaboo with essentially a flat skill level since 1990. So intensity & size remain “an issue” when forecasting tropical cyclones.
Since I’m on the subject of forecasting cyclones & the models, I’ll jump to a late afternoon session in which Richard Pasch, Hurr. Specialist from NHC addressed changes and/or updates to the forecast models. The new HWRF model is still not considered operational but was consistently used & tested in ’07. Pasch called its performance “o.k.”. Not a particularly overwhelming endorsement, but Pasch seemed optimistic that it prove its worth in the future. Some tweaks have already been done to the HWRF which proved to make the model a little better with intensity forecasting (but still marginal). The GFS model is undergoing additional changes again including: ** taking into account the time of observations (for analysis)….** More satellite data for analysis…. ** Use of solar/infrared radiation… ** flow over mountains. ’05 storms were then run using these improvements. The GFS did better with track but there was a slight degradation in intensity forecasts. The GFDL uses the GFS analysis, so it’s felt that the GFDL will benefit. One of the models that’s been light yrs. behind & of very little use – GFDN (Navy version of GFDL) – is expected to become a major player this year due to vast & expensive upgrades. In-house testing of the model during the ’07 hurricane season proved to be very encouraging so expect to see more discussions in the ’08 season regarding forecasts from the GFDN. NHC primarily uses global models for tropical forecasting because the models usually provide better resolution of the synoptic (broad) atmospheric pattern. But there have been some improvements to the NAM, a mesoscale (smaller scale) model. There have been initialization improvements, a larger domain, better overall analysis, better treatment of the mountains, better assimilation of solar & infrared radiation & 18% more coverage of the tropics. While probably not a reliable model at the moment, it’ll be interesting to see if the NAM does much better with tropical systems.
Pasch feels that a combination (avg.) of the GFDL, HWRF & GFDN will provide an improvement in especially track forecasting. They’ll also use a combination – avg. – of the following models: TCON: Fixed combination of GFS, UKMET, NOGAPS, GFDL & HWRF….TVCN: At least 2 of these: GFS, UKMET, NOGAPS, GFDL, HWRF, GFDN, ECMWF….ICON (intensity): SHIPS, LGEM, GFDL, HWRF. You’ll frequently see me refer to any or all of these models in this blog &/or “Talking the Tropics With Mike” during the upcoming season.
The late morning session was an interesting engineering workshop “Wind Loads & Effects on Buildings”. The presenters were from the University of Florida (I’m hoping to go to Gainesville sometime soon to show their “wind machine” to our viewers). Their machine is 2800 horsepower twin-turbo diesel engines that can produce wind & pressure equaling a hurricane. Water is also introduced to try to simulate wind-driven rain & how it degrades structures. They’ve done wind tests on landscaping too. What’s been found to be a common structural failure might surprise you (garages doors, entryways & improperly constructed roofs are typical failures) – windows! Not that the windows are breaking necessarily but leaking. Many windows considered hurricane “resistant” are staying intact (barring high impact from debris) but are succumbing to rain intrusion.
The early afternoon session was informative as well. Jamie Rhome, hurricane specialist at NHC spoke about some of the new products to be offered and/or enhanced this year. He highlighted the wind speed probability when a tropical cyclone is approaching…the center of the cyclone should stay within the “cone” 60% of the time…& an addition to the Tropical Weather Outlook will be genesis probability (development of a trop. cyclone) – Low: <20%; Medium: 20-50%; High: >50%. There will also be new issuance times for the Tropical Weather Outlook: 2am, 8am, 2pm & 8pm. Another new product will be the storm surge probability which has yet to be “officially” unveiled.
Steve Letro, Meteorologist-In-Charge at our own Jacksonville N.W.S., delivered an excellent presentation on the job of the local Weather Forecast Offices emphasizing that all forecasts are predicated on the Nat. Hurr. Center forecasts UNTIL the cyclone is within Doppler radar range. Letro emphasized that wind fields are not perfect in symmetry with speed ranging widely between bands & sometimes on one side of the storm vs. the other. Letro also introduced a new product – the EWW – “Extreme Wind Warning” which will be issued for inland winds of approximately 115+mph expected to occur within one hour due to the approach of an approximately Cat. 3 hurricane eyewall.
The last session I took part in was an excellent presentation by Tom Iovino with the Hillsborough County Emerg. Management Dep’t. He stressed the ever increasing apathy again now that we’ve had 2 “quiet” hurricane seasons back-to-back…the challenge is to help those that need to evacuate to understand the gravity of the situation. He used the fire vs. hurricane analogy – if there’s a fire in the house, everyone will get out in a hurry; not necessarily so for a hurricane warning. Iovino also stressed the unique needs of those that must evacuate vs. those that are not in a mandatory zone…elderly vs. young…handicapped vs. self-sufficient & pet owners.
The closing session Fri. morning centered on insurance, global warming & the ’08 forecast.
Insurance: ’06-’07 hurricane seasons gave insurance co. a much-needed break. Emphasized that the profit margin for ins. Companies – even in “good” years – is small…75% of all catastrophic losses are due to hurricanes or tornadoes…the Florida hurricane catastrophe fund is a catastrophe waiting to happen for at least another 2 yrs. due to insolvency…Florida will have to resort to some form of taxes to pick up the slack should a major hurricane strike the state within the next 24-36 mo…Florida is a “poor model” for the insurance industry….Citizen’s Ins. makes up approximately 40% of the Fl. market…1,000 per day moving to Fl. is not helping(!)…the insurance industry is planning for & expects a $100 billion event sometime in the “near future”….mitigation is the key – Fl. homes built later than 1996 (’92 Andrew codes in effect) received far less damage in hurricanes in 2004. In fact, all homeowners forced out of their homes in ’04 who had homes built after ’96 were back in their homes in less than one month.
Chris Landsea, Science & Operations Officer @ NHC gave an excellent presentation on hurricane frequency/intensity due to global warming (or not!). He emphasized that he believes global warming is occurring (we can measure it!) & that man might indeed be partially responsible but there’s little if any data to support the contention that global warming is causing more or stronger hurricanes. He pointed out the dramatic increase in population along our coastlines & the lack of good long term data (pre-satellite). Landsea contends the 1930s-1950s were just as active but advisories weren’t issued for borderline storms or those well out to sea (usually). Landsea believes the Atlantic Multidecadal Oscillation is the primary culprit.
Thomas Knutson – Geopphysical Fluid Dynamics Lab, Princeton NJ – gave a detailed presentation on climate modeling & concluded that models simply don’t prove – at this point – that a strong enough correlation exists between global warming & tropical cyclones.
The final speakers were hurricane forecasters Bill Gray & Phil Klotzbach – a true “odd couple” but only in the most sincere way. Right now their Colorado St. predictions for ’08 are for 13 named storms, 7 hurricanes – 3 of which will be major. They’ll issue an update Wed. April 9th.
Other weather “stuff”:
Our own weather could be a bit “bumpy” Sat. afternoon/evening as showers & t’storms move across the area. Many storms should produce heavy rain & frequent lightning but a few might also produce hail & high winds.
These storms will be part of the same system that’s been producing snow in the Midwest & severe storms from the Southern Plains to the Tennessee Valley. A tornado Thu. evening grazed the N.W.S. office in Little Rock, Arkansas where forecasters literally had to duck for cover. Check out their own storm report below & click here for the storm summary of that twister.
1010 PM TORNADO NORTH LITTLE ROCK AIRPO 34.83N 92.27W
04/03/2008 PULASKI AR NWS EMPLOYEE
TORNADO PASSED OVER NATIONAL WEATHER SERVICE OFFICE IN
NORTH LITTLE ROCK AT THE NORTH LITTLE ROCK AIRPORT.
DAMAGE TO BUILDINGS SURROUNDING THE AIRPORT ON AIRPORT
PROPERTY...BUT NO DAMAGE TO THE NWS OFFICE BUILDING.
