Tropical Storm Ophelia—Tropical Storm Warning for Coastal Mid-Atlantic

[Random Chaos]

1 hour ago, AACOUNTYMD said:

Question. . . should Eastern AA county expect the highest winds before, during, or after the heaviest rains? And would that be over night Friday or more during daylight hours on Saturday?  

Based on the model output, heaviest winds near the bay are likely overnight Friday into Saturday AM, probably from around midnight to 10am. This is a band well ahead of the main storm which will still be down in North Carolina at that time. Midday Saturday we should have relaxed winds (still 20kt+) and less gusty between the leading band and the main storm before it picks up again Saturday evening as the main storm center approaches, though less windy than the leading band the previous night.

Heaviest rain is harder to forecast due to substantial model divergence but seems to generally correspond to the heaviest winds.

 

[yoda]

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

$$
Forecaster Berg

[MattPetrulli]

4 minutes ago, yoda said:

40mph at 11

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

...LOW PRESSURE OFF THE SOUTHEAST U.S. COAST STRENGTHENING AND NOW
PRODUCING TROPICAL-STORM-FORCE WINDS...
...TROPICAL STORM CONDITIONS EXPECTED TO REACH THE NORTH CAROLINA
COAST FRIDAY MORNING...


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


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* Duck North Carolina to Chincoteague Virginia
* Chesapeake Bay south of Windmill Point
* Neuse and Pamlico Rivers
* Portions of Pamlico and Albemarle Sounds

A Tropical Storm Warning is in effect for...
* Cape Fear North Carolina to Fenwick Island Delaware
* Albemarle and Pamlico Sounds
* Tidal Potomac south of Cobb Island
* Chesapeake Bay south of North Beach

A Storm Surge Watch is in effect for...
* Surf City to Duck North Carolina
* Chesapeake Bay north of Windmill Point to Smith Point
* Tidal Potomac south of Colonial Beach
* Remainder of Pamlico and Albemarle Sounds

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 Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.

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.
For a depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
hurricanes.gov.

For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.


DISCUSSION AND OUTLOOK
----------------------
At 1100 PM EDT (0300 UTC), the low pressure system was centered near
latitude 29.5 North, longitude 75.3 West.  The low is moving toward 
the north-northeast near 3 mph (6 km/h).  A northward or 
north-northwestward motion is expected to begin early Friday and
continue through Sunday.  On the forecast track, the center of the
low will approach the coast of North Carolina through Friday night,
and then move across eastern North Carolina, southeastern Virginia,
and the Delmarva Peninsula Saturday and Sunday.

Maximum sustained winds have increased to near 40 mph (65 km/h)
with higher gusts.  Additional strengthening is forecast during the
next day or so, and the low is expected to become a tropical storm
before it reaches the coast of North Carolina.  Regardless of
whether it becomes a tropical storm, the system is expected to bring
tropical-storm conditions to portions of the southeast and
mid-Atlantic coasts.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...medium...60 percent.

Tropical-storm-force winds extend outward up to 240 miles (390 km)
to the north of the center.

The estimated minimum central pressure is 1007 mb (29.74 inches).

Tropical-storm-force winds extend outward up to 240 miles (390 km) to the north of the center.

[87storms]

Helluva precip gradient on the 12z’s. The storm is basically sandwiched between the mountains and Atlantic. Looks like a blocky pattern coming up, which is actually how 09/10 started.

[nw baltimore wx]

Just rehashing but according to the NHC discussion, Sixteen has estimated 50mph winds early this morning and could be Ophelia later today

[dailylurker]

By the look of this thread I figured the storm went poof. Some very interesting weather on the way. Wake up, people! We have a soon to be tropical storm basically moving up the bay tomorrow. 

[vastateofmind]

10 minutes ago, dailylurker said:

By the look of this thread I figured the storm went poof. Some very interesting weather on the way. Wake up, people! We have a soon to be tropical storm basically moving up the bay tomorrow. 

Yeah, forecasting on Baby Ophelia has been pretty solid for the past 24-36 hours, just did a lot of catching up on NHC's discussions and graphics. It does indeed read like we're going to have some moderate impact here in the metro areas. Between lurking here, finishing some taskers at work, and squeezing the weekly mowing in...gonna be a busy day!

[CAPE]

8 minutes ago, dailylurker said:

By the look of this thread I figured the storm went poof. Some very interesting weather on the way. Wake up, people! We have a soon to be tropical storm basically moving up the bay tomorrow. 

Not much left to do but wait. Good agreement among the models. Locked in. I guess the 'excitement' over whether it gets named or not? That won't change a thing wrt our sensible weather though.

[dailylurker]

2 minutes ago, vastateofmind said:

Yeah, forecasting on Baby Ophelia has been pretty solid for the past 24-36 hours, just did a lot of catching up on NHC's discussions and graphics. It does indeed read like we're going to have some moderate impact here in the metro areas. Between lurking here, finishing some taskers at work, and squeezing the weekly mowing in...gonna be a busy day!

Indeed. I'm working ot today to get everything buttoned up. I've got a 10' tall cannabis plant in full bloom that I need to build support for. I'll be out in the dark tonight doing that. Ugh.. legal weed lol

[TSSN+]

SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...31.3N 75.3W ABOUT 250 MI...465 KM ESE OF CHARLESTON SOUTH CAROLINA ABOUT 245 MI...450 KM S OF CAPE HATTERAS NORTH CAROLINA MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H PRESENT MOVEMENT...N OR 350 DEGREES AT 14 MPH...22 KM/H MINIMUM CENTRAL PRESSURE...996 MB...29.41 INCHES

 

[vastateofmind]

4 minutes ago, dailylurker said:

Indeed. I'm working to today to get everything buttoned up. I've got a 10' tall cannabis plant in full bloom that I need to build support for. I'll be out in the dark tonight doing that. Ugh.. legal weed lol

Damn! That's tall! And now that you've mentioned that, I've got a couple butterfly bushes on the front of the house almost that tall that are gonna be laid out flat tomorrow between rain/wind, if I don't shore THEM up somehow.

The forecasted northern reach of the wind field, which someone also mentioned a page ago last evening, is impressive.

[CAPE]

The mesos all look very similar. The localized bonus amounts will probably be related to convection that develops tomorrow afternoon/evening as the center of the low tracks over the area for the eastern half of the region. Orographic lift will enhance rainfall on the ridges out west.

[CAPE]

Coastal DE would be a good local chase spot. Probably see 4" of rain with winds gusting to near 60 mph tomorrow.

[Random Chaos]

Extreme tides now forecast for Annapolis:

 

[Interstate]

1 hour ago, nw baltimore wx said:

Just rehashing but according to the NHC discussion, Sixteen has estimated 50mph winds early this morning and could be Ophelia later today

Right now I look at it as a strong nor’easter 

[vastateofmind]

3 minutes ago, CAPE said:

Coastal DE would be a good local chase spot. Probably see 4" of rain with winds gusting to near 60 mph tomorrow.

I was thinking earlier that you live in a spot that might get a good show out of the incoming storm...

[Terpeast]

Anyone notice that canadian and NHC have tracks further east than gfs, euro, icon and nam?

[CAPE]

1 minute ago, vastateofmind said:

I was thinking earlier that you live in a spot that might get a good show out of the incoming storm...

Probably just a lot of rain here. Might see some gusts to 30 or so.

Found this interesting little nugget buried in the very extensive AFD from Mount Holly this morning:

Quote

One other item to keep an eye on, particularly around the Delmarva, will be some potential for thunderstorms Saturday afternoon. There may be enough shear and low-level helicity to support a low tornado threat with any storms that can become discrete and severe.

 

[Random Chaos]

2 minutes ago, CAPE said:

Found this interesting little nugget buried in the very extensive AFD from Mount Holly this morning:

 

I was looking at the shear map’s just yesterday morning expecting that. With the vorticity of a tropical cyclone when storms in its bands come ashore it’s common to get weak tornadoes.

[WxWatcher007]

18 minutes ago, Terpeast said:

Anyone notice that canadian and NHC have tracks further east than gfs, euro, icon and nam?

I went back and looked and it seems pretty similar to the euro/gfs?

[AlexD1990]

18 minutes ago, CAPE said:

Probably just a lot of rain here. Might see some gusts to 30 or so.

Found this interesting little nugget buried in the very extensive AFD from Mount Holly this morning:

 

Some of the local TV mets were mentioning this on social media yesterday. Definitely not a hazard I was initially prepared to be dealing with...

 

[konksw]

A lot of convection firing close to the center at the end of the loop. 

[nw baltimore wx]

3 minutes ago, konksw said:

A lot of convection firing close to the center at the end of the loop. 

Could that also be because of the better view as the sun rises?

[TSSN+]

Lots of lighting near the center 

[nw baltimore wx]

Never mind. 

[TSSN+]

Not saying it will but, wouldn’t shock me if this hits a cat 1

[PrinceFrederickWx]

Based on my prior experience with Isaias, I have a feeling this is going to overperform IMBY.

[BristowWx]

Just now, TSSN+ said:

Not saying it will but, wouldn’t shock me if this hits a cat 1

it's looking to take the track we always joke about here...up the bay into DC....cat 1 would cause some problems for sure

[konksw]

3 minutes ago, TSSN+ said:

Not saying it will but, wouldn’t shock me if this hits a cat 1

It’s a race against the landfall clock. 

[CAPE]

25 minutes ago, Random Chaos said:

I was looking at the shear map’s just yesterday morning expecting that. With the vorticity of a tropical cyclone when storms in its bands come ashore it’s common to get weak tornadoes.

SPC disco mentions the risk for D2. Marginal, and for now confined to eastern VA into S MD and lower Delmarva

Quote

...Mid-Atlantic... A tropical system is forecast by the National Hurricane Center to move through eastern North Carolina on Saturday. To the east of the center, instability is forecast to increase during the day from eastern north Carolina into eastern Virginia. A marginal tornado threat may develop with bands of convection that move through the stronger instability.