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TROPICAL STORM PAINE DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP172016
300 AM MDT SUN SEP 18 2016

The system's cloud pattern has very quickly exhibited increased
organization.  A relatively long band with very cold-topped
convection wraps in toward the low-level center.  The low-level
center appears to be located near the eastern end of this band,
suggesting that some northeasterly shear persists.  A Dvorak
classification of T2.5 from SAB and the latest UW-CIMSS ADT value of
2.8 are used to raise the initial intensity estimate to 35 kt.

The center location and hence the initial motion are more uncertain
than normal, especially with no recent microwave passes and after a
center reformation yesterday.  The best estimate is 310/12.  Paine
should be steered generally northwestward around the southwestern
periphery of a mid-level high over the Rio Grande Valley during the
next 24 to 36 hours.  After that time, the cyclone is expected to
then turn north-northwestward and northward when it encounters a
break in the ridge caused by a cut-off low retrograding offshore the
California coast.  The new track forecast is shifted a bit to the
right of the previous one after 12 hours, following the multi-
model consensus.

The shear affecting the cyclone is forecast to reach a relative
minimum today while Paine is still moving over warm waters. This
should allow the cyclone to intensify at near a climatological rate
of one T-number per day during the next 24 to 36 hours.
Southwesterly shear should abruptly increase by late Monday in
association with the cut-off low around the time Paine crosses the
26-deg isotherm.  This should bring whatever intensification is
occurring to a halt.  Global models show Paine decoupling as the
shear reaches 25-30 kt in 2 to 3 days, while the storm is moving
over 22-24 deg C waters. Paine is thus shown degenerating into a
remnant low in 72 hours, and dissipating before 96 hours.  The NHC
is higher than the previous one out to 36 hours and is about the
same after that, close to the multi-model consensus.

Deep-layer moisture associated with Paine is expected to be
advected into extreme southern California and the Desert Southwest
in a couple of days, which could enhance the potential for unusual
September rains across this region.


FORECAST POSITIONS AND MAX WINDS

INIT  18/0900Z 17.3N 110.7W   35 KT  40 MPH
 12H  18/1800Z 18.4N 112.7W   40 KT  45 MPH
 24H  19/0600Z 20.1N 114.8W   50 KT  60 MPH
 36H  19/1800Z 21.9N 116.5W   50 KT  60 MPH
 48H  20/0600Z 23.8N 117.6W   40 KT  45 MPH
 72H  21/0600Z 27.1N 118.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  22/0600Z...DISSIPATED

$$
Forecaster Kimberlain

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