Hurricane warnings for Baja; 94L forming spiral bands

By: Dr. Jeff Masters , 3:36 PM GMT on August 31, 2009

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Hurricane warnings are in effect for the southern tip of Mexico's Baja Peninsula, where powerful Hurricane Jimena is expected to make landfall Tuesday night or Wednesday morning. The hurricane is in an environment with low wind shear, 5 - 10 knots, and warm Sea Surface Temperatures (SSTs), 30°C. Shear is expected to remain low, and SSTs will decline to 28°C with a corresponding decrease in total oceanic heat content between now and landfall, and these conditions should mean that Jimena will be a Category 3 or 4 hurricane at landfall. Outer rain-bands of the hurricane will be appearing on Los Cabos radar soon, though the Mexican Weather Service web site has been hard to reach today. The computer models are split, with one camp calling for a landfall in southern Baja, and the other camp calling for landfall farther north near central Baja. The official NHC forecast splits the difference between these two solutions, and landfall could occur anywhere along a long stretch of the Baja coast. At this point, the UKMET model's solution taking Jimena westward out to sea is being discounted, since it is an outlier.

After Jimena makes initial landfall on Baja, it will cross over the Gulf of California and make landfall on Mainland Mexico. Depending upon how up along the coast this second landfall occurs, Arizona may receive moisture from Jimena late this week that will be capable of causing flooding rains.


Figure 1. Image of Hurricane Jimena taken by NASA'a MODIS instrument at 2020 UTC Sunday, 8/30/09.

Invest 94L
The well-organized tropical wave (94L) near 14.5N, 52W, about 500 miles east of the central Lesser Antilles Islands, continues to be a threat to develop into a tropical depression. Visible satellite imagery and this morning's QuikSCAT pass do not show a surface circulation yet, though 94L does have a large envelope of moisture and some modest heavy thunderstorm activity. QuikSCAT noted winds up to 30 mph. Water vapor satellite loops show that 94L has moistened the region surrounding it considerably, and dry air from the Saharan Air Layer is not a major impediment to development. Wind shear is a low 5 - 10 knots, and the ocean temperature are a moderately warm 28°C. Visible satellite loops over the past two hours show low-level spiral bands developing on 94L's northeast side, and I give a 70% chance the Hurricane Hunters will find a tropical depression or tropical storm on Tuesday when they investigate 94L.


Figure 2. Morning satellite image of 94L, showing low-level spiral bands developing on the northeast side.

The center of 94L probably passed over Buoy 41040, located at 14.5N, 53W over the past hour. Winds blew northeasterly early this morning, then went calm, then shifted to southerly late this morning. The winds were less than 10 knots during the center passage, so the circulation of 94L is not yet well-defined. The pressure fell significantly as 94L moved over the buoy (seen only after one removes the wiggles due to daily atmospheric tide effect present in the tropics). 94L will appear on Martinique radar on Tuesday.

The forecast for 94L
Shear will remain low, 5 -10 knots, over the next 5 days, SSTs will be warm, in the 28 - 29°C range, and dry air should have only a minor inhibiting effect, so I can't see anything that will prevent 94L from developing into a tropical depression over the next 1 - 2 days. The HWRF model develops 94L into a hurricane 4 days from now, as does the SHIPS intensity model, but other models, such as the GFDL, ECMWF, and GFS, do not develop 94L at all.

Model solutions for the track of 94L are divergent. Water vapor satellite loops show two upper-level lows to the north and northwest of 94L that are pulling the storm to the west-northwest, and 94L's motion is expected to range between the west-northwest and northwest over the next three days. By Tuesday, 94L will slow down from its current 15 mph forward speed to about 10 mph. Most of the models predict that the steering influence of the upper-level lows will pull 94L far enough north that the storm will miss the Lesser Antilles, with a closest approach occurring Wednesday and Thursday. However, the ECMWF and HWRF models have 94L passing within 200 miles of the islands, and the northern Lesser Antilles may experience tropical storm conditions on Thursday.

At the longer ranges, the fate of 94L is highly uncertain. The Canadian model turns 94L to the north near Bermuda, then out to sea, while the NOGAPS model foresees a threat to the U.S. East Coast early next week. Both of these solutions are believable. The Hurricane Hunters are scheduled to make their first flight into 94L on Tuesday afternoon at 2pm EDT.

Elsewhere in the Atlantic
The remains of an old cold front are bringing cloudiness and showers to the northern Gulf of Mexico and waters offshore North and South Carolina. The GFS and NAM models indicate an area of low pressure may develop along this old front near the Florida Panhandle or off the coast of North Carolina by Thursday. However, such a low may be extratropical and not tropical.

My next post will be between 3 - 5pm this afternoon.

Jeff Masters

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Quoting nrtiwlnvragn:
Based on the HPC discussion in post #711, we will have another week of 94L and/or whatever it is designated as. That means

14 ECMWF/CMC model cycles
28 GFS/NOGAPS/GFDL/HWRF model cycles
28 TWO
28 TWD

Lots of information to "discuss": shear, motion, intensity etc.


Exactly.
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I am not liking the way the future is shaping up for 94L.
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754. amd
Update on Jimena:

Pressure estimated now at 925.9 mb.
Max flight level winds: 149 knots

Jimena is an absolute monster
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Quoting TreasureCoastFl:


That's not true. The whole state most certainly does not feel it. I am born and raised in Miami, Fl and now live north of there and it is a fact that the whole entire state does NOT feel a storm that hit's somewhere in Florida. How silly.


You need to do some research before posting such a ridiculous comment. I am located just south of Tampa. There has been several hurricanes make landfall here in Florida the past decade and I didn't feel any affect. So your wrong.
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752. slavp
Quoting dwpearson:
no flooding for lilli in Erath. you must have been asleep. I had 3 feet of water in my house in Maurice.
Wasn't sleeping. was home the following day dry as a bone. Trees and poles down all over, but no water.
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Quoting IKE:
I see the 12Z ECMWF shows 94L doing a Bill.

I'm not surprised. I guess that's what these discussions mean as "weak high pressure".


Do you agree with this? Thanks Ike!
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I'm not buying Invest 94L as Bill: Part 2
Member Since: August 14, 2008 Posts: 0 Comments: 137
Based on the HPC discussion in post #711, we will have another week of 94L and/or whatever it is designated as. That means

14 ECMWF/CMC model cycles
28 GFS/NOGAPS/GFDL/HWRF model cycles
28 TWO
28 TWD

Lots of information to "discuss": shear, motion, intensity etc.
Member Since: September 23, 2005 Posts: 14 Comments: 11274
Quoting cirrocumulus:
fmbil: This one has been intriguing(94L). There were several areas that appeared to be the center. Now it appears that it is incorporating all sides.


Very fascinating, indeed.

If it does actually gather all that area into one system, it will be quite large. Remember the size of H. Floyd???
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Quoting PBG00:


Thats worth a ban?


Just depends on how many people are here that don't like you...all it takes is enough people to report a post
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Are these models written in stone? models have no meaning till something is there.
Member Since: July 14, 2008 Posts: 1 Comments: 9648
Quoting futuremet:
12Z ECMWF--Out to sea


Boy, it sure puts the breaks on and turns North in a hurry in that scenario. Almost a 90 degree turn.
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SJ You shoulda known you were gonna get slammed on that one. Here, it is hard to make anyone understand that line of thinking, not that i dont agree mind you.
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Still well-organized
Good outflow to all quadrants.
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739. IKE
I see the 12Z ECMWF shows 94L doing a Bill.

I'm not surprised. I guess that's what these discussions mean as "weak high pressure".
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no weakness in the high and no short wave trough = continued westward movement for 94l!

whatever 94l does become should be parked off of florida or the southeast coast in about 4-5 days




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Good Afternoon! Looking at latest models they are predicting an Andrew track, WNW until it is Northeast of Puerto Rico then west straight to Florida.
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Quoting connie1976:
...you can get banned for posting a picture...but you can curse up a storm(lol) and that's alright?


hey connie! hows it going? im at work and blogging haha!
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ALLSTAR:

I agree.. EURO might be the outlier this time..who knows!!?
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Lot of the BAM suite models (18z), 12Z GFS, 12Z UKMET are showing 94L going West once it reaches north east of PR....
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fmbil: This one has been intriguing(94L). There were several areas that appeared to be the center. Now it appears that it is incorporating all sides.
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Quoting leftovers:
but it has been the trend this yr so far that counts for alot


No offense, but not really at all. Previous patterns does not mean very much at all. Just because all these troughs have been saving us....what's to say that the high will build in this time forcing it more west?
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Quoting RitaEvac:


Doesn't matter what part of Florida, just need to know if you live in FLorida your in the crossfire. If you say TX that means from Mexico border to Louisiana border. By the way.....dont you know by now that if a storm hits Florida the whole friggin state feels it!


That's not true. The whole state most certainly does not feel it. I am born and raised in Miami, Fl and now live north of there and it is a fact that the whole entire state does NOT feel a storm that hit's somewhere in Florida. How silly.
Member Since: August 18, 2008 Posts: 0 Comments: 474
727. PBG00
Quoting BILOXISAINT2:
According to Admin it was.


I guess so..

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The '09 atlantic hurricane season is quickly turning into a global warming enthusiasts worst nightmare. lol
Member Since: August 14, 2008 Posts: 0 Comments: 137
...you can get banned for posting a picture...but you can curse up a storm(lol) and that's alright?
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no flooding for lilli in Erath. you must have been asleep. I had 3 feet of water in my house in Maurice.
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Quoting CycloneBoy:
I'm not refering to questions, I'm talking about people coming on to this blog making statements about shear, models, circulation, etc. when they have no idea what they're talking about. It's a complete waste, and serves zero purpose. I'm not an expert either, but making comments in direct conflict with those who are based on "feelings" or "observations" is what defines a troll...

thing is, all anyone has to do is look at different sites to get that info.

cimss shear map shows 20-40 kts. of shear just to the NW of the system.

the anticyclone does not encompass all of 94L which is why all the convection is east of what circulation there is.

quikscat and ascat showed that there is not a well defined circulation. the NHC even states that there isn't and that conditions are only marginally favorable.

and you don't think people should make comments on current observations? that's just silly. how else are people supposed to see what's going on?
Member Since: August 6, 2007 Posts: 0 Comments: 693
722. slavp
Quoting naynaysnanny:


I remember that one too. My mom (in Kaplan) was without power for days. Left my home in NOLA and took her a generator so she could have power. Lilli caused alot of flooding if I recall correctly too.
I'm in Erath. I don't recall too much flooding for Lili. But the year before, in 2001, TS Allison caused a lot of flooding over here.
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681. CycloneBoy 7:05 PM GMT on August 31, 2009
I'm not refering to questions, I'm talking about people coming on to this blog making statements about shear, models, circulation, etc. when they have no idea what they're talking about. It's a complete waste, and serves zero purpose. I'm not an expert either, but making comments in direct conflict with those who are based on "feelings" or "observations" is what defines a troll...


Agreed...now we will move on.....

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According to Admin it was.
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HCP Day 7 (Monday Sept 7)



Okay...here's the link
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StormW
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I just posted a new blog if anyone is interested. 94L seems to be in the process of tightening up its circulation. Its pretty broad for now.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
HPC Extended Forecast Discussion

WESTERN SUBTROPICAL ATLANTIC...
THIS MODEL CHOICE DOES NOT EXTEND TO THE TROPICAL DISTURBANCE NEAR
15.5N 53.5W...WHERE A COMBINATION OF CONTINUITY AND THE 00Z
MULTI-MODEL ENSEMBLE SPREAD WERE UTILIZED TO RECURVE THE LOW
OFFSHORE FLORIDA/THE BAHAMAS JUST AHEAD OF THE STATIONARY FRONT
AND MINIMIZE POSSIBLE ERROR. THERE IS SIGNIFICANT SPREAD BOTH IN
THE 00Z MULTI-MODEL ENSEMBLE MEMBERS AND THE DETERMINISTIC
GUIDANCE AS TO WHERE THIS SYSTEM GOES AND HOW STRONG IT WILL
BE...WITH THE 00Z CANADIAN ON THE NORTHEAST SIDE OF THE SPREAD AND
THE 00Z ECMWF/06Z GFS ON THE WEAK SIDE OF THE SPREAD...MOVING A
TROPICAL WAVE THROUGH THE FLORIDA STRAITS. HOW MUCH OF A SURFACE
LOW EXISTS OFFSHORE FLORIDA AND THE BAHAMAS IS QUESTIONABLE LATE
IN THE PERIOD...AS THE UPPER PATTERN IN THE 00Z ECMWF/06Z GFS/00Z
CANADIAN BECOMES LESS FAVORABLE NORTH OF 20N LATITUDE AND WEST OF
60W LONGITUDE. THE CURRENTLY AGREED UPON POINTS ARE SIMILAR TO
PREVIOUS PROGS AND RELATIVELY CLOSE TO THE 12Z ECMWF RUN...WHICH
FINALLY HAS A SURFACE LOW TO FOLLOW OVER THE NEXT WEEK.



Graphics
Member Since: September 23, 2005 Posts: 14 Comments: 11274
709. CapnK
Hi All -

Just poking my head outta the hatch for the first time this year to say "Hi". Looks like this is the week to get my {boat/home} ready for moving up the river on short notice!

Hopefully, this year as last, I won't have to leave the dock for 'evacuation purposes' at all. :)

Starting about Thursday, alla you EastCoasters face SE for 10 minutes/day, and BLOW as hard as you can. Maybe a thousand butterfly wings worth of air will send 94L on into the NA recurve route. ;)

It's worth a try. :D

Peace!

CapnK and the CrewDogs
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681. CycloneBoy 7:05 PM GMT on August 31, 2009
I'm not refering to questions, I'm talking about people coming on to this blog making statements about shear, models, circulation, etc. when they have no idea what they're talking about. It's a complete waste, and serves zero purpose. I'm not an expert either, but making comments in direct conflict with those who are based on "feelings" or "observations" is what defines a troll...



agreed....we will move on

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707. PBG00
Quoting BILOXISAINT2:
StormW got banned last night


Why?
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Quoting twhcracker:


when you say "florida" please be aware there is east florida peninsula, west fla peninsula, and the panhandle GOM, and of the panhandle GOM where I am, there is the big bend tallahassee area, the central panhandle and the Pensacola area. So do you mean the whole state or the east coast or the GOM or what??


Doesn't matter what part of Florida, just need to know if you live in FLorida your in the crossfire. If you say TX that means from Mexico border to Louisiana border. By the way.....dont you know by now that if a storm hits Florida the whole friggin state feels it!
Member Since: July 14, 2008 Posts: 1 Comments: 9648

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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.