Tropical Storm CRISTOBAL

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TROPICAL STORM CRISTOBAL DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042014
1100 PM EDT SUN AUG 24 2014

Cristobal is not a well-organized tropical cyclone at this time.
The deep convection has a ragged appearance, with little or no
banding features evident, and this convection is mainly
occurring well to the south of the estimated center location.
After adjusting for rain inflation, SFMR winds from aircraft
observations a few hours ago, indicated that the intensity is no
more than 40 kt.  Also, the fixes from the Air Force and NOAA
planes, which were flying at altitudes of about 1000 and 8000 feet
respectively, indicated a southward tilt of the center with height.
This is consistent with some northerly shear over the storm as
suggested by water vapor imagery.  Given the currently disorganized
state of Cristobal, not much intensification seems likely for the
next 12 hours or so.  Afterwards, the global models are predicting a
little more favorable upper-tropospheric environment with
increasingly diffluent flow over the tropical cyclone.  The official
intensity forecast is basically a blend of the SHIPS and LGEM
guidance, and only a little above the model consensus.  By 120
hours, the global models depict the cyclone embedded within a
baroclinic zone, so extratropical transition should have occurred by
that time.

The motion has been rather erratic over the past several hours, but
my best estimate is about 350/4 kt.  Cristobal is currently situated
near a col between 2 anticyclones in the mid-level flow, one over
the United States, and one over the central subtropical Atlantic.
The dynamical models indicate that, within a couple of days,
the steering of the tropical cyclone will become dominated by flow
on the northwest side of the Atlantic anticyclone and on the
southern side of a mid-latitude trough.  Therefore, the motion is
expected to gradually bend to the right with some acceleration over
the next several days.  The official track forecast is somewhat
faster than the previous one after 48 hours, but not as fast as the
latest dynamical model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  25/0300Z 24.8N  73.1W   40 KT  45 MPH
 12H  25/1200Z 25.4N  73.1W   40 KT  45 MPH
 24H  26/0000Z 26.4N  72.8W   45 KT  50 MPH
 36H  26/1200Z 27.8N  72.4W   50 KT  60 MPH
 48H  27/0000Z 29.8N  71.8W   55 KT  65 MPH
 72H  28/0000Z 33.5N  69.0W   65 KT  75 MPH
 96H  29/0000Z 37.5N  62.0W   70 KT  80 MPH
120H  30/0000Z 44.0N  50.0W   60 KT  70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch

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