Potential Tropical Cyclone Two Forecast Discussion Number 3

By | July 11, 2019

Issued at 1000 PM CDT Wed Jul 10 2019

000
WTNT42 KNHC 110245
TCDAT2
Potential Tropical Cyclone Two Discussion Number   3
NWS National Hurricane Center Miami FL       AL022019
1000 PM CDT Wed Jul 10 2019
The system is becoming better organized, and it is almost a
tropical depression.  Satellite images show a persistent area of
deep convection near the estimated center with loosely organized
bands surrounding that feature.  Earlier, the NOAA Hurricane Hunters
found that the pressure has dropped a little to 1009 mb, although
the center is not yet well defined.  The estimated initial intensity
is still 25 kt based on surface observations and the NOAA dropsonde
data.
The broad low is moving west-southwestward at about 8 kt.  The track
models are in general agreement that a mid-level ridge centered over
the Rockies should cause the system to move slowly westward on
Thursday and west-northwestward on Friday.  After that time,
however, the models diverge considerably with some solutions showing
an abrupt northward turn toward a weakness in the ridge and others
showing a more gradual one.  The latest GFS run has shifted to the
west of its previous track, closer to the previous NHC forecast,
while the HWRF model has shifted to the right.  Based on the overall
guidance spread, this track forecast is nudged to the east of the
previous forecast to be closer to the various consensus models,
which typically are the most reliable. However, this forecast is
still near the western edge of the model envelope. It should be
noted that track errors are typically larger for potential tropical
cyclones than more mature systems.  In addition, the run-to-run
consistency in the track models has been poor, so confidence in the
details of the forecast is not high at the moment.
Since the system is still in the formative stage, only slow
strengthening is likely during the next 12 hours or so.  However,
after that time more significant strengthening is likely due to
very warm SSTs across the northern Gulf of Mexico, a fairly moist
atmosphere, and a favorable upper-level pattern over the system.
The NHC intensity forecast is largely an update of the previous one
and shows the system becoming a tropical storm on Thursday and a
hurricane by late Friday.  Additional strengthening is likely
beyond the 48-hour point and the time it makes landfall, which is
predicted to occur in a little less than 3 days.  This forecast is
fairly close to the IVCN and HCCA models.
Key Messages:
1. A tropical depression is expected to form on Thursday over the
northern Gulf of Mexico. Conditions appear favorable for this system
to strengthen to a hurricane that will bring storm surge, rainfall,
and wind hazards to the central Gulf Coast.
2. A dangerous storm surge is possible in portions of southern and
southeastern Louisiana where a Storm Surge Watch is in effect.
Additional storm surge watches may be needed on Thursday. Residents
in these areas should monitor the progress of this system and listen
to any advice given by local officials.
3. A Hurricane Watch is in effect for much of the Louisiana coast
and additional tropical storm or hurricane watches and warnings
could be needed on Thursday. Residents in the watch area should
ensure they have their hurricane plan in place.
4. The slow movement of this system will result in a long duration
heavy rainfall threat along the central Gulf Coast and inland
through the lower Mississippi Valley through the weekend and
potentially into early next week. Flash flooding and river flooding
will become increasingly likely, some of which may be significant,
especially along and east of the track of the system.
FORECAST POSITIONS AND MAX WINDS
INIT  11/0300Z 27.7N  88.0W   25 KT  30 MPH...POTENTIAL TROP CYCLONE
12H  11/1200Z 27.6N  88.6W   30 KT  35 MPH...TROPICAL CYCLONE
24H  12/0000Z 27.6N  89.5W   40 KT  45 MPH
36H  12/1200Z 27.9N  90.5W   50 KT  60 MPH
48H  13/0000Z 28.3N  91.3W   65 KT  75 MPH
72H  14/0000Z 30.2N  92.1W   60 KT  70 MPH...INLAND
96H  15/0000Z 32.8N  92.3W   35 KT  40 MPH...INLAND
120H  16/0000Z 35.5N  92.3W   20 KT  25 MPH...INLAND
$$
Forecaster Cangialosi

Leave a Reply