[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 080250
TCDAT3

Tropical Storm Cristobal Discussion Number  26
NWS National Hurricane Center Miami FL       AL032020
1000 PM CDT Sun Jun 07 2020

Earlier satellite, radar, and surface observations showed that the
center of Cristobal made landfall in southeastern Louisiana around
2200 UTC.  Since that time, the storm has turned north-
northwestward with the center passing very near New Orleans.
Recent Doppler radar data and surface observations suggest that the
maximum winds have begun to decrease, and the advisory intensity is
set to 40 kt.  These winds are primarily occurring over the
northern Gulf of Mexico waters.

The initial motion estimate is 345/9 kt. Cristobal should continue
north-northwestward overnight as a high pressure ridge over the
Great Lakes slides eastward.  The cyclone is expected to turn
northward by Monday night, and then northeastward on Tuesday ahead
of a mid-latitude trough moving into the central United States. A
faster northeastward motion should bring the center of the cyclone
across the Upper Midwest on Tuesday and into Canada on Wednesday.
After that time, the system is expected to slow down after it
completes its extratropical transition.  The early portion of the
new NHC track forecast has been adjusted slightly eastward based on
the more northward and eastward initial position, however the
remainder of the track forecast is very close to the previous
advisory and the various consensus aids.

Gradual weakening should occur overnight as the circulation
continues to move over land, and Cristobal is forecast to
become a tropical depression Monday morning.  Additional gradual
weakening is anticipated while the cyclone moves over the central
U.S. through Tuesday, but some slight re-strengthening is possible
due to strong baroclinic forcing during the extratropical
transition around midweek.  The NHC intensity forecast is primarily
a blend of the global models.  As the system completes its
extratropical transition, strong gusty winds are possible mid
week behind an associated front over portions of the Midwest and
Great Lakes regions.

Although Cristobal has begun weakening, tropical-storm-force winds
and life-threatening storm surge is expected to continue over a
portion of the northern Gulf coast overnight. Heavy rains
associated with the system will also spread over portions of
the central United States over the next couple of days.


Key Messages:

1. There is a danger of life-threatening storm surge outside of the
Hurricane and Storm Damage Risk Reduction System from the Mouth of
the Mississippi River to Ocean Springs, Mississippi, and a Storm
Surge Warning is in effect for those areas.  Residents in these
locations should follow advice given by local emergency officials.

2. Tropical-storm-force winds will continue along portions of the
northern Gulf coast from central Louisiana to the western Florida
Panhandle, including metropolitan New Orleans through the overnight
hours, and a Tropical Storm Warning is in effect for this area.

3. Heavy rainfall across north Florida should diminish overnight.
Heavy rain will continue to push inland across the central Gulf
coast and into the Lower Mississippi Valley Sunday night. The
Central Gulf Coast region will be most prone to heavy rain issues
after the passage of the center of Cristobal through Monday.  This
heavy rain will move up the Lower and Mid Mississippi Valley Monday
into Tuesday, then across the Upper Mississippi Valley and Northern
Plains Tuesday and Tuesday night.  Flash flooding, and new and
renewed significant river flooding is possible, especially where
heavier rainfall occurs over portions of the Gulf Coast through the
Mississippi Valley.


FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 30.3N  90.2W   40 KT  45 MPH
 12H  08/1200Z 32.0N  91.1W   30 KT  35 MPH...INLAND
 24H  09/0000Z 34.6N  91.9W   25 KT  30 MPH...INLAND
 36H  09/1200Z 38.1N  91.3W   25 KT  30 MPH...INLAND
 48H  10/0000Z 42.9N  89.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  10/1200Z 47.5N  86.7W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  11/0000Z 50.8N  83.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  12/0000Z 52.8N  79.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  13/0000Z...DISSIPATED

$$
Forecaster Brown
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