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TROPICAL STORM FRANK DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072016
900 AM MDT FRI JUL 22 2016

Frank's deep convection is displaying more of a shear pattern this
morning with a sharp edge to the infrared cloud top temperatures on
its northeastern side.  All intensity analyses - SAB and TAFB
Dvorak, ADT, and AMSU - are in good agreement in keeping the
intensity at 45 kt.  The earlier ASCAT scatterometer pass indicates
that Frank is a relatively small tropical storm at this time.

Frank should experience moderate to low tropospheric vertical shear,
warm to hot SSTs, and a moist, unstable atmosphere for the next two
to three days.  Thus steady intensification is likely.  Beyond day
three, the tropical cyclone should encounter a more hostile
environment with cool SSTs to the west of Baja California with a
more dry, stable atmosphere.  Gradual to steady weakening should
commence around day three.  The NHC intensity forecast is unchanged
and is based upon a three member consensus of the LGEM, SHIPS, and
HWRF models.

A couple timely AMSR2 and SSMIS microwave images were helpful in
determining the location of Frank's center.  The system is moving
toward the northwest at about 12 kt, somewhat faster than estimated
earlier. Frank should turn toward the west-northwest during the next
few days at a slower rate of forward speed, as the east-west
extended deep-layer ridge to its north weakens some.  The global
models and the HWRF hurricane model are in close agreement on this
scenario and the NHC track prediction has been shifted southward
between the previous forecast and the consensus mean.

Although the forecast track keeps Frank well removed from Mexico,
interests in the southern portion of the Baja California peninsula
should continue to monitor the progress of this cyclone.  As none
of the GFS, ECWMF, or UKMET ensemble members predict a track over
or close to Baja California, it would appear that the small threat
to Baja California is diminishing.


FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 17.3N 107.4W   45 KT  50 MPH
 12H  23/0000Z 18.1N 109.0W   50 KT  60 MPH
 24H  23/1200Z 18.5N 110.5W   60 KT  70 MPH
 36H  24/0000Z 19.0N 112.0W   65 KT  75 MPH
 48H  24/1200Z 19.5N 113.2W   70 KT  80 MPH
 72H  25/1200Z 20.5N 115.0W   70 KT  80 MPH
 96H  26/1200Z 21.3N 116.8W   60 KT  70 MPH
120H  27/1200Z 22.5N 119.0W   45 KT  50 MPH

$$
Forecaster Landsea

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