Florida storm 93L a threat to the Gulf Coast

By: Dr. Jeff Masters , 2:32 PM GMT on September 19, 2007

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A non-tropical low pressure system (93L) developed yesterday afternoon off the southeast coast of Florida, and is bringing heavy rains to central Florida today. Animations of long-range radar out of Melbourne, Florida and satellite loops show a large, disorganized area of thunderstorms affecting the Florida Peninsula and adjacent waters. The surface center of circulation is right at the coast north of West Palm Beach. Water vapor satellite loops show that the upper level low pressure system that helped spawn 93L has moved off the southwest coast of Florida, and is headed westward across the Gulf of Mexico. This upper level low is bringing about 20 knots of wind shear over 93L, and pulling in some dry air from the northwest. As 93L traverses Florida today and tonight, it will bring heavy rains to the state. Radar estimated rainfall has been less than three inches thus far. No development of 93L is expected until the surface circulation emerges off the Gulf Coast of Florida Thursday.


Figure 1. Current long range radar out of Melbourne, Florida.

Once 93L emerges into the Gulf of Mexico Thursday, all of the models indicate the storm will intensify. This is a very complex forecast situation, since the storm is starting out with the cold core of an ordinary non-tropical low pressure system, and will transition to a warm-cored tropical storm. The transition to a warm core system will probably take at least a day. A storm undergoing such a process cannot intensify rapidly while this is occurring. This means that if 93L hits New Orleans Friday night/Saturday morning as the GFS and GFDL models are predicting, the storm will likely still be below hurricane strength--as predicted by the 8am EDT run of the SHIPS intensity model--or a minimal Category 1 hurricane--as predicted by this morning's 06Z run of the GFDL model. I think a tropical storm is more likely. Such a track would take it just north of the high heat content waters of the Loop Current in the central Gulf of Mexico (Figure 2). If 93L takes a more southerly track as the ECMWF and NOGAPS models predict, it will have an extra day over water, and more time to firmly establish a warm core. A warm core, fully tropical system is capable of must faster intensification rates. A more southerly track would also take the storm over the high heat content waters of the Loop Current, further aiding the transition to a warm core system. Texas could see a Category 1 or 2 hurricane on Sunday in this scenario. Slowing down the intensification will be the presence of plenty of dry air to the northwest, however, and a tropical storm may be all that Texas would see.

The NOAA jet is scheduled to fly this evening and collect data to help with the Wednesday evening (00Z Thursday) model runs. The first Air Force Hurricane Hunter mission is scheduled for Thursday afternoon.


Figure 2. Tropical Cyclone Heat Potential (TCHP) for September 18, 2007. TCHP is a measure of the total heat energy available in the ocean, and values greater than 90 kJ per square centimeter can trigger rapid intensification of tropical cyclones. The very high values of TCHP in the central Gulf of Mexico are associated with a warm ocean current known as the Loop Current. Image credit: NOAA/AOML.

Remains of Ingrid
The remains of Tropical Storm Ingrid are still kicking up some heavy thunderstorm activity a few hundred miles north of the northernmost Lesser Antilles Islands. There is still a bit a spin evident on satellite loops and this morning's QuikSCAT pass. Wind shear has dropped from 30 knots yesterday to 20 knots today, and is expected to decline below 10 knots by Thursday. We will need to watch this area for development. Ingrid's remains are moving slowly northwest. Steering currents are weak in the area, and the system will probably not move much over the next five days.

Typhoon Wipha whiffed
Typhoon Wipha made landfall just south of China's most populous city, Shanghai, at 3 am local time this morning. Wipha weakened significantly to a Category 2 storm just before landfall, and then to a tropical storm as it passed west of Shanghai. Damage from Wipha's winds and rain was far less than originally feared.


Figure 2. Radar images of Typhoon Wipha as it made landfall just south of Shanghai, China. Image credit: Taiwan Central Weather Bureau.

I'll have an update by 4pm EDT this afternoon when the next set of computer model runs become available for 93L.

Jeff Masters

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842. NEwxguy
8:09 PM GMT on September 19, 2007
I come back and looks like Ingrid has a heartbeat,amazing
Member Since: September 6, 2007 Posts: 888 Comments: 15989
841. NEwxguy
8:01 PM GMT on September 19, 2007
Hi,all,what's new with 93L
Member Since: September 6, 2007 Posts: 888 Comments: 15989
840. gwhite713
8:00 PM GMT on September 19, 2007
And what makes you think it will continue to the SW for any length of time after 24hrs if its even moving SW now?
Member Since: December 5, 2005 Posts: 0 Comments: 93
838. gwhite713
7:58 PM GMT on September 19, 2007
True Bones but considering its structure, steering currents the next few days and low shear, i'm all in for it developing into a sfc low at the bareminium within the next couple of days. If not, i'll eat crow =). Most ULL dont have as much to work with as this one does.
Member Since: December 5, 2005 Posts: 0 Comments: 93
837. flzepher
7:55 PM GMT on September 19, 2007
Good afternoon all. Just got home and turned on WFTV Channel 9 local radar on 1091 HD. I see that there is now a tight cirulation just off the coast of Cocoa and the Space Center moving WNW. There is convection trying to wrap around. I am sure you all have probally discussed this. Going back to read old post now. Sorry if this info is a repeat....
836. DallasGumby
7:55 PM GMT on September 19, 2007
I'll say this again, now that we have NHC's 18Z coordinates for 93L -- if those coordinates are accurate (and, certainly, the visual evidence shows it is plausible they are accurate -- at least that's one reasonble interpretation from the radar, vapor loops, etc.), then this "blob" is moving NNW rather than the westward movement predicted by earlier model runs, headed toward Georgia and Alabama rather than the Gulf.
Member Since: August 22, 2007 Posts: 0 Comments: 376
835. Bonedog
7:54 PM GMT on September 19, 2007
gwhite the ULL will head SW following the steering currents.

The likelyhood of development out of a ULL is low. Just because it spins and is in the Gulf doesn't mean it will work its way down.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
834. brazocane
7:54 PM GMT on September 19, 2007
Get on the updated blog fellas
Member Since: August 23, 2006 Posts: 0 Comments: 678
833. Bonedog
7:52 PM GMT on September 19, 2007
yea extreme tommorrow will set the stage. If the ULL moves far enough away then it will be less of an influence. If 93 stays close to it then it will cross florida too far north to be much of a worry.

Wait to see what happens till tomorrow. I want to also see what the Dmax does to both 93L and Ingrid.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
832. StormJunkie
7:52 PM GMT on September 19, 2007
18z BAM model runs again show 93 never making the GOM.

Quick Links-Forecast models, imagery, marine data, wind data, preparedness info, and much more from one easy to navigate page.

Dr M has a new blog up.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
831. msphar
7:49 PM GMT on September 19, 2007
Whats up with INGRID she's moving SW again.
Member Since: August 20, 2006 Posts: 0 Comments: 289
830. BrDennisH
7:51 PM GMT on September 19, 2007
Does the fact that the pressure is dropping at all the buoyes in the eastern GOM under the center of the ULL mean anything?
Member Since: September 22, 2005 Posts: 0 Comments: 60
829. nash28
7:50 PM GMT on September 19, 2007
It's hardly moving at all, so it certainly has a chance of becoming named before it finally hits the coast.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
828. brazocane
7:48 PM GMT on September 19, 2007
guys new blog up
Member Since: August 23, 2006 Posts: 0 Comments: 678
826. gwhite713
7:47 PM GMT on September 19, 2007
Bone, where do you see the ULL going? South? And for how long? I see it develop and head WNW to NW over the next 48 hrs.
Member Since: December 5, 2005 Posts: 0 Comments: 93
825. extreme236
7:49 PM GMT on September 19, 2007
But as I said earlier, the day tomorrow will tell all
Member Since: August 2, 2007 Posts: 19 Comments: 19234
824. IKE
7:49 PM GMT on September 19, 2007
18 GMT 09/19/07 28.4N 80.1W 25 1008 Invest
Member Since: June 9, 2005 Posts: 23 Comments: 37860
823. rwdobson
7:48 PM GMT on September 19, 2007
The way things are looking now, with the LLC forming further north, and the ULL moving away, the ULL could have less and less influence on the track of 93L.
Member Since: June 12, 2002 Posts: 0 Comments: 1589
822. extreme236
7:48 PM GMT on September 19, 2007
Im pretty sure that when/if it develops IMO it wil be subtropical at first
Member Since: August 2, 2007 Posts: 19 Comments: 19234
821. iahishome
7:45 PM GMT on September 19, 2007
What do you experienced people say is the dangerous point?

How far south does the CoC have to drift as it moves west over Florida before we get worried about a Katrina or Rita type scenario?

Tampa? Fort Myers? The Keys?

I think it's got a South component and will probably do some slight following of the ULL out, though typically things rotate around ULL's right? So that should keep it from going too far south I hope.
Member Since: July 24, 2005 Posts: 5 Comments: 501
819. Skyepony (Mod)
7:47 PM GMT on September 19, 2007
forgot the 93L radar loop..
Member Since: August 10, 2005 Posts: 227 Comments: 39445
818. IKE
7:46 PM GMT on September 19, 2007
Buoy east of Cape Canaveral....

Updated: 3:20 PM EDT on September 19, 2007
Air Temperature: 80 F
Wind direction (W Dir): SE (135 - 144 Degrees)
Wind Speed (W Spd): 5.8 kts (6.7 mph)
Dominant Wave Period (DWP): 8 sec
Dominant Wave Height (DWH): 6.23 ft
Dominant Wave Range (DWR): exactly 6.2 ft
Wind Wave Period (WWP): 4 sec
Wind Wave Height (WWH): 1.64 ft
Wind Wave Range (WWR): 0.82 - 2.46 ft
Wave Swell Period (WSP): 8 sec
Wave Swell Height (WSH): 6.56 ft
Wave Swell Range (WSR): 5.74 - 7.38 ft
Atmospheric Pressure (AP): 29.77 in
Member Since: June 9, 2005 Posts: 23 Comments: 37860
817. hahaguy
7:45 PM GMT on September 19, 2007
overnight i got 3 in of rain
Member Since: August 12, 2007 Posts: 2 Comments: 2838
816. Bonedog
7:45 PM GMT on September 19, 2007
in the near term extreme. As was stated before all depends on how fast the ULL pulls away.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
815. gwhite713
7:45 PM GMT on September 19, 2007
Sebastianj, if ULL deepens enough to sfc structure, it wont be that much of an inhibitor for 93, could actually help it..
Member Since: December 5, 2005 Posts: 0 Comments: 93
814. extreme236
7:45 PM GMT on September 19, 2007
well 93L should move SW eventually if the ULL continues to steer it, which will take it back in the gulf
Member Since: August 2, 2007 Posts: 19 Comments: 19234
812. KarenRei
7:44 PM GMT on September 19, 2007
Pressure falling in Naples.



the data is showing the storm is starting tof orm and much north than we thought. yes many thigns can happen but what looks LIKLELY is the storm will not reach the gulf or if it does have very little time.

Honestly, it doesn't matter all that much whether 93L goes into the gulf or not (and I wouldn't call either way until I see some of the major models weigh in). The Gulf is still ripe for development later this week. Low shear, fresh moisture, and lots of heat. They've been calling this since before 93L formed. We weren't supposed to get any development until Wed or Thurs to begin with; 93L was just "the early bird".
Member Since: September 7, 2007 Posts: 1 Comments: 940
811. extreme236
7:44 PM GMT on September 19, 2007
Posted By: MichaelSTL at 7:42 PM GMT on September 19, 2007.

the shear there is 5-10kts due to an anticyclone...wont have trouble forming there

Notice that on the shear map that the arrows are in a cyclonic, not anticyclonic direction; that is the ULL (the center of a ULL has low shear just as an anticyclone does).


rofl when I first looked at it I just glanced at it and though it was moving anticyclonically...oops yes I see, its the ULL...sorry about that
Member Since: August 2, 2007 Posts: 19 Comments: 19234
809. extreme236
7:43 PM GMT on September 19, 2007
Posted By: Bonedog at 7:42 PM GMT on September 19, 2007.

Looking at the steering currents map I see where the NW componant is coming from


So based on the steering, we should see a NW movement then a SW movement due to the ULL
Member Since: August 2, 2007 Posts: 19 Comments: 19234
808. Eyewall911
7:43 PM GMT on September 19, 2007
Wow u guys in Fl wanting all that rain well you got it. Stay safe
807. sebastianjer
7:40 PM GMT on September 19, 2007
How long till the ULL is too far away from 93L to affect it? In other words, at some point will the ULL be too far away to influence 93L and something else will dictate 93L's path. Probably a stupid question and probably won't be answered anyway, lol.
Member Since: August 26, 2005 Posts: 1030 Comments: 11197
806. gwhite713
7:42 PM GMT on September 19, 2007
Impressive flareup of colder clouds associated with the ULL.
http://www.ssd.noaa.gov/goes/east/gmex/loop-wv.html
Member Since: December 5, 2005 Posts: 0 Comments: 93
804. srada
7:42 PM GMT on September 19, 2007
Hi everyone,

So are the models stating the storm will move due north or NNW?
Member Since: August 17, 2006 Posts: 1 Comments: 774
803. Bonedog
7:42 PM GMT on September 19, 2007
Looking at the steering currents map I see where the NW componant is coming from



steering

Link
Member Since: July 14, 2005 Posts: 14 Comments: 7418
802. Skyepony (Mod)
7:42 PM GMT on September 19, 2007
Here's the 40 frame Nexrad loop out of Melbourne. You can see the rains caught in the west wind now. It's 1008.7↓mb here (in Melbourne). Fell more than a mb in the last hour. Ponys are concerned & requested afternoon hay in the barn even though it's sunny.
Member Since: August 10, 2005 Posts: 227 Comments: 39445
801. will40
7:42 PM GMT on September 19, 2007
most of the models are way left of the Xtrap. something gotta change there.the next model runs should shift some to the right
Member Since: September 19, 2005 Posts: 2 Comments: 4266
800. weatherguy03
7:41 PM GMT on September 19, 2007
JP. You can have my rain!!!
Member Since: July 5, 2005 Posts: 592 Comments: 29708
799. extreme236
7:41 PM GMT on September 19, 2007
Posted By: leftyy420 at 7:39 PM GMT on September 19, 2007.

Posted By: extreme236 at 7:34 PM GMT on September 19, 2007.
right now this storm is VERY complex...there are tons of scenarios and tons of things that could effect where this goes, such as where the true center will be at

don't wishcast. and if your not i am sorry. the data is showing the storm is starting tof orm and much north than we thought. yes many thigns can happen but what looks LIKLELY is the storm will not reach the gulf or if it does have very little time.


your hanging on this reformation way south to the ull and that just does not make any sense based off of CURRENT data.

thats my opinion and you have yours.

back to lurking peace guys


First, of all, I AM SICK OF PEOPLE CALLING OTHER PEOPLE WISHCASTERS ALL THE TIME...sorry to "yell" but I am only telling the truth, but yes based on current data this is the main center but the nhc has stated that it could also reform, so maybe their wishcasters too you think? I have never said the center would reform...but, I do believe the center will not move NW due to the steering of the ULL...
Member Since: August 2, 2007 Posts: 19 Comments: 19234
798. weatherguy03
7:41 PM GMT on September 19, 2007
That being said, the rest of the models will shift North later and this could give it less time over the water in the Gulf. Really, really depends on how far SW 93L moves into the SE Gulf and how fast it becomes tropical. Alot of questions still.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
797. surfmom
7:40 PM GMT on September 19, 2007
Bonde dog...WAVES are going to the GOMEX and my surf buddy (who ran off to the Phillipines is still visiting!!) Waves and our surf Godfather --it doesn't get better then that
Member Since: July 18, 2007 Posts: 30 Comments: 26536
796. gwhite713
7:40 PM GMT on September 19, 2007
"The problem I have with those BAMM models at 18Z is the movement to the NW. The LLC should follow the ULL to the West or SW.

Agreed! The ULL should steer 93L toward the west and the SW, then out into the gulf"

I feel that could happen more so providing if the ULL dosent fully develop to sfc L. Which ever the case, I feel the gulf is going to have at least one named storm and mid texas up to gulf of Mississippi should prepare for that kind of possiblity.
Member Since: December 5, 2005 Posts: 0 Comments: 93
794. Cavin Rawlins
7:39 PM GMT on September 19, 2007
Ingrid is showing signs of regenerating has pressures are now falling and there is clear vorticity (X)

Pressure Tendency







Member Since: July 24, 2005 Posts: 407 Comments: 19076
793. extreme236
7:39 PM GMT on September 19, 2007
Posted By: Drakoen at 7:38 PM GMT on September 19, 2007.

93L remains disorganized. Still 20-30kts of wind shear over the system. Most of the convection is associated with the upper level feed to the west of the Low pressure center.


but, since it should go into the gulf, the shear there is 5-10kts due to an anticyclone...wont have trouble forming there
Member Since: August 2, 2007 Posts: 19 Comments: 19234
792. FloridaRick
7:39 PM GMT on September 19, 2007
Tampa Spin I am with you. I agree that there is a COC off the east coast but I also think something is trying to form off the sw coast.
Member Since: July 27, 2005 Posts: 0 Comments: 18

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