[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 041445
TCDAT3

Tropical Depression Cristobal Discussion Number  12
NWS National Hurricane Center Miami FL       AL032020
1000 AM CDT Thu Jun 04 2020

With the center remaining inland, Cristobal has continued to
weaken, and the cloud pattern is becoming disorganized.  The
current intensity is reduced to 30 kt for this advisory, and the
warnings for the Bay of Campeche coast of Mexico have been
discontinued.  Assuming that the center will emerge over the Gulf of
Mexico in about 36 hours, re-intensification should begin by
tomorrow evening.  The environment over the Gulf of Mexico is not
expected to be very conducive for intensification, with moderate
southwesterly shear and some dry mid-level air.  Not surprisingly,
the intensity guidance, such as HWRF and LGEM, are not very bullish
on strengthening.  The official forecast remains a little above the
latest intensity model consensus.  It should still be noted,
however, that there is some uncertainty as to the strength of
Cristobal when it reaches the northern Gulf of Mexico coast due to
the limitations of forecasting tropical cyclone intensity change.

The cyclone continues to move slowly east-southeastward, or 120/3
kt.  Over the next day or so, Cristobal is likely to move along a
partial cyclonic loop while embedded within a broader gyre.  By
tomorrow night, the system should have begun moving northward into
a weakness in the subtropical ridge.  This generally northward
motion should continue until the center crosses the northern
Gulf coast.  There have been no important changes to the NHC track
forecast, which is a blend of the simple and corrected dynamical
model consensus aids.

The global models indicate that Cristobal's wind field will expand
as the cyclone deepens over the south-central Gulf of Mexico.
Therefore, the size of the NHC wind radii have again been increased
primarily over the eastern semicircle at 36-72 hours.  Indeed,
the models suggest that when the storm reaches the northern Gulf
coast, the worst conditions may occur at a large distance from the
center.

Key Messages:

1. Damaging and deadly flooding has already been occurring in
portions of Mexico and Central America.  Cristobal is expected to
produce additional extreme rainfall amounts through the end of the
week.  The heaviest additional rainfall is expected over far
southern Mexico and portions of the Yucatan Peninsula, while also
extending along the Pacific coast from Chiapas to Guatemala and El
Salvador.  This rainfall could cause widespread life-threatening
flash floods and mudslides. Refer to products from your local
weather office for more information.

2. Cristobal is forecast to re-emerge over the southern Gulf of
Mexico on Friday and move northward over the central and northern
Gulf of Mexico over the weekend.  There is a risk of tropical storm
force winds this weekend from Louisiana to the western Florida
Panhandle and a risk of dangerous storm surge from Louisiana to the
Florida Big Bend. These hazards, along with heavy rainfall, will
arrive well in advance of and extend well east of Cristobal’s
center.  Tropical storm and storm surge watches could be issued
tonight or Friday.

FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 17.6N  91.0W   30 KT  35 MPH...INLAND
 12H  05/0000Z 17.7N  90.5W   30 KT  35 MPH...INLAND
 24H  05/1200Z 19.0N  90.2W   30 KT  35 MPH...INLAND
 36H  06/0000Z 21.0N  90.3W   35 KT  40 MPH...NEAR THE COAST
 48H  06/1200Z 22.9N  90.7W   40 KT  45 MPH...OVER WATER
 60H  07/0000Z 24.7N  90.7W   45 KT  50 MPH...OVER WATER
 72H  07/1200Z 26.7N  90.6W   50 KT  60 MPH...OVER WATER
 96H  08/1200Z 30.8N  91.7W   35 KT  40 MPH...INLAND
120H  09/1200Z 35.0N  91.5W   25 KT  30 MPH...INLAND

$$
Forecaster Pasch

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