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From Accuweather:

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Today's Discussion

Today's Discussion Posted: August 27, 2005 2:23 p.m.

A hurricane watch is now in effect for the southeastern coast of
Louisiana east of Morgan City to the mouth of the Pearl River, including metropolitan New Orleans and Lake Pontchartrain. A hurricane watch will likely be issued later today for other portions of the northern Gulf Coast. Tropical storm warning for West of Key West to the Dry Tortugas.

Hurricane Katrina was centered near 24.5 north and 85.4 west as of 2:00 p.m. EDT Saturday. This is about 390 miles southeast of the mouth of the Mississippi River. Maximum sustained winds are near 115 mph with gusts to 140 mph, making Katrina a Category 3 hurricane. Katrina is moving west at about 7 mph. The minimum central pressure remains at 949 mb, or 28.82 inches. Tropical-storm-force winds extend outward up to 150 miles from the storm's center, while hurricane force winds have a radius of nearly 40 miles.

MAXIMUM WIND GUST REPORTS IN SOUTH FLORIDA FROM KATRINA:

MIAMI/TAMIAMI, FLORIDA: 81 MPH MIAMI, FLORIDA: 78 MPH FORT LAUDERDALE, FLORIDA: 68 MPH BOCA RATON, FLORIDA: 65 MPH PORT EVERGLADES, FLORIDA: 92 MPH KEY WEST, FLORIDA: 74 MPH DRY TORTUGAS: 81 with a gust to 105 MPH

RAINFALL THROUGHOUT THE STORM ENDING 11 A.M. SATURDAY:

HOMESTEAD, FLORIDA: 13.62" KEY WEST, FLORIDA: 9.91", MARATHON, FLORIDA: 7.89"

While Katrina remains on a westerly track, a bend to the right may begin to occur later Saturday or Saturday night and a more to the northwest on Sunday, in the general direction of the central Gulf Coast. The storm's movement is being caused by an upper-level high pressure area centered over the southeast US. This high pressure ridge will split, with one part sliding westward and the other becoming a stronger extension of the Atlantic high. Weakness will result in the upper-level wind flow over the central Gulf of Mexico Saturday and Sunday, and Katrina will be driven poleward into that weakness.

Katrina remains a Category 3 hurricane and is appears to be going through eye wall replacement as minimum pressure has risen since Saturday morning. It has an outer eye wall at 50 miles in diameter and an inner eye wall that is in the process of reforming. We should see another drop in pressure later Saturday as the inner eye wall becomes better organized. Further intensification is likely, and Katrina should be a Category 4 hurricane by Saturday night or early Sunday, and could even reach Category 5 intensity. The hurricane will be moving into an area of very warm and deep waters and upper level wind shear will be low during Saturday and Sunday.

The track and future second landfall for Katrina depends on how quickly the upper level high splits over the Southeast and how strong the upper level trough coming in from the northwest digs southwest. The most recent computer models show a consensus track over southeast Louisiana. One concern is that if the upper ridge remains stronger than expected then Katrina would continue on a westerly track longer and the overall track would shift to the west. Our latest thinking is that Katrina will make landfall Monday afternoon over extreme southeastern Louisiana. Conditions will begin to deteriorate later Sunday, well in advance of the storm, with tropical storm force winds reaching the coast later Sunday night and hurricane force winds reaching the coast later Monday morning or early Monday afternoon. In addition to the winds, which will be strong enough to down not only trees and power lines, but also bring down structures and make missiles out of debris. As the storm nears the coast Monday, a devastating storm surge will be pushed into the lower Mississippi Delta as the powerful southeasterly winds pile water into the area. The storm will also bring flooding rains well inland, and the risk for tornadoes north and east of the path of the center.

Elsewhere in the tropics Saturday, a tropical wave along 39 west, south of 18 north, is moving west at 10-15 knots. A tropical low pressure system is now located near 20 north and 51 west; this is in an area with too much shear for development now, but as the shear weakens over the next 24-48 hours, the low could become a tropical depression. This low is moving northwest at 10 knots; no threat to land in the immediate future. Another tropical wave along 88 west, south of 19 north, is moving west at 15 knots.

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