Frances Could Strengthen Somewhat Prior to Landfall

[donsutherland1]

The ingredients are falling into place for Hurricane Frances to strengthen somewhat prior to landfall:

• Frances is now over 30°C waters
• The depth of the 26°C waters is now greater than 100 meters
• The shear has been relaxing somewhat over the past 24 hours

<img src="http://www5.wright-weather.com/bb/attachment.php?s=&postid=307120">
24-Hour Wind-Shear Tendency (9/4 12z)

The Hurricane Heat Content scores are as follows:

9/4 9z: 25.207
9/4 18z: 50.000

As one can see from above, over the next 6-10 hours or so, Frances will be in a good environment for strengthening and I believe some strengthening will occur. In a worst-case scenario, Frances could regain Category 3 status prior to landfall. At this time, I would not be surprised if Frances' maximum sustained winds increase to 110 mph to 115 mph prior to landfall.

[donsutherland1]

Consistent with this morning's discussion, it now appears that Frances is taking advantage of its environment and has begun to deepen at an increasing rate. The central pressure has fallen 11 mb (0.32") since the 5 pm EDT advisory.

URNT12 KNHC 042224
VORTEX DATA MESSAGE
A. 04/2224Z
B. 26 DEG 55 MIN N
79 DEG 18 MIN W
C. 700 MB 2721 M
D. NA
E. NA
F. 142 DEG 100 KT
G. 049 DEG 039 NM
H. 951 MB
I. 9 C/ 3051 M
J. 15 C/ 3061 M
K. 15 C/ NA
L. CLOSED WALL
M. C60
N. 12345/07
O. 1 /1 NM
P. AF980 3006A FRANCES OB 08
MAX FL WIND 100 KT NE QUAD 2212Z. PARTIAL INNER EYEWALL 10-15NM
DIAMETER POORLY CORRELATED WITH FL AND SURFACE CENTER.

With several more hours to go before landfall and potentially rapid deepening that has commenced, this is a disturbing and dangerous situation for the Florida coastline. As I noted earlier, I believe Frances will likely have maximum sustained winds of 110 mph to 115 mph prior to landfall.

[tronbunny]

Thank you for your analysis.

To come onshore around Vero within the next 3-4 hours
Winds 100+ already onshore.
Now is she headed on that WNW track..
Running south of yesterdays track?

I just don't want Orlando get >TS winds

[donsutherland1]

I wish Florida all the best in weathering this dangerous hurricane. I'm quite concerned about wind damage along the coast and somewhat inland and also the flooding rains from its very slow movement.

If there's one small silver lining, it is that the hurricane does not appear as responsive to changes in the barometric pressure as some other hurricanes (e.g., Charley's winds increased faster than its central pressure dropped; he had 145 mph winds when a 941 mb pressure suggested 135 mph to 140 mph). Changes in Frances' wind speed--up and down--have consistently lagged changes in its central pressure. Hence, even as the pressure begins to fall quickly, the winds should not immediately increase.

Just another quick note, I just saw the 8 pm advisory. Maximum winds were held at 105 mph. Typically a storm with a 951 mb pressure has maximum winds in the 120 mph +/- 5 mph vicinity. This seems to confirm that strengthening in the storm's winds is lagging its drop in pressure.

I still believe one will see the winds increased at the 11 pm advisory. Hopefully, the increase won't be too significant and it will continue to lag any further decreases in its pressure.

[ncbird]

Thank you donsutherland... was just gonna ask for clarification as to what reason there could be for them not upgrading this storm. You read my mind and aswered it before my fingers to do the keyboard walk.

[donsutherland1]

Ncbird,

Given improved satellite presentation and the recent data, I would be surprised if increased winds are not reported at 11 pm.

An example of some of the lags in changes in reported pressure include:

942 mb: Implied winds: 140 mph; Reported winds: 140 mph
935 mb: Implied winds: 145 mph; Reported winds: 120 mph
938 mb: Implied winds: 145 mph; Reported winds: 145 mph
949 mb: Implied winds: 125 mph; Reported winds: 145 mph
948 mb: Implied winds: 125 mph; Reported winds: 140 mph
954 mb: Implied winds: 120 mph; Reported winds: 120 mph
961 mb: Implied winds: 110 mph; Reported winds: 115 mph
960 mb: Implied winds: 110 mph; Reported winds: 105 mph