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Archives >> 2011 News Talkbacks

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papaswamp
Verified CFHC User


Reged: Wed
Posts: 11
Loc: St.Johns, FL 30.11N 81.64W
Re: Tropical Depression 13 Forms in the Gulf of Mexico [Re: Random Chaos]
      #92145 - Sat Sep 03 2011 06:42 AM

How about that massive low with dry air center around 27 lat 30 long. Looks to be peeling moisture from Katia.

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danielwAdministrator
Moderator


Reged: Wed
Posts: 3487
Loc: Hattiesburg,MS (31.3N 89.3W)
Tropical Storm Lee [Re: papaswamp]
      #92146 - Sat Sep 03 2011 07:40 AM

Lowest pressures that I have found so far this morning.

ICAO KVNP Vermillion 26, LA, United States
LA VERMILLION26OILP KVNP VNP 29 28N 092 22W 28
Time 3 / 11:15Z
Temperature 75.2
Dew Point 75.2
RH 100
Heat Index 72.7
Wind N (10) at 33
Wind Chill N/A
Visibility 1.5
Pressure 994.9 mb
Weather Mist

Sky Condition Scattered clouds at 500ft
Scattered clouds at 800ft
Scattered clouds at 1400ft

Remarks
METAR KVNP 031115Z AUTO 01029KT 1 1/2SM BR SCT005 SCT008 SCT014 24/24 A2938 RMK A01
******************************************************

Station FRWL1 - 8766072 - Fresh Water Canal Locks, LA
29.555 N 92.305 W
Wind Direction (WDIR): N ( 350 deg true )
Wind Speed (WSPD): 22.0 kts
Wind Gust (GST): 27.0 kts
Atmospheric Pressure (PRES): 29.35 in___994.0 mb
Air Temperature (ATMP): 75.6 °F
Water Temperature (WTMP): 82.6 °F


Edited by danielw (Sat Sep 03 2011 07:51 AM)


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danielwAdministrator
Moderator


Reged: Wed
Posts: 3487
Loc: Hattiesburg,MS (31.3N 89.3W)
Re: Tropical Storm Lee [Re: danielw]
      #92147 - Sat Sep 03 2011 08:06 AM

I thought this was interesting. From a 994mb Tropical Storm and water pileup and tides.

STORM SURGE...A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS
3 TO 5 FEET ABOVE GROUND LEVEL ALONG THE LOUISIANA COAST...AND BY AS
MUCH AS 2 TO 4 FEET ABOVE GROUND LEVEL ALONG THE MISSISSIPPI AND
ALABAMA COASTS INCLUDING MOBILE BAY. SEE PRODUCTS ISSUED BY LOCAL
NATIONAL WEATHER SERVICE FORECAST OFFICES FOR MORE DETAILS. A STORM
SURGE OF NEAR 4 FEET WAS RECENTLY REPORTED AT SHELL BEACH
LOUISIANA...AND A SURGE HEIGHT OF 2.4 FEET WAS REPORTED AT GRAND
ISLE LOUISIANA.


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MichaelA
Weather Analyst


Reged: Thu
Posts: 845
Loc: Pinellas Park, FL 27.83N 82.69W
Re: Tropical Storm Lee [Re: danielw]
      #92148 - Sat Sep 03 2011 10:01 AM

It's due to the long duration and long fetch of the onshore winds, as well as the tidal influence. Lee should also be stirring the water enough to lower SSTs for a while in the central Gulf.

--------------------
Michael
2016: 13/9/4
2016 Actual: 15/7/3


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Joeyfl
Weather Guru


Reged: Mon
Posts: 112
Loc: St.Pete,FL
Re: Tropical Storm Lee [Re: MichaelA]
      #92149 - Sat Sep 03 2011 11:28 AM

Lee not your classic looking storm with it taking more the shape of comma, thanks to shear and dry air. No doubt to dump copious amounts of rain on the south. I agree with current track think it should begin to move more northeast in next 24-48hrs and accelerate into frontal system. This will in turn keep Katia offshore of U.S coast and I feeling more confident on recurve between the U.S and Bermuda. Rip currents and large swells from Katia will be biggest problem. Long term things look to stay active and I would watch Gulf/Caribbean over next couple of weeks closely...

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cieldumort
Moderator


Reged: Mon
Posts: 1403
Loc: Austin, Tx 30.40N 97.80W
Re: Lee Rain Continues as it nears the Central Louisiana Coastline [Re: MikeC]
      #92150 - Sat Sep 03 2011 12:18 PM

Lee has two distinct meso vortices within its approximate mean center this morning, in addition to several other much more transient and/or ill-defined swirls that exist throughout its full expanse.

The two primary LLCs can be seen in the image below:


Despite the existence of multiple vortices within Lee, this recent scatterometer pass from 1234UTC this morning shows that, for the most part, Lee's surface circulation has become well established.


One can also see in the WindSat pass above how the entrainment of extremely dry air from Texas has manipulated the "feeder leg" into Lee (the large fetch of convection to the center's east, south and southeast), into a front-like feature.

At this point Lee has possibly become more subtropical than tropical, but this will not prevent the cyclone from dumping copious amounts of rain, particularly on its eastern half, for many days to come. As updated model runs are calling for Lee to begin pulling out of Louisiana a bit sooner and faster than earlier expected, this is a little bit better news for that state, but potentially unwelcome news for the east - possibly once again including large parts of the Mid-Atlantic and New England.


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danielwAdministrator
Moderator


Reged: Wed
Posts: 3487
Loc: Hattiesburg,MS (31.3N 89.3W)
TS Lee Pressure drop [Re: cieldumort]
      #92151 - Sat Sep 03 2011 01:25 PM

Pressure continues to fall with the following pressure being one of the lowest current pressures.
LA VERMILLION 26 OILPLATFORM KVNP VNP 29 28N 092 22W 28 meters above sea level
ICAO KVNP
Station Name N/A
Country N/A
Location N/A
Elevation N/A
Time 3 / 17:15Z
Temperature 82.4
Dew Point 77.0
RH 84
Heat Index 90.9
Wind E (90) at 14mph, 21 gusts
Wind Chill N/A
Visibility 10.0
Pressure 991.9 mb or 29.29 in Hg
Weather
Sky Condition Few clouds at 1400ft
Broken clouds at 2300ft
Overcast at 2800ft
Remarks
METAR KVNP 031715Z AUTO 09012G18KT 070V140 10SM FEW014 BKN023 OVC028 28/25 A2929 RMK A01
****************************************************
Station MRSL1 - Marsh Island, LA / CSI03
29.440 N 92.061 W
Wind Direction (WDIR): SSE ( 160 deg true )
Wind Speed (WSPD): 21.0 kts
Wind Gust Wind Gust (GST): 24.1 kts
Atmospheric Pressure (PRES): 29.27 in or 991.1mb
Pressure Tendency (PTDY): -0.09 in ( Falling )

Edited by danielw (Sat Sep 03 2011 01:30 PM)


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berrywr
Weather Analyst


Reged: Fri
Posts: 384
Loc: Opelika, AL 32.71N 85.23W
Re: TS Lee Pressure drop [Re: danielw]
      #92152 - Sat Sep 03 2011 03:00 PM

A quick blip...it is normal from mid-morning to late afternoon for pressure falls to diurnally occur. As of 02/1825Z, at least one center is onshore, not that it will matter given it's Louisiana, flat and plenty of marsh (wet) lands and continues to exhibit subtropical characteristics. I share a few opinions that calling this system pure tropical is a stretch; however, if my funding was depended upon identifying it as tropical; I do it. This system will eventually cease to "tropical" as baroclinic processes and big, big trough play their part in veering Katia north. The SE USA will benefit tremendously from this rain; it's been big time dry around here for a spell assuming a half foot doesn't drop on us in a day.

--------------------
Sincerely,

Bill Berry

"Survived Trigonometry and Calculus I"


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danielwAdministrator
Moderator


Reged: Wed
Posts: 3487
Loc: Hattiesburg,MS (31.3N 89.3W)
Re: TS Lee Pressure drop [Re: berrywr]
      #92153 - Sat Sep 03 2011 05:10 PM

I'm watching to see if they are diurnal fluctuations. Probably are. And some of the winds are pressure gradient winds.
We dropped to less than a 1/4 mile visibility on the Interstate here in ++ heavy rain about an hour ago.

ICAO KVNP
Station Name N/A
Country N/A
Location N/A
Elevation N/A
Time 3 / 20:55Z
Temperature 84.2
Dew Point 78.8
RH 84
Heat Index 96.1
Wind N (350) at 12
Wind Chill N/A
Visibility 7.0
Pressure 988.5 mb
Weather
Sky Condition Few clouds at 1400ft
Scattered clouds at 1800ft
Broken clouds at 2700ft

Remarks
METAR KVNP 032055Z AUTO 35010KT 7SM FEW014 SCT018 BKN027 29/26 A2919 RMK A01


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Random Chaos
Weather Analyst


Reged: Sat
Posts: 1021
Loc: Maryland 38.98N 76.50W
Re: TS Lee Pressure drop [Re: danielw]
      #92161 - Sun Sep 04 2011 01:32 PM

Eye has become clearly visible on Katia in the last hour of IR passes. ADT raw T number is up to 5.4 with the eye now visible, which would be consistent with 95-100kt winds. Given original speeds of 85kt at 11am NHC update, in 2.5 hours that increase is plausible. AdjustedT numbers are still 4.8 by ADT, only because they require consistent higher raw T numbers to increase, which would be 85-90kt, or consistent with the 11am guidance.

I want to note that the 0Z NOGAPS has joined the UKMET is showing a non-recurving westward track. Still waiting on the 12Z NOGAPS and ECMWF. 12Z GFS is continuing to show recurvature, while 0Z ECMWF is showing a slower recurvature. Everyone needs to continue watching this storm.


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typhoon_tip
Meteorologist


Reged: Wed
Posts: 572
Re: TS Lee Pressure drop [Re: Random Chaos]
      #92163 - Sun Sep 04 2011 03:08 PM

Quote:

Eye has become clearly visible on Katia in the last hour of IR passes. ADT raw T number is up to 5.4 with the eye now visible, which would be consistent with 95-100kt winds. Given original speeds of 85kt at 11am NHC update, in 2.5 hours that increase is plausible. AdjustedT numbers are still 4.8 by ADT, only because they require consistent higher raw T numbers to increase, which would be 85-90kt, or consistent with the 11am guidance.

I want to note that the 0Z NOGAPS has joined the UKMET is showing a non-recurving westward track. Still waiting on the 12Z NOGAPS and ECMWF. 12Z GFS is continuing to show recurvature, while 0Z ECMWF is showing a slower recurvature. Everyone needs to continue watching this storm.




Couple of quick comments on this:

The NOGAPS and UKMET are the less reliable guidance (statistically) of those mentioned.

The lesser intensity of the UKMET's cyclone may atone for that westerly placement, as a shallower system would be less integrated with the steering around the western periphery of the Atlantic subtropical ridge.

That said, the 12Z NOGAPS and UKMET have joined in with the other numerical guidance in depicting a parabolic recurve into the N Atlantic with limited impact felt along the East Coast of north America beyond elevated surf. The important thing to remember is that average error balloons to at or greater than 250 nautical miles (although the current the 5-year running mean is a bit better) from the NHC.

It isn't entirely clear just how far west the weakness in the atmosphere left by Lee will induce a leftward position with Katia; that will become more clear with shorter term guidance in about 2 days. Until then, it appears the west trend in the runs has stopped for the time being and some consensus is emerging - that of course is never 100% at D4-6.


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Random Chaos
Weather Analyst


Reged: Sat
Posts: 1021
Loc: Maryland 38.98N 76.50W
Re: TS Lee Pressure drop [Re: typhoon_tip]
      #92166 - Mon Sep 05 2011 09:50 AM

Annularity of Katia:

Over the past several hours, Katia has gone from what appeared to be a disorganized cyclone to having a very large, well defined eye. NHC had Katia as disorganized this morning at the 5am update, however, it appears they misunderstood the structure of Katia.

Katia is following a very classic evolution to an Annular state, as described in Annular Hurricanes by Knaff, Kossin, and DeMaria. The specific example I am refering to is Hurricane Howard in 1998 which has had nearly identical evolution to Katia over the past day. A day before the annular transition Howard had a small, nearly pinhole eye. This is very similar to what was seen on Katia yesterday with a very tiny, often ill-defined eye.

The transition continued with both storms with what appeared to be dry air entrainment. However, in both storms this large dry air bulge actually became a new, giant eye. Over the course of 10 hours Howard completed the transition from giant eye to Annular. Katia is now about three hours into this transition.

In reference, I am attaching the following pictures:

Katia shown over a several hour period on September 5th, 2011


Extracted page from Annular Hurricanes by Knaff, Kossin, and DeMaria showing Hurricane Howard, 1998


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danielwAdministrator
Moderator


Reged: Wed
Posts: 3487
Loc: Hattiesburg,MS (31.3N 89.3W)
Katia Eye [Re: Random Chaos]
      #92167 - Mon Sep 05 2011 10:15 AM

nice catch. The following two photos appear back up the possibility of the annular Eye. Notice the extremely nice outflow around the periphery as evidenced by the high thin cirrus, horsetail clouds.
Time difference is about 75 minutes between the two photos.





Latest GOES Visible.. Eye centered.



Edited by danielw (Mon Sep 05 2011 10:19 AM)


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MichaelA
Weather Analyst


Reged: Thu
Posts: 845
Loc: Pinellas Park, FL 27.83N 82.69W
Re: TS Lee Pressure drop [Re: Random Chaos]
      #92168 - Mon Sep 05 2011 10:18 AM

That does seem to be what may be happening with Katia. Also, using Knaff's mean wind speed, does that mean that Katia could intensify to a 125mph storm rather quickly?

--------------------
Michael
2016: 13/9/4
2016 Actual: 15/7/3


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danielwAdministrator
Moderator


Reged: Wed
Posts: 3487
Loc: Hattiesburg,MS (31.3N 89.3W)
Re: TS Lee Pressure drop [Re: MichaelA]
      #92169 - Mon Sep 05 2011 10:27 AM

It would be interesting to see if Katia actually goes above the latest SHIPS forecast. I believe the max wind forecast was 104 knots, or 120 mph.
Wait and see. As with all tropical cyclones.

Tropical Storm Lee has given me 7.53 inches since Friday, and it is still raining.
Never underestimate the Weather.


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Random Chaos
Weather Analyst


Reged: Sat
Posts: 1021
Loc: Maryland 38.98N 76.50W
Re: TS Lee Pressure drop [Re: danielw]
      #92170 - Mon Sep 05 2011 10:32 AM

Look at the new IR image of Katia and the eye becoming much more round and the deep convection fully encircling the eye:



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danielwAdministrator
Moderator


Reged: Wed
Posts: 3487
Loc: Hattiesburg,MS (31.3N 89.3W)
Re: TS Lee Pressure drop [Re: Random Chaos]
      #92171 - Mon Sep 05 2011 10:52 AM

HURRICANE KATIA DISCUSSION NUMBER 30
NWS National Hurricane Center MIAMI FL AL122011
1100 AM AST MON SEP 05 2011

KATIA APPEARS TO HAVE GONE THROUGH AN EYEWALL REPLACEMENT AND NOW
HAS A 30 N MI WIDE EYE SURROUNDED BY A RELATIVELY NARROW BAND OF
THE COLDEST CLOUD TOPS. Dvorak INTENSITY ESTIMATES HAVE RISEN TO
T5.0 FROM TAFB AND SAB...AND THE OBJECTIVE NUMBERS ARE AT T5.5.
THE INITIAL INTENSITY IS THEREFORE BEING RAISED TO 95 KT....

...DUE TO THE EYEWALL REPLACEMENT...IT APPEARS THAT THE WIND FIELD HAS
EXPANDED A BIT...AND THIS IS REFLECTED IN THE ANALYSIS AND FORECAST.

Edited by danielw (Mon Sep 05 2011 10:53 AM)


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Random Chaos
Weather Analyst


Reged: Sat
Posts: 1021
Loc: Maryland 38.98N 76.50W
Re: TS Lee Pressure drop [Re: danielw]
      #92172 - Mon Sep 05 2011 11:02 AM

Here is what confounds me about Katia. We have a Category 2 hurricane with 95kt winds that has gone through an ERC and has a giant well defined eye.

Normally ERCs don't occur until strong Cat 3 or better storms, with most ERCs happening in Cat 4 and Cat 5 storms. Further, large eyes generally do not occur in category 2 storms. And you generally need at least a category 3 storm before you get a well defined eye of any size.

How long will this storm stay at category 2 before the wind speeds and pressure catch up with it's significant structural changes?

From the 11am NHC discussion:
WITHIN THE NEXT 24 HOURS OR SO...THE HURRICANE WILL BE MOVING OVER OCEAN HEAT CONTENT VALUES THAT DO NOT NORMALLY SUPPORT SIGNIFICANT INTENSIFICATION.

This is actually a classic requirement for an annular storm. Annular storms tend to need lower SSTs than the traditional hurricane and also a light sheer environment, also present.


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Ed DunhamAdministrator
Meteorologist & CFHC Forum Moderator


Reged: Sun
Posts: 2562
Loc: Melbourne, FL
Annular Katia? [Re: Random Chaos]
      #92173 - Mon Sep 05 2011 01:27 PM

While Katia does exhibit some of the fundamentals for an annular hurricane, she is not quite there yet. Here is a good definition of Annular hurricanes from Wikipedia:

Annular Hurricane

Note that one of the formation requirements IS an eyewall replacement cycle. Another is a lack of banding features - and Katia still has a feeder band to the northeast. SSTs are at 28C which is within the acceptable range, but its on the high side. Although highly uncommon I've seen ERCs in Cat I and Cat II storms. Why they happen in some weaker hurricanes but not others is still one of the mysteries of hurricanes.

Regarding the size of the eye, its actually a misconception that a large eye size normally means a stronger hurricane. In August, 2000, Hurricane Alberto varied from a Tropical Storm to a Cat III Hurricane over a period of almost 3 weeks and was considered to be annular at various times during its evolution - including Cat I in the north Atlantic - with a 60 mile wide eye. In 1978, Hurricane Fico in the eastern and central Pacific moved to the west just to the north of 15N for 9 straight days with a 60 mile wide eye and intensities that varied from Cat I to Cat IV, but Fico was not annular. Fico still had a 60 mile wide eye when it passed southeast of the Big Isle on August 20th as a Cat II. However, you are probably correct that an annular hurricane always has a large eye.

Maybe Katia will get to the annular state in a day or so. Certainly a topic of good discussion as long as we can keep it focused on Katia.
ED


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Ed in Va
Weather Master


Reged: Fri
Posts: 489
Loc: 36.02N 75.67W
Re: Annular Katia? [Re: Ed Dunham]
      #92178 - Mon Sep 05 2011 08:53 PM

Hmmm...looks like the 18 GFDL moved quite a bit west...have to see if it's a trend.

I was at the soundside of OBX this weekend. My house had 16" of water in the basement. The rd outside ent from dry to chest- high water in about an hour at the end of Irene. Worst flooding there that anyone could remember. The oceanfront, in comparison, was completely untouched. Not so to the south on Hatteras Island, which will be without a road for about a month.

Re my GFDL comment...I just realized I was looking at the 95l model...which shows a different path for Katia than the Katia model itself.

--------------------
Survived Carol and Edna '54 in Maine. Guess this kind of dates me!

Edited by Ed in Va (Mon Sep 05 2011 10:20 PM)


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