Tropical Storm CRISTOBAL
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TROPICAL STORM CRISTOBAL DISCUSSION NUMBER 9...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014
500 PM EDT MON AUG 25 2014
Corrected forecast motion through 72 hours
Cristobal remains in a moderate shear environment with the low-level
center still fully exposed on the north side of the deep convection.
A recent Air Force Reserve reconnaissance flight indicated maximum
850 mb flight-level winds of 65 kt in the southeast quadrant where
SFMR winds of 51 kt were noted, and the central pressure has
remained at 993 mb. Based on these data, the initial intensity has
been held at 50 kt.
Aircraft fixes indicate that Cristobal is now moving at a more
reliable north-northeastward motion of 020/04 kt. There is no
significant change to the previous forecast track or reasoning. The
latest NHC model guidance continues to be in excellent agreement on
the subtropical ridge to the north of Cristobal slowly eroding
due to a strong mid/upper-level trough just off the U.S. southeast
coast continuing to dig southward as noted in water vapor imagery.
The combination of increasing southwesterly flow on the east side of
the trough and a building ridge to the south of the cyclone should
act to lift Cristobal slowly northeastward over the next 72 hours.
After that, Cristobal is forecast to become embedded in deep
mid-latitude westerlies and accelerate off to the northeast and
east-northeast, becoming a large and powerful extratropical cyclone
over the far north Atlantic by 120 hours. The official forecast
track is essentially just an update of the previous advisory track,
and lies just to the right of the consensus model TVCA.
The shear is forecast to ebb and flow over the next 48 hours or so,
and the intensity forecast has followed this trend with
strengthening indicated during the periods when the vertical shear
subsides. Cristobal is still expected to become a hurricane when the
cyclone passes to the west and north of Bermuda on Wednesday and
Thursday. On Days 4 and 5, Cristobal will be passing over much
cooler waters and encountering strong southwesterly wind shear as
the cyclone becomes embedded in the mid-latitude westerlies, which
will result in extratropical transition by 120 hours. However, the
system is likely to receive a boost from baroclinic effects,
remaining as a strong extratropical cyclone.
Owing to the slow motion of Cristobal, heavy rainfall and possible
flooding will remain a threat for the southeastern Bahamas and the
Turks and Caicos through Tuesday. Heavy rainfall is expected to
continue across Bermuda through Wednesday ahead of Cristobal.
FORECAST POSITIONS AND MAX WINDS
INIT 25/2100Z 25.3N 72.5W 50 KT 60 MPH
12H 26/0600Z 26.6N 71.9W 55 KT 65 MPH
24H 26/1800Z 28.9N 71.2W 55 KT 65 MPH
36H 27/0600Z 31.2N 70.4W 60 KT 70 MPH
48H 27/1800Z 33.4N 68.5W 70 KT 80 MPH
72H 28/1800Z 38.1N 60.5W 65 KT 75 MPH
96H 29/1800Z 44.3N 47.3W 60 KT 70 MPH
120H 30/1800Z 51.5N 34.5W 50 KT 60 MPH...POST-TROP/EXTRATROP