ATL: HARVEY - Post-Tropical - Discussion

[BZSTORM]

I appreciate most of you on this board are concerned about TS Harvey after it has crossed Belize/Yucatan and USA threat but there are still Belizean, Hondurans and Mexicans who right now are more concerned with where Harvey will landfall and on our borders and intensity. The models even at 3 days out are still all over the place changing intensity and route almost run to run. I am fast coming to conclusion that we might not know this until Monday or IF/when there is a more decisive move NW to W on Sunday. I would appreciate the pro mets on the board for their take on when we might have more conclusive idea as so far model tracks almost seem to be reruns of previous years tracks for other storms. What I can add is climatically Belize has felt hotter and more humid than previous years, since April like we are 2 months ahead of ourselves for average temperatures, the humidity has been especially higher then normal, Belize water table is already at max, so even 3" rain will cause flooding in Belize. Also the Tropical wave currently across Eastern Cuba which is travelling slower than TS Harvey so not sure if that would cross Belize and Yucatan before TS reaches Gulf of Honduras there appears to be almost 8mph difference in speed right now. Could any of the pro-mets explain if or how is this likely to affect TS Harvey i.e regeneration or disruption I don't know enough about the physics of one system on another. All I know right now is this much uncertainty on track always makes me a bit jumpy. We are always prepared for worst here and hope for the best but Belize is a small country and when you have the whole country as a target it narrows down where you can move to get away for a storm. Many thanks for any input/observations 16 yrs watching these systems and I am still learning.

the track up to Belize has been high confidence. The models are also showing the heavy rains south fo the center as it impacts Honduras, so the threat of major flooding is high. Cannot rule out a repeat of Matthew from 2010 in Honduras

Thanks Alyono for that observation - TS Matthew did indeed bring major flooding to Honduras and Belize and did allot of coastal damage for piers in Southern Belize. You don't need a a full out cyclone to make a disaster. Fortunately Belize has a good track record for ppl listening to warnings and NEMO advisories to move to higher location if in flood zone, so we have much lower mortality rates for storms in our region, most being zero a trend I hope continues.

[cycloneye]

...HARVEY STILL A TROPICAL STORM BUT LESS ORGANIZED THAN
YESTERDAY...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...13.9N 68.1W
ABOUT 125 MI...205 KM NNE OF CURACAO
ABOUT 1010 MI...1630 KM E OF CABO GRACIAS A DIOS ON NIC/HON BORDER
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES

Tropical Storm Harvey Discussion Number 9
NWS National Hurricane Center Miami FL AL092017
1100 AM AST Sat Aug 19 2017

Harvey has become less organized in visible imagery since this
time yesterday, with the convective pattern becoming elongated and
the circulation looking less well defined. In addition, an Air
Force Reserve Hurricane Hunter aircraft could not close the
circulation at 850 mb, but was able to close the circulation at 1000
ft. The plane has not yet reported tropical-storm-force winds, but
the northwestern quadrant was not well sampled. Thus, the initial
intensity is held at a possibly generous 35 kt.

The initial motion is now 275/19. A low- to mid-level ridge
extending across the western Atlantic should keep Harvey on a fast
westward course across the Caribbean Sea for the next 36-48 hours.
Thereafter, there should be a weakness in the ridge north of
Harvey caused by a strong mid/upper-level low currently seen in
water vapor imagery over the Gulf of Mexico. This pattern should
cause a turn toward the west-northwest and a decrease in forward
speed. The track guidance is in good agreement that Harvey should
pass near or just north of northeastern Honduras, and then cross
Belize and/or the Yucatan Peninsula into the Bay of Campeche, and
based on this the new forecast track follows the guidance with only
minor changes from the previous track.

The ongoing moderate vertical shear should continue for another
12-24 h or so, and combined with the current lack of organization
should allow at best only slow strengthening. After that, the
upper-level winds are expected to become favorable for strengthening
as the system moves over the deep warm waters of the western
Caribbean. The intensity forecast follows the previous forecast in
calling for a peak intensity of 60 kt just before the system
reaches Belize or the Yucatan Peninsula. Harvey should weaken as it
crosses the southern portion of the Yucatan Peninsula between 72-96
h, followed by some re-intensification over the Bay of Campeche. It
should be noted that any additional loss of organization in the next
12-24 h would result in the cyclone degenerating into an easterly
wave.


FORECAST POSITIONS AND MAX WINDS

INIT 19/1500Z 13.9N 68.1W 35 KT 40 MPH
12H 20/0000Z 14.1N 70.9W 35 KT 40 MPH
24H 20/1200Z 14.4N 74.9W 40 KT 45 MPH
36H 21/0000Z 14.9N 78.7W 45 KT 50 MPH
48H 21/1200Z 15.7N 82.4W 50 KT 60 MPH
72H 22/1200Z 17.5N 88.0W 60 KT 70 MPH
96H 23/1200Z 19.0N 91.5W 30 KT 35 MPH
120H 24/1200Z 19.5N 93.5W 40 KT 45 MPH

$$
Forecaster Beven

[wxman57]

Couldn't find TS winds, but didn't downgrade it yet.

[Nimbus]

The ULL north of Cuba isn't moving very fast and the HWRF has this moving up almost into the mid gulf. Initially the low may provide an outflow channel for Harvey and there may be more to the forecast in 24 hours once the shear lets up.

[Sanibel]

Hostile conditions did a number on both Lows...Don't exclude possible rebounds...

[msbee]

FYI, here is a page with some of the damage and flooding in Barbados.
http://www.turtle48.de/en/country/bb/20 ... /main.html

[Cunxi Huang]

TXNT24 KNES 191759
TCSNTL

A. 09L (HARVEY)

B. 19/1745Z

C. 14.2N

D. 68.8W

E. FIVE/GOES-E

F. T1.0/2.0/W1.0/24HRS

G. IR/EIR/VIS

H. REMARKS...DT=1.0 BASED ON SHEAR PATTERN DEFINED BY LOOSE CLOUD LINES,
PROXIMITY WITHIN 1.25 DG FROM CONVECTION, SMALL SIZE. PT=1.0. MET=1.0. FT
IS BASED ON DT.

I. ADDL POSITIONS

NIL


...SCHWARTZ

NHC really should downgrade Harvey to a TD at 18z...it looks like a wave right now.

[tarheelprogrammer]

NHC really should downgrade Harvey to a TD at 18z...it looks like a wave right now.

Yep, another struggling TC/Strong wave in August, which has been the theme in recent years.

[Cunxi Huang]

AL, 09, 2017081918, , BEST, 0, 140N, 690W, 30, 1007, TD, 34, NEQ, 0, 0, 0, 0, 1009, 100, 60, 0, 0, L, 0, , 0, 0, HARVEY, M, 0, , 0, 0, 0, 0, genesis-num, 019,

AL, 09, 201708191745, 10, DVTS, CI, , 1420N, 6900W, , 3, 35, 2, 1005, 2, DVRK, , , , , , , , , , , , , , L, TAFB, JL, VI, 5, 2025 /////, , , GOES13, CSC, T, System appears to be very disorganized and may be an

TD. Even TAFB suggests a T2.0/2.5.

[wxman57]

I'm 100% certain it's "post-tropical" now. There's no significant LLC, and no organized convection. It's an open wave. However, NHC will probably downgrade it to a depression this afternoon and then to post-tropical this evening.

[AxaltaRacing24]

I'm 100% certain it's "post-tropical" now. There's no significant LLC, and no organized convection. It's an open wave. However, NHC will probably downgrade it to a depression this afternoon and then to post-tropical this evening.

You don't think this makes it to the BOC?

[wxman57]

I'm 100% certain it's "post-tropical" now. There's no significant LLC, and no organized convection. It's an open wave. However, NHC will probably downgrade it to a depression this afternoon and then to post-tropical this evening.

You don't think this makes it to the BOC?

I think it may make the southern BoC, but looking much like it does now. Could regenerate into a TS before the Yucatan, weaken to a remnant low over the Yucatan, then regenerate into a TS in the western BoC before landfall. Or, it may have already seen its best days...

I think I'll opt for regeneration for now.

[floridasun78]

this season feel like it elnino season system fighting for their life not La Niña

[Nimbus]

Some outflow boundaries this afternoon indicating not much general inflow.
Still seems to be plenty of energy so maybe Monday we see some regeneration.
Glad to see both these systems having a tough time staying classified.

[cycloneye]

Tropical Depression Harvey Discussion Number 10
NWS National Hurricane Center Miami FL AL092017
500 PM EDT Sat Aug 19 2017

The cloud pattern of Harvey has continued to decay during the day,
at least in part due to 15-20 kt of northerly shear. The convective
area near the center is neither very concentrated or curved, and
overall the pattern more resembles that of an open wave than a
tropical cyclone. Based on the decay and data from the aircraft
mission this morning, the cyclone is downgraded to a tropical
depression. Another Air Force Reserve Hurricane Hunter aircraft
will investigate the system this evening to see if the circulation
still exists.

The intensity forecast is problematic. The current shear should
subside over the next 24 h, and the statistical guidance responds
to this by forecasting significant strengthening. On the other
hand, the structure of the cyclone has decayed to the point where
it may not be able to take advantage of the better environment, as
suggested by the ECMWF and GFS. The intensity forecast follows the
trend of the previous forecast, albeit with lower intensities, in
showing gradual strengthening until landfall in Belize or Yucatan.
However, an alternative forecast scenario is that the system
degenerates to an open wave and is unable to regenerate during the
next 72 h.

The initial motion remains 275/19. There is no change in the
forecast philosophy from the previous advisory, and there are only
minor tweaks to the forecast track. A low- to mid-level ridge
extending across the western Atlantic should keep Harvey, or its
remnants, on a fast westward course across the Caribbean Sea for the
next 36 h. Thereafter, there should be a weakness in the ridge north
of Harvey caused by a strong mid/upper-level low currently seen in
water vapor imagery over the Gulf of Mexico. This pattern should
cause a turn toward the west-northwest and a decrease in forward
speed. The track guidance remains in good agreement that Harvey
should pass near or just north of northeastern Honduras, and then
cross Belize and/or the Yucatan Peninsula into the Bay of Campeche.

A Tropical Storm Watch could be required for portions of the
northern coast of Honduras and northeastern Nicaragua tonight. At
the present time, there is enough uncertainty about whether Harvey
will actually be a tropical storm in 48 h that a watch is not
warranted.

FORECAST POSITIONS AND MAX WINDS

INIT 19/2100Z 14.1N 70.0W 30 KT 35 MPH
12H 20/0600Z 14.3N 73.0W 30 KT 35 MPH
24H 20/1800Z 14.6N 77.0W 35 KT 40 MPH
36H 21/0600Z 15.2N 80.5W 40 KT 45 MPH
48H 21/1800Z 16.0N 83.8W 45 KT 50 MPH
72H 22/1800Z 18.0N 89.0W 45 KT 50 MPH...INLAND
96H 23/1800Z 19.0N 92.0W 30 KT 35 MPH...OVER WATER
120H 24/1800Z 19.5N 94.0W 40 KT 45 MPH

$$
Forecaster Beven

[Hammy]

Good chance we see the last advisory at 11 unless something drastic changes in organization. Don't see regeneration happening at this point.

[Alyono]

looks let net surface divergence

I'd give this maybe a 30 percent chance of regeneration in the BOC

[SoupBone]

Good chance we see the last advisory at 11 unless something drastic changes in organization. Don't see regeneration happening at this point.

Huh? What happened?

[Hammy]

Good chance we see the last advisory at 11 unless something drastic changes in organization. Don't see regeneration happening at this point.

Huh? What happened?

Recon barely found any sort of circulation earlier. Structure has degenerated quite badly thanks to the shear dry air and conditions are looking less and less favorable down the road.

[lrak]

Thank goodness I was about to purchase a generator for my reef tank. Too much at stake. Now I'm hoping for some swells and a little rain. Bye - "I hope Harvey".