ATL: Tropical Storm Cristobal in North Atlantic

[BigA]

In the past 6 hours, the center has gone from completely exposed to covered by "orange" convection. Though this system may not be a depression yet, it sure appears to be on that road. The radar presentation continues to improve, though I agree with the notion that there are unstacked centers.

[LAwxrgal]

Wow did this thing spin up quickly. I wouldn't be surprised if this gets upgraded to TD3 tonight or tomorrow. Certainly looking better than 94L, that we've been watching for days.

[Brent]

2pm TWO:

THUNDERSTORM ACTIVITY IS CONTINUING TO INCREASE IN ASSOCIATION WITH
A LOW PRESSURE SYSTEM LOCATED JUST OFF THE COASTS OF SOUTH CAROLINA
AND GEORGIA. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR FURTHER
DEVELOPMENT... AND A TROPICAL DEPRESSION COULD FORM LATER TODAY OR
TOMORROW. AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS
SCHEDULED TO INVESTIGATE THIS SYSTEM TOMORROW...IF NECESSARY. ALL
INTERESTS ALONG THE COASTS OF GEORGIA...SOUTH CAROLINA...AND NORTH
CAROLINA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. LOCALLY HEAVY
RAINFALL AND GUSTY WINDS ARE POSSIBLE IN THESE AREAS DURING THE
NEXT COUPLE OF DAYS AS THIS SYSTEM MOVES SLOWLY NORTHEASTWARD NEAR
THE COAST. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE CONSULT
STATEMENTS FROM YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST
OFFICE.

[MiamiensisWx]

The following post is NOT an official prognosis.

If the mid level dry air to the NW doesn't significantly affect the convection via intrusion, I believe this one has a significant chance to eventually gain TS classification. Currently, a H5-H85 shortwave is moving ENE off New England, leaving 96L under low level ridging immediately to its north. Steering should remain weak over the next 24 hours, allowing adept time over water. WV data indicates the upper low further south is partially providing excellent ventilation and divergence, while diffluence from the low levels to upper levels is very good. Shear is clearly minimal for the system. Additionally, 96L is located over warm coastal SSTs, with higher OHC (oceanic heat content) associated with the deep Gulf Stream located under the eastern semicircle. This is contributing to an unstable boundary layer over the eastern portion of the system (east of the LLC, which is located just off the GA/SC border). Rapid ascent of parcels is allowing unabated development of additional convection in all quadrants, especially the eastern one over the Gulf Stream. This is important, as I will demonstrate in the next paragraph.

The NWS doppler radar composite for the Southeast indicates the LLC is offshore near the Georgia/South Carolina border, as I previously mentioned. Mid level rotation is evident further southeast in the vicinity of the most expansive convection and thunderstorms. With convection increasing in this region over the Gulf Stream, I would not be surprised if the current LLC eventually dissipates and reforms further SE (even further offshore), coinciding with the location of the broad mid level rotation. This makes sense, since the boundary layer is most unstable in this region, and stronger thunderstorms should result in greater low level inflow in the area adjacent to the mid level circulation. This would allow even more time offshore, so TS status is very probable. 850 mb low level vorticity is sufficient in the immediate vicinity as well.

This one could intensify more than some anticipate... watch it.

[OuterBanker]

Derek, Senor and other mets. A couple questions.

1 - Is 96L in an area in which upwelling can inhibit formation, or does this not occur in weak systems?

I know that if it gets into the gulf stream it's a moot point because of deep warm water.

2 - How far is center from gulf stream in the area of 96L.

[senorpepr]

Derek, Senor and other mets. A couple questions.

1 - Is 96L in an area in which upwelling can inhibit formation, or does this not occur in weak systems?

I know that if it gets into the gulf stream it's a moot point because of deep warm water.

2 - How far is center from gulf stream in the area of 96L.

Derek may be better on the upwelling question, but with a weaker system, upwelling would be slower to occur. FWIW, it appears water temperatures are slightly cool (by a few degrees) where 96L is at versus a couple hundred miles eastward (gulf stream).

[MiamiensisWx]

The following post is NOT an official prognosis.

If the mid level dry air to the NW doesn't significantly affect the convection via intrusion, I believe this one has a significant chance to eventually gain TS classification. Currently, a H5-H85 shortwave is moving ENE off New England, leaving 96L under low level ridging immediately to its north. Steering should remain weak over the next 24 hours, allowing adept time over water. WV data indicates the upper low further south is partially providing excellent ventilation and divergence, while diffluence from the low levels to upper levels is very good. Shear is clearly minimal for the system. Additionally, 96L is located over warm coastal SSTs, with higher OHC (oceanic heat content) associated with the deep Gulf Stream located under the eastern semicircle. This is contributing to an unstable boundary layer over the eastern portion of the system (east of the LLC, which is located just off the GA/SC border). Rapid ascent of parcels is allowing unabated development of additional convection in all quadrants, especially the eastern one over the Gulf Stream. This is important, as I will demonstrate in the next paragraph.

The NWS doppler radar composite for the Southeast indicates the LLC is offshore near the Georgia/South Carolina border, as I previously mentioned. Mid level rotation is evident further southeast in the vicinity of the most expansive convection and thunderstorms. With convection increasing in this region over the Gulf Stream, I would not be surprised if the current LLC eventually dissipates and reforms further SE (even further offshore), coinciding with the location of the broad mid level rotation. This makes sense, since the boundary layer is most unstable in this region, and stronger thunderstorms should result in greater low level inflow in the area adjacent to the mid level circulation. This would allow even more time offshore, so TS status is very probable. 850 mb low level vorticity is sufficient in the immediate vicinity as well.

This one could intensify more than some anticipate... watch it.

...and most people are perplexingly focusing on 94L, which clearly does not have a chance and is not threatening land (Central America/Mexico) at the immediate moment. I'm curious on why reconnaissance is focusing on 94L instead of 96L.

Hopefully, Southeast coastal residents are keeping a close eye on this one.

[storms in NC]

Tropical Depression

Once a group of thunderstorms has come together under the right atmospheric conditions for a long enough time, they may organize into a tropical depression. Winds near the center are constantly between 20 and 34 knots (23 - 39 mph).

A tropical depression is designated when the first appearance of a lowered pressure and organized circulation in the center of the thunderstorm complex occurs. A surface pressure chart will reveal at least one closed isobar to reflect this lowering.



Image provided by TPC
When viewed from a satellite, tropical depressions appear to have little organization. However, the slightest amount of rotation can usually be perceived when looking at a series of satellite images. Instead of a round appearance similar to hurricanes, tropical depressions look like individual thunderstorms that are grouped together. One such tropical depression is shown here.



--------------------------------------------------------------------------------

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/stages/td.rxml

[kurtpage]

The following post is NOT an official prognosis.

If the mid level dry air to the NW doesn't significantly affect the convection via intrusion, I believe this one has a significant chance to eventually gain TS classification. Currently, a H5-H85 shortwave is moving ENE off New England, leaving 96L under low level ridging immediately to its north. Steering should remain weak over the next 24 hours, allowing adept time over water. WV data indicates the upper low further south is partially providing excellent ventilation and divergence, while diffluence from the low levels to upper levels is very good. Shear is clearly minimal for the system. Additionally, 96L is located over warm coastal SSTs, with higher OHC (oceanic heat content) associated with the deep Gulf Stream located under the eastern semicircle. This is contributing to an unstable boundary layer over the eastern portion of the system (east of the LLC, which is located just off the GA/SC border). Rapid ascent of parcels is allowing unabated development of additional convection in all quadrants, especially the eastern one over the Gulf Stream. This is important, as I will demonstrate in the next paragraph.

The NWS doppler radar composite for the Southeast indicates the LLC is offshore near the Georgia/South Carolina border, as I previously mentioned. Mid level rotation is evident further southeast in the vicinity of the most expansive convection and thunderstorms. With convection increasing in this region over the Gulf Stream, I would not be surprised if the current LLC eventually dissipates and reforms further SE (even further offshore), coinciding with the location of the broad mid level rotation. This makes sense, since the boundary layer is most unstable in this region, and stronger thunderstorms should result in greater low level inflow in the area adjacent to the mid level circulation. This would allow even more time offshore, so TS status is very probable. 850 mb low level vorticity is sufficient in the immediate vicinity as well.

This one could intensify more than some anticipate... watch it.

...and most people are perplexingly focusing on 94L, which clearly does not have a chance and is not threatening land (Central America/Mexico) at the immediate moment. I'm curious on why reconnaissance is diverted to 94L instead of 96L.

Hopefully, Southeast coastal residents are keeping a close eye on this one.

Because there was not a 96L when they started recon on 94L. I do not believe that they diverted anything...

[Stratosphere747]

I'm curious on why reconnaissance is diverted to 94L instead of 96L.

That's just not true. Recon was never diverted.

[MiamiensisWx]

I'm curious on why reconnaissance is diverted to 94L instead of 96L.

That's just not true. Recon was never diverted.

My wording was false; I meant that recon was originally scheduled for 94L.

I know that "diverted" and "planned" are different definitions.

Regardless, it may be prudent for one of the two flights to be diverted to 96L, since the current one is clearly finding a surface trough/no LLC with 94L.

Note: I edited my original post... I apologize to the excellent recon/NOAA crews out there!!!

[storms in NC]

Derek, Senor and other mets. A couple questions.

1 - Is 96L in an area in which upwelling can inhibit formation, or does this not occur in weak systems?

I know that if it gets into the gulf stream it's a moot point because of deep warm water.

2 - How far is center from gulf stream in the area of 96L.

Derek may be better on the upwelling question, but with a weaker system, upwelling would be slower to occur. FWIW, it appears water temperatures are slightly cool (by a few degrees) where 96L is at versus a couple hundred miles eastward (gulf stream).

It all dependes where you are at. Just here in NC it can be 50 miles to 100 miles out. here is a map of the gulf stream

[cycloneye]

On page 12 there is what NHC plans for this system in terms of recon.

[Stratosphere747]

I'm curious on why reconnaissance is diverted to 94L instead of 96L.

That's just not true. Recon was never diverted.

My wording was false; I meant that recon was originally scheduled for 94L.

I know that "diverted" and "planned" are different definitions.

Fair enough and as Pojo and some of the more knowledgeable folks about recon can attest to. Planning and organizing a recon mission is a much more complex issue than many realize.

[senorpepr]

Derek, Senor and other mets. A couple questions.

1 - Is 96L in an area in which upwelling can inhibit formation, or does this not occur in weak systems?

I know that if it gets into the gulf stream it's a moot point because of deep warm water.

2 - How far is center from gulf stream in the area of 96L.

Derek may be better on the upwelling question, but with a weaker system, upwelling would be slower to occur. FWIW, it appears water temperatures are slightly cool (by a few degrees) where 96L is at versus a couple hundred miles eastward (gulf stream).

It all dependes where you are at. Just here in NC it can be 50 miles to 100 miles out. here is a map of the gulf stream

I was basing my numbers from observations.

[Ed Mahmoud]

...and most people are perplexingly focusing on 94L, which clearly does not have a chance and is not threatening land (Central America/Mexico) at the immediate moment. I'm curious on why reconnaissance is focusing on 94L instead of 96L.

Hopefully, Southeast coastal residents are keeping a close eye on this one.

I was quite certain Miami was wrong on his call on 94L mid-morning. I was certain recon would find a 40-ish knot storm. I can't even find a West wind of note, meaning 94L is less organized today than yesterday. I'll have to remember that next time I publically doubt his analysis.


96L obviously is well organized, even if the winds aren't up yet. 94L should have had a recon today based on satellite imagery, but this is closer to land and a more immediate threat.

[fci]

...and most people are perplexingly focusing on 94L, which clearly does not have a chance and is not threatening land (Central America/Mexico) at the immediate moment. I'm curious on why reconnaissance is focusing on 94L instead of 96L.

Hopefully, Southeast coastal residents are keeping a close eye on this one.

I was quite certain Miami was wrong on his call on 94L mid-morning. I was certain recon would find a 40-ish knot storm. I can't even find a West wind of note, meaning 94L is less organized today than yesterday. I'll have to remember that next time I publically doubt his analysis.


96L obviously is well organized, even if the winds aren't up yet. 94L should have had a recon today based on satellite imagery, but this is closer to land and a more immediate threat.

Amatuer here, but isn't 96L's proximity to the coast a reason recon isn't needed since there are surface and radar observations that can keep the NHS well informed?

[Hurricanewatcher2007]

No Recon will be needed. However 96L pretty much popped up quickly and it takes time to get a recon mission together. Recon will be started on 96L tomorrow.

[storms in NC]

Growing as time gos by.

http://www.ssd.noaa.gov/goes/flt/t4/loop-vis.html

[Brent]

Growing as time gos by.

http://www.ssd.noaa.gov/goes/flt/t4/loop-vis.html

I'll be surprised if this isn't a TD by the end of the day(as in 11pm).