Thread: TD Emily - off SE Florida coast

Bulletin
tropical depression emily advisory number 15
nws national hurricane center miami fl al052011
1100 pm edt sat aug 06 2011

...emily moving slowly northward...
...heavy rains occurring on grand bahama island...


Summary of 1100 pm edt...0300 utc...information
-----------------------------------------------
location...27.4n 78.2w
about 70 mi...115 km nne of freeport grand bahama island
maximum sustained winds...35 mph...55 km/h
present movement...n or 360 degrees at 8 mph...13 km/h
minimum central pressure...1011 mb...29.85 inches


watches and warnings
--------------------
there are no coastal watches or warnings in effect.


Discussion and 48-hour outlook
------------------------------
at 1100 pm edt...0300 utc...the center of tropical depression emily
was located near latitude 27.4 north...longitude 78.2 west. The
depression is moving toward the north near 8 mph... 13 km/h. A
turn toward the northeast with an increase in forward speed
is expected on sunday. On the forecast track...the depression will
be moving away from the bahamas and the u.s. East coast.

Maximum sustained winds are near 35 mph...55 km/h...with higher
gusts. Some slight strengthening is possible during the next 48
hours...and emily could regain tropical storm status on sunday.

Estimated minimum central pressure is 1011 mb...29.85 inches.


Hazards affecting land
----------------------
rainfall...emily is expected to produce additional rainfall
accumulations of 1 to 3 inches over the northwest bahamas through
sunday. Isolated maximum storm total amounts of 6 inches are
possible in association with emily.

Wind...wind gusts to tropical storm force are possible in heavy
squalls in the northwestern bahamas overnight.


Next advisory
-------------
next complete advisory...500 am edt.

$$
forecaster stewart



tropical depression emily discussion number 15
nws national hurricane center miami fl al052011
1100 pm edt sat aug 06 2011

an air force reserve reconnaissance aircraft this afternoon found
1000-ft flight-level winds as high as 48 kt in the southern
quadrant of the low-level circulation of emily. However...these
winds were occurring near isolated small convective cells and were
not considered to be representative of the storm-scale circulation.
However...other flight-level and sfmr surface wind data indicate
that emily is a solid 30-kt depression.

The initial motion estimate is northward or 360/07 kt. Emily is
forecast to move slowly northward tonight and gradually turn toward
the northeast on sunday as the small cyclone moves around the
western periphery of a subtropical ridge that extends east-west
along 28n latitude. By 24 hours...a shortwave trough currently
along the u.s. Mid-atlantic coast is expected to capture emily and
accelerate it to the east-northeast within the mid-latitude
westerlies. Emily is forecast to merge with a frontal system around
the 48-hour time period. The forecast track is similar to but a
little south of the previous advisory track...and is along the
right side of the nhc guidance envelope.

After looking reasonably impressive earlier this afternoon...emily
is now experiencing 10-15 of northeasterly shear...which has
elongated both the convective pattern and the surface wind field in
a northeast-southwest orientation. Modest northeast to easterly
shear is expected to continue for the next 12-18 hours...which
should inhibit any significant development. By 24 hours...
However...the vertical shear is forecast to relax...which may allow
for some slight intensification to occur before westerly wind shear
begins to affect the cyclone and induces weakening. The exact
timing of merger with a weak frontal system that extends from the
carolinas to near bermuda is difficult to assess this time of the
year over such warm ssts. Although dissipation is forecast to occur
shortly after the 48-hour time period...it would not be out of the
question for emily to maintain its identity out to 72 hours as
indicated by the ships/lgem intensity models. The official
intensity forecast is similar to the previous advisory and is a
blend of the ships/lgem models.

Another reconnaissance flight is scheduled for sunday afternoon.


Forecast positions and max winds

init 07/0300z 27.4n 78.2w 30 kt 35 mph
12h 07/1200z 29.2n 76.9w 35 kt 40 mph
24h 08/0000z 30.9n 74.0w 35 kt 40 mph
36h 08/1200z 32.5n 69.1w 35 kt 40 mph
48h 09/0000z 34.0n 62.0w 30 kt 35 mph
72h 10/0000z...dissipated

$$
forecaster stewart

Tropical depression emily discussion number 17
nws national hurricane center miami fl al052011
1100 am edt sun aug 07 2011

visible satellite imagery shows that emily consists of an exposed
swirl of low clouds located well northeast of the remaining deep
convection. This structure is consistent with 20 to 25 kt of
northeasterly shear as shown by the ships model and uw-cimss
satellite analysis. The initial intensity is held at 30 kt on the
basis of continuity and a dvorak ci-number of 2.0 from tafb. The
intensity guidance continues to show little change through the
forecast period...with the northeasterly shear expected to continue
and the cyclone moving over gradually cooler waters until it is
absorbed into a frontal system in 36 to 48 hours. The nhc
intensity forecast follows this trend and is unchanged from the
previous advisory. If deep convection does not return near the
center...emily could become a remnant low later today or tonight...
Or the system could open up into a trough earlier than dissipation
is indicated here.

Satellite fixes show that the center is ahead of previous estimates
and a little to the left of the previous forecast. The initial
motion estimate is toward the northeast...035 degrees...at 15 kt.
Overall...the track forecast reasoning remains unchanged...as emily
will continue accelerating northeastward and east-northeastward
under the influence of a gradually amplifying mid-latitude trough
moving off the coast of the united states. The new nhc track
forecast is left of and faster than the previous one...due to the
initial position and motion and an adjustment toward the new
multi-model consensus.


Forecast positions and max winds

init 07/1500z 30.1n 76.0w 30 kt 35 mph
12h 08/0000z 31.6n 74.1w 30 kt 35 mph...post-trop/remnt low
24h 08/1200z 33.4n 69.2w 30 kt 35 mph...post-trop/remnt low
36h 09/0000z 35.2n 63.1w 30 kt 35 mph...post-trop/remnt low
48h 09/1200z...dissipated

$$
forecaster brennan