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Major Hurricane Fiona


GaWx
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18 minutes ago, MJO812 said:

But way weaker. The trough sweeps this out .

The theme right now is a recurve on all the models but plenty of time .

The weakness in the NW Atlantic when Fiona nears Hispaniola has gotten stronger which causes more poleward movement making it easier to get swept by the next trough. 

If it gets left behind like the Euro shows then it would come close to the coast. 

Early guess with 70% certainty is that it gets swept halfway between coast and Bermuda. 

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2 minutes ago, SnoSki14 said:

The weakness in the NW Atlantic when Fiona nears Hispaniola has gotten stronger which causes more poleward movement making it easier to get swept by the next trough. 

If it gets left behind like the Euro shows then it would come close to the coast. 

Early guess with 70% certainty is that it gets swept halfway between coast and Bermuda. 

Yes right now but we know the models can change quickly in regards to the tropics.

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11 minutes ago, MJO812 said:

Yes right now but we know the models can change quickly in regards to the tropics.

You are going to need a meridional flow pattern with a big east central deep US trough if you are looking for this to come up the coast.  No ensemble support for this currently.  As SnoSki 14 said this thing is likely gone once it passes through or even east of the Bahamas (assuming it crosses Hispaniola).

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3 minutes ago, Tatamy said:

You are going to need a meridional flow pattern with a big east central deep US trough if you are looking for this to come up the coast.  No ensemble support for this currently.  As SnoSki 14 said this thing is likely gone once it passes through or even east of the Bahamas.  

We are still talking a week out so nothing is likely this far out. Although we should always expect a recurve with the tropics.

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First short visible loop on the day still shows a sheared system but much better than when the sun set yesterday.  Bursting convection is now on the eastern edge of the circulation.  If that trend can continue today and I think it will then Fiona has better chance to strengthen as it enters the NE Caribbean tomorrow.  All in all I think Fiona looks better than I would have expected this morning.  The longer she keeps on a west or slightly south of due west course the better the chances of intensification over the Caribbean and a later turn to the NW down the road.   The later the turn to the WNW and NW the better the odds of impacting the U.S. down the road.  Not out of the question just yet in my mind.  Movement next 24 hours more west than anything.  Not expecting much if any additional loss in latitude today.

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As the effects of Typhoon Merbok on the general NH longwave pattern, CONUS wavebreaking event, and subsequent downstream trough come into focus, we should start to see more of a consensus develop on the future of Fiona. The ultimate destination of this system (if it survives the Greater Antilles intact) will be beholden to the structure of the rossby wave pattern.

The run to run differences in the positioning of the 500mb trough on the Euro and GFS runs remains quite significant, and likely won't be resolved until ET Merbok completes building the ridge over the Aleutians and the Bering Sea.

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Decent winds, >50 knots on the NE side, but Fiona is barely closed.  Very light W winds S of the center.  I think either the center reforms or it opens into a wave.  Even if it does open before 11 am advisory, I'd think NHC would keep advisories for another cycle or two as TS winds are likely in the NE L. Antilles tonight, even if Fiona is an open wave.

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I'm not writing it off until the Euro also fishes after the G. Antilles.  The LLC looks to cross Guadeloupe, and 1500 m volcanoes shouldn't mean much, but the L. Antilles helped Dorian organize, by destroying the LLC that was SW of the MLC, allowing a new LLC to develop under the MLC.

Not saying that happens, but for a more than half exposed LLC with gentle W breezes S of the center, the 2 small volcanoes may be enough to open it back up.

 

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Tropical Storm Fiona Discussion Number   9
NWS National Hurricane Center Miami FL       AL072022
1100 AM AST Fri Sep 16 2022

Convective activity is occurring much closer to the low-level
center of Fiona this morning, suggesting that the deep-layer
westerly shear has decreased a bit.  Air Force Reserve and NOAA
Hurricane Hunters have been flying through Fiona during the past
several hours, and winds as high as 57 kt were reported about 2500
ft above the surface, along with SFMR winds slightly higher than 45
kt.  The initial intensity remains 45 kt for now, but Fiona 
could easily attain 50 kt soon if the deep convection remains close 
to the center.

After losing latitude most of the day yesterday and overnight,
Fiona has started moving north of due west, with an initial motion
of 275/12 kt.  A north-of-due-west motion with some slowing of the 
forward speed is expected through early Sunday, with Fiona steered 
across the Leeward Islands and the far northeastern Caribbean Sea 
by subtropical ridging over the western Atlantic.  Fiona then 
reaches the western extent of the ridge just beyond 48 hours, and 
it is expected to move more slowly and turn northwestward across 
Hispaniola in 3-4 days, and then be near the Turks and Caicos 
Islands and southeastern Bahamas in about 5 days.  The spread among 
the deterministic track models and the ensembles has decreased since 
yesterday, and there's therefore a little bit more confidence in 
the NHC track prediction.  In addition, there has not been much 
shift in the guidance since the previous forecast cycle, and the 
updated NHC forecast lies very close to the previous prediction, 
and in the middle of the guidance envelope close to the TVCN and 
HCCA consensus aids.

Fiona is located near a tight gradient of deep-layer shear, and 
it's possible that its south-of-due-west motion since yesterday 
brought it into a lighter-shear environment for the convection to 
build back closer to the center.  Model guidance indicates that the 
shear is likely to remain moderate for much of the forecast period, 
but at the same time, upper-level divergence and mid-level moisture 
are forecast to increase.  Coupled with the expected decrease in 
forward speed, these factors could allow Fiona's structure to 
become more vertically stacked over the northeastern Caribbean Sea, 
and gradual strengthening is still anticipated during the next 3 
days.  Based on this forecast, Fiona could be very near hurricane 
strength as it approaches the southern coast of the Dominican 
Republic.  The terrain of Hispaniola is likely to disrupt Fiona's 
circulation, but the global models suggest that Fiona shouldn't 
have much trouble reorganizing itself once over the far 
southwestern Atlantic, and the NHC forecast now calls for the 
cyclone to become a hurricane by the end of the 5-day forecast 
period.  This prediction is slightly below the IVCN and HCCA 
consensus aids.


Key Messages:

1. Tropical storm conditions are expected across the Leeward Islands
within the warning area starting this afternoon, and will spread 
westward across the U.S. Virgin Islands on Saturday and Puerto 
Rico late Saturday and Saturday night.  Tropical storm conditions 
are possible over Dominica tonight and in the British Virgin 
Islands on Saturday.

2. Heavy rains from Fiona will reach the Leeward Islands by this 
evening, spreading to the British and U.S. Virgin Islands and Puerto 
Rico Saturday, reaching the Dominican Republic Sunday, and the Turks 
and Caicos Monday night or Tuesday. This rainfall may produce 
considerable flood impacts including flash and urban flooding, along 
with mudslides in areas of higher terrain. 

3. Fiona is expected to strengthen gradually over the northeastern 
Caribbean Sea, and it could be near hurricane strength as it 
approaches the southern coast of the Dominican Republic Sunday 
night and early Monday.  Watches could be required for portions of 
the Dominican Republic later today.

4. Fiona is forecast to strengthen after moving across Hispaniola 
early next week, and interests in the Turks and Caicos Islands and 
southeastern Bahamas should continue to monitor forecasts for the 
storm.


FORECAST POSITIONS AND MAX WINDS

INIT  16/1500Z 16.0N  59.4W   45 KT  50 MPH
 12H  17/0000Z 16.2N  61.2W   50 KT  60 MPH
 24H  17/1200Z 16.6N  63.5W   50 KT  60 MPH
 36H  18/0000Z 17.0N  65.6W   55 KT  65 MPH
 48H  18/1200Z 17.3N  67.3W   55 KT  65 MPH
 60H  19/0000Z 17.8N  68.6W   60 KT  70 MPH
 72H  19/1200Z 18.5N  69.6W   60 KT  70 MPH...S COAST OF DOM. REP.
 96H  20/1200Z 20.5N  71.3W   55 KT  65 MPH...OVER WATER
120H  21/1200Z 22.5N  72.4W   65 KT  75 MPH

$$
Forecaster Berg

 

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We really won't know the long term track until we know how it gets past Hispaniola. The models are pretty much all showing it sliding just east of the mountain range with minimal disruption. If these models were 20 miles west, it would mean an entirely different outcome. 

07L_tracks_latest.png

c_sAKJjGjbte2eeWu7Jvq3CYQahImarewquctvJAGm0.jpg

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The above post is exactly what I am looking at too.  We are going to believe this storm, in its current state, is going to slide over this island and immediately start deepening?  What would be the outcome if it is still in the same state it is now after going through Hispanola?  Interested to hear a pro mets thoughts.

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15 minutes ago, Normandy said:

The above post is exactly what I am looking at too.  We are going to believe this storm, in its current state, is going to slide over this island and immediately start deepening?  What would be the outcome if it is still in the same state it is now after going through Hispanola?  Interested to hear a pro mets thoughts.

I don't buy the quick deepening right after getting over water either. Though it does help that Fiona remains disorganized and weak so that should limit the effects of land and the mountains on its core structure. Tropical systems have an easier time strengthening after interacting with the islands if they're very weak compared to when they hit if they're very strong.  But I still don't think the speed at which this strengthens is likely

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  • GaWx changed the title to Major Hurricane Fiona

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