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Tropical Storm Cristobal Discussion Number 19
NWS National Hurricane Center Miami FL AL032020
400 AM CDT Sat Jun 06 2020
Satellite imagery this morning shows that Cristobal does not have a
classic tropical cyclone structure, probably due to interaction with
a mid- to upper-level trough and the associated entrainment of dry
air. The circulation is elongated north-south near the center, and
multiple low-cloud swirls are preset. In addition, the strongest
convection is well removed from the center of Cristobal to the north
and east. The initial intensity is held at 40 kt based on earlier
scatterometer data and continuity from the previous advisory.
The initial motion is now 350/12. There is no change in the track
forecast philosophy from the previous advisory. A south to north
steering flow between a deep-layer ridge over the western Atlantic
and the aforementioned trough over the western Gulf of Mexico
should cause Cristobal to continue moving generally northward for
the next 36 h or so. This motion should take the center of the
storm across the Louisiana coast by Sunday night. Around the
landfall time, a slight turn to the northwest is expected as a
mid-level ridge moves across the central and eastern U.S. to the
north of the cyclone. Overall, the models remain in good
agreement, although the GFS and ECMWF have shifted a little to the
left of their previous forecasts. The new official forecast is
similar to the previous forecast and lies near the various
consensus models.
Cristobal is expected to slowly strengthen until it makes landfall
along the northern Gulf coast in a couple of days. However, the
broad structure of the cyclone, the dry air entrainment, and
moderate wind shear should prevent a significant amount of
intensification. One change from the previous forecast is that the
global models suggest that Cristobal will undergo extratropical
transition over the upper Mississippi River valley in about 4 days,
and it should persist a little longer than previously forecast.
Cristobal is likely to remain a broad and asymmetric storm when it
makes landfall. Therefore, users are urged to not focus on the
exact forecast path as the associated winds, storm surge, and
rainfall will extend well to the east of the center.
Key Messages:
1. Damaging and deadly flooding was already occurring in portions of
Mexico and Central America. Additional rainfall from Cristobal will
continue to slowly subside, however life threatening flash floods
and mudslides will still be possible into Saturday. Refer to
products from your local weather office for more information.
2. 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. Life-threatening
storm surge remains possible along the Florida Big Bend and in other
portions of southern and southeastern Louisiana where a Storm Surge
Watch is in effect. Residents in these locations should follow
advice given by local emergency officials.
3. Tropical storm force winds are expected by late Saturday night
along the northern Gulf Coast from southeastern Louisiana to the
western Florida Panhandle, including metropolitan New Orleans, and
a Tropical Storm Warning is in effect for this area. These winds
will arrive well in advance of and extend well east of Cristobal’s
center.
4. Heavy rainfall will spread into portions of the Gulf Coast,
from east Texas to Florida, this weekend into early next week, with
areas of flash flooding. Significant flooding will be possible on
the smaller tributaries, especially where heavier rainfall occurs
over portions of the Mid-South and Gulf Coast.
FORECAST POSITIONS AND MAX WINDS
INIT 06/0900Z 23.8N 90.2W 40 KT 45 MPH
12H 06/1800Z 25.0N 90.4W 45 KT 50 MPH
24H 07/0600Z 26.8N 90.4W 50 KT 60 MPH
36H 07/1800Z 28.8N 90.5W 50 KT 60 MPH
48H 08/0600Z 30.6N 91.3W 40 KT 45 MPH...INLAND
60H 08/1800Z 33.2N 92.1W 30 KT 35 MPH...INLAND
72H 09/0600Z 36.4N 92.4W 25 KT 30 MPH...INLAND
96H 10/0600Z 45.0N 89.0W 25 KT 30 MPH...POST-TROP/EXTRATROP
120H 11/0600Z 52.5N 83.5W 25 KT 30 MPH...POST-TROP/EXTRATROP
$$
Forecaster Beven
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