ATL: HARVEY - Post-Tropical - Discussion

[GCANE]

They just recorded 1003.8mb surface pressure.

[Emmett_Brown]

Looks like the plane found some pressure readings as low as 1003.8mb so far.

Oops, posted at the same time

[Thetxhurricanemaster]

Looks like the plane found some pressure readings as low as 1003.8mb so far.

Ignore those reading they climbed in altitude during that time !

[SouthDadeFish]

The low extrapolated reading came around the time the plane was climbing to 850 mb, so I'm not sure they are reliable. The fact that they are flying at 850 mb now is interesting. Maybe 1000 ft wasn't safe to penetrate the convective burst?

[cg2916]

The low extrapolated reading came around the time the plane was climbing to 850 mb, so I'm not sure they are reliable. The fact that they are flying at 850 mb now is interesting. Maybe 1000 ft wasn't safe to penetrate the convective burst?

I also think the NHC likes to fly at 850 mb for tropical storms. Maybe they really did declare this thing mid-flight.

[Thetxhurricanemaster]

The low extrapolated reading came around the time the plane was climbing to 850 mb, so I'm not sure they are reliable. The fact that they are flying at 850 mb now is interesting. Maybe 1000 ft wasn't safe to penetrate the convective burst?

I also think the NHC likes to fly at 850 mb for tropical storms. Maybe they really did declare this thing mid-flight.

They did basically declare this thing but your correct they do fly 850MB for tropical storms

[Thetxhurricanemaster]

This is from ADT
Tropical Storm NINE
As of 18:00 UTC Aug 17, 2017:

Location: 13.0°N 55.0°W
Maximum Winds: 35 kt Gusts: N/A
Minimum Central Pressure: 1006 mb
Environmental Pressure: 1012 mb
Radius of Circulation: 120 NM
Radius of Maximum Wind: 30 NM
Eye Diameter: N/A

34 kt Wind Radii by Quadrant

[CrazyC83]

The low extrapolated reading came around the time the plane was climbing to 850 mb, so I'm not sure they are reliable. The fact that they are flying at 850 mb now is interesting. Maybe 1000 ft wasn't safe to penetrate the convective burst?

I also think the NHC likes to fly at 850 mb for tropical storms. Maybe they really did declare this thing mid-flight.

They did basically declare this thing but your correct they do fly 850MB for tropical storms

Typically, low-level flights (a couple hundred feet) are used for invests to close off lows. 925 mb (1,500 feet) is rarely used today but would be mainly for tropical depressions and weak storms. 850 mb (5,000 feet) is normal for tropical storms and category 1 hurricanes, while 700 mb (10,000 feet) is generally used for stronger hurricanes.

[tolakram]

Looks like SLIDER is having update issues again. GOES16 using the BYO page.

https://weather.msfc.nasa.gov/cgi-bin/get-abi?satellite=GOESEastfullDiskband02&lat=14&lon=-55&width=1400&height=900&zoom=2&type=Animation&numframes=15&quality=90

[GCANE]

[blp]

We have Harvey..

...HURRICANE HUNTER FINDS THAT THE DISTURBANCE HAS BECOME
TROPICAL STORM HARVEY...

[cycloneye]

BULLETIN
Tropical Storm Harvey Advisory Number 2
NWS National Hurricane Center Miami FL AL092017
500 PM AST Thu Aug 17 2017

...HURRICANE HUNTER FINDS THAT THE DISTURBANCE HAS BECOME
TROPICAL STORM HARVEY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...13.0N 55.8W
ABOUT 250 MI...400 KM E OF BARBADOS
ABOUT 355 MI...570 KM E OF ST. LUCIA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

Tropical Storm Harvey Discussion Number 2
NWS National Hurricane Center Miami FL AL092017
500 PM AST Thu Aug 17 2017

An Air Force Reserve Hurricane Hunter aircraft found a well-defined
circulation in the low pressure area east of the Lesser Antilles,
with the center near a cluster of sheared, but strong, convection.
The aircraft data suggest that the maximum winds are near 35 kt
and that the central pressure is near 1004 mb. Based on these
data, the disturbance is upgraded to Tropical Storm Harvey.

The initial motion is 270/16. There is no change to the forecast
philosophy since the previous advisory. A deep-layer ridge to the
north of the system should steer it quickly just north of due west
through the forecast period, with this motion expected to bring the
system through the Lesser Antilles and into the eastern Caribbean
Sea in 12-24 h, into the central Caribbean by 48-72 h, and to the
western Caribbean by 96-120 h. One adjustment is that the 96-120 h
points have been nudged a little southward in response to a shift in
the guidance, and thus now lie closer to Central America than on
the previous forecast. The forecast track again lies near the
center of the tightly clustered guidance envelope and the various
consensus models.

The system is in an area of moderate easterly vertical shear, and
the large-scale models suggest that light/moderate shear should
continue through at least 72 h. The conflicting forecast scenarios
alluded to in the previous advisory remain, with the SHIPS and
LGEM models still showing steady intensification while the GFS and
ECMWF models still forecast degeneration to an easterly wave over
the central Caribbean. The new intensity forecast again follows the
trend of the SHIPS/LGEM models, but it remains on the low side of
the guidance envelope out of respect for the GFS/ECMWF. The 96-120 h
intensities have been decreased a little due to the forecast track
showing more land interaction.


FORECAST POSITIONS AND MAX WINDS

INIT 17/2100Z 13.0N 55.8W 35 KT 40 MPH
12H 18/0600Z 13.1N 58.3W 35 KT 40 MPH
24H 18/1800Z 13.4N 61.6W 40 KT 45 MPH
36H 19/0600Z 13.7N 65.1W 45 KT 50 MPH
48H 19/1800Z 14.0N 68.8W 45 KT 50 MPH
72H 20/1800Z 14.5N 76.5W 55 KT 65 MPH
96H 21/1800Z 15.5N 83.5W 60 KT 70 MPH
120H 22/1800Z 17.0N 88.5W 55 KT 65 MPH...INLAND

$$
Forecaster Beven

[northjaxpro]

That did not take long at all for Harvey to be born!

[floridasun78]

i see plane found wind of 42.6 and pressure of 1005 not surprise nhc calling it HARVEY

[Thetxhurricanemaster]

i see plane found wind of 42.6 and pressure of 1005 not surprise nhc calling it HARVEY

Yeah and it continues to fire good convection

[NDG]

Ever since I looked at the HR Visible satellite loop this morning and reports from the nearby buoy I knew they were going to find Harvey.
Easterly shear should help it make it across the Caribbean at least as a Tropical Storm, just like the NHC forecasts it do. Is usually a westerly shear that these fast moving Caribbean storms have to deal with which is more destructive. IMO.

[HurricaneRyan]

I hope this at least makes a run for hurricane.

[Thetxhurricanemaster]

I hope this at least makes a run for hurricane.

Conditions that are forecasted can very well support a hurricane before the western Caribbean

[RL3AO]

Is usually a westerly shear that these fast moving Caribbean storms have to deal with which is more destructive. IMO.

Yes. Easterly shear is better since it develops the convection (pressure falls) where the low is going instead of where the low is moving away from.

[Blown Away]

18z... Shear on the increase late in the forecast...