| Random Chaos |
| (Weather Analyst) |
| Thu Aug 25 2011 10:31 AM |
|
Re: Hurricane Watches Up for the Outer Banks as Irene Heads Through the Bahamas
|
We also have Tropical Depression 10 in the mid Atlantic. It's heading north and should do nothing but spin fish.
Recon
6:30am update: Vortex recon about an hour ago found the eye to be 30nm in diameter, but the max winds out at a band around 45nm diameter. Looks like the ERC mentioned at 11pm is wrapping up and it's now trying to clear out the old core. Central pressure has been steady around 950mb for the last several hours, with an HDOB message within the last few minutes still at that level.
6:50am update: HDOB messages from AF300 found the strongest winds around 35 miles from the center at 112kt. This supports surface winds up to 115mph, matching the 5am advisory. Miss Piggy will be sampling that same region in the next half hour or so.
7:00am update:
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 25th day of the month at 10:49Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 300)
Storm Number & Year: 09L in 2011
Storm Name: Irene (flight in the North Atlantic basin)
Mission Number: 19
Observation Number: 11
A. Time of Center Fix: 25th day of the month at 10:24:50Z
B. Center Fix Coordinates: 25°08'N 76°18'W (25.1333N 76.3W)
B. Center Fix Location: 65 miles (105 km) to the E (86°) from Nassau, Bahamas.
C. Minimum Height at Standard Level: 2,687m (8,816ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 55kts (~ 63.3mph)
E. Location of the Estimated Maximum Surface Wind: 27 nautical miles (31 statute miles) to the SSW (210°) of center fix
F. Maximum Flight Level Wind Inbound: From 290° at 58kts (From the WNW at ~ 66.7mph)
G. Location of Maximum Flight Level Wind Inbound: 25 nautical miles (29 statute miles) to the SSW (208°) of center fix
H. Minimum Sea Level Pressure: 952mb (28.11 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 12°C (54°F) at a pressure alt. of 3,045m (9,990ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 3,051m (10,010ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 11°C (52°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the southwest
M. Eye Shape & Diameter: Circular with a diameter of 30 nautical miles (35 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 2 nautical miles
Remarks Section - Remarks That Were Decoded...
Maximum Wind Outbound: 112kts (~ 128.9mph) in the northeast quadrant at 10:32:00Z
Maximum Flight Level Wind: 112kts (~ 128.9mph) in the northeast quadrant at 10:32:00Z
Remarks Section - Additional Remarks...
EYE WALL WELL DEFINED 020-090
Every IR satellite update the storm is looking healthier right now. Eye is starting to become visible on the last image and is clearing out nicely. It is open south (rotated some from the southwest noted in the vortext recon), but I would expect that to fill quickly. The storm looks very healthy and very large. There is nothing to stop it strengthening over the next few hours.
Track
Majority of the models have shifted far enough west to make the hit in North Carolina rather than Long Island in around 72 hours. There is some divergence following landfall, with some models having the storm re-exit land in North Carolina, while other models drag the storm inland after landfall. This is still far enough off that models will continue to shift, and the storm could move east or west of it's current official track. Given it's track nearly parallel to land, a small shift can result in a huge difference in where landfall occurs, anywhere from South Carolina through Canada.
Land effects on hurricanes tend to drag them to the right when impacting directly due to the spin of the storm and the land-based drag due to the terrain. However, if a storm grazes land on it's left side, as this storm will do, I am not sure if this will cause a faster or slower landfall. The models do not take into account this effect.
The models showing the more inland track are the GFDL and kin, including the GFDT, GFDI, and GFTI. The GFNI and GFDN also make an inland jog, but not so much. Given the accuracy of the GFDL and kin models with past storms, I would not ignore the potential of these tracks. See: http://www.ral.ucar.edu/guidance/realtim..._track_late.png