re: Laura - President Trump visits Lake Charles, Louisiana for Hurricane Response Update

...MARCO STRENGTHENING QUICKLY... ...FORECAST TO BECOME A HURRICANE LATER TODAY...
10:00 AM CDT Sat Aug 22
Location: 20.9°N 85.3°W
Moving: NNW at 12 mph
Min pressure: 992 mb
Max sustained: 65 mph

Tropical Storm Marco Discussion Number 9
NWS National Hurricane Center Miami FL AL142020
1000 AM CDT Sat Aug 22 2020

Reconnaissance data, geostationary and microwave satellite imagery,
and radar data from Cuba all indicate that Marco is strengthening
quickly this morning. The Air Force Reserve Hurricane Hunters
measured a peak 850-mb flight-level wind of 69 kt, and there were
several SFMR measurements of 50-55 kt to the northeast of the
center. These data support raising Marco's initial intensity to 55
kt, and the central pressure based on dropsonde data has fallen to
992 mb. The crew on the plane reported the formation of a partial
eyewall, which agrees with what we've seen on recent microwave and
radar images.

The track forecast has been complicated by the fact that the plane
has fixed Marco's center to the east of the previous forecast
track, and that makes the current motion north-northwestward, or
340/10 kt. The subtropical ridge currently located over the
southwestern Atlantic is forecast to build westward along the
northern Gulf Coast during the next few days, and this expanding
ridge is expected to push Marco northwestward and then eventually
westward while the cyclone moves across the Gulf of Mexico. This
general thinking has not changed, but the adjusted initial position
ended up shifting the track guidance to the north and east on this
cycle. In response, the new NHC track forecast has been adjusted
eastward and northward during the first 3 days and is generally
between the HCCA and TVCN consensus aids.

Marco has finally tapped into the favorable conditions over the
northwestern Caribbean Sea, and the cyclone's overall small size and
small radius of maximum winds makes it susceptible to quick changes
in intensity. The tropical storm is just beginning to move into a
higher zone of shear to its north, but conditions should remain
conducive enough for Marco to intensity to a hurricane during the
next 24 hours. After that time, southwesterly shear is expected to
increase over 20 kt by day 2 and then over 30 kt by day 3, and those
conditions, along with the cyclone's small size, should cause
weakening as Marco gets closer to the central and northwestern Gulf
coast. The updated NHC intensity forecast has been increased during
the first 2 days and lies above the HCCA/Florida State
Superensemble solutions but below the SHIPS/LGEM scenarios. The
intensity forecast comes back in line with the previous forecast by
day 3 during the expected weakening phase, and Marco is ultimately
expected to dissipate over Texas by the end of the forecast period.

The updated track forecast suggests that watches could be required
for a portion of the central Gulf Coast later today.

Key Messages:

1. Marco is forecast to strengthen to a hurricane as it moves into
the southeastern Gulf of Mexico by tonight, and tropical storm
conditions are expected over the northeastern coast of the Yucatan
Peninsula and in extreme western Cuba. Heavy rainfall is also
expected in the eastern portions of the Mexican states of Quintana
Roo and Yucatan, and across far western Cuba, which could result in
flash flooding.

2. Marco is expected to move across the central Gulf of Mexico as a
hurricane Sunday and approach the central Gulf Coast on Monday.
There is an increasing risk of impacts from storm surge, winds, and
heavy rainfall from the upper Texas coast to Louisiana early next
week, and interests there should monitor the progress of Marco, as
storm surge, tropical storm, and/or hurricane watches could be
issued later today.


FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 20.9N 85.3W 55 KT 65 MPH
12H 23/0000Z 22.1N 86.0W 65 KT 75 MPH
24H 23/1200Z 23.9N 87.1W 75 KT 85 MPH
36H 24/0000Z 25.6N 88.4W 75 KT 85 MPH
48H 24/1200Z 27.2N 89.9W 70 KT 80 MPH
60H 25/0000Z 28.5N 91.6W 60 KT 70 MPH
72H 25/1200Z 29.1N 93.6W 50 KT 60 MPH
96H 26/1200Z 29.3N 96.6W 35 KT 40 MPH...INLAND
120H 27/1200Z...DISSIPATED

$$
Forecaster Berg

So if Marco moves more to the north and East, what does that do to Polo (Laura)?

Just when it looked like things were falling into place, twelve hours later things are a mess.

no one knows where these things are going until like the monday-tuesday time frame

i see a spread of models that shows between corpus christi and fricking mobile for laura

interesting from the Laura discussion

quote:

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At this time the influence of
small tropical cyclone Marco, which should move over the
northwestern Gulf about a day or two before Laura, is not expected
to be significant. This could change in the coming days however.

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more interesting stuff from the Laura discussion

quote:

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The official track forecast is only slightly north of the
dynamical model consensus at 36-72 hours and essentially the same as
the consensus otherwise. The GFS and its ensemble mean are
significantly farther west of the official forecast at days 3 and
beyond, which suggests relatively low confidence in the longer-range
track of Laura.

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