Stan storms ashore; Florida getting pounded by a powerful tropical disturbance

By: Dr. Jeff Masters , 1:40 PM GMT on October 04, 2005

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Tropical disturbance approaching Florida
The tropical disturbance over the central Bahama Islands is poised to hit Florida Tuesday night and Wednesday with heavy rains and high winds. Although the disturbance is not a threat to develop into a tropical depression today, the impact on Florida will be similar to that of a tropical depression--sustained winds of 30 mph, with gusts to 45 mph along the coast, along with 3 - 6 inches of rain and large battering waves. The disturbance currently has a weak surface circulation center just south of Andros Island. There is no cloud cover on the west side of the circulation center, and shearing winds blowing from the west are keeping all of the convection pushed over to the east side of the disturbance. Contrary to yesterday's computer model projections of much reduced shear affecting the disturbance, the shear over the storm has almost doubled, to 20 - 30 knots. This shear is in part associated with strong upper-level outflow flowing northeastward out of Hurricane Stan. No development of any kind is possible while the shear remains this strong, and I believe that this system will not develop into a tropical depression at all. Instead, the disturbance will interact with an upper-level low pressure system forecast to develop in the Gulf of Mexico on Wednesday, and become a large--and very wet--ordinary low pressure system. This may also turn into hybrid system called a subtropical storm--a system that is similar to a tropical storm, but has its main winds 100 miles or so away from the center. If this happens, the system will be named Subtropical Storm Tammy. Our skill in forecasting these types of hybrid systems is low.

Once in the Gulf of Mexico, the storm is expected to meander for several days, until a cold front pushes into northern Florida Friday and pulls the storm northeastward across Florida and the Carolinas on Thursday through Saturday, dumping very heavy rains across the region. At the same time, another low pressure area may form along the front near the Carolinas and move northeastward across New England. This second low is not expected to be tropical in nature, but will still dump a lot rain and bring high winds to the East Coast.

I speculated about the possibility yesterday of a tropical storm forming near the Carolinas and moving northwards along the coast. This no longer seems likely, due to the high wind shear over the area today.


Figure 1. BAMM model forecast track of Bahamas suspect area. The intensity forecast numbers from the SHIPS model are far too high; this system will be lucky to make it to tropical storm strength (40 mph winds).

Hurricane Stan
Hurricane Stan presents a classic example of why the National Hurricane Center issues hurricane warnings for a much larger area of coast than seems reasonable. Stan made a sudden turn to the southwest last night and speeded up his forward speed from 6 mph to 10 mph, and is now making landfall on the coast of Mexico, a full 24 hours before expected. This change of course and speed were completely unanticipated my any of the forecast models. However, since the NHC was conservative, the area of the coast the eye of Stan is hitting has been under a hurricane warning for a full day, so the sudden turn should not catch the affected area completely unprepared. Why did the models miss this turn? Perhaps because of Stan's interaction with the mountainous terrain nearby, or because of interaction with the developing upper-level low pressure system in the Gulf of Mexico.

Elsewhere in the tropics
Clouds from the tropical disturbance over the Bahamas extend southeastward to Puerto Rico and the Lesser Antilles Islands. The area of disturbed weather near Puerto Rico bears watching, as wind shear values here are 5 - 10 knots, the lowest of anywhere in this disturbance.

The region between Africa and the Lesser Antilles is quiet.

Jeff Masters

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478. DocNDswamp
9:11 PM GMT on October 04, 2005
Thanks StSimons and thelmores, for refreshing my ancient memory of neutercanes. Ton of great info to be gleaned from all bloggers.

guygee, ..thanks for that excerpt last nite on atmospheric tides / barometric occilations - more great info.

Looks like old Stan may find a healthy enviro in Pacific.
Member Since: September 21, 2005 Posts: 94 Comments: 4783
477. WillJax
9:04 PM GMT on October 04, 2005
The Puerto Rico system has developed an upper level anticyclone in the past three hours.

It is also nearly separated from the circulation of the Bahama system, MUCH more so than it was even a few hours ago.

The Puerto Rico is gonna have lots of space to intensify. I'm also still surprised that Bahama Blob isn't a TD.





The PR blob is also sitting in very low shear,
and both blobs are predicted to experience reduced sheer in the future
Member Since: September 7, 2005 Posts: 0 Comments: 33
476. weatherdude65
9:00 PM GMT on October 04, 2005
C-MAN Station Settlement Point Grand Bahama

Link
475. IKE
9:00 PM GMT on October 04, 2005
The good Dr. has a new blog/thread.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
472. thelmores
8:59 PM GMT on October 04, 2005
A neutercane is an obsolete meteorological term that was used between 1972 and 1973 by the National Hurricane Center. It was introduced by Dr. Robert Simpson, creator of the Saffir-Simpson scale. The American Meteorological Society (AMS) Glossary of Meteorology describes a neutercane as "a large storm possessing both tropical and extratropical characteristics". However this is not entirely accurate as one characteristic of the system is that it is mesoscale, not more than a couple of hundred miles in diameter.

NHC originally described it as "a subtropical cyclone which has acquired a synoptic scale area of sustained winds of storm or hurricane strength with a radius of maximum winds much less than 100 nautical miles and whose thermal structure is intermediate between the typical cold core subtropical and the warm core tropical cyclone." It forms in horizontal shear zones near dying cold fronts or in occluded extratropical lows, and exists almost entirely over warm ocean waters.

The first identified neutercane was Neutercane Bravo, which developed in August 1972 northeast of Bermuda and went on to become Hurricane Betty. In late September, an advisory was issued for Neutercane Charlie. However resistance to the term cropped up among meteorologists. The word neutercane suggested that hurricane is a compound word (with the pronoun "her" -- at that time, all hurricanes received women's names), and that neuter referred to a gender rather than the proper term of neutral.

The term was retired in 1973 by Dr. Neil Frank, the new NHC director. It was not used in AMS journals after 1976. Systems that have neutercane characteristics are now loosely referred to as subtropical cyclones or subtropical storms.


WOWSA, NEVER HEARD OF A neutercane BEFORE....... LOL
Member Since: September 8, 2005 Posts: 0 Comments: 3788
469. thelmores
8:52 PM GMT on October 04, 2005
if the "BLOB" moves just a little farther north, we could have a bigger BLOB! LOL

still quite a bit of shear from stans outflow.

go-go-go stan...... you may end up in the pacific.... quite a feat for an atlantic storm! ;)
Member Since: September 8, 2005 Posts: 0 Comments: 3788
468. guygee
8:52 PM GMT on October 04, 2005
weatherdude65 & billsfaninsofla: For me Gordon was one of
those unforgettable storms, the worst part by far was when
we were in the NE quadrant, since it was hybrid the
lightning and thunder flashed and rolled on with incredible
intensity for a very long time. Also it was my first full
hurricane season in Florida.


jldfish - It looks like the weather NE of the embryonic
Tammy is extensive and incredible at this time. If the
center rolls west over the peninsula it could be another one
to remember for sure. Just wondering if/when NHC will
finally call it



For the locals online, you may recall the beaches really
took a big hit from Gordon, I used to jog the beach barefoot
from Pelican Park down to the Hilton and back (sadly no
more). It severely undermined the "pink house" north of the
park in Indian Harbor, the owner shored it up but I think
it was finally abandoned after the ravages of Floyd, Irene
et.al.

Member Since: September 16, 2005 Posts: 0 Comments: 3060
467. IKE
8:51 PM GMT on October 04, 2005
Looking at the visible floater loop on blob...it appears the shear is lessening.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
466. DocNDswamp
8:49 PM GMT on October 04, 2005
Hey billsfaninsofla and Cosmic, thanks...I was likely still editing this when you guys checked..slight update, still my thoughts as of noon...decided to post here....

Good afternoon all,
Well I had to check my expert advisors today - the ANTS...after climbing the heights of my utility pole yesterday, they were headed back down today - to get some longjohns! Preparing for either eventuality, I guess.

Ok, enough foolishness - you know I was wondering what the GFDL was inhaling w/ that loop de loop, but I see some possibilities. Once again, as the forecast is fine tuned, the HPC has slowed the frontal passage to Fri. morning/midday for SE LA coast - how far S is questionable. Meanwhile the Bahamas surface low is becoming defined and moving steadily WNW toward S FL w/ most convection over Nassau NE/SE of center Tue. morning. No use me to repeat what NHC and Dr. Masters have already said. You know what's coming.

Found it interesting watching WV loop yesterday as the expected development of E Gulf ULL formed late aftn. off the trof over coastal SC, GA to N FL. You could see 2 spikes upper convection racing SW of the Bend into Gulf outlining it's formation. Appears the ULL has expanded and moving southwestward below Appalachicola. How far south and west the ULL continues will likely determine where and how far west BahamaBlob goes in the Gulf, until clashing w/ front.

Guess the ULL could hold up SW movement, remain stationary in mid-E Gulf and force BahamaBlob more northward up the gut thru FL like the BAMM (and latest GFDL) currently indicates. With the Atlantic ridge still entrenched, I get the feel the ULL wants to move southwestwardly around the periphery....Time will tell.

Also guess we could have TD21 maybe before crossing S FL tomorrow, if afore mentioned scenario happens w/ ULL but more probable if it enters Gulf by early Thursday. That's yet to be seen.

Another question is if it developes into TS Tammy or STS Tammy. I would probably expect it to be a TS, but given it's origins the STS designation is possible.

As a side note on subtropical storms, TS Frances '98, if my memory serves correctly (?), had characteristics of a STS but don't believe it was officially designated as so. While located off coast of S TX in SW Gulf w/ 60 mph sustained winds near the center, winds gusting up to 105 mph were recorded on oil platforms below LA - over 200 miles away from the center! Talk about a wide wind field.

A good way to visualize the powerful winds of a STS is to compare it to a wheel with the outer rim spinning faster than the hub. We don't want to ever see one of these strengthen beyond Cat1 hurricane force! If one does I believe the terminology for it is called a neutercane. Of course, I'm recalling from memory right now - don't quote me.

Just my 2 cents.
Member Since: September 21, 2005 Posts: 94 Comments: 4783
465. weatherdude65
8:47 PM GMT on October 04, 2005
if that shear lets up, I think we may have something
463. weatherdude65
8:42 PM GMT on October 04, 2005
The blob is trying very hard to drop that status

Link
460. matilda101
8:39 PM GMT on October 04, 2005
Thel,
It's nothing to concren yourself at this time but it just area of interest to watch for next week as it moves in a westward motion
Member Since: August 28, 2005 Posts: 0 Comments: 281
458. coastie24
8:37 PM GMT on October 04, 2005
You guys want to talk about snow storms. Try living in Northern Michigan, right on the coast of Lake Superior. Growing up, we had nothing but lake effect snow. My senior year of high school it started snowing in October and didn't let up until late April. That's why I live in FL.
457. thelmores
8:36 PM GMT on October 04, 2005
i dont think we have any good models on stan atm! ROFL!
Member Since: September 8, 2005 Posts: 0 Comments: 3788
454. 8888888889gg
8:26 PM GMT on October 04, 2005
where is hurricane stan going when it is done in MX?


her i what i meanLink
452. Hawkeyewx
8:25 PM GMT on October 04, 2005
It looks to me like the Bahamas blob is trying to organize a bit more in the Andros Island, Nassau, Grand Bahama area, pretty much the same spot Katrina spun up. The wind over Andros Island has turned to the ssw and the convective blobs have increased quite a bit in that area. If the system moves to the northwest it should be ok because the shear in that area is really diminishing today. However, there is a stream of strong westerly upper level wind quickly approaching the "center" of the sysem from the west/wsw. The system has a chance to be a tropical or hybrid cyclone if it can get farther north.
Member Since: July 5, 2005 Posts: 2 Comments: 1923
450. thelmores
8:23 PM GMT on October 04, 2005
i guess the remnants of td19 are nothing to be concerned with?

Member Since: September 8, 2005 Posts: 0 Comments: 3788
449. jldfish
8:23 PM GMT on October 04, 2005
guygee

VERY interesting discussion on Gordan we need to watch the Bam and GFDL closely if the similarities hold true

448. sngalla
8:21 PM GMT on October 04, 2005
Lefty, lived in warrenton in '96. Got 44 inches of snow with that one storm. Roads weren't cleared for a week.
Member Since: February 18, 2003 Posts: 57 Comments: 5363
446. leftyy420
8:19 PM GMT on October 04, 2005
thelmores thats the remnants of td 19
Member Since: August 24, 2005 Posts: 35 Comments: 1987
445. thelmores
8:18 PM GMT on October 04, 2005
matilda! LOL

we both saw the same thing! ROFL! :)

least we are observant! :D
Member Since: September 8, 2005 Posts: 0 Comments: 3788
444. thelmores
8:17 PM GMT on October 04, 2005
Hey Lefty......

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/watl-vis-loop.html

whats your take on the spinning feature at approx 22.5n and 42.5w?

to my untrained eye, this appears to be a exposed low level circulation.

i guess since it is in the middle of the ocean, and colder waters, little if anything to be concerned of! ;)
Member Since: September 8, 2005 Posts: 0 Comments: 3788
443. 8888888889gg
8:16 PM GMT on October 04, 2005
leftyy420 do you no what kind of winter ca will see for 2005 and 2006 year
442. matilda101
8:16 PM GMT on October 04, 2005
Has anyone noticed rements of TD19 spinning out in the middle of the Atlantic heading WNW and may just have some staying power to make it across the ocean as you can see a sprawling High Pressure system to its north moving southward. Is this the potential development in the SW Atlantic next week?
Member Since: August 28, 2005 Posts: 0 Comments: 281
441. Dunhill3
8:15 PM GMT on October 04, 2005
Barefoot Bay=Tornado Magnet since the first trailer dropped anchor there.
440. billsfaninsofla
8:14 PM GMT on October 04, 2005
Guygee... thanks for the link to Gordon.. remember him well, we were just discussing him yesterday...
Member Since: September 5, 2005 Posts: 0 Comments: 5247
439. weatherdude65
8:14 PM GMT on October 04, 2005
guygee, I remember Gordon. That twister really messed up Barefoot Bay.
438. leftyy420
8:12 PM GMT on October 04, 2005
hey hake thats also why i loive va. i am close to the canes, get the snow, coastal storms and t-storms in the spring, albiet not the monsters u see in iowa. couldn;t ask for a better placeto live weather wise lol
Member Since: August 24, 2005 Posts: 35 Comments: 1987
437. leftyy420
8:11 PM GMT on October 04, 2005
hawke, i am 25 almost 26 and i donl;gt just love snow, i love the coastal storms. they are as dynamic of hurricanes and can bring u a vierity of weather. best part is snow usually melts in a wekk just in time for another shot. last time we had 18 named storms in the atlantic, which corrolated with weak to no el-nino, we had 3 huige snowstorms here on the east coast as well as the blizzard of 96. 2.5 feet here in va. looked at the outlook for 2005-2006 winter, weak elnino so its setting up to be a hell of a winter.
Member Since: August 24, 2005 Posts: 35 Comments: 1987
436. dashwildwood
8:11 PM GMT on October 04, 2005
lefty if this is a winter set up then there will be plenty of dissapointed folks, this onshore wind will really cut snowfall totals and raise temps along the coasts and piedmonts...which will cause plenty of rain changing to snow or ice changing to snow situations this setup would have a hard time producing significant snow south of the mason dixon line unless you were in the foothills and mountains
435. guygee
8:11 PM GMT on October 04, 2005
Current Weather Conditions:
Cocoa / Patrick Air Force Base, FL, United States
(KCOF) 28-14N 080-36W 3M
Conditions at

2005.10.04 1924 UTC
Wind from the NE (050 degrees) at 22 MPH (19 KT)
gusting to 32 MPH (28 KT)
Visibility 7 mile(s)
Sky conditions mostly cloudy
Weather Showers in the vicinity
Cumulonimbus clouds observed
Temperature 78 F (26 C)
Dew Point 73 F (23 C)
Relative Humidity 83%
Pressure (altimeter) 29.87 in. Hg (1011 hPa)
Member Since: September 16, 2005 Posts: 0 Comments: 3060
434. cgableshurrycanegal
8:10 PM GMT on October 04, 2005
Hey you dodo-birds!!! I'm in FL, not Canada!!! That's where you send for your Rx!!! ROFL!!!
Member Since: July 12, 2005 Posts: 24 Comments: 212
433. Dunhill3
8:10 PM GMT on October 04, 2005
Hey Hawk..if ya love hurricanes and hate the cold, do like the rest of the US and relocate here to Florida...plenty of weather to study and no real cold to deal with...move here and keep the taxes low.
432. Pensacola21
8:08 PM GMT on October 04, 2005
LOL Hous, Cgables... Me too!
Member Since: September 16, 2005 Posts: 30 Comments: 3912
431. tornadoty
8:08 PM GMT on October 04, 2005
Personally, Lefty, I'm thinking very potent (near hurricane-force?) subtropical system because of how warm the water is. Tammy could be one to remember, at least for use who pay attetion to these things.
430. cgableshurrycanegal
8:08 PM GMT on October 04, 2005
Now it's pouring. ARGH! Think I'll go medicate myself!
LOL!!! Now, what to take... catch you all later!!!
Member Since: July 12, 2005 Posts: 24 Comments: 212
428. cgableshurrycanegal
8:07 PM GMT on October 04, 2005
LOL!!! Houston, I think you mean Imitrex!!!
Valium WOULD calm me down...
Member Since: July 12, 2005 Posts: 24 Comments: 212

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.