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 VAbeachhurricanes:


can i get a link to that nrt, ive always ment to ask you.


ATCF
Member Since: September 23, 2005 Posts: 14 Comments: 10875
Iam guessing masters is going by the SHIPS forcast.
Member Since: May 14, 2006 Posts: 8 Comments: 13626

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Quoting VAbeachhurricanes:


i didnt ask that... asked why DR. Masters and the NHC think shear will be low.


Not too favorable as stated by the NHC

"CONDITIONS ARE MARGINALLY
FAVORABLE FOR THIS SYSTEM TO BECOME A TROPICAL DEPRESSION DURING
THE NEXT DAY OR SO"
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Quoting Grothar:


Hey there Patrap. Is this the same graphic posted earlier? Tell us the models are not shifting to the west! I hope they are not that sophisticated.


Just a repost from earlier to Compare to the 18 Z to come
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Quoting TreasureCoastFl:

So he and Dr Masters are in agreement.Good to know. can you ask him where he thinks it will end up now? ;)


He's very Conservative he's not going to speculate on that
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Quoting VAbeachhurricanes:


i didnt ask that... asked why DR. Masters and the NHC think shear will be low.

NHC said conditions are only marginally favorable which means it is under some shear.
Member Since: August 6, 2007 Posts: 0 Comments: 693
94L 18Z

...INITIAL CONDITIONS...
LATCUR = 15.6N LONCUR = 53.4W DIRCUR = 300DEG SPDCUR = 13KT
LATM12 = 14.3N LONM12 = 50.9W DIRM12 = 305DEG SPDM12 = 13KT
LATM24 = 12.7N LONM24 = 48.6W
WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1010MB OUTRAD = 180NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

Member Since: September 23, 2005 Posts: 14 Comments: 10875
As noted theres nothing really well defind at the surface with this disturbance,still a broad and elongated circulation.
Member Since: May 14, 2006 Posts: 8 Comments: 13626
496. DDR
Quoting TriniGirl26:
Good evening all...whats 94L current direction? NW?

Hi Trinigirl
Yes it is moving toward the NW away from us,which is good.
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Wow @ Jimena.
Member Since: August 14, 2008 Posts: 0 Comments: 137
Quoting hurricanejunky:

I think that was Lili wasn't it?


yes. Lily. thanks.
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Quoting Patrap:
12 Z Dynamic Models (More sophisticated models)



Hey there Patrap. Is this the same graphic posted earlier? Tell us the models are not shifting to the west! I hope they are not that sophisticated.
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Quoting edmac:
How do you come to this conclusion, have you been looking at any current charts, or just spit balling.


Use the quote feature.
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Quoting nrtiwlnvragn:
AL 94 2009083118 BEST 0 156N 534W 25 1008 DB


Good ways out in front of the convection. Still has a ways to go.
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Quoting nrtiwlnvragn:
AL 94 2009083118 BEST 0 156N 534W 25 1008 DB


can i get a link to that nrt, ive always ment to ask you.
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Quoting louisianaboy444:
For whom it may concern....I'm in the Weather Research lab at ULM and just asked my Professor of Atmosperic Sciences what he thinks of 94L he thinks shear is affecting it now but is expecting shear to become more favorable for development in the next 24 to 36 hours...

So he and Dr Masters are in agreement.Good to know. can you ask him where he thinks it will end up now? ;)
Member Since: August 18, 2008 Posts: 0 Comments: 467
Would be nice to say "folks all is clear for the CONUS this season of 09' have a great and Happy Thanksgiving and Merry Christmas and Happy New Year and we'll see you next hurricane season in 2010"
Member Since: July 14, 2008 Posts: 1 Comments: 9628
Quoting hurricane23:


SHIPS always explodes everything to cat 5's.


i didnt ask that... asked why DR. Masters and the NHC think shear will be low.
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485. edmac
How do you come to this conclusion, have you been looking at any current charts, or just spit balling.
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NATIONAL WEATHER SERVICE CHARLESTON SC
135 PM EDT MON AUG 31 2009

.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA LATE THIS AFTERNOON
THROUGH TONIGHT. THE FRONT WILL THEN STALL OFFSHORE AND TO THE
SOUTH TUESDAY AND LINGER THROUGH THE UPCOMING WEEKEND AS A WEDGE
OF HIGH PRESSURE BUILDS SOUTH.

NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1121 AM EDT MON AUG 31 2009

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
LONG TERM LOOKS UNSETTLED AS UPPER LOW PERSISTS OVER THE SOUTHEAST
INTO THE LAST PART OF THE WEEK. EVEN AS THE UPPER RIDGE BUILDS
INTO THE EASTERN STATES BY THE WEEKEND...

NATIONAL WEATHER SERVICE TALLAHASSEE FL
315 AM EDT MON AUG 31 2009

.LONG TERM (THURSDAY THROUGH MONDAY)...THE EXTENDED PERIOD COMMENCES
WITH THE MID/UPPER LEVEL TROUGH DIGGING WITH ITS AXIS THROUGH THE
FLORIDA PANHANDLE. HOWEVER...BY FRIDAY...THE TROUGH LIFTS AND
RETROGRADES WWD AS HIGH PRESSURE/ RIDGING BUILDS IN FROM THE EAST
AND FLOW BECOMES MORE ZONAL. DURING THE LATTER PART OF THE EXTENDED
PERIOD...RIDGING SHOULD BECOME MORE PROMINENT ACROSS THE SOUTHEAST
WITH AN INCREASE IN UPPER HEIGHTS. E.G PER GFS 588DM HEIGHT LINE
SHIFTS FROM S FL TO CNTRL GA THURS INTO SAT.

NATIONAL WEATHER SERVICE MIAMI FL
405 AM EDT MON AUG 31 2009

ON WED...AN INVERTED TROUGH LOOKS TO MOVE INTO THE BAHAMAS FROM
THE EAST...AND THIS FEATURE WILL COMBINE WITH A DEVELOPING
FRONTAL TROUGH ACROSS NORTH FL TO OFF THE CAROLINA COAST BY THU.
FINALLY WEAK RIDGING BUILDS IN FOR LATE IN THE WEEK AS THE TROUGH
MOVES NORTHEASTWARD. HAVE INCREASED POPS TO LIKELY INTERIOR FOR
WED...AND KEPT CHANCE POPS FOR THE REST OF THE FORECAST PERIOD IN
LINE WITH GFS MOS.

My point is they all mention the trough moving northeastwards and a ridge building over the SE CONUS. I know a lot can change by then, but this is not a pattern I like with 94L moving towards this general direction.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
Quoting Grothar:


Anyone who has ever been in a big one, NEVER wants to see another one. I have been in 6. Most very small except for Wilma. I lived and worked in Miami during Andrew. One never forgets those sights or sounds. They are not fun, they are not exciting! They not only leave scars on the landscape, they leave it on your psyche as well.


actually a hurricane would probably help the economy, the goods that would be bought before and after the storm would likely help the economy. IM NOT WISHING A STORM ON ANYONE. just saying it would help the economy.
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Shear has been increasing throughout the system though.


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AL 94 2009083118 BEST 0 156N 534W 25 1008 DB
Member Since: September 23, 2005 Posts: 14 Comments: 10875
Quoting Tropicsweatherpr:


There is a circulation now but what do we look for to see when there is a well defined circulation?


llc is what we're waiting for... it has to make it to the surface to be classified. I have a feeling that once it is determined to be at the surface it might skip TD or at the very least will probably only be a TD between 1 or 2 updates
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Quoting VAbeachhurricanes:


then why do DR. Masters and the NHC believe that shear will be low for the next 5 days?


SHIPS always explodes everything to cat 5's.
Member Since: May 14, 2006 Posts: 8 Comments: 13626
Quoting StormJunkie:


These are some good video tutorials on using the model pages. It also helps explain when the models were ran, and what time we see the output data from the various models.

Afternoon all


Thanks!
Member Since: August 18, 2008 Posts: 0 Comments: 467
Jimena AVN Still

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Quoting truecajun:
i asked this last year and was answered. but I was 8 days over my due date, so I don't remember the answer.

what was the hurricane - i think it was in 2002 - that was supposed to make landfall near new iberia, LA (near where andrew made one of his landfalls) then disappeared in the middle of the night? i think it was a she.

Was it Lili you are thinking of? It was supposed to make landfall as a 4, then dropped to a 2, then a 1 at landfall. We still had a lot of damage, but thank God it dropped in intensity. It came up Vermillion Bay if I remember right. We were without power at our home in Lafayette for 5 days.
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For whom it may concern....I'm in the Weather Research lab at ULM and just asked my Professor of Atmosperic Sciences what he thinks of 94L he thinks shear is affecting it now but is expecting shear to become more favorable for development in the next 24 to 36 hours...
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Quoting hurricane23:
Shear should only increase from here on out in my view and if any development does occur it will be slow.Only 2 models really doing anything with 94 are HWRF/CMC models which are likely over doing intensity.


How will the anticyclone effect the shear forecast?
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Quoting hurricane23:
Shear should only increase from here on out in my view and if any development does occur it will be slow.Only 2 models really doing anything with 94 are HWRF/CMC models which are likely over doing intensity.


then why do DR. Masters and the NHC believe that shear will be low for the next 5 days?
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Quoting Patrap:
Sorry about the 18 Z

I wanted the 12 Z Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models) from 31 August


A lot of those take it on a more southernly track. Could it end up getting destroyed in the Cuban mountains?
Member Since: August 18, 2008 Posts: 0 Comments: 467
Quoting truecajun:
i asked this last year and was answered. but I was 8 days over my due date, so I don't remember the answer.

what was the hurricane - i think it was in 2002 - that was supposed to make landfall near new iberia, LA (near where andrew made one of his landfalls) then disappeared in the middle of the night? i think it was a she.

I think that was Lili wasn't it?
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Shear should only increase from here on out in my view and if any development does occur it will be slow.Only 2 models really doing anything with 94 are HWRF/CMC models which are likely over doing intensity.
Member Since: May 14, 2006 Posts: 8 Comments: 13626
Quoting Bordonaro:

After the year the USA has had with the economy, the LAST thing we need is a Cat 3 or 4 hurricane adding insult to injury! I would encourage everyone in the Carribean and up and down the Atlantic Seaboard to keep their eyes on 94L! Even during an El Nino cycle, there will be at least 2 or 3 Cat 3 or bigger storms! As much as we love to see hurricanes grow, none of us wants to see the loss of life and/or property anywhere!


Anyone who has ever been in a big one, NEVER wants to see another one. I have been in 6. Most very small except for Wilma. I lived and worked in Miami during Andrew. One never forgets those sights or sounds. They are not fun, they are not exciting! They not only leave scars on the landscape, they leave it on your psyche as well.
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Quoting TreasureCoastFl:


When were those models ran?


These are some good video tutorials on using the model pages. It also helps explain when the models were ran, and what time we see the output data from the various models.

Afternoon all
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Quoting RayRayfromLa:


I do not think it is fair to tell someone that it is never going to enter the gulf with all of the uncertainy of the path. Did you see the Euro model? that is what they are predicting and that has been the most reliable model so far this Hurricane season. Everyone needs to be on guard to monitor the situation no matter where you live in my opinion.


i wasnt talking about the gulf... i was talking about shear
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Quoting truecajun:


a bunch were fives, just not at landfall - i think??
He was asking about the East Pac
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Quoting SykKid:
94L is going to get torn apart.



You said that 24 hours ago and look what happened. lol
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Quoting HadesGodWyvern:
National Hurricane Center
Special Immediate Advisory
SEVERE TROPICAL CYCLONE JIMENA (EP132009)
18:00 PM UTC August 31 2009
===============================

SUMMARY OF 1100 AM PDT INFORMATION...
LOCATION...18.1N 108.9W
MAXIMUM SUSTAINED WINDS...150 MPH
PRESENT MOVEMENT...NORTHWEST AT 8 MPH
MINIMUM CENTRAL PRESSURE...936 MB

-----
130 knots 936 hPa.. 5 knots from achieving Category 5 on the Simpson-Saffir scale (scary)


Be the first since Ioke in 2006, though that was a CPac storm.. so Kenna of '02 if it manages it. Sort of similar track as well to that storm.
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Good evening all...whats 94L current direction? NW?
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Quoting HadesGodWyvern:
National Hurricane Center
Special Immediate Advisory
SEVERE TROPICAL CYCLONE JIMENA (EP132009)
18:00 PM UTC August 31 2009
===============================

SUMMARY OF 1100 AM PDT INFORMATION...
LOCATION...18.1N 108.9W
MAXIMUM SUSTAINED WINDS...150 MPH
PRESENT MOVEMENT...NORTHWEST AT 8 MPH
MINIMUM CENTRAL PRESSURE...936 MB

-----
130 knots 936 hPa.. 5 knots from achieving Category 5 on the Simpson-
Saffir scale (scary)

ANYONE IN THE PATH OF THIS STORM, please heed all warnings by the local authorities! Please advise the local population of the threat ASAP! THIS IS A LIFE THREATENING SITUATION!!My prayers are with everyone to be affected on the Baja Peninsula
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Quoting VAbeachhurricanes:


its never going to enter it


I do not think it is fair to tell someone that it is never going to enter the gulf with all of the uncertainy of the path. Did you see the Euro model? that is what they are predicting and that has been the most reliable model so far this Hurricane season. Everyone needs to be on guard to monitor the situation no matter where you live in my opinion.
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Recon passing over Turks and Caicos due north of Haiti is seeing very light *northeasterly* winds at 400 mb ... in the 5 knot range. If it is dropping into St. Croix, as seems likely, we will get a peek at lower levels as it approaches the island (400 mb approx 28000 ft)

- WTO
Member Since: July 15, 2005 Posts: 3 Comments: 1262

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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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