Major Hurricane Franklin | Peak 150mph, 926mb |post-tropical

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Edited September 2, 2023 by StretchCT

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000
WTNT43 KNHC 202057
TCDAT3

Tropical Storm Franklin Discussion Number   1
NWS National Hurricane Center Miami FL       AL082023
500 PM AST Sun Aug 20 2023

This afternoon we have received a wealth of data from both a NOAA
reconnaissance mission and satellite imagery near the area of low
pressure located in the eastern Caribbean Sea. Earlier visible
satellite imagery showed the system had likely formed a tight
low-level vortex based on the earlier cloud motions before a
convective burst obscured the center. Scatterometer data that
clipped the system on the east side also showed winds near tropical
storm intensity. The NOAA aircraft flew through the system shortly
thereafter, and found the system had indeed formed a well-defined
center, with 950-mb flight level winds of 51 kt just to the
northeast of the center. All this information confirms that
Tropical Storm Franklin has formed this afternoon, with an initial
intensity set at 40 kt.

The initial motion is off to the west-northwest at 290/12 kt. Over 
the next 24 hours this general motion should continue while the 
system remains steered by a narrow mid-level ridge. Thereafter, a 
large mid-ocean trough over the western Atlantic will produce a 
pronounced weakness in this ridging, likely causing the tropical 
storm to make a sharp turn northward, bringing the storm near or 
over the large island of Hispaniola in about 48-60 h. Afterwards, 
another mid-latitude trough is forecast to amplify southward, 
maintaining this weakness, and resulting in Franklin turning 
northeastward towards the end of the forecast period. There is a 
decent amount of spread in the track guidance, related to just when 
Franklin will make the initial northward turn. For this initial 
forecast, the NHC track forecast will stick close to the track 
consensus TVCN, which favors a track in between the latest ECMWF and 
GFS solutions, favoring the GFS a bit more.

Intensity wise, Franklin may have to deal with a bit of westerly
wind shear in the short-term, limiting more robust intensification
early on. However, this shear drops off as the system makes its turn
northward towards Hispaniola a bit more intensification is shown
with a 55-kt intensity peak as Franklin approaches the coast. The
intensity forecast then is complicated by the fact that Franklin
will likely pass near or over the island sometime in the 2-3 day
time period, and some weakening is shown during this time.
However, the forecast environment after the system re-emerges into
the Western Atlantic looks mostly favorable, with reintensification
likely as long as the system is not too disrupted by the higher
terrain of Hispaniola. The NHC intensity forecast is in good
agreement with the consensus aids, and lies closest to the HFIP
corrected consensus approach through the forecast period.

Based on the current track forecast, a tropical storm watch has
been issued for the entire southern coastline of Haiti and the
Dominican Republic.

 

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Advisorsy 1A!!

 

766 
WTNT33 KNHC 202358
TCPAT3

BULLETIN
Tropical Storm Franklin Intermediate Advisory Number 1A
NWS National Hurricane Center Miami FL       AL082023
800 PM AST Sun Aug 20 2023

...NOAA AIRCRAFT DATA SHOWS FRANKLIN MAINTAINING STRENGTH...


SUMMARY OF 800 PM AST...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...14.8N 67.8W
ABOUT 240 MI...385 KM SSE OF ISLA SAONA DOMINICAN REPUBLIC
ABOUT 280 MI...450 KM SSW OF SAN JUAN PUERTO RICO
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES

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Good morning, Franklin

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[StretchCT]

Franklin seems a bit messy.  More like Pigpen.

The term used in the disco was chaotic. But the cloud tops are -90c, very cold.  Shear is expected to lessen over the next 24 hrs. Track guidance is dependent on where the storm forms/reforms

Spoiler

Tropical Storm Franklin Discussion Number   4
NWS National Hurricane Center Miami FL       AL082023
1100 AM EDT Mon Aug 21 2023

There are no lack of cold cloud tops associated with Tropical Storm 
Franklin this morning. The structure on satellite consists of a 
large bursting pattern, with cloud tops as cold as -90C close to and 
just east of the estimated center. However, it is unclear if any of 
this deep convection has resulted in structural improvement to 
the storm, with the most recent microwave imagery from a SSMIS F-16 
pass at 1007 UTC showing a chaotic structure, with evidence the 
center remains near the western edge of this large convective 
shield. The latest subjective satellite intensity estimates form 
TAFB is unchanged from earlier this morning. Thus, the initial 
intensity will remain 45 kt this advisory, which is also close to 
the latest D-MINT and D-PRINT estimates from UW-CIMSS. 

Franklin does appear to be slowing down a tad this morning while 
moving westward, with the latest estimate at 270/5 kt. The track 
forecast in the short-term is a bit problematic, with a large spread 
in model solutions even at 12 h, much higher than the climatological 
spread. This initial uncertainty may be related intensity 
differences in the global models, with some of the stronger guidance 
suggesting the tropical cyclone might reform further to the north 
and east over the next 12-24 hours. Thereafter, a large weakness to 
the north of Franklin, produced by a large mid-ocean trough draped 
across the Western Atlantic, should allow the storm to begin moving 
northward. A mid-latitude trough reinforces this weakness to the 
north in 60-72h, allowing the storm to begin moving northeastward. 
The most significant change in the guidance this cycle is the 
majority are quite a bit slower than the prior cycle, and the NHC 
forecast track was slowed down a bit, but not as much as some of the 
consensus aids.

Currently, Franklin is experiencing some moderate 15-20 kt westerly 
shear, which has paused its intensification for the time being. 
However, this shear is forecast to gradual decrease as it begins to 
move more northward, providing an opportunity for the tropical storm 
to strengthen as it approaches Hispaniola. Some weakening appears 
likely once the system moves over Hispaniola, especially if the 
storm moves over the highest terrain in the Dominican Republic. By 
Thursday, Franklin should be back over open waters in the Atlantic 
Ocean and has an opportunity to start strengthening again. However, 
the environment does not appear to be especially pristine, with the 
ECMWF showing more southwesterly vertical wind shear than the GFS. 
For now, its assumed this shear will not prevent slow 
intensification, possibly because the storm should be moving in the 
same direction as the shear vector, and the NHC intensity forecast 
will still show Franklin becoming a hurricane towards the end of the 
forecast period. This forecast is in best agreement with the HFIP 
corrected consensus approach (HCCA) but remains lower than some of 
the more aggressive regional-hurricane models (COAMPS-TC, HWRF).


KEY MESSAGES:

1. Heavy rainfall from Franklin is expected across portions of
Puerto Rico and Hispaniola through the middle of the week.  The
heavy rainfall may produce areas of flash and urban flooding as well
as river rises and mudslides.  Across Hispaniola, significant and
potentially life-threatening flash flooding is possible Tuesday into
Wednesday.

2. Franklin is expected to bring tropical storm conditions to
portions of the Dominican Republic and Haiti beginning on Tuesday
where Tropical Storm Warnings are in effect.


FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 15.0N  70.1W   45 KT  50 MPH
 12H  22/0000Z 15.2N  70.5W   45 KT  50 MPH
 24H  22/1200Z 15.7N  71.0W   50 KT  60 MPH
 36H  23/0000Z 17.3N  70.9W   55 KT  65 MPH
 48H  23/1200Z 19.2N  70.6W   45 KT  50 MPH...INLAND
 60H  24/0000Z 21.2N  69.9W   45 KT  50 MPH...OVER WATER
 72H  24/1200Z 22.8N  68.4W   55 KT  65 MPH
 96H  25/1200Z 24.4N  65.2W   65 KT  75 MPH
120H  26/1200Z 26.4N  63.7W   75 KT  85 MPH

$$
Forecaster Papin

 

[StretchCT]

Approx center with wind radii.  A little troubling that ADT is over 65kts. 

[StretchCT]

Probably should watch this one. There's a trough connection needed to take it out to sea and since we aren't sure how it's going to develop, particularly after Hispaniola, there could be changes. Icon brings it pretty close. Really nothing to stop it.

Euro isn't far off OBX

 

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[LiveWire_13]

6 hours ago, StretchCT said:

Probably should watch this one. There's a trough connection needed to take it out to sea and since we aren't sure how it's going to develop, particularly after Hispaniola, there could be changes. Icon brings it pretty close. Really nothing to stop it.

Euro isn't far off OBX

 

The NWS forecast for tonight has the storm west of Bermuda with a cone of uncertainty angling less out to sea. It's still a ways out, but this may not be the fish storm everyone has written it off as.

[StretchCT]

These blobular systems are such a pain until they get their act together. There appears to be a swirl to the west of the convection (red L) and then there seems to be some kind of rotation where it should be, in the signature S.  I think this may be a mid level L (orange L)

 

Discussion mentions the swirl off the the west. 

A NOAA Hurricane
Hunter aircraft investigating the system found a broad low-level
cyclonic wind field exposed to the west of the deep convection, but
this feature is well to the west of where we would have expected the
center to be.

Here's the rest of the discussion:  basically Franklin is not healthy, not well organized with 32kt wind. Max flight level wind was 41kts.  Though they don't mention a bunch of the SFMR winds that are >40kts including one 50kt reading.  They are still banking on the end of the forecast to pan out, despite the confusion going on right now.

Spoiler

Tropical Storm Franklin Discussion Number   9
NWS National Hurricane Center Miami FL       AL082023
500 PM EDT Tue Aug 22 2023

Franklin is not a healthy tropical cyclone--and there is still some
question if it even is a tropical cyclone.  A NOAA Hurricane
Hunter aircraft investigating the system found a broad low-level
cyclonic wind field exposed to the west of the deep convection, but
this feature is well to the west of where we would have expected the
center to be.  At the same time, developing deep convection with
some mid-level turning is noted about 90 n mi to the east, which
would more closely follow persistence from previous forecasts.
Either way, Franklin is not well organized, and for now the initial
position is held closer to the convection in case a new center
re-forms in that area.  In fact, a dropsonde recently released by
the NOAA crew near the convection measured a surface pressure
of 1003 mb with winds of 32 kt, giving additional credence that a
new center could be forming.  The crew also reported that the SFMR
winds were running too high, and the highest 850-mb flight-level
wind was 41 kt, suggesting that Franklin's initial intensity is
probably down to about 35 kt.

The smoothed 12-hour motion remains northwestward (320 degrees) at
6 kt.  The track model guidance continues to insist that Franklin
will move slowly northward and then northeastward during the next 3
days or so, toward broad troughing located over the western
Atlantic.  This track should take Franklin northward across
Hispaniola during the next 12-36 hours, with the system then
turning northeastward over the western Atlantic.  By days 4 and 5,
a shortwave trough is expected to amplify near the northeastern
U.S. while a stronger mid-level ridge develops over the central
Atlantic, likely causing Franklin to turn back to the north by the
end of the forecast period.  Despite the possibility of center
re-formations, which could cause Franklin's track to jump around,
the model guidance is in good agreement on this general forecast
scenario, even if all the details are not yet ironed out.

The new intensity forecast probably has the biggest change from the
previous advisory, at least in the short term.  Little change in
strength is expected during the next 48 hours or so due to
Franklin's current disheveled state and its expected crossing of the
high terrain of Hispaniola on Wednesday.  Once Franklin moves over
the western Atlantic waters, a more diffluent upper-level
environment could foster some intensification, and the NHC forecast
continues to show the system becoming a hurricane by the end of the
5-day forecast period.  This forecast remains close to the HCCA and
IVCN consensus aids.


KEY MESSAGES:

1. Heavy rainfall from Franklin is expected across portions of
Hispaniola and Puerto Rico into Thursday. The heavy rainfall may
produce areas of flash and urban flooding as well as river rises and
mudslides. Across Hispaniola, significant and potentially
life-threatening flash flooding is possible Tuesday into Wednesday.

2. Franklin is expected to bring tropical storm conditions to
portions of the Dominican Republic and Haiti, where Tropical Storm
Warnings are in effect, beginning later tonight and continuing
through Wednesday.


FORECAST POSITIONS AND MAX WINDS

INIT  22/2100Z 15.8N  71.4W   35 KT  40 MPH
 12H  23/0600Z 17.0N  71.3W   40 KT  45 MPH
 24H  23/1800Z 19.1N  70.9W   35 KT  40 MPH...OVER HISPANIOLA
 36H  24/0600Z 20.9N  70.3W   35 KT  40 MPH...OVER WATER
 48H  24/1800Z 22.0N  69.3W   40 KT  45 MPH
 60H  25/0600Z 22.5N  68.2W   45 KT  50 MPH
 72H  25/1800Z 22.9N  67.3W   50 KT  60 MPH
 96H  26/1800Z 24.3N  66.7W   60 KT  70 MPH
120H  27/1800Z 27.6N  67.7W   75 KT  85 MPH

$$
Forecaster Berg

 

 

[StretchCT]

ADT puts the center in deeper.

CI seems overdone, although then again the sfmr winds were nearing 50kts

Shear isn't destroying it either. 

[LiveWire_13]

That cone has shifted and tilted further west today. I have no idea what global patterns may push, pull or ignore the storm, but there's 80 degree waters almost to southern Jersey. It may not be the nitroglycerin in the Gulf of Mexico, but the southern/central Atlantic Ocean would provide plenty of gunpowder if Franklin meanders this way.

[Burr]

30 minutes ago, LiveWire_13 said:

That cone has shifted and tilted further west today. I have no idea what global patterns may push, pull or ignore the storm, but there's 80 degree waters almost to southern Jersey. It may not be the nitroglycerin in the Gulf of Mexico, but the southern/central Atlantic Ocean would provide plenty of gunpowder if Franklin meanders this way.

A little westward zag in bath water temperatures after visiting Turks and Caicos?

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[StretchCT]

Franklin looking the best I think it's looked, and it made landfall.  The convective burst to the east is Gert, whose CoC is still exposed but still active enough to kick off t storms on the east side.

 

Edited August 23, 2023 by StretchCT

[StretchCT]

Starting to feel better about the track, but would wait until Friday and see where it is compared to the forecast.  It doesn't seem to want to go anywhere fast after leaving Hispaniola.

[LiveWire_13]

20 minutes ago, StretchCT said:

Starting to feel better about the track, but would wait until Friday and see where it is compared to the forecast.  It doesn't seem to want to go anywhere fast after leaving Hispaniola.

Is there a feature that's been identified as pushing this out to sea? I'm in favor of saving lives, but I need a reason before i buy in. Just a few days ago they had this hooking east of Bermuda into the Atlantic; now it's pushing north-northeast for of the lower 48.

[StretchCT]

18 hours ago, LiveWire_13 said:

Is there a feature that's been identified as pushing this out to sea?

This is a look at upstream effects.  The trough coming through the Great Lakes should kick this out to sea.  The flow ahead of the trough over the NE is pretty strong and from the west.  As Franklin and the trough approach, the flow goes SW.  The trough is positively tilted. In this scenario, the trough kicks it out.  Change the speed of the trough, the speed of Franklin or the orientation/placement of the trough and you change the outcome. So if the trough is more negative, the flow becomes southerly pushing Franklin north. If the trough cuts off over say Missouri or Tennessee, the flow could actually end up from the east, allowing Franklin to track west.   If the trough speeds up and Franklin slows down, they may miss one another and if Franklin speeds up and the trough slows down, depending on downstream influences, Franklin could end up further west.  

[StretchCT]

First vortex message  has max flight level winds at 71mph and max sfc winds at 62mph. Pressure at 999

Model tracks from Tropical Atlantic . Franklin and Gert on the west side and Emily and Invest 92L in the central Atl.

[StretchCT]

Dropsonde with 48kt winds at surface, so 55 mph.  HDOB up to 62mph.  

 

 

Edited August 24, 2023 by StretchCT

[StretchCT]

Last vortex message of the run had 1004 pressure, 55mph flight level and 50mph surface winds.  This was at 17:15z or 1:15pm edt

11am update was

SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...22.2N 69.9W
ABOUT 90 MI...145 KM ENE OF GRAND TURK ISLAND
ABOUT 765 MI...1230 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...NE OR 40 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES