SUBTROPICAL STORM ANDREA, Analysis, Sat Pics, Models Thread

[cvalkan4]

Jeff Morrow on TWC just said this is a subtropical storm.

[CrazyC83]

The center seems quite exposed - is that normal for subtropical storms? Since it is banding quite nicely now...

[Coredesat]

Jeff Morrow on TWC just said this is a subtropical storm.

Ah, but remember, TWC isn't official, and they tend to get details wrong from time to time.

[skysummit]

Jeff Morrow on TWC just said this is a subtropical storm.

Ah, but remember, TWC isn't official, and they tend to get details wrong from time to time.

Especially when they forget to the check the forums.

[Opal storm]

Jeff Morrow on TWC just said this is a subtropical storm.

Ah, but remember, TWC isn't official, and they tend to get details wrong from time to time.

I only listen to Steve Lyons and Jim Cantore when it comes to the tropics.

[NDG]

Did anyone noticed that the ship reporting near the center of the low is now reporting steady SE Winds in the mid 40mph. That's fairly strong for being so close to the center of the low, "officially" a non-tropical low.

Buoy and ship reports near low pressure center

I've been watching that ship track from SW-NE all day. It went right through the center. Currently, it's in a squall area, which would account for the 40kt wind.

Was 1002 MB the lowest pressure it recorded? That's all I could find.

Also, do you think for being officially a non-tropical system that it has fairly strong winds near its center, correct me if I'm wrong, but don't most non-tropical systems have fairly calm winds around their broad center.

[JonathanBelles]

000
NOUS42 KNHC 081330
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0930 AM EDT TUE 08 MAY 2007
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (WSPOD)
VALID 09/1100Z 10/1100Z MAY 2007
WSPOD NUMBER.....07-001

I. ATLANTIC REQUIREMENTS
1. FLIGHT ONE AREA OFF SOUTH CAROLINA
A. 09/1200Z
B. AFXXX 01AAA INVEST
C. 09/0930Z
D. 31.8N 79.4W
E. 09/1100Z-09/1800Z
F. SFC TO 10,000FT

2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE
WVW

[MiamiensisWx]

With a surface ridge over the low-level circulation, shear has been reduced in the lower levels. Due to deeper heat content and marginally favorable thermodynamics, convection has been developing over the meso signature (and low-level center). As the pressure gradient has relaxed, winds have decreased. As the system has gained some mild warm-core characteristics, there is a transition from a non-tropical low to a hybrid system. Ahead of a frontal boundary, mid-level shear has been preventing further vertical stacking. I believe there is a slight chance for further development before mid-level drier air, lower heat content, and tropospheric shear takes its toll.

http://www.ssd.noaa.gov/goes/east/watl/loop-vis.html

I believe this system might be nearing subtropical depression status.

[CrazyC83]

With a surface ridge over the low-level circulation, shear has been reduced in the lower levels. Due to deeper heat content and marginally favorable thermodynamics, convection has been developing over the meso signature (and low-level center). As the pressure gradient has relaxed, winds have decreased. As the system has gained some mild warm-core characteristics, there is a transition from a non-tropical low to a hybrid system. Ahead of a frontal boundary, mid-level shear has been preventing further vertical stacking. I believe there is a slight chance for further development before mid-level drier air, lower heat content, and tropospheric shear takes its toll.

http://www.ssd.noaa.gov/goes/east/watl/loop-vis.html

I believe this system might be nearing subtropical depression status.

It would become a subtropical storm if it gets the warm core.

[jaxfladude]

Interestingly, this is what NRL has.

20070508.1214.f13.x.85hw.90LINVEST.50kts-NAmb-304N-773W.76pc.jpg

There I posted it!!!

[Thunder44]

Some here are talking about whether this low is cold core or warm core. Well, according to definition of the a "subtropical cyclone" on NHC site glossary, that is irrelevant to determining this is "subtropical". Only that it has no fronts and has both tropical and extratropical characteristics, which this probably has. I feel this system fits more the "second type" of subtropical cyclone.

Subtropical Cyclone:
A non-frontal low pressure system that has characteristics of both tropical and extratropical cyclones.

The most common type is an upper-level cold low with circulation extending to the surface layer and maximum sustained winds generally occurring at a radius of about 100 miles or more from the center. In comparison to tropical cyclones, such systems have a relatively broad zone of maximum winds that is located farther from the center, and typically have a less symmetric wind field and distribution of convection.

A second type of subtropical cyclone is a mesoscale low originating in or near a frontolyzing zone of horizontal wind shear, with radius of maximum sustained winds generally less than 30 miles. The entire circulation may initially have a diameter of less than 100 miles. These generally short-lived systems may be either cold core or warm core.

http://www.nhc.noaa.gov/aboutgloss.shtml

[CrazyC83]

I'm sure there is some debate among the NHC mets right now...a few are probably saying this is currently Subtropical Storm Andrea...

[wxman57]

With a surface ridge over the low-level circulation, shear has been reduced in the lower levels. Due to deeper heat content and marginally favorable thermodynamics, convection has been developing over the meso signature (and low-level center). As the pressure gradient has relaxed, winds have decreased. As the system has gained some mild warm-core characteristics, there is a transition from a non-tropical low to a hybrid system. Ahead of a frontal boundary, mid-level shear has been preventing further vertical stacking. I believe there is a slight chance for further development before mid-level drier air, lower heat content, and tropospheric shear takes its toll.

http://www.ssd.noaa.gov/goes/east/watl/loop-vis.html

I believe this system might be nearing subtropical depression status.

I'm not sure what you're trying to say, but there is no surface ridge, it's a surface low. The low center extends all the way up to the tropopause, typical fo a cold-core low. You can see the various levels on the 12Z GFS 4-panel valid 18Z. Strong low from the surface to 200mb. The surface ridge is well to the northeast - north and west of Bermuda.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _006.shtml

[CrazyC83]

What are the chances of this becoming fully tropical?

[NDG]

What are the chances of this becoming fully tropical?

Very low if any for fully tropical, a little better for subtropical, if it isn't already or real close, but time is running out.

[Coredesat]

I'm sure there is some debate among the NHC mets right now...a few are probably saying this is currently Subtropical Storm Andrea...

They won't do it without recon. Most of the winds are due to the pressure gradient and aren't necessarily from the low itself.

[jaxfladude]

What are the chances of this becoming fully tropical?

Sub-Tropical
NHC/TPC to issue a special statement.
Sub-Tropical Andrea has formed.
The center is located about 240 ese of Brunswick, Ga
Max winds 45. Possible TS watches and/or warnings for Ga south of Savannah to Cape Canaveral Fl.
Those in the affected areas should monitor local NWS and media for official statements.
The above is not an official statement, but, rather, a form of humor due to the history of Stom2K Forums when it comes to TD/TS/'Canes...

[MGC]

Looking at the latest visible loop, it appears that this low has become slightly better organized today with convection now developing closer to the center. Currently I'm betting that the NHC proceeds with recon tomorrow considering how close the system is to the coast. Would not be surprised if recon finds some type of hybrid system and it is declared a STD or STS.....MGC

[Cryomaniac]

What are the chances of this becoming fully tropical?

Very low if any for fully tropical, a little better for subtropical, if it isn't already or real close, but time is running out.

All I'm going to say is, stranger things have happened at sea...

[djones65]

The ship that wxman57 has been tracking all day has moved from west to east through the low pressure system. The sea heights do not seem to be accurate, but the wind speeds, wind direction, and pressure has been consistent since 1200 UTC. The ship has consistently been reporting 35kt northerly winds and a SLP or 29.65" or 1001 mb. Then there was a two hour period with no reports. At 2000 UTC it is on the east side of the circulation center reporting 42kt southeast winds and the surface pressure was 29.60 or 999 mb. It is on the rise now. At the time of the 999 mb pressure the winds were 35-40 kt so one can assume the minimum pressure could be possibly 3 mb lower, but due to the nontropical nature, that may be too steep a gradient, and the likely lowest pressure in my humble opinion is 998 mb. I am assuming at least one mb lower due to the 40kt wind. In other words, the data from this unidentified ship near 31.0N and 77.1W seems to be consistent and the 42kt is not just a squall, but likely due to the eastern side of the low level circulation. The lowest pressure measured by the ship was at 1800 UTC. The pressure is now 29.66 or 1001 mb.
Just my opinion, but there appears to be a nice concentration of maximum winds near the center. I am estimating the radius of maximum wind to be 60 miles since while the ship was traversing the southwestern quadrant they were persistent 35-37kt. As it moved into the northeastern quadrant they increased slightly to 42kt. There were two hours of missing data when the ship would have been very near the center.

My .02 is that this is more non-tropical than tropical, but the appearance on satellite and the winds near the cyclone tells me that it will eventually warrant classification as a subtropical storm either Andrea tomorrow, or #1 in post-analysis at the end of the season.