ATL: IRMA - Post-Tropical - Discussion

[RL3AO]

very pronounced double wind maximum from recon... inner eye still has some juice left so a few more hours it seems.

I was just wondering if an EWRC was starting...

It's been in one for 6 to 8 hours now.

[GCANE]

Saw a strong mesovort circulating CCW in the eye.

[knotimpaired]

I am interested in any potential storm surge forecasts for North Miami Beach. Anyone have thoughts or sources?

Heather, keep in mind we're talking about POTENTIAL storm surge, not a storm surge forecast. Using the SLOSH model for a Category 4 tracking NNW at 6 mph during high tide, I'm seeing 7-9 feet into Miami proper and 11-12 feet into Biscayne Bay. Same if it's coming from due south. For a Cat 3 of similar size, reduce those numbers by a foot or so. However, if the wind field expands due to interaction with Cuba, then it would produce a surge similar to the Cat 4 numbers.

Northern Miami is less surge-prone than the city itself, perhaps reduce the numbers above by a foot or two.

Now all this is just a rough estimate of what kind of surge COULD impact SE Florida for a particular storm. Those numbers are NOT my forecast. They're just to give you an idea what the area MIGHT see as far as surge. We do not know the most important variables yet - exact track of Irma, exact size of Irma's wind field, speed of movement, etc.

and don't forget exact intensity- perhaps
The least known variable.

Can anyone take a guesstimate of how much storm surge could be expected for Vieques?

[dixiebreeze]

Anyone have thoughts about the Florida Big Bend area. Especially if Irma heads into the Gulf? Trends are for 'canes to target the N. gulf coast or veer east. thanks.

[Hurricane Andrew]

very pronounced double wind maximum from recon... inner eye still has some juice left so a few more hours it seems.

I was just wondering if an EWRC was starting...

It's been in one for 6 to 8 hours now.

In that case...this thing might really take off soon. Waiting for recon to sample the NE quadrant...

[1900hurricane]

very pronounced double wind maximum from recon... inner eye still has some juice left so a few more hours it seems.

I was just wondering if an EWRC was starting...

It's been in one for 6 to 8 hours now.

Getting close to completion too since the outer now has stronger flight level winds and SFMR values than the dissipating inner.

[wxman57]

and don't forget exact intensity- perhaps
The least known variable.

Exact intensity is not really that significant in storm surge forecasting. Whether the storm has winds 10-20 mph higher over a few square miles won't make much difference. It's the scope of the stronger wind that's more significant, not the peak number.

[RL3AO]

In that case...this thing might really take off soon. Waiting for recon to sample the NE quadrant...

Remember with the westward movement, the NW quad is the strongest.

[GCANE]

Drop just came in

946mb
16:52z
16.7N 53.7W

[RL3AO]

and don't forget exact intensity- perhaps
The least known variable.

Exact intensity is not really that significant in storm surge forecasting. Whether the storm has winds 10-20 mph higher over a few square miles won't make much difference. It's the scope of the stronger wind that's more significant, not the peak number.

Yep. Track is most important, followed by size and timing. Timing matters more in mid-Atlantic and NE where tidal ranges are larger.

[Hurricane Andrew]

In that case...this thing might really take off soon. Waiting for recon to sample the NE quadrant...

Remember with the westward movement, the NW quad is the strongest.

Well...I feel silly now, LOL.

[Weatherboy1]

I really hope people are paying very close attention and taking steps to prepare here in South Florida (east or west coast). With some of today's midday models (including the GFS) trending a bit further north, Irma may not interact as much if at all with Cuba before she starts her forecasted turn to the NW or N. That means we could be talking about a very powerful system - and a large one in terms of wind radius. Still 6ish days out so things could change. But this looks like a potentially very dangerous system. (Note: I am a semi-educated amateur; listen to the experts/NHC for the best advice and information )

[Hurricaneman]

Pressure still dropping and I hate to think of what this will do when the ewrc is completed

[Extratropical94]

URNT15 KNHC 041714
AF309 0311A IRMA HDOB 20 20170904
170500 1617N 05313W 6964 03080 9991 +078 +078 212066 071 056 012 03
170530 1616N 05312W 6969 03079 0007 +078 +078 214066 068 054 012 03
170600 1614N 05311W 6970 03083 0008 +076 +076 216064 067 054 011 00
170630 1613N 05310W 6967 03090 0010 +074 //// 216063 065 053 006 01
170700 1612N 05309W 6970 03091 0007 +076 +074 216065 066 052 004 00
170730 1611N 05308W 6966 03103 0001 +085 +072 215063 065 050 003 00
170800 1610N 05306W 6969 03100 0000 +086 +075 214063 064 048 003 00
170830 1609N 05305W 6965 03107 0011 +082 +081 214060 063 047 004 00
170900 1607N 05304W 6970 03103 0009 +086 +077 213059 060 047 004 00
170930 1606N 05303W 6967 03113 0006 +091 +075 216058 059 046 002 00
171000 1605N 05302W 6966 03114 0011 +089 +075 215056 057 046 001 00
171030 1604N 05301W 6966 03117 0012 +090 +074 215055 056 045 004 00
171100 1603N 05259W 6966 03120 0016 +090 +080 213054 055 046 003 00
171130 1602N 05258W 6964 03127 0019 +086 +076 209052 052 043 001 01
171200 1600N 05257W 6968 03128 0022 +091 +073 206051 051 044 001 00
171230 1559N 05256W 6969 03125 0025 +090 +073 208051 052 042 001 03
171300 1558N 05255W 6963 03135 0025 +090 +073 209050 052 041 001 00
171330 1557N 05254W 6971 03125 0025 +095 +067 208046 048 041 001 00
171400 1556N 05252W 6966 03134 0028 +094 +059 210044 045 040 000 00
171430 1554N 05251W 6971 03129 0034 +090 +066 208044 045 039 000 00

[GCANE]

[GCANE]

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 4th day of the month at 17:12Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF99-5309
Storm Number & Year: 11 in 2017
Storm Name: Irma (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 07 ( See all messages of this type for this mission. )
A. Time of Center Fix: 4th day of the month at 16:52:20Z
B. Center Fix Coordinates: 16°43'N 53°43'W (16.7167N 53.7167W)
B. Center Fix Location: 465 statute miles (749 km) to the ENE (58°) from Bridgetown, Barbados.
C. Minimum Height at Standard Level: 2,621m (8,599ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 92kts (~ 105.9mph)
E. Location of the Estimated Maximum Surface Wind Inbound: 17 nautical miles (20 statute miles) to the NW (310°) of center fix
F. Maximum Flight Level Wind Inbound: From 34° at 102kts (From between the NNE and NE at ~ 117.4mph)
G. Location of Maximum Flight Level Wind Inbound: 25 nautical miles (29 statute miles) to the NW (305°) of center fix
H. Minimum Sea Level Pressure: 946mb (27.94 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 9°C (48°F) at a pressure alt. of 3,049m (10,003ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 16°C (61°F) at a pressure alt. of 3,043m (9,984ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 12°C (54°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Closed
M. Eye Shape: Concentric (has an inner and outer eye)
M. Inner Eye Diameter: 26 nautical miles (30 statute miles)
M. Outer Eye Diameter: 32 nautical miles (37 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile

Remarks Section:
Maximum Flight Level Wind: 102kts (~ 117.4mph) which was observed 25 nautical miles (29 statute miles) to the NW (305°) from the flight level center at 16:44:30Z
Dropsonde Surface Wind at Center: From 170° at 16kts (From the S at 18mph)

[Extratropical94]

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 4th day of the month at 17:12Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF99-5309
Storm Number & Year: 11 in 2017
Storm Name: Irma (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 07
A. Time of Center Fix: 4th day of the month at 16:52:20Z
B. Center Fix Coordinates: 16°43'N 53°43'W (16.7167N 53.7167W)
B. Center Fix Location: 465 statute miles (749 km) to the ENE (58°) from Bridgetown, Barbados.
C. Minimum Height at Standard Level: 2,621m (8,599ft) at 700mb
D. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 92kts (~ 105.9mph)
E. Location of the Estimated Maximum Surface Wind Inbound: 17 nautical miles (20 statute miles) to the NW (310°) of center fix
F. Maximum Flight Level Wind Inbound: From 34° at 102kts (From between the NNE and NE at ~ 117.4mph)
G. Location of Maximum Flight Level Wind Inbound: 25 nautical miles (29 statute miles) to the NW (305°) of center fix
H. Minimum Sea Level Pressure: 946mb (27.94 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 9°C (48°F) at a pressure alt. of 3,049m (10,003ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 16°C (61°F) at a pressure alt. of 3,043m (9,984ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 12°C (54°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Closed
M. Eye Shape: Concentric (has an inner and outer eye)
M. Inner Eye Diameter: 26 nautical miles (30 statute miles)
M. Outer Eye Diameter: 32 nautical miles (37 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile

Remarks Section:
Maximum Flight Level Wind: 102kts (~ 117.4mph) which was observed 25 nautical miles (29 statute miles) to the NW (305°) from the flight level center at 16:44:30Z
Dropsonde Surface Wind at Center: From 170° at 16kts (From the S at 18mph)

[RL3AO]

URNT12 KNHC 041712
VORTEX DATA MESSAGE AL112017
A. 04/16:52:20Z
B. 16 deg 43 min N
053 deg 43 min W
C. 700 mb 2621 m
D. 92 kt
E. 310 deg 17 nm
F. 034 deg 102 kt
G. 305 deg 25 nm
H. 946 mb
I. 9 C / 3049 m
J. 16 C / 3043 m
K. 12 C / NA
L. CLOSED
M. CO26-32
N. 12345 / 7
O. 0.02 / 1 nm
P. AF309 0311A IRMA OB 07
MAX FL WIND 102 KT 305 / 25 NM 16:44:30Z
CNTR DROPSONDE SFC WIND 170 / 16 KT
;

Concentric eyewalls of 26 and 32 miles. Should keep the winds steady for a bit.

[Blinhart]

Pressure still dropping and I hate to think of what this will do when the ewrc is completed

I really hope I'm not correct, but I wouldn't be surprised once this EWRC is complete and if she doesn't start another for say 24 hours, she will go down to around 920 mb and have wind speed around 155 to 170

[Extratropical94]

That was the eye dropsonde, 946 mbar with 16 kt