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Tropical Storm Erick Discussion Number   7
NWS National Hurricane Center Miami FL       EP062019
500 PM HST Sun Jul 28 2019

There have been some significant changes with Erick during the past
several hours.  First, as foreshadowed in the previous advisory,
microwave and scatterometer data indicate that the center has
re-formed under a very strong convective cluster farther to the
south.  Second, the overall cloud pattern has become much better
organized, with a CDO-like feature forming near the center and
a notable increase in curved banding in the southern and western
quadrants of the storm.  Erick appears to be in the beginning stages
of rapid intensification, and the intensity will be increased to 55
kt for this advisory based on a consensus of estimates from TAFB,
SAB and the CIMSS ADT.

This is one of these rare forecasts where it is difficult to find a
reason not to predict rapid intensification.  Erick is expected to
be in an environment of very low vertical wind shear and warm water
during the next 48 hours.  While earlier forecasts were concerned
about mid-level dry air, the southward reformation will probably
help insulate the storm from that influence, along with the very low
shear limiting mixing.  Although there is no low-level ring present
yet in the latest 37 gHz microwave channel, this signal can be both
before and/or concurrent with rapid strengthening.  Notably, the
SHIPS-rapid intensification index is showing about a 70 percent
chance of both a 30-kt increase during the next 24 hours and a 55-kt
rise in 48 hours.  It's pretty hard to ignore the signal from that
model, considering these are values you might see a few times a
year.  In addition, dynamical models have also come up sharply from
the previous cycle, and three typically reliable models now show
Erick becoming a major hurricane.  Thus, the new NHC intensity
forecast is considerably higher than the previous one through 48
hours, at the upper-end of the guidance envelope, and just a little
above the corrected-consensus models.  The forecast after that time
required little adjustment, as a combination of higher shear and dry
air aloft should contribute to steady weakening by the end of the
forecast period.

After accounting for the center re-formation, the initial motion
estimate is 270/14 kt.  A gradual turn to the west-northwest is
forecast during the next couple of days as a ridge weakens to the
north, then a turn back to the west is anticipated due to Erick
weakening and the ridge slightly strengthening.  Model guidance
remains in very good agreement this evening, with no significant
outlier solutions.  While the new track forecast has been shifted
southwest of the previous one, it is mostly due to the center
re-formation, and the forecast continues to be close to the eastern
Pacific model consensus TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 11.7N 133.1W   55 KT  65 MPH
 12H  29/1200Z 11.9N 135.3W   65 KT  75 MPH
 24H  30/0000Z 12.5N 138.2W   80 KT  90 MPH
 36H  30/1200Z 13.2N 141.0W   90 KT 105 MPH
 48H  31/0000Z 13.9N 143.6W  100 KT 115 MPH
 72H  01/0000Z 15.1N 147.9W   85 KT 100 MPH
 96H  02/0000Z 16.0N 152.5W   55 KT  65 MPH
120H  03/0000Z 16.5N 157.3W   40 KT  45 MPH

$$
Forecaster Blake

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