ATL: HERMINE - Post-Tropical - Discussion

[drezee]

well.. convection is increasing.. but still not even close to a TS..maybe next mission..

Actually one of the drops(ob 17) from the GlobalHawk is borderline...but it could justify upgrade.

[Aric Dunn]

well.. convection is increasing.. but still not even close to a TS..maybe next mission..

Actually one of the drops(ob 17) from the GlobalHawk is borderline...but it could justify upgrade.

have not seen it.. but doubtful they will rely on that as its still a work in progress.

[GCANE]

Some good towers firing with -80C tops.
Dry air to the west seems to be filling in somewhat with mid-level moisture.
In fact, I checked GFS 500mb and that dry air slot is forecast to abate in about 36 to 48 hrs.
Also, the dry air to the north has moistened as well due to convection that fired over FL yesterday afternoon and from shear that was induced by TD9's outflow.
Shear is a problem on the west of the convection with High-Level winds out of the south at 10 knots and Mid-Level winds out of the north at 15 knots.

[johngaltfla]

No upgrade to a TS but big pressure drop confirmed, down to 1003 mb per 0500 Advisory from the NHC:

SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...23.8N 86.6W
ABOUT 305 MI...495 KM W OF KEY WEST FLORIDA
ABOUT 270 MI...435 KM W OF HAVANA CUBA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES

[caneman]

Winds should follow with that pressure drop.

[cycloneye]

TROPICAL DEPRESSION NINE DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016
400 AM CDT TUE AUG 30 2016

Although there has been an increase in convection over the
southeastern portion of the depression's circulation, the system is
still being affected by westerly shear, with the low-level center
exposed to the west of the deep convection. Recent observations
from a NOAA Hurricane Hunter aircraft and the unmanned NASA Global
Hawk indicate that the tropical cyclone remains just below tropical
storm strength. The NOAA aircraft has reported peak flight level
winds in the southeastern quadrant of 32 kt, and believable SFMR
winds of around 30 kt. A dropsonde from the Global Hawk reported
33 kt surface winds, but the mean-layer wind over the lowest 150 m
support winds closer to 30 kt. A very recent center drop from the
unmanned aircraft indicate that the minimum pressure is 1003 mb.

The westerly shear over the depression is forecast to decrease
somewhat during the next day or so, however dry mid-level air is
expected to remain near and to the west of the system. As a
result of the marginal environment, only gradual strengthening
is predicted during the next couple of days. This is supported
by the global models which do not significantly deepen the system
until is moves over the western Atlantic and interacts with an
upper-level trough. The NHC intensity forecast is unchanged from
the previous advisory and remains near the intensity consensus
model IVCN.

The aircraft fixes show that the depression has moved westward
since the previous advisory, and the initial motion estimate is
275/6 kt. The cyclone is forecast to turn west-northwestward, then
northwestward tonight around a low- to mid-level ridge over
the western Atlantic and Florida. After that time, a deepening
mid-latitude trough over the southeastern United States should
cause the system to turn northeastward toward the Florida Big
Bend region. The dynamical models continue to agree on this
scenario, but there are some differences in the forward speed of
the system after 36 hours, and the NHC track is near the consensus
of the GFS and ECMWF models. The more westward initial position has
required a westward adjustment to the track through 24 hours, but
otherwise, the new NHC track forecast is similar to the previous
advisory.

Given the current forecast, a tropical storm or hurricane watch may
be required for a portion of the Florida Gulf coast later today.


FORECAST POSITIONS AND MAX WINDS

INIT 30/0900Z 23.8N 86.6W 30 KT 35 MPH
12H 30/1800Z 24.2N 87.3W 35 KT 40 MPH
24H 31/0600Z 24.9N 87.6W 40 KT 45 MPH
36H 31/1800Z 26.2N 86.9W 45 KT 50 MPH
48H 01/0600Z 27.7N 85.5W 55 KT 65 MPH
72H 02/0600Z 30.7N 81.1W 50 KT 60 MPH
96H 03/0600Z 33.2N 74.0W 50 KT 60 MPH
120H 04/0600Z 35.5N 67.5W 50 KT 60 MPH

$$
Forecaster Brown

[Tampa Bay Hurricane]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service.

Granted since the area where I live will be impacted by this cyclone, I do my best not to hype it, which lets be honest, can be a challenge sometimes.

Storms now getting closer to the center, just as the NHC forecasted. Yesterday I did not think this would intensify much at all since shear lasted quite a long time, and the anticyclone was well south of the system, but looks like shear is abating and mid level dry air slowly moistening. With the high heat content of the loop current and high SSTs, but with some shear and dry air to contend with, the NHC forecast of 65 mph at landfall is very reasonable. At the peak of the storm Wednesday Night and Thursday, I think 40-50 mph winds and at least 6 inches of rain (but not more than 10 inches since the storm will be moving quickly) will be experienced in the immediate Tampa Bay areas, but I would not be surprised if some of the stronger squalls contained gusts to 60 mph, since the potential for eastern sector shear leading to isolated tornadoes and severe thunderstorm winds being brought to the surface may occur, just like with Debby 4 years ago. Tides will rise and should cause street flooding on low lying areas- the usual spots just like with Colin and Debby, but more than with Colin due to forecast intensity and expanse of the system.

Now if dry air and shear were to dramatically decrease- which I don't expect to happen at this point- but still a possibility, then a Hurricane at landfall is certainly possible- and winds would obviously be higher than what is forecast.

Again check NWS and NHC. My forecast intensity is now pretty close to what they have.

I think the biggest impacts will be flooding of the usual spots from heavy rain and tidal elevations. Some scattered power outages are likely too, perhaps more widespread where the center makes landfall. We should see tropical storm warnings for the Big Bend and West Coast probably down to Sarasota, and hurricane watches further north of Tampa Bay.

[Blinhart]

No upgrade to a TS but big pressure drop confirmed, down to 1003 mb per 0500 Advisory from the NHC:

SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...23.8N 86.6W
ABOUT 305 MI...495 KM W OF KEY WEST FLORIDA
ABOUT 270 MI...435 KM W OF HAVANA CUBA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES

I could of swore it was 1002 at 10PM CDT?

[drewschmaltz]

Wow, the NHC sure is good at what it does. Lots of convection firing all around the center.

http://www.nrlmry.navy.mil/nexsat-bin/n ... PE=Instant

[caneman]

Yes, it's blowing up big time. When is next recon?

[GCANE]

Wow, that is a massive tower going off now.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

Wish it was daylight, I would like to see the visible satellite loop for that.

Looks like it is moving into a ridge of unstable air to the immediate NW with Theta-E at 362 and CAPE at 3000 which likely set it off.

The last I saw of the core, there was an inversion. It looks like that may have just cut loose.

With the mid levels moistening, we may get a little shear abatement from this.

[jlauderdal]

Yes, it's blowing up big time. When is next recon?

http://www.nhc.noaa.gov/recon.php

[GCANE]

Two impressive towers both with cloud tops colder than -80C.
First time getting heavy convetion on the NE quad of the CoC.
Watching for something to fire on the NW side.

[Nimbus]

No upgrade to a TS but big pressure drop confirmed, down to 1003 mb per 0500 Advisory from the NHC:

SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...23.8N 86.6W
ABOUT 305 MI...495 KM W OF KEY WEST FLORIDA
ABOUT 270 MI...435 KM W OF HAVANA CUBA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES

That shows that 9 is still able to slowly organize embedded within the wide shallow 1007 mb background area.
The ULL southeast of Texas has been shearing the system with dry air but this morning it looks like Some high pressure is starting to expand WNW bringing moisture from the Yucatan channel.

The ULL off the southeast coast is filling in and the next trough is still up near Chicago so I wouldn't completely rule out some model changes in a day or so.

[drewschmaltz]

HWRF has this struggling from something for the next 30 some hours. 27 hours after 06z it only drops 1mb.

[blazess556]

Latest recon data suggests TD9 still has a rather broad low pressure area (~1004-1005 mb)

[Alyono]

Yes, it's blowing up big time. When is next recon?

there's one in there now. It isn't showing any intensification

[jlauderdal]

Looks very healthy this morning. Time will tell but this just might suprise some people in the next few days.

IR looks impressive but dont be fooled by pretty colors, recon is what really matters as far as structure goes

[NDG]

Yes, it's blowing up big time. When is next recon?

there's one in there now. It isn't showing any intensification

Its mission has finished.

[caneman]

I think most people are getting bored and frustrated with this thing, I know I am. As my Dad use to say, s#it or get off the pot