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Wtnt33 knhc 302042
tcpat3
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tropical storm fiona advisory number 1
nws tpc/national hurricane center miami fl al082010
500 pm edt mon aug 30 2010
...tropical storm fiona forms east of the leeward islands...
Summary of 500 pm edt...2100 utc...information
----------------------------------------------
location...14.4n 48.7w
about 890 mi...1435 km e of the leeward islands
maximum sustained winds...40 mph...65 km/hr
present movement...w or 270 degrees at 24 mph...39 km/hr
minimum central pressure...1007 mb...29.74 inches
watches and warnings
--------------------
none.
Interests in the northern leeward islands should monitor the
progress of fiona. A tropical storm watch may be required for a
portion of this area later this evening or tonight.
Discussion and 48-hour outlook
------------------------------
at 500 pm edt...2100 utc...the center of tropical storm fiona was
estimated near latitude 14.4 north...longitude 48.7 west. Fiona is
moving toward the west near 24 mph...39 km/hr. A turn toward the
west-northwest is expected on tuesday...followed by a turn toward
the northwest and a decrease in forward speed on wednesday. On
this track...fiona could be near or just to the northeast of the
northern leeward islands by early wednesday.
Maximum sustained winds are near 40 mph...65 km/hr...with higher
gusts. Some strengthening is forecast during the next 48 hours.
Tropical storm force winds extend outward up to 140 miles...220 km
to the northeast of the center.
Estimated minimum central pressure is 1007 mb...29.74 inches.
Hazards affecting land
----------------------
none
next advisory
-------------
next complete advisory...1100 pm edt.
$$
forecaster berg
000
wtnt43 knhc 302047
tcdat3
tropical storm fiona discussion number 1
nws tpc/national hurricane center miami fl al082010
500 pm edt mon aug 30 2010
earlier today...about 30 dropsondes were released during a g-v
research mission being conducted by the national center for
atmospheric research near the area of low pressure located about
800 miles east of the lesser antilles. One of the dropsondes
measured a surface wind of 35 kt approximately 120 n mi to the
northeast of the estimated center. This measurement agrees with an
ascat pass from 1208 utc...which showed a swath of 30-35 kt winds
in that same area. Convection has been a little thin for most of
the day...but banding features have recently become more prominent
mainly over the western semicircle. Given the increase in
convection and since tropical storm force winds are already
occurring...the system is being directly upgraded to tropical storm
fiona.
Since fiona still lacks some organization and the wind field is
somewhat large...the cyclone will likely have a difficult time
intensifying over the next day or so. I do not believe this
structure is handled well by the statistical intensity
guidance...which intensify fiona to a hurricane in 36 to 48
hours...so i am inclined to lean closer to the dynamical gfdl and
hwrf at this point. In fact...the gfs dissipates the cyclone within
2 to 3 days. The official forecast therefore shows minimal
strengthening over the next 1 to 2 days and then levels out the
intensity for days 3 through 5...when it appears that increasing
vertical shear could become a limiting factor.
The surface center has been a little difficult to locate...and the
initial motion is an uncertain 270/21. Track model guidance is in
good agreement for the next 48 hours and shows fiona turning toward
the northwest...generally following earl around the western
periphery of the subtropical ridge. After that...the
gfdl...hwrf...and gfs keep fiona as a weak system and show it
continuing to the north in the low-level flow behind earl. The
ecmwf...on the other hand...shows a stronger fiona and suggests
that the subtropical ridge could build back to the west before the
cyclone can recurve. The official forecast is very close to the
model consensus tvcn for the first 48 hours but then lies a little
north of the consensus in favor of the tracks of the weaker gfdl
and hwrf.
Forecast positions and max winds
initial 30/2100z 14.4n 48.7w 35 kt
12hr vt 31/0600z 14.9n 51.9w 35 kt
24hr vt 31/1800z 15.8n 55.9w 40 kt
36hr vt 01/0600z 17.2n 59.2w 45 kt
48hr vt 01/1800z 19.3n 62.0w 45 kt
72hr vt 02/1800z 24.0n 66.0w 40 kt
96hr vt 03/1800z 27.5n 68.0w 40 kt
120hr vt 04/1800z 29.0n 69.0w 40 kt
$$
forecaster berg
000
font13 knhc 302047
pwsat3
tropical storm fiona wind speed probabilities number 1
nws tpc/national hurricane center miami fl al082010
2100 utc mon aug 30 2010
at 2100z the center of tropical storm fiona was located near
latitude 14.4 north...longitude 48.7 west with maximum sustained
winds near 35 kts...40 mph...65 km/hr.
Z indicates coordinated universal time (greenwich)
atlantic standard time (ast)...subtract 4 hours from z time
eastern daylight time (edt)...subtract 4 hours from z time
central daylight time (cdt)...subtract 5 hours from z time
i. Maximum wind speed (intensity) probability table
chances that the maximum sustained (1-minute average) wind speed of
the tropical cyclone will be within any of the following categories
at each official forecast time during the next 5 days.
Probabilities are given in percent. X indicates probabilities less
than 1 percent.
- - - maximum wind speed (intensity) probabilities - - -
valid time 06z tue 18z tue 06z wed 18z wed 18z thu 18z fri 18z sat
forecast hour 12 24 36 48 72 96 120
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
dissipated 2 2 3 4 8 9 12
trop depression 33 21 16 19 24 23 25
tropical storm 64 72 69 61 53 52 47
hurricane 2 6 12 16 15 15 16
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
hur cat 1 1 5 10 13 11 12 13
hur cat 2 x 1 2 2 2 2 1
hur cat 3 x x 1 1 1 1 1
hur cat 4 x x x x x x x
hur cat 5 x x x x x x x
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
fcst max wind 35kt 40kt 45kt 45kt 40kt 40kt 40kt
ii. Wind speed probability table for specific locations
chances of sustained (1-minute average) wind speeds of at least
...34 kt (39 mph... 63 kph)...
...50 kt (58 mph... 93 kph)...
...64 kt (74 mph...119 kph)...
For locations and time periods during the next 5 days
probabilities for locations are given as ip(cp) where
ip is the probability of the event beginning during
an individual time period (individual probability)
(cp) is the probability of the event occurring between
18z mon and the forecast hour (cumulative probability)
probabilities are given in percent
x indicates probabilities less than 1 percent
probabilities for 34 kt and 50 kt are shown at a given location when
the 5-day cumulative probability is at least 3 percent.
Probabilities for 64 kt are shown when the 5-day cumulative
probability is at least 1 percent.
- - - - wind speed probabilities for selected locations - - - -
from from from from from from from
time 18z mon 06z tue 18z tue 06z wed 18z wed 18z thu 18z fri
periods to to to to to to to
06z tue 18z tue 06z wed 18z wed 18z thu 18z fri 18z sat
forecast hour (12) (24) (36) (48) (72) (96) (120)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
location kt
cape hatteras 34 x x( x) x( x) x( x) x( x) 1( 1) 2( 3)
bermuda 34 x x( x) x( x) x( x) x( x) 5( 5) 2( 7)
san juan 34 x x( x) x( x) 1( 1) 2( 3) x( 3) 1( 4)
saint thomas 34 x x( x) x( x) 2( 2) 3( 5) x( 5) x( 5)
saint croix 34 x x( x) x( x) 2( 2) 2( 4) x( 4) x( 4)
saint maarten 34 x x( x) 1( 1) 10(11) 3(14) 1(15) x(15)
saint maarten 50 x x( x) x( x) 2( 2) 2( 4) x( 4) x( 4)
saint maarten 64 x x( x) x( x) x( x) 1( 1) x( 1) x( 1)
st kitts-nevis 34 x x( x) 1( 1) 6( 7) 3(10) x(10) x(10)
barbuda 34 x x( x) 3( 3) 17(20) 1(21) x(21) x(21)
barbuda 50 x x( x) x( x) 5( 5) x( 5) x( 5) x( 5)
barbuda 64 x x( x) x( x) 2( 2) x( 2) x( 2) x( 2)
antigua 34 x x( x) 2( 2) 10(12) 1(13) x(13) x(13)
antigua 50 x x( x) x( x) 2( 2) 1( 3) x( 3) x( 3)
guadeloupe 34 x x( x) 2( 2) 4( 6) 1( 7) x( 7) x( 7)
$$
forecaster berg
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