M, N, O... P?

By: Dr. Jeff Masters , 1:12 PM GMT on September 06, 2005

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The tropics are really cooking now, with activity typical of what sees at the height of a busy hurricane season. We are only in the 4th inning of a 9-inning ball game, and already have our 14th named storm, with the 15th likely on the way! At this rate, the old record of 21 tropical storms set in 1933 will easily be eclipsed, and we'll have to start naming storms using the Greek Alphabet--Alpha, Beta, Gamma, etc. So let's dig in and start discussing the storms, from most important to least important.

Depression developing near Miami
The area of most serious immediate concern is the stationary tropical low centered about 75 miles east of Ft. Lauderdale, FL. This low has increased its deep convection markedly in the past six hours, and appears that a tropical depression will form here later today. The hurricane hunters are scheduled to investigate the system this afternoon.

The best to way to track the storm is on Miami radar. The radar loop shows a large circular ring of strong echoes developing. Doppler radar estimates of the wind velocity from the Miami radar (see image below) show peak winds in the 20 - 26 knot range, which is still below the threshold for a tropical depression (30 kt).


Figure 1. Doppler wind velocities from the Miami radar. The storm to the east of Miami is rotating counter-clockwise, so winds to the northeast of the city blow towards the radar, and winds to the southeast of the city are blowing away from the radar. Wind speeds over the ocean to the northeast of Miami are coded shades of green, meaning winds are blowing at 10 - 26 knots towards the radar (the radar is located in the exact center of the image, and is denoted by a hard-to-see white cross). To the southeast of the radar, the winds are colored yellow to orange, meaning winds are blowing 10 - 26 knots away from the radar. Ignore the echoes over land, most of these echoes are ground clutter. Velocities marked pink (RF) mean that the echoes are too far from the radar for velocities to be determined.

This system should move very slowly the next three days, since it is trapped under a strong high pressure ridge where steering currents are very weak. A slow northward or northwestward motion is indicated by most of the models, which would bring heavy rains to the east coast of Florida starting Wednesday. Most of the models bring the system inland over Central Florida by Thursday as a weak tropical storm and dissipate it. However, some models keep it just off the coast of Florida, and forecast that as the storm tracks further north, it will move more northeasterly away from Florida, following Nate out through a weakness in the ridge. This all depends upon how strong Nate becomes. However, none of the models forecast that the system will follow Nate all the way out to sea. A strong ridge of high pressure is forecast to build in behind Nate and force the system back towards Florida. This system seems destined to spend most of the coming week hanging around Florida. As far as intensity goes, shear levels over the system are 5 - 10 knots, which should allow for some modest strengthening. It is likely we'll have Tropical Storm Ophelia by Thursday. Shear levels are forecast to decrease even lower the next few days, so if the system remains off of the coast of Florida, it has a chance to be a hurricane by the end of the week.


Figure 2. Early forecast model tracks for the developing system east of Ft. Lauderdale.

Tropical Storm Nate
Nate formed last night on the eastern lobe of the same trough of low pressure that spawned the system near Ft. Lauderdale. Remarkably, the GFS forecast from last Thursday correct predicted that two separate storms might emerge from this trough. Nate's satellite signature has improved markedly the past six hours, is over warm waters, and has light shear overhead. We're likely to see Hurricane Nate by Thursday. Nate is moving very slowly, as it is trapped under a strong ridge of high pressure. A trough moving off the east coast Friday should create a weakness in the ridge that will allow Nate to follow Maria out to sea. The only threat from Nate to the U.S. coast will be some high surf that may develop late in the week.

Hurricane Maria
Maria peaked in intensity early this morning, and is now showing significant deterioration thanks to wind shear and cold water. She barely made it to major (Category 3) status last night, with 115 mph winds, the 4th major hurricane of the season. Maria is expected to continue zooming northeastward and turn into a huge and powerful extratropical low that will slam Iceland with high winds and heavy rain on Saturday. Maria's remnants will then weaken, but still bring Norway significant wind and rain on Tuesday.

P?
So, we've talked about M, N, and O, but not P yet. Well, I have no speculations about where the "P" storm might form. My long-range eyes can't see any evidence of other threats in the tropics. The tropical wave that just entered the eastern Caribbean has strong easterly winds at high levels that are shearing it, so that is not a threat. There is a low pressure center off the coast of Africa near 13N 33W, but convection is limited there. The ITCZ is pretty quiet, so for now we just have the M, N, and O storms to worry about.

Dr. Jeff Masters

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227. podunk
1:51 AM GMT on September 07, 2005
What is a TROF?

What is ITCZ?

Thanks!:-)

podunk
226. 8888888889gg
10:28 PM GMT on September 06, 2005

it look like we may see TD17 it is in the gulf and it is a low that may be come TD17
225. TybeeIslandGA
9:17 PM GMT on September 06, 2005
Obsidian...It has been raining steady here on Tybee since about 3:00. A LOT!! NE winds about 30 - 35 mph.
224. TVwxman
7:37 PM GMT on September 06, 2005
I don't know lefty...I'm having a tough time discerning an obvious llc. You are indeed correct about training rains though. I've had over 5" since Sunday! It's nice though. It takes the bite out of the inccessant heat we've endured all summer long.
223. Obsidian
7:36 PM GMT on September 06, 2005
As far north as Savannah Ga, I can look to the South and East towards Tybee Island and it's extremly overcast, and to the west it begins to clear up. No rain yet that I know of, but the sky looks very threatening. Hmm nevermind here comes the rain...
222. weatherguy03
7:35 PM GMT on September 06, 2005
yeah its been terrible today so far, alot of rain here, I was mentioning before this could turn out to be a big coastal flooding and beach erosion event for us here..With these NE winds that continue to pile up here.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
221. weatherguy03
7:33 PM GMT on September 06, 2005
Getting ready to get blasted again with some big rains here..Another huge wave of rain moving in from ocean.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
220. leftyy420
7:32 PM GMT on September 06, 2005
weatherguy, this is a big system as well and i think her impact might be some training resluting in some bad flooding. these bands have just been swinging in and some parts of florida have or will get alot of rain from this
Member Since: August 24, 2005 Posts: 35 Comments: 1987
219. stormydee
7:31 PM GMT on September 06, 2005
theres a new update folks
Member Since: August 25, 2005 Posts: 39 Comments: 517
218. leftyy420
7:31 PM GMT on September 06, 2005
ist only slightly north of the nhc 2pm location. maybe 50 milesmore north. if this did indeed happen than we might see some decent streggthening into a ts by late tonight. intensity beyond that is sketchy but we will have to watch it
Member Since: August 24, 2005 Posts: 35 Comments: 1987
217. weatherguy03
7:29 PM GMT on September 06, 2005
yes you can see that on the visible as well...Link..Deftinately north of where it was this morning.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
216. weatherguy03
7:27 PM GMT on September 06, 2005
YW stormy..sorry at work had to deal with people...Seems about right leftyy, hard to pinpoint it but I would go with that.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
215. leftyy420
7:27 PM GMT on September 06, 2005
in vis sat immagery earlier today allc was clearly visible east or miami. since that time that llc as dissipated and the over all circulation is now centred more north. appears llc redveloped underneath the deep convection as she fights that bit of shear.
Member Since: August 24, 2005 Posts: 35 Comments: 1987
214. leftyy420
7:25 PM GMT on September 06, 2005
based on radar and sat, i belive the center is or has reformed more north or east of fort peirce. she appears to also be drifting ever so slowly north or nnw.
Member Since: August 24, 2005 Posts: 35 Comments: 1987
213. stormydee
7:17 PM GMT on September 06, 2005
loop-d-loops r going down again, but its the end of my day. I guess TD16 wants to hold up and let the shear let up. More banding is starting to wrap around her...maybe she won't get her name by 5PM, but you can tell, she wants to get her act together...she has all day to wait for the winds to die down...she isn't going anywhere anytime soon....maybe tomorrow we'll be talking about Ophelia (who came up with these names anyway?...) and hopefully Nate will pull on out of here...
Member Since: August 25, 2005 Posts: 39 Comments: 517
212. TVwxman
7:06 PM GMT on September 06, 2005
p.s. gfdl has handled this sytem poorly from its inception. Take it with a grain of salt until a better llc is discovered.
211. TVwxman
7:02 PM GMT on September 06, 2005
As I mentioned last night. The shear was "somewhat" hostile and continues to be. That's why we have minimal depression right now. And latest recon has it below a depression. But as shear weakens I think we will see an "average" ts within 24-36 hrs. Look out though for the huge ridge in New England to weaken. If it does look for a possible track out to sea or NC/SC. If not, probably Jacksonville. Of course, track is very uncertain at this time and these are just my opinions. We have to wait for more recon reports etc.
210. stormydee
6:57 PM GMT on September 06, 2005
Link
Now that is what I was looking for...thanks again weatherguy!
Member Since: August 25, 2005 Posts: 39 Comments: 517
209. stormydee
6:54 PM GMT on September 06, 2005
weatherguy, I'll be busy checking out that site..thank you so much!
Member Since: August 25, 2005 Posts: 39 Comments: 517
208. sngalla
6:54 PM GMT on September 06, 2005
I agree, Stormydee. Guess the whole east coast of FL needs to keep a watchful eye on it.
Member Since: February 18, 2003 Posts: 57 Comments: 5363
207. weatherguy03
6:52 PM GMT on September 06, 2005
I am here in St. Augustine. I am on the intercoastal here. I can see it from my window. So i just go over the bridge and I am there in like 5 minutes..lol..
Member Since: July 5, 2005 Posts: 592 Comments: 29708
206. stormydee
6:52 PM GMT on September 06, 2005
boy sngalla, seems they aren't agreeing on much right now....
Member Since: August 25, 2005 Posts: 39 Comments: 517
205. weatherguy03
6:51 PM GMT on September 06, 2005
Again this is also good...Link..but doesnt update fast enough forme..lol..
Member Since: July 5, 2005 Posts: 592 Comments: 29708
204. stormydee
6:50 PM GMT on September 06, 2005
what beach u going to after work weatherguy? Closest I have is Cocoa Bch...
Member Since: August 25, 2005 Posts: 39 Comments: 517
203. sngalla
6:50 PM GMT on September 06, 2005
Here is another link http://euler.atmos.colostate.edu/~vigh/guidance/atlantic/early2.pngLink
Member Since: February 18, 2003 Posts: 57 Comments: 5363
202. stormydee
6:49 PM GMT on September 06, 2005
thanks weatherguy, much better models... :-)
Member Since: August 25, 2005 Posts: 39 Comments: 517
201. weatherguy03
6:46 PM GMT on September 06, 2005
Here stormy you can check this out..this is some of them from this morning...Link..Should have new stuff soon..I am at work dont have all my sites here, but at least you have some to look at.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
200. sngalla
6:43 PM GMT on September 06, 2005
Storydee, it is not your pc. All the models look distorted at the bottom.
Member Since: February 18, 2003 Posts: 57 Comments: 5363
199. stormydee
6:42 PM GMT on September 06, 2005
can anyone get TD's computer models off this website? Mine are all messed up looking, not sure if its my computer or the website...
Member Since: August 25, 2005 Posts: 39 Comments: 517
198. StormJunkie
6:42 PM GMT on September 06, 2005
Convection is starting to bulid to the S in the lower Bahamas. That strengthen is forcasted for the diernal period also Dee. Have to watch tonight and see how organization does. We need a well defined center to get an idea of where she is going.
Member Since: August 17, 2005 Posts: 26 Comments: 16970
197. Skyepony (Mod)
6:40 PM GMT on September 06, 2005
oh, i'm in the TS warning. Can anyone think of a storm that has developed to hurricane stength on top of or around fl historically, like Katrina did? I remember 1 or 2 as a kid that crossed or moved around fl as TS then moved off to develope. & wftv said a recon is headin to TD16 now.
Member Since: August 10, 2005 Posts: 284 Comments: 40789
196. stormydee
6:38 PM GMT on September 06, 2005
from the latest discussion:
A BIT OF SHEAR IS HITTING THE DEPRESSION BUT WILL DISAPPEAR ONCE AN UPPER LEVEL RIDGE DEVELOPS ON TOP OF IT. THE DEPRESSION IS FORECAST TO BE IN WARM WATERS DURING THE NEXT TWO OR THREE DAYS...AND THUS GRADUAL STRENGTHENING IS FORECAST LATER TONIGHT OR WEDNESDAY. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS STRETCH FROM THE CENTRAL BAHAMAS NEAR 24N TO 31N BETWEEN 75W AND THE COASTS OF FLORIDA AND GEORGIA.
Member Since: August 25, 2005 Posts: 39 Comments: 517
195. leftyy420
6:36 PM GMT on September 06, 2005
i would like to see another run or two to see if it has a handel on the system. remebr it had a cane in the gulf 2 days ago and dissipated it all day yesterday. so it has not had any concitency
Member Since: August 24, 2005 Posts: 35 Comments: 1987
194. stormydee
6:32 PM GMT on September 06, 2005
glad u could join Lefty, u seem to have good knowledge.
Member Since: August 25, 2005 Posts: 39 Comments: 517
193. StormJunkie
6:31 PM GMT on September 06, 2005
Lefty I know you liked the GFDL with Katrina, but what is your take on the GFDL on this one?
Member Since: August 17, 2005 Posts: 26 Comments: 16970
192. weatherguy03
6:31 PM GMT on September 06, 2005
New vortex in...Link..Barely a depression.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
191. leftyy420
6:30 PM GMT on September 06, 2005
the key to track will be where her center is as she develops and the strngth of the ridge to her north. that ridge is suppose to weaken and split. that will be key
Member Since: August 24, 2005 Posts: 35 Comments: 1987
190. stormydee
6:29 PM GMT on September 06, 2005
thanks tampawx...that answered some of my wondering questions...
Member Since: August 25, 2005 Posts: 39 Comments: 517
189. StormJunkie
6:29 PM GMT on September 06, 2005
The further N she moves the further she will get away from Katrina's wake.
Member Since: August 17, 2005 Posts: 26 Comments: 16970
188. leftyy420
6:29 PM GMT on September 06, 2005
yeah this one could get interesting
Member Since: August 24, 2005 Posts: 35 Comments: 1987
187. StormJunkie
6:28 PM GMT on September 06, 2005
Afternoon Lefty. I will be watching this one closely. Have to head to work in about 20 mins.
Member Since: August 17, 2005 Posts: 26 Comments: 16970
186. leftyy420
6:26 PM GMT on September 06, 2005
stormydee. that is unlikely. nate and td 16 all formed from a complex system. td 16 from an area of low pressure that built in behind a low trof. nat developed from the trof. as of right now there would be no other mechanism to form another system from td 16. i do belive we may see as she forms for the center to redevelop somewhere with in the deepest convection and this will likely affect the track of this sytem and the length over water
Member Since: August 24, 2005 Posts: 35 Comments: 1987
185. StormJunkie
6:26 PM GMT on September 06, 2005
The diernal period should be intresting tonight. Widespread convection should die down some, but deeper convection should develop around the center. Shear should continue to weaken if the forcasts I have read are correct. Ships brings it to 70mph in 72 hrs.
Member Since: August 17, 2005 Posts: 26 Comments: 16970
184. tampawx
6:24 PM GMT on September 06, 2005
some interesting insights from the tampa nws afternoon update (kinda lengthy sorry)

THE UPPER LOW IN THE GULF IS GRADUALLY GETTING OUT OF THE WAY...EXIT STAGE LEFT. THIS SHOULD ALLOW WHATEVER SHEAR IN THE NEAR STORM ENVIRONMENT (MAINLY IN THE EASTERN GULF) TO WEAKEN. COMBINE THIS WITH THE LOCATION OF THE CYCLONE NEAR/OVER THE GULF STREAM...SEE NO
REASON WHY THE CYCLONE WON`T STEADILY INTENSIFY OVER THE NEXT DAY OR SO. HOW QUICKLY? NOT SURE YET...BUT NOTE THAT NEARBY WATER TEMPERATURES HAVE LOWERED IN THE WAKE OF KATRINA.

SECOND...TRACK. THOUGH THE CENTRAL GULF LOW IS SLIDING WEST...THERE SHOULD BE ENOUGH RESIDUAL SOUTH/SOUTHWEST FLOW...ALBEIT LIGHT...IN THE EASTERN GULF TO NUDGE THE SYSTEM ALONG ITS CURRENT FORECAST NORTH-NORTHWEST TRACK FOR THE NEXT COUPLE OF DAYS. BUT IT`S GONNA BE CLOSE. THE WINDS AROUND THE GULF TROUGH ARE QUITE TIGHT (NOTE
THAT ATLANTA`S RAOB HAS DECENT SOUTHWESTERLIES ABOVE 400 MB WHILE BIRMINGHAMS`S WERE NORTHEAST!). THE LATEST GFDL NOW TAKES THE SYSTEM MORE WESTWARD...SO MID AND UPPER LEVEL WIND FIELDS WILL NEED TO BE MONITORED CLOSELY.

THEREAFTER...THE MOVEMENT WILL DEPEND ON WHETHER THE CYCLONE GETS FAR ENOUGH NORTH TO "FEEL" THE FAIRLY DEEP TROUGH MOVING OFF THE NORTHEAST U.S. COAST TOWARD THE END OF THE WEEK. IF IT DOES...IT SHOULD MAKE THE TURN WITH THE WESTERLIES AND HEAD AWAY FROM THE REGION.

HOWEVER...IF IT DOESN`T...THE LATEST MODELS SHOW UPPER RIDGE BUILDING NORTH AND EAST...WHICH WOULD ULTIMATELY STEER THE SYSTEM OR ITS REMNANTS BACK TO THE WEST AND PERHAPS INTO THE GULF. STAY TUNED!

183. leftyy420
6:22 PM GMT on September 06, 2005
goodmorning. wow td 16. man when i said 12-24hrs yesterday i expected it would take a little longer. now we need to see where she goes
Member Since: August 24, 2005 Posts: 35 Comments: 1987
182. stormydee
6:21 PM GMT on September 06, 2005
On Friday, before they were even classified as tropical, TD16 and Nate were very close and then Nate moved away...now looking at TD16, it is possible she could branch and become 2 tropical storms? Anyone know????
Member Since: August 25, 2005 Posts: 39 Comments: 517
181. subtropic
6:21 PM GMT on September 06, 2005
For those of you in South Fl that haven't seen this yet:
Area forecast discussion

National Weather Service Miami Florida
205 PM EDT Tuesday Sep 6 2005


Discussion...
forecast package all dependant on what T.D. 16 does and GOES. All
models in fair agreement to drift it to the north-northwest and
official forecast track is as such. Main problem is how extensive
rain banding will be on the SW side of the system. Seems to be
enough subsidence occurring that convection is not developing over
the peninsula where sun has been shining all day. This even when
the precipitable water well over two inches. For now have lowered probability of precipitation just a
tad to account for the inactivity but may not have lowered enough.
The other factor are the temperatures as enough clouds around on the East
Coast to keep temperatures down and GFS/mav has initialized far better
than the met guidance. As 16 drifts north S fla to stay under a
lot of moisture feeding into the system from the S and SW so will
leave scattered coverage in for Wednesday/Thursday with the East Coast being the
most vulnerable at least by Thursday. By the weekend system far enough
to the north that drier air could spread across the region.
Member Since: August 29, 2002 Posts: 209 Comments: 4434
180. weatherguy03
6:08 PM GMT on September 06, 2005
So far this morning here, three of these rain squalls have come in giving us almost an inch of rain here. Gusts have been ranging from 30 to 40 mph with each of these.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
179. stormydee
6:08 PM GMT on September 06, 2005
TD isn't wrapping its southern end...must be the shear. Remember, we've all seen shear tear these systems up. Anyone have links to the shearing forecasted for the storm? Or when/if it will let up?
Member Since: August 25, 2005 Posts: 39 Comments: 517
178. weatherguy03
6:07 PM GMT on September 06, 2005
Again SJ big rain event for us here in FLorida, with coastal flooding and beach erosion a big factor..Hopefully that is all we will see.
Member Since: July 5, 2005 Posts: 592 Comments: 29708
177. LpAngelRob
6:06 PM GMT on September 06, 2005
Here's a link with better Fujiwara stuff. This link makes the claim that eventually, the two tropical systems merge.

This particular link describes how a MCS (mesoscale convective system) affects the path of a tropical cyclone, and vice versa.
Member Since: July 15, 2005 Posts: 0 Comments: 41

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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.

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