ATL: HARVEY - Post-Tropical - Discussion

[cycloneye]

BULLETIN
Hurricane Harvey Advisory Number 19
NWS National Hurricane Center Miami FL AL092017
1000 PM CDT Thu Aug 24 2017

...HARVEY EXPECTED TO STRENGTHEN AS IT MOVES TOWARDS THE TEXAS
COAST...
...LIFE-THREATENING AND DEVASTATING FLOODING EXPECTED NEAR THE
COAST DUE TO HEAVY RAINFALL AND STORM SURGE...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.2N 94.6W
ABOUT 250 MI...400 KM SE OF CORPUS CHRISTI TEXAS
ABOUT 245 MI...400 KM SSE OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...973 MB...28.74 INCHES
---------------------------------------------------------


Hurricane Harvey Discussion Number 19
NWS National Hurricane Center Miami FL AL092017
1000 PM CDT Thu Aug 24 2017

Harvey's rapid intensification seems to have slowed for the moment,
as an eye seen earlier in satellite imagery has lost definition
during the past few hours. In addition, reports from an Air Force
Reserve Hurricane Hunter aircraft show that 700-mb flight level
winds are in the 75-80 kt range, with reliable surface wind
estimates from the Stepped Frequency Microwave Radiometer remaining
near 75 kt. The aircraft also reported that the central pressure
has slowly fallen to 973 mb inside the 16 n mi wide eye. Based on
these data, the initial intensity remains 75 kt, and this could be a
little conservative.

Harvey has turned a little to the left since the last advisory with
the initial motion now 315/9. A mid-level anticyclone over the
eastern Gulf of Mexico is expected to steer Harvey generally
northwestward with a decreasing forward speed for the next 36-48 h,
with the center now forecast to make landfall on the middle Texas
coast in about 36 h. This part of the new forecast track has been
nudged a little to the left based mainly on the initial position
and motion. After landfall, the cyclone is likely to get stuck
between the Gulf anticyclone and a stronger anticyclone over the
western United States, with little motion likely from 48-96 h.
A slow eastward motion appears likely by 120 h due to the influence
of a trough in the westerlies digging into the eastern United
States. There is some spread in the guidance at that time, with
the GFS showing Harvey drifting slowly eastward and the ECMWF
showing a faster motion. The new forecast track splits this
difference of 5-day forecasts and lies near the consensus models.

It is unclear why the intensification has slowed, although it is
possibly due to some dry air seen earlier wrapping around the north
side of the core convection. Otherwise, Harvey remains in an
favorable environment for further strengthening with low vertical
shear and high oceanic heat content. The intensity forecast will
use the scenario that rapid intensification will resume tonight,
with Harvey becoming a major hurricane before landfall in Texas.
After landfall, the intensity forecast is based on the scenario that
Harvey will weaken over land, but it will remain close enough to
the coast so that the weakening will be slower than normal. Thus,
the forecast keeps Harvey as a tropical storm from 72-120 h.

It is critical that users not focus on the exact forecast track
of Harvey, since cycle-to-cycle adjustments are likely. All
locations within the hurricane and storm surge warning areas should
be preparing for the possibility of major hurricane-force winds and
life-threatening storm surge.

Key Messages:

1. Harvey is expected to be a major hurricane at landfall, bringing
life-threatening storm surge, rainfall, and wind hazards to portions
of the Texas coast. Preparations to protect life and property should
be completed by tonight, as tropical-storm-force winds will first
arrive in the hurricane and storm surge warning areas on Friday.

2. A Storm Surge Warning is in effect for much of the Texas coast.
Life-threatening storm surge flooding could reach heights of 6 to 12
feet above ground level at the coast between the north entrance of
the Padre Island National Seashore and Sargent. For a depiction of
areas at risk, see the Storm Surge Watch/Warning Graphic at
hurricanes.gov.

3. Devastating and life-threatening flooding is expected across the
middle and upper Texas coast from heavy rainfall of 15 to 25 inches,
with isolated amounts as high as 35 inches, from Friday through next
Wednesday. Please refer to products from your local National Weather
Service office and the NOAA Weather Prediction Center for more
information on the flooding hazard.

4. The Potential Storm Surge Flooding Map is available on the NHC
website. This product depicts a reasonable worst-case scenario -
the amount of inundation that has a 10 percent chance of being
exceeded at each individual location. This map best represents
the flooding potential in those locations within the watch and
warning areas.


FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 25.2N 94.6W 75 KT 85 MPH
12H 25/1200Z 26.1N 95.6W 95 KT 110 MPH
24H 26/0000Z 27.2N 96.5W 110 KT 125 MPH
36H 26/1200Z 28.1N 97.1W 100 KT 115 MPH...INLAND
48H 27/0000Z 28.6N 97.3W 70 KT 80 MPH...INLAND
72H 28/0000Z 28.5N 97.5W 35 KT 40 MPH...INLAND
96H 29/0000Z 28.5N 97.0W 35 KT 40 MPH...INLAND
120H 30/0000Z 29.5N 95.0W 35 KT 40 MPH...INLAND

$$
Forecaster Beven

[JaxGator]

The most recent F-16 pass makes me think that Harvey is nearly a lock for an eventual major hurricane.

They are flying f-16s into harvey?

As a military nerd, this is the exact same thing I thought, lol. I would hate to fly a little jet fighter into a hurricane, lol.

I thought the same too (what are the odds), though F-16s can't fly through hurricanes. That would be ride no one could forget. Its good to know there's a fellow weather and military nerd on the board/forum. Back on Harvey, the footage on GOES 16 shows how fast its east eyewall and the CDO have improved and the eye reemerging. Not good.

[NWgeorgiastormdawg]

WTNT24 KNHC 250234
TCMAT4

HURRICANE HARVEY FORECAST/ADVISORY NUMBER 19
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092017
0300 UTC FRI AUG 25 2017

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A STORM SURGE WARNING IS IN EFFECT FOR...
* PORT MANSFIELD TO HIGH ISLAND TEXAS

A STORM SURGE WATCH IS IN EFFECT FOR...
* SOUTH OF PORT MANSFIELD TEXAS TO THE MOUTH OF THE RIO GRANDE

A HURRICANE WARNING IS IN EFFECT FOR...
* PORT MANSFIELD TO SARGENT TEXAS

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* NORTH OF SARGENT TO HIGH ISLAND TEXAS
* SOUTH OF PORT MANSFIELD TEXAS TO THE MOUTH OF THE RIO GRANDE

A HURRICANE WATCH IS IN EFFECT FOR...
* SOUTH OF PORT MANSFIELD TEXAS TO THE MOUTH OF THE RIO GRANDE

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* SOUTH OF THE MOUTH OF THE RIO GRANDE TO BOCA DE CATAN MEXICO

A STORM SURGE WARNING MEANS THERE IS A DANGER OF LIFE-THREATENING
INUNDATION...FROM RISING WATER MOVING INLAND FROM THE COASTLINE...
DURING THE NEXT 36 HOURS IN THE INDICATED LOCATIONS. FOR A DEPICTION
OF AREAS AT RISK...PLEASE SEE THE NATIONAL WEATHER SERVICE STORM
SURGE WATCH/WARNING GRAPHIC...AVAILABLE AT HURRICANES.GOV. THIS
IS A LIFE-THREATENING SITUATION. PERSONS LOCATED WITHIN THESE AREAS
SHOULD TAKE ALL NECESSARY ACTIONS TO PROTECT LIFE AND PROPERTY FROM
RISING WATER AND THE POTENTIAL FOR OTHER DANGEROUS CONDITIONS.
PROMPTLY FOLLOW EVACUATION AND OTHER INSTRUCTIONS FROM LOCAL
OFFICIALS.

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. A WARNING IS TYPICALLY ISSUED
36 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-STORM-
FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT
OR DANGEROUS. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE
RUSHED TO COMPLETION.

A STORM SURGE WATCH MEANS THERE IS A POSSIBILITY OF LIFE-
THREATENING INUNDATION...FROM RISING WATER MOVING INLAND FROM THE
COASTLINE...IN THE INDICATED LOCATIONS DURING THE NEXT 48 HOURS.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA.

IN ADDITION...INTERESTS IN SOUTHWESTERN LOUISIANA SHOULD CONTINUE
TO MONITOR THE PROGRESS OF THIS SYSTEM.

HURRICANE CENTER LOCATED NEAR 25.2N 94.6W AT 25/0300Z
POSITION ACCURATE WITHIN 15 NM

PRESENT MOVEMENT TOWARD THE NORTHWEST OR 315 DEGREES AT 9 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 973 MB
EYE DIAMETER 15 NM
MAX SUSTAINED WINDS 75 KT WITH GUSTS TO 90 KT.
64 KT....... 20NE 10SE 10SW 10NW.
50 KT....... 30NE 20SE 20SW 30NW.
34 KT....... 90NE 50SE 40SW 60NW.
12 FT SEAS.. 90NE 75SE 60SW 90NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 25.2N 94.6W AT 25/0300Z
AT 25/0000Z CENTER WAS LOCATED NEAR 25.1N 94.5W

FORECAST VALID 25/1200Z 26.1N 95.6W
MAX WIND 95 KT...GUSTS 115 KT.
64 KT... 30NE 15SE 10SW 15NW.
50 KT... 50NE 40SE 30SW 40NW.
34 KT...110NE 70SE 50SW 80NW.

FORECAST VALID 26/0000Z 27.2N 96.5W
MAX WIND 110 KT...GUSTS 135 KT.
64 KT... 35NE 30SE 20SW 30NW.
50 KT... 60NE 50SE 40SW 50NW.
34 KT...130NE 100SE 70SW 100NW.

FORECAST VALID 26/1200Z 28.1N 97.1W...INLAND
MAX WIND 100 KT...GUSTS 120 KT.
64 KT... 35NE 30SE 30SW 20NW.
50 KT... 60NE 60SE 50SW 40NW.
34 KT...140NE 110SE 80SW 70NW.

FORECAST VALID 27/0000Z 28.6N 97.3W...INLAND
MAX WIND 70 KT...GUSTS 85 KT.
50 KT... 40NE 40SE 30SW 20NW.
34 KT...120NE 100SE 70SW 50NW.

FORECAST VALID 28/0000Z 28.5N 97.5W...INLAND
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 90NE 70SE 30SW 0NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 200 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 29/0000Z 28.5N 97.0W...INLAND
MAX WIND 35 KT...GUSTS 45 KT.

OUTLOOK VALID 30/0000Z 29.5N 95.0W...INLAND
MAX WIND 35 KT...GUSTS 45 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 25.2N 94.6W

NEXT ADVISORY AT 25/0900Z

$$
FORECASTER BEVEN

[MississippiWx]

Not forecasted to move back into the GOM per the NHC's latest track.

They are splitting the difference between the Euro and GFS. Not really anything to it other than respect for both models. Very difficult track forecast after landfall (assuming Harvey even makes it inland).

[WeatherGuesser]

What am I seeing in the 5 day cone? Coming ashore, stalling, turning, back to the gulf, then NNE?

[RL3AO]

Harvey one hour apart. Look at the noticeable change in the northern eyewall.

[MississippiWx]

973mb extrap. pressure with 75kt. flight level winds in the SW quadrant this pass. About to penetrate the center.

[SouthDadeFish]

Edit: Read the wrong dropsonde sorry. Nonetheless, it seems Harvey is still intensifying judging by extrapolated with strong FL winds.

[Aric Dunn]

check radar.. the northern eyewall has become solid for once.. should show up on satellite shortly

[Blinhart]

BULLETIN
Hurricane Harvey Advisory Number 19
NWS National Hurricane Center Miami FL AL092017
1000 PM CDT Thu Aug 24 2017

...HARVEY EXPECTED TO STRENGTHEN AS IT MOVES TOWARDS THE TEXAS
COAST...
...LIFE-THREATENING AND DEVASTATING FLOODING EXPECTED NEAR THE
COAST DUE TO HEAVY RAINFALL AND STORM SURGE...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.2N 94.6W
ABOUT 250 MI...400 KM SE OF CORPUS CHRISTI TEXAS
ABOUT 245 MI...400 KM SSE OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...973 MB...28.74 INCHES
---------------------------------------------------------


Hurricane Harvey Discussion Number 19
NWS National Hurricane Center Miami FL AL092017
1000 PM CDT Thu Aug 24 2017

Harvey's rapid intensification seems to have slowed for the moment,
as an eye seen earlier in satellite imagery has lost definition
during the past few hours. In addition, reports from an Air Force
Reserve Hurricane Hunter aircraft show that 700-mb flight level
winds are in the 75-80 kt range, with reliable surface wind
estimates from the Stepped Frequency Microwave Radiometer remaining
near 75 kt. The aircraft also reported that the central pressure
has slowly fallen to 973 mb inside the 16 n mi wide eye. Based on
these data, the initial intensity remains 75 kt, and this could be a
little conservative.

Harvey has turned a little to the left since the last advisory with
the initial motion now 315/9. A mid-level anticyclone over the
eastern Gulf of Mexico is expected to steer Harvey generally
northwestward with a decreasing forward speed for the next 36-48 h,
with the center now forecast to make landfall on the middle Texas
coast in about 36 h. This part of the new forecast track has been
nudged a little to the left based mainly on the initial position
and motion. After landfall, the cyclone is likely to get stuck
between the Gulf anticyclone and a stronger anticyclone over the
western United States, with little motion likely from 48-96 h.
A slow eastward motion appears likely by 120 h due to the influence
of a trough in the westerlies digging into the eastern United
States. There is some spread in the guidance at that time, with
the GFS showing Harvey drifting slowly eastward and the ECMWF
showing a faster motion. The new forecast track splits this
difference of 5-day forecasts and lies near the consensus models.

It is unclear why the intensification has slowed, although it is
possibly due to some dry air seen earlier wrapping around the north
side of the core convection. Otherwise, Harvey remains in an
favorable environment for further strengthening with low vertical
shear and high oceanic heat content. The intensity forecast will
use the scenario that rapid intensification will resume tonight,
with Harvey becoming a major hurricane before landfall in Texas.
After landfall, the intensity forecast is based on the scenario that
Harvey will weaken over land, but it will remain close enough to
the coast so that the weakening will be slower than normal. Thus,
the forecast keeps Harvey as a tropical storm from 72-120 h.

It is critical that users not focus on the exact forecast track
of Harvey, since cycle-to-cycle adjustments are likely. All
locations within the hurricane and storm surge warning areas should
be preparing for the possibility of major hurricane-force winds and
life-threatening storm surge.

Key Messages:

1. Harvey is expected to be a major hurricane at landfall, bringing
life-threatening storm surge, rainfall, and wind hazards to portions
of the Texas coast. Preparations to protect life and property should
be completed by tonight, as tropical-storm-force winds will first
arrive in the hurricane and storm surge warning areas on Friday.

2. A Storm Surge Warning is in effect for much of the Texas coast.
Life-threatening storm surge flooding could reach heights of 6 to 12
feet above ground level at the coast between the north entrance of
the Padre Island National Seashore and Sargent. For a depiction of
areas at risk, see the Storm Surge Watch/Warning Graphic at
hurricanes.gov.

3. Devastating and life-threatening flooding is expected across the
middle and upper Texas coast from heavy rainfall of 15 to 25 inches,
with isolated amounts as high as 35 inches, from Friday through next
Wednesday. Please refer to products from your local National Weather
Service office and the NOAA Weather Prediction Center for more
information on the flooding hazard.

4. The Potential Storm Surge Flooding Map is available on the NHC
website. This product depicts a reasonable worst-case scenario -
the amount of inundation that has a 10 percent chance of being
exceeded at each individual location. This map best represents
the flooding potential in those locations within the watch and
warning areas.


FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 25.2N 94.6W 75 KT 85 MPH
12H 25/1200Z 26.1N 95.6W 95 KT 110 MPH
24H 26/0000Z 27.2N 96.5W 110 KT 125 MPH
36H 26/1200Z 28.1N 97.1W 100 KT 115 MPH...INLAND
48H 27/0000Z 28.6N 97.3W 70 KT 80 MPH...INLAND
72H 28/0000Z 28.5N 97.5W 35 KT 40 MPH...INLAND
96H 29/0000Z 28.5N 97.0W 35 KT 40 MPH...INLAND
120H 30/0000Z 29.5N 95.0W 35 KT 40 MPH...INLAND

$$
Forecaster Beven

He/She put this out real early.

[MississippiWx]

Believe they will be updating the strength again shortly...

[SunnyThoughts]

Well if those 2 pics that RL3AO posted are any indication, one more hour and its going to be off to the races I'm afraid.

[SouthDadeFish]

Extrapolated pressure down to 966 mb...

[NDG]

Pressure continues to drop, perhaps now down to 968-969 mb after adjustment.

024630 2512N 09443W 6959 02895 9659 +174 +113 331021 025 023 001 03

[RL3AO]

Extrapolated pressure down about 3mb in 90 minutes. Flight level temperature up about 2C during that time. Cold thunderstorms now surround the eye. Rapid intensification possibly underway.

[Exalt]

100% this is getting retired. First hurricane to make landfall as a major since Wilma? The sheer amount of flooding this is about to cause? God I can't bear to think about the devastation.

[MississippiWx]

965mb extrap pressure...Yep, here we go again.

[CrazyC83]

I'd think if they find 85 kt winds there will be a Tropical Cyclone Update. No real need for a new full package since the forecast would still be on track.

[Hurricane Andrew]

Extrapolated pressure down about 3mb in 90 minutes. Flight level temperature up about 2C during that time. Cold thunderstorms now surround the eye. Rapid intensification possibly underway.

Wow, you can see the eye warm several degrees in this loop, less than a half hour long. Deep grey almost entirely surrounds the center now.

http://weather.cod.edu/satrad/exper/?pa ... o1-13-48-1

[Exalt]

Extrapolated pressure down about 3mb in 90 minutes. Flight level temperature up about 2C during that time. Cold thunderstorms now surround the eye. Rapid intensification possibly underway.

With the satellite improvement that's shown within the hour, I'd say it is underway.