Sunday, October 23, 2011

Good evening all,

The area of disturbed weather in the western Caribbean has finally developed a low level circulation. The latest Air Force Hurricane Hunter aircraft found a low level center and NHC has issued the first advisory on TD-18. The last Vortex message from the recon aircraft was:

URNT12 KNHC 232100
A. 23/20:38:20Z
B. 15 deg 39 min N
  081 deg 52 min W
D. 17 kt
E. 090 deg 0 nm
F. 160 deg 12 kt
G. 093 deg 15 nm
H. EXTRAP 1008 mb
I. 25 C / 211 m
J. 25 C / 212 m
K. 23 C / NA
N. 35 / 1
O. 0.02 / 10 nm
P. AF306 01KKA INVEST             OB 14
MAX FL WIND 12 KT E QUAD 20:33:00Z

The decode information is as follows:
Product: Air Force Vortex Message (URNT12 KNHC) 
Transmitted: 23rd day of the month at 21:00Z 
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306) 
Mission Purpose: Investigate tenth suspect area (flight in the North Atlantic basin) 
Mission Number: 1
Observation Number: 14 
A. Time of Center Fix: 23rd day of the month at 20:38:20Z 
B. Center Fix Coordinates: 15°39'N 81°52'W (15.65N 81.8667W)  
B. Center Fix Location: 255 miles (410 km) to the S (187°) from George Town, Cayman Islands (GBR). 
C. Minimum Height at Standard Level: Not Available 
D. Estimated (by SFMR or visually) Maximum Surface Wind: 17kts (~ 19.6mph) 
E. Location of the Estimated Maximum Surface Wind: 0 nautical miles (0 statute miles) to the E (90°) of center fix
F. Maximum Flight Level Wind Inbound: From 160° at 12kts (From the SSE at ~ 13.8mph) 
G. Location of Maximum Flight Level Wind Inbound: 15 nautical miles (17 statute miles) to the E (93°) of center fix
H. Minimum Sea Level Pressure: 1008mb (29.77 inHg) - Extrapolated 
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 25°C (77°F) at a pressure alt. of 211m (692ft) 
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 25°C (77°F) at a pressure alt. of 212m (696ft) 
K. Dewpoint Temp (collected at same location as temp inside eye): 23°C (73°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 
O. Navigation Fix Accuracy: 0.02 nautical miles 
O. Meteorological Accuracy: 10 nautical miles 
Remarks Section:
Maximum Flight Level Wind: 12kts (~ 13.8mph) in the east quadrant at 20:33:00Z
Maximum Flight Level Wind Outbound: 31kts (~ 35.7mph) in the southwest quadrant at 20:54:00Z 
Sea Level Pressure Extrapolation From: Below 1,500 feet

The maximum sustained winds are near 30 knots and it is expected that the storm will strengthen and become tropical storm Rina within the next day or so. 
Steering flow is very weak and upper level shear to the north is increasing from around 40 knots to near 60 knots over the southern Gulf of Mexico. 
The forecast solutions are a bit diverse in the current runs as they have the storm in slightly different locations across the western Caribbean to the western tip of Cuba before it gets sheared apart. Below is the National Hurricane Center forecast points which has split the difference in the forecast points from the GFS and the ECMWF. 

So the main area of concern will include the Gulf of Honduras which our friends Delfina and Mitch Mitchell live on an island off the coast of Belize. 

The only forecast issue for south Florida and the Keys will be potential for rain. The further north the system drifts, the more likely we will have a rainfall event, hopefully not similar to last week. So we wait for  a few more model runs with the initialized circulation dropped into the algorithm to have a more cohesive result.


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