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wtpa45 phfo 260900
tcdcp5
tropical storm hilda discussion number 16
nws central pacific hurricane center honolulu hi ep112009
1100 pm hst tue aug 25 2009
hilda...in spite of minimal shear and warm sst/s...is barely hanging
on. The possible reason for the ongoing struggle is the intake of
dry mid-level air that surrounds hilda to the north...as depicted
by water vapor satellite imagery. The fix agencies and an adt all
report a 24 hour weakening trend with subjective dvorak estimates
ranging from 35 to 55 kt...the latter kept high due to dvorak
constraints. Deep convection has persisted near the storm center
over the last several hours...so rather than dropping the intensity
with this forecast...will keep it at 40 kt.
Hilda continues to move to the west-southwest...the result of
northeasterly winds flowing around a high centered northwest of
hawaii. There is good agreement amongst the objective aids that
hilda will remain on this course for 24 hours whilst under the
influence of the high to its northwest. Beyond 24 hours...global
models retreat the high to the north...allowing hilda to assume a
westerly course through 48 hours then a west-northwesterly track
thereafter. Most of the objective aides indicate to a degree that
this will occur. The official forecast is down the middle of a
somewhat tight aid envelop and is closest to consensus tvcn and the
regional hwrf model.
The intensity forecast remains a work in progress. It maintains the
slow weakening trend through 12 hours...followed by an equally slow
strengthening trend through 72 hours. Beyond 72 hours... Increasing
vertical shear is expected to slowly weaken hilda. About half of
the intensity aids maintain or slowly weaken hilda...while the
other half slowly strengthen the cyclone. All of the aids as does
the official forecast keep hilda below the 65 knot hurricane
threshold. The official forecast follows lgem through 72 hours then
ends up near hwrf icon and ivcn at 120 hours.
Forecast positions and max winds
initial 26/0900z 13.6n 150.6w 40 kt
12hr vt 26/1800z 13.2n 151.7w 35 kt
24hr vt 27/0600z 12.8n 153.2w 40 kt
36hr vt 27/1800z 12.7n 154.8w 45 kt
48hr vt 28/0600z 12.8n 156.7w 45 kt
72hr vt 29/0600z 13.5n 161.3w 50 kt
96hr vt 30/0600z 14.5n 165.7w 50 kt
120hr vt 31/0600z 16.3n 170.0w 45 kt
$$
forecaster craig
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