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Humberto's winds rising as it approaches landfall

By: Dr. Jeff Masters, 12:28 AM GMT on September 13, 2007

The winds of Tropical Storm Humberto are increasing as the storm closes in on the Texas coast east of Galveston. The Hurricane Hunters in their 6:34pm EDT center fix reported a pressure of 998 mb, 7 mb lower than the estimated pressure from the 2 pm EDT advisory from NHC. The pressure was also 998 mb at 7:03pm, indicating that Humberto was taking a break from its intensification spurt. The drop in pressure has driven some stronger winds. The SFMR instrument on the aircraft measured one spot of 67 mph winds at 7:26 pm EDT, 59 mph at 7:08pm EDT, and 61 mph at 6:30pm EDT. These winds were judged as being too isolated to be representative of Humberto's large scale wind field by NHC, which kept Humberto's winds at 50 mph for the 7pm EDT advisory. The storm's relatively high central pressure of 998 mb is reasonable justification for this decision. The Hurricane Hunter airplane has now left Humberto, and a new plane is due to arrive at 2 am EDT.

Radar animations from Houston show a well-defined circulation, with plenty of low-level spiral bands wrapping around the center. The region of winds above 35 knots (40 mph) as estimated by the Houston Doppler radar have shown a steady increase, and there are now a few spots of 50 knot winds (58 mph) in the right front quadrant of Humberto. (keep in mind that due to the curvature of the earth, these winds are measured at an altitude of roughly 2,000 feet 50 miles from the radar). Radar shows that Humberto has not yet begun building an eyewall. With a pressure of 998 mb and only about six hours left before landfall, it is unlikely Humberto will have time to become a hurricane.

Figure 1. Latest radar image from Houston, Texas.

Since Humberto is slow moving, it has the potential to drop rain amounts in excess of ten inches along the Texas and Louisiana coasts over the next two days. It now appears that the Houston area will escape the worst of these rains, which will be concentrated more towards the Texas/Louisiana border region. These rains may cause widespread destructive flooding. Rainfall amounts of 2-3 inches have already occurred along the coast, from Freeport to just beyond the Louisiana border, as estimated by radar. Freeport may have had as much a five inches already.

Links to watch tonight:
Buoy 25 miles east of Galveston
Sabine, Texas C-MAN coastal station.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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