Post-Storm Analysis - Andrea

[JonathanBelles]

It's time to take a look back at this historic storm. It was the first wave of change on tropical products from the NHC, and it dumped more than a foot of rain in south Florida.

If you were doing the post-storm analysis, what would you change in the official track or intensity?

Do you agree with how the NHC handled the non-tropical chapter of Andrea's life?


For me, I would like to take a strong look at the time frame between noon and when the Hurricane Hunters made their only pass on 6/6. The only change I would make to the non-tropical advisory suite would be to pick up where the HPC left of and to offer a product with the highest rainfall totals and highest winds.

[chaser1]

I was out of town during the genesis of Andrea (freshman orientation for daughter at FSU - Go Noles ). During the time, I only really had time for quick peeks at satellite during Andrea's development but was surprised when I heard the first advisory for Andrea. NHC no doubt felt that Andrea exhibited the required winds & enough classic warm core criteria to warrant T.S. advisories, but I think that greater inconsistency now exists with how satellite interpretation would have been used towards prior year classification (or the definition) of a tropical cyclone, as compared to those benchmarks now in place. Global warming, early advanced landfall warnings, and all other social/political discussion aside....., it just seems that NHC is quicker to pull the trigger on T.S. classification now and was significantly more conservative in the past.

I believe that satellite interpretation was relied upon more to determine whether a tropical cyclone met required defined criteria based on a number of presentation factors such as co-located convection, banding features, system symmetry, non diurnal consistent convection etc. I recall many past T.W.O. discussions where despite buoy or recon measured wind, T.D. or T.S. classification was held off unless/until greater convection or tropical system organization had taken place. Based on Satellite (and in spite of ship reported winds) alone, I would argue that other similar in appearance tropical systems during years past, especially those occurring in the Eastern or Central Atlantic, were often carried as "waves" or Depressions far longer - at least until greater Satellite presentation criteria was met.

I think this point extends beyond any conversation whether Andrea would have still been classified in years past, but as "sub-tropical" verses "tropical". I do not think that prior year Satellite required parameters would have resulted in Andrea to be classified as a T.S. (or possibly even a T.D.) as early as it was initiated during this event. So, has the "science" regarding what defines a tropical depression or tropical storm changed, or has public policy changed the science?

This is not necessarily a new debate, and am sure many claim the increased number of annual tropical cyclones is a result of both enhanced satellite capabilities as well as newly defined criteria (to meet the need of increased shipping, insurance companies, etc).

Unfortunately, NHC is caught in the middle in so many different ways. They are ultimately responsible not only for adequate US warnings, but unfairly held to a level of responsibility of individual preparedness and how the public reacts to risk itself. I do now know how widespread 60 second measured 39 mph. winds were actually measured at the surface in or near landfall, however real flooding rains and some wind damage did occur. In fact area's far from Andrea's center received significant impact such as Aventura in Miami-Dade county with nearly a foot of rain. In the old days however, I remember being a kid so excited to see the effects of a hurricane, yet everytime one came within 500 miles of S. Florida, was so disappointed when the weatherman confidently announced that the torrential rains we were to see were simply "not" directly associated with the storm well to the south (or west) and to "not worry". Now, the general public thinks that each days' rain or drought impacting them, is a direct result of W. Pacific SST's.... and of course that EVERY year is a El Nino or La Nina year?!! To the general public, it is real and a "weather event" regardless of name or label. As I see it coastal population, personal responsibility (or ignorance) and increased demand for any/all tropical system weather related impact warnings has further fallen on NHC to manage. Not only has this Federal agency been pressured to develop better (and longer range) forecast capabilities, but beyond the science of tropical meteorology has increasingly been tasked with additional social pressure & responsibility of redefining the science that they have been measuring for such a long time.

Who knows, perhaps one day even squall lines & tropical down-bursts will be required by society "of being named" .

[CrazyC83]

I think it was handled appropriately. The lack of warnings for wind north of the Chesapeake Bridge-Tunnel was also correct, since whether tropical or not, winds were nowhere near tropical storm force there.

I'd change the peak intensity to 60 kt, at 1200 UTC June 6, based on the Recon data around 1730 UTC (which supported 55 kt) and the weaker radar signature by then. In addition, the landfall intensity I would decrease to 50 kt, as it appeared to weaken a bit more before landfall. A full BT I am about to write.

[CrazyC83]

Here is how I would set the best track (NOT OFFICIAL by any means!!!) - uses the HURDAT2 format except I deleted the size columns

AL012013, ANDREA, 18,
20130605, 0000, , LO, 24.3N, 87.0W, 25, 1008,
20130605, 0600, , LO, 24.6N, 87.0W, 30, 1006,
20130605, 1200, , LO, 24.9N, 86.9W, 30, 1005,
20130605, 1800, , LO, 25.3N, 86.6W, 35, 1003,
20130605, 2100, G, TS, 25.3N, 86.6W, 40, 1002, Genesis at 2100 UTC (when Recon first flew in)
20130606, 0000, , TS, 25.6N, 86.5W, 45, 1000,
20130606, 0600, , TS, 26.8N, 86.2W, 50, 998,
20130606, 1200, , TS, 27.8N, 84.9W, 60, 994, Peak intensity (wind)
20130606, 1800, , TS, 28.9N, 83.9W, 55, 992,
20130606, 2200, L, TS, 29.5N, 83.4W, 50, 991, Landfall at Big Grassy Island, FL and minimum pressure
20130607, 0000, , TS, 29.8N, 83.0W, 45, 992,
20130607, 0600, , TS, 31.5N, 81.6W, 40, 995,
20130607, 1200, , TS, 33.5N, 80.2W, 45, 995,
20130607, 1800, , PT, 35.2N, 78.6W, 45, 996,
20130608, 0000, , PT, 37.4N, 76.2W, 40, 997,
20130608, 0600, , PT, 39.9N, 73.6W, 35, 997,
20130608, 1200, , PT, 42.4N, 70.4W, 35, 997,
20130608, 1800, , PT, 44.3N, 67.3W, 35, 999,

[JonathanBelles]

Crazy: What evidence do you have (pictures or data) for lowering the landfall intensity?

Chaser1: Go Noles indeed!

[psyclone]

Well with respect to intensity I have long believed that intensity tends to be overestimated and this storm is no exception. The national weather service Tampa has published an extensive list of peak wind gusts (the northern extent of their CWA is Levy county, which is just south of the landfall point) and the highest GUST was 60mph, and that was at an elevated marine station off of Anna Maria island. Cedar Key's peak GUST was 51mph and they were just below the landfall point. One would think they (or someone else in Tampa's expansive CWA) should have reported much more. Shouldn't someone have reported at least a gust close to the advertised sustained winds of the storm? After all, if sustained winds were 65, then peak gusts should have been significantly higher.

[CrazyC83]

Crazy: What evidence do you have (pictures or data) for lowering the landfall intensity?

Chaser1: Go Noles indeed!

Basis is that the radar velocities suggested lower winds after Recon left. Likewise the peak intensity is where they suggested higher winds.

[CrazyC83]

Well with respect to intensity I have long believed that intensity tends to be overestimated and this storm is no exception. The national weather service Tampa has published an extensive list of peak wind gusts (the northern extent of their CWA is Levy county, which is just south of the landfall point) and the highest GUST was 60mph, and that was at an elevated marine station off of Anna Maria island. Cedar Key's peak GUST was 51mph and they were just below the landfall point. One would think they (or someone else in Tampa's expansive CWA) should have reported much more. Shouldn't someone have reported at least a gust close to the advertised sustained winds of the storm? After all, if sustained winds were 65, then peak gusts should have been significantly higher.

Almost always, the strongest winds are in a small area over water. In very few storms (usually storms that are rapidly intensifying) are they recorded over land. The area is not very well sampled, and I know Cedar Key had a 10-min wind of 41 mph (about 46 mph after conversions).

[psyclone]

Well with respect to intensity I have long believed that intensity tends to be overestimated and this storm is no exception. The national weather service Tampa has published an extensive list of peak wind gusts (the northern extent of their CWA is Levy county, which is just south of the landfall point) and the highest GUST was 60mph, and that was at an elevated marine station off of Anna Maria island. Cedar Key's peak GUST was 51mph and they were just below the landfall point. One would think they (or someone else in Tampa's expansive CWA) should have reported much more. Shouldn't someone have reported at least a gust close to the advertised sustained winds of the storm? After all, if sustained winds were 65, then peak gusts should have been significantly higher.

Almost always, the strongest winds are in a small area over water. In very few storms (usually storms that are rapidly intensifying) are they recorded over land. The area is not very well sampled, and I know Cedar Key had a 10-min wind of 41 mph (about 46 mph after conversions).

That's the standard line but it's just worn out with me. I mean we're not even close here. Now I could be wrong and I'm not a met but this is just an observation of mine. If the storm really had 65mph sustained winds then peak gusts should have been far greater ( I would suggest close to 80mph) than that which means recording a peak gust that equals the advertised sustained winds should be a fairly effortless endeavor. and yet, despite all those obs...crickets. Speaking anecdotally, the winds in my neck of the woods were far less than those experienced with Debby...we barely knocked loose pine needles off the trees. Now to be sure, this was an entertaining storm but I remain unconvinced of it's advertised intensity.

[TropicalAnalystwx13]

Well with respect to intensity I have long believed that intensity tends to be overestimated and this storm is no exception. The national weather service Tampa has published an extensive list of peak wind gusts (the northern extent of their CWA is Levy county, which is just south of the landfall point) and the highest GUST was 60mph, and that was at an elevated marine station off of Anna Maria island. Cedar Key's peak GUST was 51mph and they were just below the landfall point. One would think they (or someone else in Tampa's expansive CWA) should have reported much more. Shouldn't someone have reported at least a gust close to the advertised sustained winds of the storm? After all, if sustained winds were 65, then peak gusts should have been significantly higher.

Almost always, the strongest winds are in a small area over water. In very few storms (usually storms that are rapidly intensifying) are they recorded over land. The area is not very well sampled, and I know Cedar Key had a 10-min wind of 41 mph (about 46 mph after conversions).

That's the standard line but it's just worn out with me. I mean we're not even close here. Now I could be wrong and I'm not a met but this is just an observation of mine. If the storm really had 65mph sustained winds then peak gusts should have been far greater ( I would suggest close to 80mph) than that which means recording a peak gust that equals the advertised sustained winds should be a fairly effortless endeavor. and yet, despite all those obs...crickets. Speaking anecdotally, the winds in my neck of the woods were far less than those experienced with Debby...we barely knocked loose pine needles off the trees. Now to be sure, this was an entertaining storm but I remain unconvinced of it's advertised intensity.

The hurricane hunters observed 65 mph winds in their flight into Andrea before landfall. Surely that gives equal credence, or trumps, any wind gusts observed on land, no?

[psyclone]

The hurricane hunters observed 65 mph winds in their flight into Andrea before landfall. Surely that gives equal credence, or trumps, any wind gusts observed on land, no?

I really don't know. Some of these obs were marine observations. We have a 65mph storm landing in an area rich with both marine and land observations and the max gust observed (In Tampa's CWA) was 60mph (and it was a marine observation at that). My suspicions regarding strength may indeed be incorrect. But expecting a recorded gust that at least matches the stated sustained winds isn't a very high standard. as a side note, the 4 tornadoes recorded in Tampa's CWA were all rated E-F0 with winds ranging from 60-80mph. those storms did cause some damage (as the report linked on their website shows). it therefore seems logical to me that someone somewhere should have some similar damage caused by Andrea's non tornadic winds even if it's a small immediate coastal area in a region of onshore flow. I know of no such damage (perhaps it does exist and I just missed it)
http://www.srh.noaa.gov/images/tbw/TopN ... aWinds.pdf

http://www.srh.noaa.gov/images/tbw/TopN ... nadoes.pdf

[TropicalAnalystwx13]

The hurricane hunters observed 65 mph winds in their flight into Andrea before landfall. Surely that gives equal credence, or trumps, any wind gusts observed on land, no?

I really don't know. Some of these obs were marine observations. We have a 65mph storm landing in an area rich with both marine and land observations and the max gust observed (In Tampa's CWA) was 60mph (and it was a marine observation at that). My suspicions regarding strength may indeed be incorrect. But expecting a recorded gust that at least matches the stated sustained winds isn't a very high standard. as a side note, the 4 tornadoes recorded in Tampa's CWA were all rated E-F0 with winds ranging from 60-80mph. those storms did cause some damage (as the report linked on their website shows). it therefore seems logical to me that someone somewhere should have some similar damage caused by Andrea's non tornadic winds even if it's a small immediate coastal area in a region of onshore flow. I know of no such damage (perhaps it does exist and I just missed it)
http://www.srh.noaa.gov/images/tbw/TopN ... aWinds.pdf

http://www.srh.noaa.gov/images/tbw/TopN ... nadoes.pdf

Weakening tropical storms on landfall appear weaker than they actually were much like strengthening hurricanes seem stronger than they are at landfall.

[chaser1]

Well with respect to intensity I have long believed that intensity tends to be overestimated and this storm is no exception.

Psyclone, I couldn't agree with you more!

(In spite of overstating the obvious here, the following represents Post-Storm Analysis, and therefore represents "my opinion" on the subject and related discussion).

The worse part is that I believe any overestimated wind speeds which may be measuring higher atmospheric elevations perhaps not mixing down to the surface, has less to do with the experienced professionals at NHC, their forecasting skills, or tools at their disposal. I believe this might have more to do with potentially required government policy (or public demand?) as dictated to them for any number of reasons. The result might be less reliance on wind, pressure, or convective consistency (in terms of duration of time) or less conclusive data or observations required to classify a system or for more finite forecasts. The speed that conditions might need to be ingested & reported to the public, may well serve a "better safe than sorry" policy rather than a policy of greater forecast accuracy. Such nuances might strip a seasoned forecaster from one's subjective analysis of any particular storm, present conditions, and near term forecast, to a broader "safer" policy that could affect anything from storm classification to storm warnings.

If society itself is causing greater need to re-define how we classify tropical cyclones so that government officials may better "psychologically reach" the population in potential warning zones (which is my assertion)...., then are we not even further reinforcing the "cry wolf" syndrome when such an event does takes place - and nothing happens??

Tropical Storm Andrea impacted millions with torrential rains and flooding in various locations. Minor wind damage by a much smaller number were predominately experienced by already noted F0 tornadoes and perhaps by other individual storm cells. In many of these cases, far removed from the center (..and yes, this is why we are to pay attention to the "cone" and not simply a point on the map...). Andrea WAS certainly a significant weather event, but a Tropical Storm landfall event? Shouldn't some weather conditions or risk factors still still be associated with "the point on the map" though? Some weather events such as a micro burst effect a town or just a few blocks. Others such as a large gale impacting the Atlantic seaboard might be caused by a very strong pressure gradient. Both may result in severe impact to a neighborhood, a plane, or even to millions experiencing coastal flooding. Regardless, such events do not define a tropical storm or hurricane.

Finally (and quite "tongue in cheek"), perhaps we should simply eliminate the term "tropical depression" and replace it and "tropical storms" with - "Tropical Cone" One day future warnings might sound like "...Tropical Cone Andrea continues moving northeastward and winds within the cone could approach up to 65mph. Remember, everyone in the cone may or may not experience any of the following conditions including (but not limited too) high winds, coastal or area flooding, excessive rains, dry mouth, headaches, rashes and other possible side effects (more severe conditions such as flying roofs, floating barnyard animals, or cargo ships moving through should be reported to your local agency as soon as observed...)...".

If the assertion that most severe conditions within a tropical cyclone typically appear close to (and often to the right of) its center, then in my opinion Andrea misses the mark. If ship reports, dropsounds, buoy's, coastal reporting stations, etc. are not able to measure sustained wind in some direct relationship to the center of a distinct landfall point, then downgrade the status to a Tropical depression. On the other hand, if those standing at sea level and in the path (or just to the right) of Andrea throughout this storms life span were to never experience sustained 39 mph winds, than why are we even giving the storm a name? Very marginal or borderline storm classification might cause greater and earlier public warning but also dummies down the science. As I see it, the risk might be the opposite of how better warnings are intended to serve the general population. That could mean that those who might claim that they experienced Tropical Storm Andrea, might be less inclined to take warnings seriously when the next one comes along.