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Atlantic Tropical Action 2014

hurricaneman

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Ground Scouring

Ground Scouring

Posted
Posted

yea the upper level anticyclone is still displaced a little south of 91L, so its still experiencing light to moderate northwesterly shear. This is probably going to continue for the short term as a shortwave trough passes it by to the northeast. That could result in a little bit of dry air intrusion if it were to lose a lot of the convection that developed north of the llc earlier today. Overall though, the environment isn't too bad, and when the system is forecast to stall closer to the FL coast by the end of the weekend, it could find itself in a near zero shear environment and under ~28 C water temperatures. 

Some dry-air intrusion seems to be occurring in the NW semicircle. I know that northwesterly shear would tend to allow such dry-air intrusion, but what is the source of the dry air? Given the circumstances, 91L seems to be faring decently this evening, as the dry-air intrusion could also concentrate convection to form a tighter LLC. As the system in two days will be stronger than what most models have expected, the center will likely fail to head to the SW for a sustained period of time. But if the shortwave ridging building between the successive troughs is stronger, then the odds increase that 91L will eventually make LF somewhere on the Space Coast of FL before recurving.

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wxmeddler

wxmeddler

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Posted

Some dry-air intrusion seems to be occurring in the NW semicircle. I know that northwesterly shear would tend to allow such dry-air intrusion, but what is the source of the dry air?

 

I don't think it's dry air, it's just lack of convection. The soundings on the coast and the NAM initialization show no dry air in the area of 91L (except N of the front E of VA Beach)

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phil882

phil882

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I don't think it's dry air, it's just lack of convection. The soundings on the coast and the NAM initialization show no dry air in the area of 91L (except N of the front E of VA Beach)

 

Yea the dry air is still too far to the north to really be directly influencing 91L. I was suggesting in the next 24-36 hours it could make it closer to the llc to have a larger impact... the circulation as a whole is still under northwesterly shear, which would probably explain the somewhat asymmetrical appearance currently. Its helping itself by moving south though as it drifts into warmer SSTs and a continued moist environment. 

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phil882

phil882

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Posted

Again the storm continues to outperform expectations of the global and even higher resolution models. The HRRR even its its most recent depictions of the system had it as a naked swirl at around this time devoid of convection. A nice curved band instead has developed along 91L southeastern flank and its looks relatively well organized despite the overall coverage of convection decreasing from earlier today. 

 

ulwrf_t6nta_f08.png

 

post-1749-0-07171600-1404015610_thumb.jp

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Hurr_Tracker13

Hurr_Tracker13

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Posted

Again the storm continues to outperform expectations of the global and even higher resolution models. The HRRR even its its most recent depictions of the system had it as a naked swirl at around this time devoid of convection. A nice curved band instead has developed along 91L southeastern flank and its looks relatively well organized despite the overall coverage of convection decreasing from earlier today. 

 

ulwrf_t6nta_f08.png

 

attachicon.gifir.jpg

I honestly wonder what this system has in store for everyone. could it be a sneaky hurricane who knows.

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phil882

phil882

Posted
Posted

After some digging the only model I found showing anything close to a realistic simulation of the storm currently was the 12z WRF-ARW run... which actually has a decent vortex currently with organized banded convection (not too much unlike what we see currently)

 

wrf-arw_ref_seus_18.png

 

The model goes on to slowly deepen 91L as a 997 hPa system just north of the Bahamas by 12z Monday. I'd say it has just as much validity at the 00 UTC GFS (although does appear to be a touch too strong). 

 

wrf-arw_ref_seus_48.png

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phil882

phil882

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ECMWF takes it down to 994mb off Hatteras @ 144hrs, then down to 979mb off New England @ 168hrs.

 

Yep... the upper-level trough is sharper this run, so it lifts out 91L much faster and east of 12z UTC. Its a close call, but no US landfall. Still this is a 5-7 day forecast and a lot can change. 

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GaWx

GaWx

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ECMWF takes it down to 994mb off Hatteras @ 144hrs, then down to 979mb off New England @ 168hrs.

Whereas anything is possible, it has been noted that the Euro has become somewhat of a weenie model at times during the last several years due to overstrengthening TC's outside of the tropics. We'll see.

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Kory

Kory

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It's looking sickly this morning.  The northerly shear is really affecting it.  It needs to move more SW to get away from the main shear axis affecting it, but as the trough moves off the East Coast, shear should start decreasing.  

 

vis-animated.gif

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U_Thant

U_Thant

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Posted

It's looking sickly this morning.  The northerly shear is really affecting it.  It needs to move more SW to get away from the main shear axis affecting it, but as the trough moves off the East Coast, shear should start decreasing. 

 

While convectively, it's still pretty disorganized, structurally (from the standpoint of low level vorticity), the low cloud elements look much better to me than 24 hours ago. Additionally, the northerly shear is quite divergent (you can see this pretty easily in the CI outflow), which is ventilating the convection. If I was putting 2-day/5-day  development probs on 91L, I would probably have something closer to 80/90 rather than 40/60.

 

YOMV.

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phil882

phil882

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Note: today's recon flight has been cancelled. They will depart at 0930z tomorrow to investigate the system, if necessary.

 

Cancelling the mission today doesn't make any sense (unless they want to save resources)... the storm looks reasonably well organized with decent banding. There was a decent chance they would have made a vortex fix and named this a TD. 

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Srain

Srain

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While the low level vorticity clearly has increased, 91L likely will require another 24 to 36 hours to develop as it nears the Gulf Stream. It is also noteworthy that 91L is being somewhat steered by the U/L/ moving W across the Eastern Gulf. The upper sub tropical ridge should continue to influence this motion for the next 72 hours. Until convection increases significantly, the influence of the upper low may allow a SW drift to continue.

 

wv-animated.gif

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Ground Scouring

Ground Scouring

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Posted

Cancelling the mission today doesn't make any sense (unless they watn to save resources)... the storm looks reasonably well organized with decent banding. There was a decent chance they would have made a vortex fix and named this a TD. 

Cancelling reconnaissance normally occurs if the system deteriorates structurally. This system has held its own since yesterday, so this decision is absolutely senseless. At least we have a well-defined center, so model initializations should improve over the next day.

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Superstorm93

Superstorm93

Posted
Posted

ZCZC MIATWOAT ALL

TTAA00 KNHC DDHHMM

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SUN JUN 29 2014

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. Satellite wind data and surface observations indicate that the low
pressure system located about 230 miles east of St. Augustine,
Florida, is gradually becoming better defined as it moves slowly
southward to southwestward. Although upper-level winds are only
marginally favorable, a tropical depression could still form during
the next day or two. However, the system's proximity to dry air
could inhibit significant development until environmental conditions
become more conducive by late Tuesday while the low meanders
offshore of the Florida east coast. The Air Force Reserve
reconnaissance aircraft that was scheduled to investigate the
disturbance this afternoon has been canceled, and the flight has
been rescheduled for Monday morning, if necessary.
* Formation chance through 48 hours...high...60 percent.
* Formation chance through 5 days...high...80 percent.

 

GFS can't even sniff out genesis on it's own countries doorstep.

 

 

post-3675-0-22871000-1404063142_thumb.pn

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wxeyeNH

wxeyeNH

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So we are up to 80% prob formation chances over 5 days.   I guess the bigger question is where does it go?

 

What does a recon flight cost to go into a system like this?   25K, 50K?   Does recon data get feed into model guidance or would the only purpose at this point is to see if we have a TD or not?   If it is just for that, I would rather save the tax money unless recon data  would tell us more than just looking at the sat loop and surface obs.

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AvantHiatus

AvantHiatus

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So we are up to 80% prob formation chances over 5 days.   I guess the bigger question is where does it go?

 

What does a recon flight cost to go into a system like this?   25K, 50K?   Does recon data get feed into model guidance or would the only purpose at this point is to see if we have a TD or not?   If it is just for that, I would rather save the tax money unless recon data  would tell us more than just looking at the sat loop and surface obs.

This, I imagine it was a combination of saving money and the fact that today is Sunday. Though, they often sample the surrounding environment using dropsondes which supposedly is ingested into the models. 

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phil882

phil882

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Posted

So we are up to 80% prob formation chances over 5 days.   I guess the bigger question is where does it go?

 

What does a recon flight cost to go into a system like this?   25K, 50K?   Does recon data get feed into model guidance or would the only purpose at this point is to see if we have a TD or not?   If it is just for that, I would rather save the tax money unless recon data  would tell us more than just looking at the sat loop and surface obs.

 

I do think at dropsondes get ingested into the models IIRC, and potentially flight level winds.

 

My nagging concern is that the GFS (and CMC to a lesser degree) have done a poor job with the system's evolution thus far, and they continue to forecast little or no development in a seemingly favorable environment.

 

It would be useful to get as much data as possible to see if its an IC error or something in the model physics that are unfavorable for 91L. Moreover the NHC have used recon flights on less impressive systems (including closed circulations occurring in this same area!). I believe there are a certain amount of resources outlined in a budget that are allocated for reconnaissance missions, and considering the likelihood this will be an inactive year, why not go for it, especially when the system is close to land?

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