Tropical Storm Ophelia | Peak 70mph 986mb | post-tropical, lingering

[StretchCT]

Since the official forecast is for this to become tropical, I'll put this here instead of the NEMA thread.

This has jumped several steps, going from 30% chance to 50 then 60% chance to potential cyclone in a half day.  

While the formation chance is at 60%, the NHC discussion is a little more bullish.

INIT  21/1500Z 28.7N  75.9W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 12H  22/0000Z 30.0N  75.5W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 24H  22/1200Z 31.7N  75.4W   45 KT  50 MPH...POTENTIAL TROP CYCLONE
 36H  23/0000Z 33.2N  75.6W   50 KT  60 MPH...TROPICAL CYCLONE
 48H  23/1200Z 35.1N  76.4W   50 KT  60 MPH...TROPICAL CYCLONE
 60H  24/0000Z 37.3N  76.4W   40 KT  45 MPH...TROPICAL CYCLONE
 72H  24/1200Z 38.8N  76.1W   30 KT  35 MPH...POST-TROPICAL
 96H  25/1200Z 40.4N  71.8W   25 KT  30 MPH...POST-TROPICAL
120H  26/1200Z...DISSIPATED

Currently there is a broad area of low pressure associated with the tail end of a front.  Once it's detached from the front, then it should be considered tropical. 

A broad non-tropical area of low pressure has formed well east of 
the east coast of Florida this morning.  Although this system is 
forecast to remain non-tropical during the next 12-24 hours, the 
dynamical model guidance indicates that it will likely acquire 
tropical characteristics late Friday and early Saturday as it 
approaches the coast of North Carolina.  Although it is unclear as 
to whether the cyclone detaches from a front that is forecast to 
extend northeastward from the center, the guidance suggests a 
tropical-cyclone like core and structure when it nears the coast. 

There is a tight swirl on the satellite embedded the broader circulation. It's not convective in nature yet, so not going to call it tropical.

Models are unclear how to classify (warm/cold, symmetrical/asymmetrical)

The effects will be rain, some wind (as noted in the NHC disco)  and probably some coastal flooding as predicted below. 

Edited September 24, 2023 by StretchCT

[clm]

Yep, I am in its path.  Whether it becomes a tropical storm or not remains to be seen.  Definitely will get some rain and wind out of this.

 

[StretchCT]

Was waiting for the 12z Euro to post on precip since there was some debate about how far north and west it got.

 

Ukie remains the outlier.

Euro hadn't been that consistent with this either but at least put two runs together that were comparable. 

[StretchCT]

Looks pretty hostile

GFS has high shear the entire way

[Sentinel]

This is expected to intensify in 60 Knots wind sheer. 🤨

[Burr]

SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION -----------------------------------------------

LOCATION...29.5N 75.3W ABOUT 355 MI...570 KM SE OF CHARLESTON SOUTH CAROLINA ABOUT 395 MI...635 KM S OF CAPE HATTERAS NORTH CAROLINA

MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT

MOVEMENT...NNE OR 15 DEGREES AT 3 MPH...6 KM/H

MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES

[Burr]

NHC discussion includes, “Baroclinic processes associated with a sharp upper-level trough to the west of the low are expected to induce strengthening“

Spoiler

Potential Tropical Cyclone Sixteen Discussion Number   3
NWS National Hurricane Center Miami FL       AL162023
1100 PM EDT Thu Sep 21 2023

Nighttime proxy-visible satellite imagery suggests that the center
of the low pressure system off the southeastern U.S. coast has
become better defined this evening.  Nearly all of the associated
deep convection remains oriented in a curved band extending around
the northern and eastern sides of the circulation, although a few
convective elements are beginning to fill in on the back side of
the system as well.  Based on 1-minute wind observations from NOAA
buoy 41002 and ship reports, the initial intensity is raised to 35
kt, with all tropical-storm-force winds currently north of the
center on the north side of an attached warm front.

The center does not appear to have moved much since the time it 
became better defined.  Based on previous fixes, the current motion 
is estimated to be north-northeastward (015 degrees) at 3 kt.
The dynamical guidance indicates that the center should begin moving
northward--or re-form to the north--overnight, with a northward or
north-northwestward motion continuing through Sunday morning.  This
forecast track brings the center of the low inland across eastern
North Carolina on Saturday, and then across the southern Chesapeake
Bay and the Delmarva Peninsula Saturday night and Sunday.  Except
for the errant HWRF (which appears too far west), the rest of the
guidance is tightly clustered, and the NHC forecast is near the
middle of the envelope.  This new forecast is a bit east of the
previous prediction, mainly for the portion of the track over land.

Baroclinic processes associated with a sharp upper-level trough to
the west of the low are expected induce strengthening, and the NHC
intensity forecast is close to the GFS, ECMWF, and HCCA solutions,
bringing the maximum winds to 50 kt in 24-36 hours before the
center reaches the North Carolina coast.  In addition, simulated
satellite imagery suggests there could be an increase of deep
convection near the low's center by Friday evening, and phase-space
diagrams show the system just barely entering the deep warm core
regime.  Therefore, transition to a tropical cyclone is shown by 24
hours, although there still is some uncertainty on that occurrence
due to frontal boundaries still in the area.  Weakening is forecast
after the center moves onshore, and the system is expected to
become extratropical again by 60 hours.  An official forecast is
only provided out through 72 hours since global model fields
show the low becoming absorbed by the associated frontal boundary
off the New Jersey coast by 96 hours.


Key Messages:

1. Low pressure off the southeastern U.S. coast is producing
tropical-storm-force winds and is forecast to strengthen further
before it reaches the coast of North Carolina on Saturday.  Tropical
storm conditions are expected along portions of the southeastern and
mid-Atlantic U.S. coasts within the Tropical Storm Warning area
beginning on Friday and continuing into Saturday night.

2. There is a danger of life-threatening storm surge inundation
over portions of eastern North Carolina and southeastern Virginia,
including Pamlico and Albemarle Sounds, and the lower Chesapeake
Bay, where Storm Surge Warnings are in place.  Residents in these
areas should follow advice given by local officials.

3. Heavy rainfall from this system could produce localized urban
and small stream flooding impacts across the eastern mid-Atlantic
states from North Carolina to New Jersey Friday through Sunday.

4.  Swells generated by this system will affect much of the U.S.
east coast through the weekend, likely causing life-threatening
surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0300Z 29.5N  75.3W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 12H  22/1200Z 31.2N  75.5W   45 KT  50 MPH...POTENTIAL TROP CYCLONE
 24H  23/0000Z 32.5N  76.1W   50 KT  60 MPH...TROPICAL CYCLONE
 36H  23/1200Z 34.4N  76.5W   50 KT  60 MPH
 48H  24/0000Z 36.4N  76.6W   40 KT  45 MPH...INLAND
 60H  24/1200Z 37.9N  76.2W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  25/0000Z 39.0N  75.2W   30 KT  35 MPH...POST-TROP/EXTRATROP
 96H  26/0000Z...DISSIPATED

 

 

Edited September 22, 2023 by Burr

[MaineJay]

Looking like just some overcast up here. The Canadian models had been advertising a real soaker, but have politely backed off.

 

[clm]

2 hours ago, MaineJay said:

Looking like just some overcast up here. The Canadian models had been advertising a real soaker, but have politely backed off.

 

Was hoping for a good soaker so I could take my yearly shower.

[StretchCT]

NHC disco says it's getting closer to tropical

Spoiler

The low pressure system off the southeast U.S. coast is gradually 
organizing and strengthening this morning.  The cyclone is 
developing subtropical characteristics with deep convection 
consolidating on the system's north side and the center gaining 
definition, but there are still some frontal features associated 
with it.  NOAA buoy 41002 well off the coast of Cape Hatteras has 
seen a significant pressure drop during the past several hours, and 
the latest report was down to 1002 mb with 30-kt winds.  A 
saildrone measured winds of 32 kt well northeast of the center 
several hours ago.  Based on these pressure and wind observations as 
well as satellite intensity estimates, the initial intensity is 
increased to 45 kt.  Based on recent trends, it seems likely that 
the low will become a subtropical or tropical cyclone later today.

Convection is popping to the north of the center. I'd expect the southern part to stay mostly exposed as the shear pushes that convection off to the north.

It does look like a cyclone should as it comes up the coast

 

[clm]

22 minutes ago, StretchCT said:

NHC disco says it's getting closer to tropical

  Reveal hidden contents

The low pressure system off the southeast U.S. coast is gradually 
organizing and strengthening this morning.  The cyclone is 
developing subtropical characteristics with deep convection 
consolidating on the system's north side and the center gaining 
definition, but there are still some frontal features associated 
with it.  NOAA buoy 41002 well off the coast of Cape Hatteras has 
seen a significant pressure drop during the past several hours, and 
the latest report was down to 1002 mb with 30-kt winds.  A 
saildrone measured winds of 32 kt well northeast of the center 
several hours ago.  Based on these pressure and wind observations as 
well as satellite intensity estimates, the initial intensity is 
increased to 45 kt.  Based on recent trends, it seems likely that 
the low will become a subtropical or tropical cyclone later today.

Convection is popping to the north of the center. I'd expect the southern part to stay mostly exposed as the shear pushes that convection off to the north.

It does look like a cyclone should as it comes up the coast

 

Looks good enough that if this were in the Atlantic it would definitely turn into a TS.  My opinion is if it makes it to a TS status, it will be very short lived as it is projected to go inland in NC and VA.

[clm]

NAM 3k showing completely disorganized but still cyclonic.  Looks like part of it will break away and bring me rain and what looks like good downpours. 

 

[StretchCT]

Upped the forecast to 65mph.

ORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 32.3N  75.6W   45 KT  50 MPH...POTENTIAL TROP CYCLONE
 12H  23/0000Z 33.2N  76.3W   55 KT  65 MPH...TROPICAL CYCLONE
 24H  23/1200Z 34.9N  76.8W   50 KT  60 MPH...INLAND
 36H  24/0000Z 36.8N  77.0W   40 KT  45 MPH...INLAND
 48H  24/1200Z 38.3N  77.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 60H  25/0000Z 39.3N  76.5W   25 KT  30 MPH...POST-TROP/EXTRATROP
 72H  25/1200Z...DISSIPATED

Buoy data

Onslow Bay buoy in front of it.

[NWOhioChaser]

Not a good day to be in the OBX

[StretchCT]

This is the coastal flood warning for Ocean County, same for Cape May and Atlantic. They cite the inability of bays to empty and a long duration event. Moderate flooding is expected. Monmouth is under a flood advisory, north of there nothing yet.  Delaware beaches are expected to have major flooding.  These areas also under high wind warnings. South of DE is covered by Tropical Storm/Storm Surge warnings.

 

Spoiler

Coastal Ocean-
646 AM EDT Fri Sep 22 2023

...HIGH RIP CURRENT RISK REMAINS IN EFFECT THROUGH SATURDAY
EVENING...
...HIGH SURF ADVISORY IN EFFECT FROM 6 AM TO 8 PM EDT SATURDAY...
...COASTAL FLOOD WARNING REMAINS IN EFFECT FROM NOON TO 8 PM EDT
SATURDAY...

* WHAT...For the High Rip Current Risk, dangerous rip currents.
  For the High Surf Advisory, large breaking waves of up to 8
  feet expected in the surf zone. For the Coastal Flood Warning,
  one to two feet of inundation above ground level expected in
  low- lying areas near shorelines and tidal waterways.

* WHERE...Coastal Ocean.

* WHEN...For the High Rip Current Risk, through Saturday
  evening. For the High Surf Advisory, from 6 AM to 8 PM EDT
  Saturday. For the Coastal Flood Warning, from noon to 8 PM EDT
  Saturday.

* IMPACTS...At this level, widespread roadway flooding occurs in
  coastal and bayside communities and along inland tidal
  waterways. Many roads become impassable. Some damage to
  vulnerable structures may begin to occur. Dangerous swimming
  and surfing conditions and localized beach erosion. Rip
  currents can sweep even the best swimmers away from shore into
  deeper water.

* ADDITIONAL DETAILS...With the long duration of onshore winds
  expected, the back bays may struggle to drain during low
  tides. This could result in minor to moderate coastal flooding
  lingering after high tide. Additionally, minor flooding is
  possible again with the Sunday afternoon high tide.

Time of high total tides are approximate to the nearest hour.

Barnegat Bay at Barnegat Light
MLLW Categories - Minor 3.5 ft, Moderate 4.5 ft, Major 5.5 ft
MHHW Categories - Minor 1.0 ft, Moderate 2.0 ft, Major 3.0 ft

             Total      Total    Departure
 Day/Time    Tide       Tide     from Norm   Flood
            ft MLLW    ft MHHW       ft      Impact
 --------  ---------  ---------  ---------  --------
 22/01 PM     3.1        0.6        0.4       None
 23/02 AM     2.9        0.4        0.9       None
 23/03 PM     4.6        2.1        1.9     Moderate
 24/02 AM     3.8        1.3        1.9      Minor
 24/03 PM     4.0        1.5        1.3      Minor

Spoiler

.HIGH RIP CURRENT RISK REMAINS IN EFFECT THROUGH SATURDAY
EVENING...
...HIGH SURF ADVISORY IN EFFECT FROM 6 AM TO 8 PM EDT SATURDAY...
...COASTAL FLOOD WARNING REMAINS IN EFFECT FROM NOON TO 8 PM EDT
SATURDAY...

* WHAT...For the High Rip Current Risk, dangerous rip currents.
  For the High Surf Advisory, large breaking waves of up to 9 feet
  expected in the surf zone. For the Coastal Flood Warning, two to
  three feet of inundation above ground level expected in low-
  lying areas near shorelines and tidal waterways.

* WHERE...Delaware Beaches.

* WHEN...For the High Rip Current Risk, through Saturday
  evening. For the High Surf Advisory, from 6 AM to 8 PM EDT
  Saturday. For the Coastal Flood Warning, from noon to 8 PM EDT
  Saturday.

* IMPACTS...At this level, flooding may become severe enough to
  cause structural damage along with widespread roadway flooding
  in coastal and bayside communities, and near inland tidal
  waterways. Some locations may become isolated by the flood
  waters. Dangerous swimming and surfing conditions and
  localized beach erosion. Rip currents can sweep even the best
  swimmers away from shore into deeper water.

* ADDITIONAL DETAILS...With the long duration of onshore winds
  expected, the back bays may struggle to drain during low
  tides. This could result in minor to moderate coastal flooding
  lingering after high tide. Additionally, minor flooding is
  possible again with the Sunday afternoon high tide.

Delaware Bay at Lewes
MLLW Categories - Minor 6.0 ft, Moderate 7.0 ft, Major 8.0 ft
MHHW Categories - Minor 1.3 ft, Moderate 2.3 ft, Major 3.3 ft

             Total      Total    Departure
 Day/Time    Tide       Tide     from Norm   Flood
            ft MLLW    ft MHHW       ft      Impact
 --------  ---------  ---------  ---------  --------
 22/03 PM     5.8        1.2        1.1       None
 23/03 AM     5.8        1.2        2.4       None
 23/04 PM     8.0        3.3        3.3      Major
 24/04 AM     5.4        0.8        1.9       None
 24/05 PM     5.9        1.2        1.0       None

 

Edited September 22, 2023 by StretchCT

[StretchCT]

I'm wondering if it makes it to land before being classified, if they'd name it after landfall.

[Burr]

000
WTNT31 KNHC 221751
TCPAT1

BULLETIN
Tropical Storm Ophelia Intermediate Advisory Number 5A
NWS National Hurricane Center Miami FL       AL162023
200 PM EDT Fri Sep 22 2023

...CYCLONE BECOMES TROPICAL STORM OPHELIA... 
...TROPICAL STORM CONDITIONS CONTINUING ACROSS COASTAL PORTIONS OF 
NORTH CAROLINA...


SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...32.7N 76.0W
ABOUT 150 MI...240 KM SE OF CAPE FEAR NORTH CAROLINA
ABOUT 185 MI...295 KM S OF CAPE HATTERAS NORTH CAROLINA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...NNW OR 345 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...992 MB...29.29 INCHES

[Burr]

[Iceresistance]

Just saw someone mention that Radar Velocities are going over 90 mph in Ophelia, she's going to try to become a Hurricane

[StretchCT]

Recon had some pretty impressive readings.  Already 60kts sfmr 70kts flight level. 

Edited September 22, 2023 by StretchCT

[StretchCT]

28 minutes ago, Iceresistance said:

Just saw someone mention that Radar Velocities are going over 90 mph in Ophelia, she's going to try to become a Hurricane

Sonde data has 90mph winds at 942mb and 76mph winds at surface. They could make that call. 

Onslow bay Buoy hasn't updated since 2:08.

[StretchCT]

Gonna guess this hit the gulf stream

[StretchCT]

5:00 PM EDT Fri Sep 22
Location: 32.9°N 76.3°W
Moving: NNW at 13 mph
Min pressure: 986 mb
Max sustained: 70 mph

From the Disco:

The intensity forecast is more challenging given the unexpected
strengthening trend observed today. Most of the intensity guidance
shows little change in strength before landfall, although the global
models show additional deepening of the low. However, some
additional strengthening cannot be ruled out as Ophelia traverses
the warm waters of the Gulf Stream on its approach to eastern North
Carolina. While this does not seem like the most likely outcome and
is not explicitly forecast, the increased risk warrants the issuance
of a Hurricane Watch for a portion of the North Carolina coast from
north of Surf City to Ocracoke Inlet. 

Edited September 22, 2023 by StretchCT

[StretchCT]

The NHC update has it moving NNW at 13mph. But the new center looks nearly due west.

[StretchCT]

Second Vortex message with 75kt flight and 70kt surface winds. 

Spoiler

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 22nd day of the month at 21:19Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5305
Tropical Depression: Sixteen (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 18

A. Time of Center Fix: 22nd day of the month at 20:47:40Z
B. Center Fix Coordinates: 32.80N 76.54W
B. Center Fix Location: 126 statute miles (203 km) to the SE (141°) from Wilmington, NC, USA.
C. Minimum Height at Standard Level: 1,294m (4,245ft) at 850mb
D. Minimum Sea Level Pressure: 987mb (29.15 inHg)
E. Dropsonde Surface Wind at Center (Undecoded): NA
F. Eye Character: Not Available
G. Eye Shape: Not Available
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 42kts (48.3mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 36 nautical miles (41 statute miles) to the NNE (31°) of center fix at 20:36:00Z
J. Maximum Flight Level Wind Inbound: From 133° at 53kts (From the SE at 61.0mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 44 nautical miles (51 statute miles) to the NE (35°) of center fix at 20:33:30Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 70kts (80.6mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 17 nautical miles (20 statute miles) to the SW (227°) of center fix at 20:52:30Z
N. Maximum Flight Level Wind Outbound: From 327° at 70kts (From the NNW at 80.6mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 49 nautical miles (56 statute miles) to the SW (231°) of center fix at 21:02:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,514m (4,967ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 1,515m (4,970ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F)
R. Sea Surface Temp (collected at same location as temp inside eye): Not Available
S. Fix Determined By: Penetration, Wind and Pressure
S. Fix Level: 850mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 6 nautical miles