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TROPICAL STORM CRISTINA DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032014
800 AM PDT TUE JUN 10 2014

Inner-core thunderstorm activity has increased during the past
several hours and two overnight ASCAT passes indicate that the
radius of maximum winds has contracted down to about 25 nmi, which
is more than a 50 percent decrease from this time yesterday. The
advisory intensity estimate of 40 kt is based on a blend of
satellite intensity estimates of T2.9/43 kt from UW-CIMSS, T2.5/35
kt from TAFB, and T2.0/30 kt from SAB, plus the appearance of a
partial mid-level eye noted in 1237 UTC TRMM microwave imagery.

The initial motion estimate is 275/04 kt.  Both the track forecast
and reasoning remain unchanged. Cristina appears to have begun to
move out of a region of weak steering currents, and the cyclone is
expected to move steadily westward along the southern periphery of
a building deep-layer subtropical ridge located to its north. On
Day 2, the cyclone is forecast to turn west-northwestward at a
faster forward speed as Cristina strengthens and becomes a more
vertically deep system that will be influenced by stronger
deep-layer easterly steering flow. The NHC track forecast is
essentially just an update of the previous advisory track, and
follows the consensus model TVCE.

A large nocturnal thunderstorm complex that developed over central
Mexico has ejected a large band of southward-moving cirrus outflow
that appears to have temporarily increased the northerly shear
across Cristina overnight. However, that thunderstorm complex
has dissipated and water vapor imagery and satellite-derived winds
indicate that the upper-level shear has abated over the past
several hours. As a result, the environmental shear is forecast by
the SHIPS model to weaken today and continue to decrease through
at least the 72-hour period.  This should allow for Cristina to
gradually strengthen despite being embedded within a relatively dry
mid-level moisture environment. By 96 hours and beyond, the cyclone
is forecast to move into a thermodynamically unfavorable
environment, over SSTs cooler than 26C, and encounter increasing
southwesterly shear, a combination that should induce gradual to
possible rapid weakening. The NHC intensity forecast is similar to
the previous advisory and follows the multi-model consensus IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  10/1500Z 15.5N 102.9W   40 KT  45 MPH
 12H  11/0000Z 15.6N 103.8W   45 KT  50 MPH
 24H  11/1200Z 15.7N 105.1W   50 KT  60 MPH
 36H  12/0000Z 15.9N 106.5W   60 KT  70 MPH
 48H  12/1200Z 16.4N 107.9W   65 KT  75 MPH
 72H  13/1200Z 17.7N 110.5W   65 KT  75 MPH
 96H  14/1200Z 18.8N 112.7W   50 KT  60 MPH
120H  15/1200Z 19.8N 115.1W   35 KT  40 MPH

$$
Forecaster Stewart

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