Olga's uncertain status

[MiamiensisWx]

Stu Ostro asks, "Did Olga Make Landfall In Florida As A Tropical Storm?"

This is a fascinating study. Here are my thoughts.

One factor may argue against tropical storm status at the supposed "landfall" in FL. Firstly, the low-level circulation was completely absorbed prior to landfall by the sfc frontal bounday as per satellite data. The circulation east of Clearwater Beach, FL was likely a baroclinically enhanced mesoscale feature. Undoubtedly, a vigorous and broad MLC was likely present. Look at the third radar image in his blog. There is a secondary curvature WSW of Iverness, FL; this is well north of the first circulation's landfall near Clearwater Beach, FL. Again, this is a classic signature of a broad MLC with a transitioning baroclinic system. Personally, I believe the strong dynamics produced a non-representative circulation within the line echo wave pattern. This was supported by the fact that a (much broader) MLC was still present. The strong convective regeneration via interaction with the s/w trough likely produced some tropical-esque dynamics; thus the question says, "What defines a tropical storm or TC regeneration in these cases?" Regardless, I think data is too inconclusive to suggest this was a TS at "landfall" in FL.

I think the Clearwater Beach obs were accurate, but they don't tell the whole story.

Does anyone think this was a "warm" frontal low that was still a baroclinic system in its essence, thus precluding TS classification?

In a nutshell, this is still very interesting synoptic research.

[CrazyC83]

Interesting study. Would it be the latest US tropical storm ever if that is the case?

In my opinion, it was not a tropical cyclone, but rather a squall line.

[JonathanBelles]

It was absorbed by the front before landfall, and therefore extraropical.

[Coredesat]

It also had lost its surface circulation - tropical cyclones by definition have surface circulations. Convection alone does not make something a tropical cyclone.

[HURAKAN]

We have noted many times how tropical cyclones get a kick in organization as a cold front approaches the storm. We saw this with Noel this year. Nonetheless, Olga was a remnant system of its old self. There was some energy left that once felt the effect of the cold front was able to fire intense convection, but nothing that lasted enough to warrant the development of a surface circulation, less an upgrade.

[tolakram]

How is the rapid pressure drop explained?

I'll say it again, we want nice neat little packages for our tropical storms, but nature doesn't work that way. Here you had a pressure drop, wind shift, and a small surge. Without Olga's remnants nearby I doubt this would have happened. So here we are wondering if this blob of weather fit the description of a tropical storm. How is that helpful to protecting people?

In this case the NHC was convinced this was not tropical in nature, so no reconnaissance was done on the system. We missed a learning opportunity. Would this be a concern if we weren't counting storms?

[HURAKAN]

Does anyone have a loop of the time period in question?

[MiamiensisWx]

Interesting points, tolakram.

Firstly, many transitioning baroclinic systems (i.e. former tropical cyclones) retain vorticity or an area of low pressure, which is often aided by the sfc front, trough, or baroclinic factors. Many rapid pressure drops have been observed in these situations. They have also been observed with nor'easters. Obviously, this was not a nor'easter, but you can generally observe pressure drops with any mid-latitude or transitioning system.

I completely agree that the narrow definition of "tropical storm" ignores the threat that transitioning systems (i.e. Olga in FL and Noel in Canada) pose to people. Both of these cases were significant wind events. Additionally, ex-Olga and ex-Noel produced storm surge effects, although ex-Noel (a true nor'easter with a remnant shallow warm residual core) was more severe in this case. Additionally, ex-Olga was a partial contributor to the damaging squall line and tornadoes from the Panhandle to central Florida. Too many people ignore these systems because they are no longer considered "tropical".

A similar attitude can be seen on this boards (not you, tolakram). So much emphasis is placed on tropical cyclones. Obviously, this is understandable because a significant chunk of this board's audience is based on the Gulf coast and other coastal regions, many of which are susceptible to tropical cyclones. On the other hand, weather-related meteorological threats do not end when the hurricanr season ends. You have severe weather, frosts, mid-latitude systems, damaging coastal lows, strong winds via 500 mb gradient, droughts, and numerous additional factors. That's one reason as to why I am surprised these subjects receive so little attention during the Atlantic tropical "off season" (quotations added because of uncertainity regarding the true "end" of the season).

[Coredesat]

How is the rapid pressure drop explained?

Fronts are troughs of low pressure; the pressures associated with the extratropical system were lower than that of the remnants of Olga; the pressure dropped when ex-Olga became incorporated into the front.

[Ptarmigan]

We have noted many times how tropical cyclones get a kick in organization as a cold front approaches the storm. We saw this with Noel this year. Nonetheless, Olga was a remnant system of its old self. There was some energy left that once felt the effect of the cold front was able to fire intense convection, but nothing that lasted enough to warrant the development of a surface circulation, less an upgrade.

I know some tropical systems have become tropical storms over land, when cold fronts interact with them. Agnes and Danny come to mind.

[Ptarmigan]

Interesting throught. If true, than Olga would be the latest landfalling storm. However, that is debatable since it got merged by a cold front.

[boca]

We have noted many times how tropical cyclones get a kick in organization as a cold front approaches the storm. We saw this with Noel this year. Nonetheless, Olga was a remnant system of its old self. There was some energy left that once felt the effect of the cold front was able to fire intense convection, but nothing that lasted enough to warrant the development of a surface circulation, less an upgrade.

I know some tropical systems have become tropical storms over land, when cold fronts interact with them. Agnes and Danny come to mind.

I know Danny formed in 1997 from a cold front that stalled in the N GOM and festered their for a while. Didn't Danny become a storm in the GOM, not over land but in the Gulf of Mexico.

[cag1953]

If I remember right,they upgraded Danny back to tropical storm before it came off the east coast. They said there was so much rain that the storm reacted as if it was over water.

[tbstorm]

Alright, look, this is definately a tropical storm. Closed circulation before landfall, no change of airmass. I can speak personally I observed a low of 1004 mb during the peak winds in St. Petersburg, about 5am. The winds started howling 40+ sustained well before (60 mins) the "squall line' hit.

Let's hope the NCH gives this a FAIR and SCIENTIFIC ANALYSIS.

With the way politics are in Florida, I don't doubt this gets pushed under the rug.

A landfalling Tropical Storm in December? Believe it. It just happened..

[MiamiensisWx]

Alright, look, this is definately a tropical storm. Closed circulation before landfall, no change of airmass. I can speak personally I observed a low of 1004 mb during the peak winds in St. Petersburg, about 5am. The winds started howling 40+ sustained well before (60 mins) the "squall line' hit.

Let's hope the NCH gives this a FAIR and SCIENTIFIC ANALYSIS.

With the way politics are in Florida, I don't doubt this gets pushed under the rug.

A landfalling Tropical Storm in December? Believe it. It just happened..

The TPC didn't hide anything. There is no conspiracy. Every meteorological event is different. If the NHC misses a storm, politics do not play a role, regardless of residents' opinions. The NHC is the only governmental organization that does not "cover up" data. I don't trust governmental decisions and policies, but I think the NHC is a rare exception to the norm.

I have seen several systems (non-tropical) where winds increase because of the gradient. You can observe gusts above TS force prior to any squall line or inclement conditions. You may not believe this is the case, but I have seen this occurrence based on personal experience (like you).

These comments (as a general rule) irritate me. This is not directed specifically toward you.

I'm don't worship every decision made by the TPC, and I have disagreed with some calls, but I think your post doesn't make any sense in this case.

[Derek Ortt]

the winds were not directly due to the circulation.

It may have been a depression, but possibly it was undergoing ET at "landfall"

Besides, why the quibbling over a "40 mph TS"

[Ptarmigan]

If I remember right,they upgraded Danny back to tropical storm before it came off the east coast. They said there was so much rain that the storm reacted as if it was over water.

It appears that Danny was a TS over land right before it went back into the Atlantic. Yes, it had a lot of water, which would explain why Dauphin Island got 36 inches of rain.

Weather Underground-Hurricane Danny 1997

[Coredesat]

Alright, look, this is definately a tropical storm. Closed circulation before landfall, no change of airmass. I can speak personally I observed a low of 1004 mb during the peak winds in St. Petersburg, about 5am. The winds started howling 40+ sustained well before (60 mins) the "squall line' hit.

Let's hope the NCH gives this a FAIR and SCIENTIFIC ANALYSIS.

With the way politics are in Florida, I don't doubt this gets pushed under the rug.

A landfalling Tropical Storm in December? Believe it. It just happened..

There was no closed surface circulation; tropical cyclones by definition must have well-defined surface circulations. It was associated with a very strong cold front, and even then, pressures were much lower to the north of where ex-Olga was absorbed; stations around here were reporting pressures of 996-998 hPa, and we were nowhere near Olga's remnants (which did not move up the front)! Convection alone does not a tropical cyclone make; all the system had was convection, which was mainly due to the cold front. Winds were caused by the pressure gradient between the frontal system and the surface ridge to the east.

This was not a tropical cyclone at landfall. There is no coverup or conspiracy, this is simply what happened. You are out of line for suggesting one.

[brunota2003]

Alright...a few questions to ask.

1) Did it have a closed circulation at the SURFACE?
2) Was it warm-cored?
3) Were the winds gradient induced, or from the "storm" itself?
4) Was it, during any time of this, interacting with the cold front? (ie, becoming absorbed while this was happening, cold front was forcing the convection, otherwise there would of been none, etc...)

If you answer "no" to either 1 or 2, then it does not qualify as a tropical cyclone.

If you answer "yes" to 4, then it does not qualify as a TC.

#3 is just there to determine the status of the system, if it were indeed a TC.


We get TS force winds (or close to it) here in Coastal NC all the time from Nor' Easters, including some that may of been borderline on the warm-cored side of the spectrum, should we include those as Tropical Cyclones? No, because it does not meet all the criteria.

[Squarethecircle]

And, you know, just saying because it hasn't been mentioned, the fact that it didn't even lookthat much like a tropical cyclone was a helpful clue as well.