Hurricane Gustav – 2008-7

Gustav a Major Category 3 Hurricane

At 7:00am CDT –

– Hurricane warnings continue for the Cayman Islands and
southern/western parts of Cuba.

– The eye of Category 3 Hurricane Gustav was located 85 miles
southeast of the Isle of Youth. General movement is towards the
northwest at 12mph, after a jog to the north-northwest earlier today.
This general motion is expected to continue for the next 24 hours.
Maximum sustained winds have increased to 120mph and Gustav could
reach Category 4 tomorrow. Minimum surface pressure is 955mb.

– Hurricane force winds extend outward to 60 miles from the center and
tropical storm force winds 160 miles from the center.

– Gustav is a large cyclone, do not focus on the pinpoint location or track.

– Tropical Storm Hanna continues north of Puerto Rico with the five
day forecast cone just north of Cuba by early Thursday.

Discussion:

Gustav has undergone the rapid strengthen that has been anticipated
for several days. 11:21z (06:21 CDT) vortex message from the
Hurricane Hunters indicates that 700mb level has decreased over 100
meters during the night time hours. Additionally, the pressure has
dropped to 956, an impressive 19mb drop since 18:20 CDT yesterday. As
such, Gustav is now a major hurricane. The 7am NHC update shows a
pressure of 955, indicative of the rapid changes we're seeing with
Gustav. The forecast intensity remains the same through 24 hours.
Gustav will be moving over very warm waters and the loop-current.
Additional strengthening is likely and Gustav may reach Category 4 by
Sunday morning. After that time Gustav will have passed over the
warmest waters of the Gulf. Additionally, models continue to show a
mid-level trof to the west of Gustav as it moves into the northern
Gulf on Monday. This may induce some shear upon the cyclone. These
two factors could very well weaken Gustav a little. However, at this
time Gustav is expected to make landfall as a Major Category 3
Hurricane. Several of the reliable models have Gustav at 120 kts (Cat
4) Monday morning, with a slight weakening trend to Cat 3 at landfall
Tuesday morning.

The forecast track philosophy remains the same. Gustav is moving on
the western edge of a mid-level ridge over Florida/Bermuda ridge.
This is expected to be the case through the next 48 hours or early
Monday morning. Beyond that time period there are some considerable
uncertainties regarding the track of Gustav. The 00z/06z models are
tightly clustered with landfall on the Louisiana Coast Tuesday
morning. The 00z GFS ensembles are a significant outlier and for now
NHC has ignored these runs. Said runs generally take Gustav away from
the coast and back into the central Gulf. The reliable hurricane
models are clustered in the overall guidance envelope, which is the
Louisiana Coastline. As Gustav approaches landfall late Monday into
Tuesday there are model indications that a high over Ohio will have
developed. Models differ on how far south the ridging extends into
the southeast/south-central U.S. This is why the models significantly
diverge shortly before landfall and especially after. Current
thinking from the NHC is that Gustav will make landfall early Tuesday
morning and slow down. There may also be a bend to the west, which
would take Gustav into east Texas. The slow movement of Gustav is
likely to pose a significant flooding threat for parts of Texas,
Louisiana, and Mississippi.

Finally, the frequency of discussions will increase as landfall approaches.

Note, yesterday I skipped sequence number 5, I'll just keep it going
from here.

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About Putnam Reiter

Putnam has been storm chasing since 1990 and is a co-founder of Hook-Echo.com. For his day job, Putnam works in emergency management for information technology.
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