WeatherNut
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Something else odd was in the latest vortex was an 8C temp difference inside the center and out. Thats 2C higher than Bret had
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Born into Cleo (64)...been stuck on em ever since
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hogrunr
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Other info that changed in the 10am CDT update...305 (was 300) degree motion...faster at 14mph instead of 10mph previously, and the TS winds extend up to 60 miles (changed from 45 miles previously).
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MichaelA
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Quote:
13:49:30Z 24.017N/ 89.917W extrapolated surface pressure 999.5 mb(~ 29.52 inHg)
This looks to be the pressure and wind center here. Lowest pressure, and wind direction switched nearly 180 degrees.
That puts the center very near the north edge of the convection, so this looks like it may be a tilted system with the mid-level CoC to the south of the surface center.
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Michael
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WesnWylie
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Quick question: With a tilted system (displaced mid-level circulation), aside from a re-developing/re-locating LLC, is there anyway for it to become vertically stacked?
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Quote:
13:49:30Z 24.017N/ 89.917W extrapolated surface pressure 999.5 mb(~ 29.52 inHg)
This looks to be the pressure and wind center here. Lowest pressure, and wind direction switched nearly 180 degrees.
That puts the center very near the north edge of the convection, so this looks like it may be a tilted system with the mid-level CoC to the south of the surface center.
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2011 Season Forecast: 16/09/04
2011 Systems: 10/01/01
Edited by WesnWylie (Thu Jul 28 2011 03:30 PM)
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Ed Dunham
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)
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Note that the Discussion Bulletin expects the northerly wind shear to remain over the system until landfall, so the short answer regarding a vertically stacked system is 'not very likely'. That is the same reason, along with continued entrainment of drier air from the west, that hurricane intensity is not very likely as well.
ED
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MikeC
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Recon is finding the strongest winds away from the center, it recently found a 50 knot flight level wind. Likely means Don will strengthen a little more, but likely not too much more than it is now.
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danielw
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Quote:
Something else odd was in the latest vortex was an 8C temp difference inside the center and out. That's 2C higher than Bret had
Thanks, I missed that.
That could be significant. Shows the system is beginning to act more like a vacuum.
Thought for the Mets. ULL to the east gives Don a northerly upper level wind flow on the eastern side of the storm. AND ULL to the west gives Don a southerly wind flow on the western side of the storm.
Increasing the vorticity?? in the upper levels??
Visible satellite photos are still showing the arcs of cumulus to the NW of DON. Suggestive of no lower level shear.
Edited by danielw (Thu Jul 28 2011 04:16 PM)
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danielw
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Remarks Section:
Maximum Flight Level Wind: 52kts (~ 59.8mph) in the northeast quadrant at 15:26:00Z
Latest Eye dropsonde is indicating 1005mb (29.68 inHg).
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 16:15Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Storm Number & Year: 04L in 2011
Storm Name: Don (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 11
A. Time of Center Fix: 28th day of the month at 15:48:40Z
B. Center Fix Coordinates: 24°15'N 90°19'W (24.25N 90.3167W)
B. Center Fix Location: 396 miles (638 km) to the S (182°) of New Orleans, LA, USA.
C. Minimum Height at Standard Level: 1,458m (4,783ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 45kts (~ 51.8mph)
E. Location of the Estimated Maximum Surface Wind: 86 nautical miles (99 statute miles) to the NE (48°) of center fix
F. Maximum Flight Level Wind Inbound: From 150° at 52kts (From the SSE at ~ 59.8mph)
G. Location of Maximum Flight Level Wind Inbound: 70 nautical miles (81 statute miles) to the NE (48°) of center fix
H. Minimum Sea Level Pressure: 1005mb (29.68 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,524m (5,000ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 24°C (75°F) at a pressure alt. of 1,524m (5,000ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 9°C (48°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 52kts (~ 59.8mph) in the northeast quadrant at 15:26:00Z
Edited by danielw (Thu Jul 28 2011 04:29 PM)
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berrywr
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This is my first post on the website this season so let me first say hello to everybody. I've looked at the new 12Z package and read everybody's post as of noon ET.
The shear over the storm is currently between 10 & 15 knots from the north and northeast with less than 5 knots in a generally north to south axis just ahead of its track. The amount of shear is not enough to impose any strengthening issues at this time.
Water vapor imagery shows relatively dry air along the track and I did look at the most current dry air imagery from CIMMS and there is dry air indicated to the west and less so to the NW of the storm and particularly over land where almost the entire state of TX is experiencing an "Exceptional" drought.
As per , the models are split; half along a NW track, the other half more west.
The vortex structure; it is in fact not aligned and as satellite imagery indicates...it's not too well put together and what appears as the center on satellite is the mid-level center displaced from the surface which is to the northeast under convection.
Not to stray too much from what I posted over on the Flhurricane FaceBook page...Don may become a minimum hurricane but it's greatest benefit is for it to be a strong Tropical Storm and it's bands to gradually open outward as it spirals downward following landfall and provide the beneficial rainfall TX needs.
Edited by danielw (Thu Jul 28 2011 04:38 PM)
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danielw
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Thanks, Bill.
Last drop indicates the warm air is indeed being ingested into the Center.
843mb 23.0°C (73.4°F) near 5000 feet__Dew Point Approximately 9°C (48°F) 41% Humidity
1005mb 28.2°C (82.8°F) (Surface)__Dew Point 27.4°C (81.3°F) 95% Humidity
Edited by danielw (Thu Jul 28 2011 05:04 PM)
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Fairhopian
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If the low-level center were to eventually align with the mid-level center (say later today), would we likely be able to actually see an eye, and would that eye likely be the size of the current mid-level center as it appears now? If so, would an eye that large tend to steer the storm in a more polar direction?
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Ed Dunham
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)
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While the near-term shear level is low and by itself would not hinder intensification, as noted above, the verticle displacement of the current cyclone is considerable - probably around 70NM between the low-level and high-level circulation centers. This displacement with height to the south would take quite some time to vertically align. Even if the dry air was not a factor it would be difficult for the system to have enough time to align in the vertical prior to landfall.
Its worth noting that the windshear is expected to increase considerably (admittedly from a product) between tonight and Friday morning (time-sensitive link) although the near-shore windshear should be lower:
UNISYS 36hr Shear Forecast
ED
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danielw
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Visible below is somewhat centered on the LLC. Low Level Center. LLC can be imagined by locating the outer bands/ arcs at the surface.
The second photo is the enhanced IR image with a CHT, Convective Hot Tower developing near where the LLC should be. CHT is near the green blob. Which is the cauliflower looking cloud in the middle of the upper photo.
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WesnWylie
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The blow-up near the LLC continues to grow. Don has begun to look more like a Tropical Storm over the last hour or so. It'll be interesting to see what the next RECON flight reports. By the way, the latest BAM models have tightened up and show a landfall between Brownsville and Corpus Christi.
5:10 PM CDT Update: Correct me if I am wrong guys, but is the latest RECON reporting winds over 60 mph with Don? (Source: http://tropicalatlantic.com/recon/) Time: 21:56 UTC
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2011 Season Forecast: 16/09/04
2011 Systems: 10/01/01
Edited by WesnWylie (Thu Jul 28 2011 10:15 PM)
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MikeC
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There may be a center relocation coming fo Don, a few points south, closer to the convection, which would give it another shot to intensify some, but also move the forecast track further south.
That entire recon report is suspect, the rainfall rate was a bit too crazy too.
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MikeC
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Then again, recon was in the area of this possible hot tower.
So it's definitely something to verify first. If this sustains, then that center reformation may really be occurring, and things change a bit. Not too alarming yet, but it would bring the track further south than is currently in the forecast.
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danielw
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I see quite a bit of outflow around Don. Not bad for a suppressed/ squeezed cyclone.
I don't know how much the outflow will assist in Don intensifying.
It also indicates the wind shear is lightening up in the area of Don.
Oop, Sorry about that Mike i didn't know you were posting. Image removed... See Mike's above.
Edited by danielw (Thu Jul 28 2011 10:36 PM)
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cieldumort
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In regards to Don re-centering within deep convection, here is a screen shot (Google Earth) of the latest recon mission, clearly showing the surface center now aligning itself much more with the deepest convection, and likely as well, with the mid-level circulation.
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MikeC
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A second recon plane is en route to Don now, the NOAA (NOAA2) plane is the one with the high wind reading, the Air force one (307) is about halfway to Don now. It'll be interesting to see if there was anything to it. It definitely caught my eye once I double checked it with satellite.
A few more passes, along with the air force plane, to confirm this will tell a lot.
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Ed Dunham
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)
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Upper level outflow does seem to be improving - to the west. Will be interesting to see if changes anything with the Intermediate update. Probably just wait until the 11pm when they will have more recon data to work with.
ED
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