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Atlantic Tropical Action 2014


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This is the best it has looked all day for sure. Convection in the S-SE quadrant like you said, and the convection in the center has persisted a bit. On the visible you can also see higher storm tops firing up in spots.

 

 

Agreed. There is no real rush here. 

 

Yep....and there's almost no doubt in my mind that we'll have advisories initiated at 5.

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Yeah, SFMR really lighting up now. Also one thing to note is that when the plane was descending through 700mb, the air was pretty dry. 8/-5°C

 

Yep... and that's something that the system will have to work on the next 24 hours... will take some time to moisten up the column.

 

Comparing flight-level data against GFS soundings, looks like GFS was thermodynamically more favorable (more moist) but dynamically lagging behind (winds too weak)... once again demonstrating the need for in-situ obs.  How the ingestion of these new data will affect the 18Z run remains to be seen. 

 

Looks like the 12Z MFL sounding was MUCH more moist than what the hurricane hunters are seeing.  Now that the northerly shear has relaxed, it's only a matter of time that this system mixes out that dry air and becomes more characteristic of the environment it's currently working its way into. 

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Looks like the 12Z MFL sounding was MUCH more moist than what the hurricane hunters are seeing.  Now that the northerly shear has relaxed, it's only a matter of time that this system mixes out that dry air and becomes more characteristic of the environment it's currently working its way into. 

 

It appears that the dew point sensor on the aircraft is malfunctioning, they are down at 970mb and it's showing 22/-8ish°C which is grade A BS.

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A discussion has evolved about how the NHC counts a storm that is a numbered TD at end of one month and gets a name in the following month. In their stats, would that count in the first or second month?

 

There was one example of such a storm with Chris 2006, it was numbered on July 31 but named on August 1st. However, I can't find any monthly counts of storms to see what they did there. Also it was numbered on the evening of July 31st when it was already August 1 in z time. So that may not actually count as an example.

 

For the contest I've ruled that we will count storms in months when first named, but curious as to NHC protocol, or if they have ever updated the numbers in earlier publications where you can see storms by month. A link to any such updated list would be greatly appreciated. (not the updated annual numbers, I know where to find those)

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or79xs.jpg

 

2r42715.jpg

 

This system is still partially interacting with the flow of/some sort of combination between the flow of the older gulf low and the one slowly drifting south of Texas. 

There seem to be possible signs there will be a small unpredictable change in the southeast weather pattern along with this system's development; it could be another weak low forming somewhere north of all of this. 

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The low-level center is rapidly becoming more aligned with the mid-level circulation as it moves SW over the warm Gulf Stream. Given current trends, I expect the system to be much better stacked in the next day. When the transition is complete, the system will likely be deep enough to be pulled N by the trough. When that transition is finished will determine whether the system will make landfall on the east-central FL coast. Currently, the center is following the short-term movements of the fastest models, so I think that the system will make landfall in the Cape Canaveral area before re-emerging over the Atlantic in the Daytona Beach area. Anyway, we'll definitely have Arthur at 5:00 p.m. EDT.

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I'm using google earth for recon, so I don't know how to post (yet) but is anyone else seeing that recon is finding more surface winds over 35kts? Looks to be in one of the storms south of the center.

 

Edit:

 

Time: 18:23:00Z Coordinates: 27.3833N 78.0167W Acft. Static Air Press: 966.0 mb (~ 28.53 inHg) Acft. Geopotential Hgt: 420 meters (~ 1,378 feet) Extrap. Sfc. Press: 1014.6 mb (~ 29.96 inHg) D-value: - Flt. Lvl. Wind (30s): From 206° at 27 knots (From the SSW at ~ 31.0 mph) Air Temp: 18.7°C (~ 65.7°F) Dew Pt: -14.4°C (~ 6.1°F) Peak (10s) Flt. Lvl. Wind: 28 knots (~ 32.2 mph) SFMR Peak (10s) Sfc. Wind: 43 knots (~ 49.4 mph) SFMR Rain Rate: 17 mm/hr (~ 0.67 in/hr) (*) Denotes suspect data

 

Edit again: rain rate contamination?

 

Yea anything over 10 mm/hr I consider rain contaminated so you have to be careful with what wind obs it provides. However SFMR obs in general have pretty high error bars associated with them, so anything that causes the measurement to be more uncertain is essentially thrown out. Those obs on the NW side in the rain free air were in the 35-40 knot range though, so even if these higher obs in the SE corner are thrown out, we have a TS on our hands.

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Watching visible this afternoon has been awesome. You can see how the deeper convection in the southern quadrant of the storm is now drawing in the small surface circulation. The wind core is pretty broad, so this inner wind circulation can easily be "pulled" in the direction where the strongest vertical motion is inducing vortex stretching to the outer wind maxima (in this case in the Southern Quadrant).

 

http://climate.cod.edu/flanis/satellite/1km/index.php?type=S_Florida-vis-48

 

Its also funny how you can see a tiny convective cloud in the inner core that is sheared off to the north as the llc gets drawn into the much larger convective complex to its south.

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That has been interesting to watch this afternoon. Would the llc getting "pulled" under more consistent and deep convection result in better organization?

 

Possibly... this happens with asymmetrical systems all the time. 91L is a good candidate because the winds with the small cloud center we have been following are not as impressive as the winds located 100-200 km outside of the core. The convection is occurring at this outer wind maximum and is possibly inducing vortex stretching where updrafts are "stretching" the vorticity, making it more concentrated and stronger. When this doesn't happen symmetrically around the system (in this case the convection is primarily south of the small vortex) it can force the mean center to shift in the direction of the strongest updrafts, and that appears to be what is happening this afternoon.

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Possibly... this happens with asymmetrical systems all the time. 91L is a good candidate because the winds with the small cloud center we have been following are not as impressive as the winds located 100-200 km outside of the core. The convection is occurring at this outer wind maximum and is possibly inducing vortex stretching where updrafts are "stretching" the vorticity, making it more concentrated and stronger. When this doesn't happen symmetrically around the system (in this case the convection is primarily south of the small vortex) it can force the mean center to shift in the direction of the strongest updrafts, and that appears to be what is happening this afternoon.

Also, pressures are a bit lower just SW of the CoC

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Phil, I agree that the llc is making a beeline for the convection.  What effect, if any, will this have on landfall and eventual track of the TC?  

 

Well if the convection remains offshore, the llc will probably remain offshore... if you are looking at radar the center has actually started to rotate cyclonically around the broader circulation and is moving more due south rather than south-southwest like earlier.

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You can see the dry air nicely looking at WV (and a nice PW overlay product provided by the NHC).

 

GpfOw0u.png

 

PW to the northwest of the system is below 2.00" and drops below 1.50" as you approach the Carolina coastline... its this dry air that had been feeding into the circulation and keeping most of the NW quadrant clear of significant convection. This probably also favors a small TC developing rather than a large sprawling center (like what we see with TC Douglas in the EPAC which have very high mid-level moisture according to SHIPS). If it can just mix out the dry air in its immediate vicinity, it may have the potential for a significant intensification episode in the days to come.

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Sometimes I just don't get the NHC.  Here we have a system, just off the Florida coast that is obviously getting its act together and will impact Florida/SE coast in some way.  So many times we have a crap system way down in the tropics that gets a TD status when it could be argued its not.  Even though at 5pm this system may be just slightly,slightly below the threshold, why in the hell not error on the side that it is a TD.  For the 6pm newscasts, for all the boating interests, on a holiday week a TD is going to get more attention than a system that is not.  Give the heads up now not later this   evening, instead of waiting a few hours when people are not watching news. People will wake up tomorrow AM and have a 50mph named storm just off the coast.Thunderstorms are wrapping around the center, pressure is falling so use common sense and start getting the word earlier verses later.  

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One think I've noticed since the tenure of Dr. Knabb is the reluctance to classify a system unless it absolutely meets the convective criteria. I'm not sure specifically what that threshold is (probably more subjective than objective), but as soon as a system in the EPAC is devoid of convection, it almost immediately becomes a remnant low. I remember in the late 90's and early 00's that those systems were probably held on for and additional 12-24 hours to account for the TC to "spin down" but more recently I've seen the NHC declare a system post tropical even when TS wind criteria is still being met. NHC is just waiting it out to see if the convection is persistent near the center.

 

I'm sure its a pretty difficult decision for them out there, but I would generally agree that this has the criteria of a TD at the very least.

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Recon is done for the day, but it looks like we should have plenty of missions going starting tomorrow afternoon.

000NOUS42 KNHC 301653REPRPDWEATHER RECONNAISSANCE FLIGHTSCARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.0100 PM EDT MON 30 JUNE 2014SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)         VALID 01/1100Z TO 02/1100Z JULY 2014         TCPOD NUMBER.....14-030I.  ATLANTIC REQUIREMENTS    1. SUSPECT AREA (OFF THE FLORIDA EAST COAST)       FLIGHT ONE -- TEAL 70      FLIGHT TWO -- NOAA 49       A. 01/1800Z                A. 02/0000Z       B. AFXXX 02BBA INVEST      B. NOAA9 03BBA SURV       C. 01/1600Z                C. 01/1730Z       D. 28.0N 78.8W             D. NA       E. 01/1745Z TO 01/2200Z    E. NA       F. SFC TO 10,000 FT        F. 41,000 TO 45,000 FT       FLIGHT THREE -- TEAL 71    FLIGHT FOUR -- NOAA 42       A. 02/0600Z, 1200Z         A. 02/0900Z       B. AFXXX 0401A CYCLONE     B. NOAA2 0501A CYCLONE       C. 02/0400Z                C. 02/0600Z       D. 28.6N 80.1W             D. 28.8N 80.0W       E. 02/0530Z TO 02/1200Z    E. 02/0700Z TO 02/1100Z       F. SFC TO 15,000 FT.       F. 12,000 FT    2. SUCCEEDING DAY OUTLOOK:       A. CONTINUE 6-HRLY FIXES.       B. POSSIBLE G-IV MISSION FOR 03/0000Z.       C. POSSIBLE P-3 MISSION AT 02/1800Z    3. REMARKS: MISSION SCHEDULED FOR 01/0000Z AND 01/0600Z       CANCELED BY NHC AT 30/1400Z.II. PACIFIC REQUIREMENTS    1. NEGATIVE RECONNAISSANCE REQUIREMENTS.    2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
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The original LLC seems to be becoming less and less defined over the last several hrs.  Meanwhile, persistent deep convection near Grand Bahama has been resulting in some slow but steady PV re-arrangement.  Unless the original center starts to recover over the next several hrs, I wouldn't be surprised to see the center jump to just north of Grand Bahama island. 

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The original LLC seems to be becoming less and less defined over the last several hrs.  Meanwhile, persistent deep convection near Grand Bahama has been resulting in some slow but steady PV re-arrangement.  Unless the original center starts to recover over the next several hrs, I wouldn't be surprised to see the center jump to just north of Grand Bahama island. 

 

Agree completely, especially with the strongest radar echoes coming out of the complex near Grand Bahama, there is probably plenty of LHR to generate a localized low-level +PV anomaly. Even if the original llc survives, it appears to be rotating counter-clockwise around the larger center that is involved with the stronger feeder band tied to the Grand Bahama convection.

 

x9I2z4A.gif

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Agree completely, especially with the strongest radar echoes coming out of the complex near Grand Bahama, there is probably plenty of LHR to generate a localized low-level +PV anomaly. Even if the original llc survives, it appears to be rotating counter-clockwise around the larger center that is involved with the stronger feeder band tied to the Grand Bahama convection.

 

x9I2z4A.gif

I took a snap shot of the recon which i believe was is the area,is this where you are talking about

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