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 hurricane23:
12z EURO a tad stronger but suggest recurve.


Yup it does a shortwave trough and recurves it. If it does that for three more runs, then we may be looking at a trend here.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
636. sandyoaksea 6:57 PM GMT on August 31, 2009
So....for those of us who want to really learn and be prepared and help others we take up "space"???

Sorry just a bit offended. If each of you here are professional metereologists (spelling may be wrong) then I apologize.

I am just trying to learn so I don't sound like an idiot and so I can learn weather patterns



No apology needed Sandy....I didn't and like you was offended by the idiotic statement.
Member Since: September 13, 2007 Posts: 0 Comments: 312
You know hurricanes are exciting when there out in the water. Its a different thing when they hit land!! Ive been in many hurricanes since 1979 and every time one gets close the excitement goes up. Ive come to realize this excitement is fear and i have learned to respect this awesome force. Take advantage of this time and be prepared for a hurricane. Its easy to underestimate if you have not been in one. Use Patraps list on here and any other list you can get. Also old school tracking on a map will never let you down.
653. eddye
everyone it becoming better organized and i think this could be the one that fl needs to watch
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651. Relix
@viequessun : Never, absolutely never, drop your guard. It's just prediction based on movements. Watch it until it's north or even over us. All is possible with nature!!!
Member Since: August 3, 2006 Posts: 0 Comments: 2725
Quoting futuremet:
12Z ECMWF--Out to sea


Sorry, didn't see yours!!
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Member Since: September 6, 2007 Posts: 0 Comments: 6596
Quoting TreasureCoastFl:

I agree with Rita Evac about the mountains, if it were to go that way. Why would divdog find that offensive? weird..


He's a wishcaster
Member Since: July 14, 2008 Posts: 1 Comments: 9630
2 p.m. Discussion says "favorable," and 2 p.m. Outlook says "marginally favorable."
Is there some disagreement within the NHC?
Pasch wrote the Outlook and Huffman wrote the Discussion...The plot thickens.
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Quoting AllStar17:
My....my--this blog changes it's feelings on a system every second.


Agreed it does.
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12z EURO a tad stronger but suggest recurve.
Member Since: May 14, 2006 Posts: 8 Comments: 13804
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643. Relix
I have a bag of crow ready if I miss predictions though haha! Good afternoon WU!
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Quoting AllStar17:
Anyone read this from Dr. M?

"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."

i assume just about everyone did.

only problem is shear is higher than what he says.
Member Since: August 6, 2007 Posts: 0 Comments: 693
12z ECMWF - Out to sea...

ECMWF
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likely south florida hit according to nogaps
with ridging building in the track is locked.

all stormchasers active! Gear up people!!
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Quoting AllStar17:
Anyone read this from Dr. M?

"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."


everyone thinks they are the experts
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12Z ECMWF--Out to sea
Member Since: July 19, 2008 Posts: 43 Comments: 4051
So....for those of us who want to really learn and be prepared and help others we take up "space"???

Sorry just a bit offended. If each of you here are professional metereologists (spelling may be wrong) then I apologize.

I am just trying to learn so I don't sound like an idiot and so I can learn weather patterns....
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Quoting Txwxchaser:
566. CycloneBoy 6:43 PM GMT on August 31, 2009
amateur afternoon kind of has new meaning today....I've never understood how people can make entries on this blog without first reading the update from Dr. Masters. It would almost be funny if it didn't take up so much space.


Don't be sooo quick to judge. An amateur may not completely understand. Since when did it become problematic for "anyone" to ask a question and take up space. Last I looked, this was WU space. I'll certainly keep asking, whether it offends you or not.

you are right. If they don't want us asking questions even if they appear stupid, then they should not use the blog
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Quoting Relix:
Well 94L went a bit too far north. I would say the islands are spared from a direct impact though it might feel indirect bands and stuff from the wave. Not much ATM to speak either, it just doesn't want to develop into anything =P
do you think we need to be aware here in Puerto Rico or is another Bill or Ana passing by?
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Quoting divdog:
better than wasting time reading your junk .. poof
Quoting leftovers:
newcomer already poofing! rita evac been around this blog for along time

I agree with Rita Evac about the mountains, if it were to go that way. Why would divdog find that offensive? weird..
Member Since: August 18, 2008 Posts: 0 Comments: 474
Quoting WaterWitch11:
LOS ANGELES, California (CNN) -- A fast-moving wildfire in Southern California has nearly doubled in size and is threatening 10,000 homes on Monday, officials said.

I don't want Mexico to get hit by Jimena, but I wish that the rain would go to Southern California.



I so agree with you!!!!
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Quoting EarthMuffin:


In the weeks that followed Katrina, some areas saw 25% unemployment rates, not to mention the thousands of folks who lost their homes and businesses. I do not see the effects of major storms helping the locally affected economy.


Indeed ... the massive destruction of physical capital from a major hurricane is nowhere near offset by the economics of rebuilding. This is the "broken window" fallacy - if you break your largest plate glass window and have a glass company out to repair it, and 50 of your neighbors do the same, there will be a measurable positive influence on the glass company. But any gain is offset by your loss of the original window. There is a transfer of wealth for that which can be repaired, rebuilt or replaced (you lose, whoever does the repairs wins). Many things are completely destroyed and must be rebuilt from the group up with materials that are suddenly in short supply.

Hurricanes are massive destroyers of wealth and carry a very high economic cost. It's like evacuating a city, carpet bombing it, and then celebrating that the contractors are going to have some work to do. If it were a positive economic force, we should designate a few major cities (Vegas?) and do this every few years.

And then there is the cost in human lives and suffering.
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630. Relix
I put my bag of crow in the basket. Before I go to actually work here are impact predictions! =D!!

Antilles = 5% (would need a sudden turn west to affect the islands there)

Northern Antilles = 40% (it will pass close and depends on the ridge and strength)

Puerto Rico = 15% (really unlikely at the moment seeing its movement and strenght. Will leave minor rains)

RD = 10% (some models predict it going west or south after passing the islands)

Since that is within thr 3 day cone of error I'll leave it at that =). I'll be back later!
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628. eddye
94l is wrapping convection along the west side of the circulation
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Quoting Cotillion:
Oh, "apparently" we're going to get the remnants of Danny too.

Met Office has it around a 984mb low over us on Thursday (of what I figure will be it anyway). Just to fit in with the current regime of wind and rain. Yippee.
You are welcome ; )
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Anyone read this from Dr. M?

"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."
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Quoting P451:
Short Wave imagery really shows you what's going on. You can see the southerly shear ripping off the TStorm tops and you can see the lower level flow and the broad circulation west of the large area of convection. Note the end of the loop - seems the convection is being pulled north by the southerly shear. That, or, the system is pushing a bit more northerly.



Nice loop P451. A very similar thing occurred last night too where it looked like it was pulling north.
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DATE/TIME LAT LON CLASSIFICATION STORM
31/1745 UTC 15.5N 53.6W T1.5/1.5 94L
31/1145 UTC 15.2N 51.5W T1.5/1.5 94L
31/0615 UTC 14.1N 49.5W T1.0/1.5 94L
30/2345 UTC 12.4N 48.4W T1.0/1.5 94L
30/1745 UTC 11.9N 47.5W T1.5/1.5 94L
30/1145 UTC 11.9N 46.1W T1.5/1.5 94L
30/0345 UTC 10.7N 45.2W T1.0/1.0 94L
29/2345 UTC 10.3N 44.8W T1.0/1.0 94L
29/1745 UTC 10.3N 44.1W T1.0/1.0 94L
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Quoting mkmand:

lol people, including myself, were calling this one Erika 3 days ago...


lol me too...i'll get myself some crow for that..lol
Member Since: August 18, 2009 Posts: 0 Comments: 201
Just watched the jack__s on Fox13's webcast (out of tampa) say not to be worried about 94L here in TampaBay as its going to follow the same path as Bill and the other systems previous. I realize that its still a possible scenario to curve out to see, but I CANT STAND IT when meteorologists don't leave other possibilities in the forecast.
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Quoting bingcrosby:
Jimena may end up devastating the Baja region with mudslides. I wonder if Cantore is heading down to Cabo?

The WU resident Jim Cantore, CycloneOz is en route with live webcam in tow. We'll hopefully be treated to front row action from Jimena.
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Ill be back later.
Member Since: June 9, 2007 Posts: 4 Comments: 15921
Oh, "apparently" we're going to get the remnants of Danny too.

Met Office has it around a 984mb low over us on Thursday (of what I figure will be it anyway). Just to fit in with the current regime of wind and rain. Yippee.
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LOS ANGELES, California (CNN) -- A fast-moving wildfire in Southern California has nearly doubled in size and is threatening 10,000 homes on Monday, officials said.

I don't want Mexico to get hit by Jimena, but I wish that the rain would go to Southern California.
Member Since: August 11, 2008 Posts: 3 Comments: 1634
CONDITIONS ARE MARGINALLY FAVORABLE FOR THIS SYSTEM TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO..."
hmmm...marginally favorable?
This is also the 2 p.m. post, so could it have been amended?!
SPECIAL FEATURES...

A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A 1008 MB LOW IS CENTERED NEAR 15N52W. MAXIMUM VALUES OF LOW-LEVEL VORTICITY AND TOTAL PRECIPITABLE WATER ARE OBSERVED IN THE VICINITY OF THE LOW BASED ON CIMSS WAVETRAK MODEL GUIDANCE AND TPW IMAGERY. THE ASSOCIATED CONVECTION IS BEING ENHANCED AND MAINTAINED BY AN UPPER LEVEL RIDGE ALONG 17N THAT IS PROVIDING UPPER LEVEL DIVERGENCE AND A FAVORABLE ENVIRONMENT TO THE NW OF THE LOW CENTER. SCATTERED/NUMEROUS STRONG CONVECTION IS FROM 13N-17N BETWEEN 49W-53W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE ELSEWHERE FROM 13N-16N BETWEEN 54W-58W AND FROM 17N-20N BETWEEN 48W-52W. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO AS IT MOVES WNW NEAR 12 KT. INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.
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Weak system goes west, stronger goes poleward. Anything in between goes to mountains and DIES. 94L! it's over NEXT!

lol
Member Since: July 14, 2008 Posts: 1 Comments: 9630
Quoting CycloneBoy:
amateur afternoon kind of has new meaning today....I've never understood how people can make entries on this blog without first reading the update from Dr. Masters. It would almost be funny if it didn't take up so much space.



have a problem? pack up and ship out love...its the world wide web :)
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My....my--this blog changes it's feelings on a system every second.
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recon data from jimena ?? anyone getting data?
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Tropical Discussion International Desk

THE PERTURBATION ALONG 52W BECAME VERY ACTIVE DURING THE EARLY
MORNING HOURS...TAKING ADVANTAGE OF CONVECTIVE INSTABILITY TO
SUSTAIN A FLARE UP IN CONVECTIVE ACTIVITY. BUT MODERATE SHEAR
COMBINED WITH INFLOW OF DRY AIR DAMPENED FURTHER
INTENSIFICATION...WITH IR IMAGES NOW SHOWING WARMING TOPS. THE
INFLOW OF DRY AIR IS EVIDENT ON THE BLENDED TPW PRODUCT...AND BOTH
THE GFS/ECMWF SEEM TO HAVE CAPTURE THIS QUITE WELL. AS THE
PERTURBATION ENTERS THE CARIBBEAN THE MODELS AGREE ON SOME OF THE
ENERGY SHEARING NORTH OF THE ISLANDS WHILE THE REST CONTINUES TO
THE WEST ACROSS THE BASIN. THEY THEN FORECAST THE NORTHERN SEGMENT
TO EVOLVE INTO AN ILL ORGANIZED LOW BY MID CYCLE. THE SOUTHERN
SEGMENT WILL CONTINUE INTO THE CARIBBEAN AS INDICATED ABOVE. OVER
THE ISLAND CHAIN WE EXPECT ACCUMULATION OF 00-05MM/DAY AND MAXIMA
OF 10-15MM/DAY ON DAY 02...WHILE OVER THE VIRGIN ISLANDS/PUERTO
RICO IT WILL FAVOR ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
25-50MM/DAY. OVER NORTHERN GUYANA/ORINOCO DELTA REGION WE EXPECT
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 25-40MM/DAY.




EXTENDED OUTLOOK: THE CLIMATOLOGICAL MODELS CONTINUE TO DIVERGE ON
HOW LONG THE CURRENT MJO CYCLE IS GOING TO LAST. THE EMPIRICAL
WAVE PROPAGATION (EWP) CONTINUES TO FORECAST FAVORABLE CONDITIONS
TO PERSIST DURING THE NEXT FOUR TO SIX WEEKS... WHICH SEEMS
UNUSUALLY LONG. THE CLIMATE FORECAST SYSTEM PEAKS DURING THE NEXT
TEN DAYS...THEN SHOWS POSITIVE ANOMALIES/LESS FAVORABLE
ENVIRONMENT TO ESTABLISH BY MID SEPTEMBER. THE GFS IS THE ONLY ONE
THAT SHOWS A RAPID TRANSITION TO A LESS FAVORABLE ENVIRONMENT
DURING THE FIRST WEEK IN SEPTEMBER...AND THIS EXPLAINS WHY THE
MODELS HAS BEEN SOMEWHAT RELUCTANT TO DEVELOP TROPICAL CYCLONES
OVER THE BASIN.

AT UPPER LEVELS THE PATTERN REMAINS THE SAME...NUMEROUS TUTT(S)
AND TUTT LOWS DOMINATING THE FLOW TO THE NORTH OF 20N AND TO THE
EAST OF 70W. ALTHOUGH CELLS OF THE SUBTROPICAL RIDGE TRY TO
ESTABLISH...THEY ARE MIGRATORY AND OF SHORT DURATION. THIS IS
RESULTING IN A GENERALLY DISORGANIZED MEANDERING FLOW PATTERN. AT
850 HPA RIDGING LIMITS TO THE ATLANTIC AND TO THE NORTH OF
30N...WHICH FAVORS TRADES OF 10-15KT ACROSS THE TROPICAL ATLANTIC
TO THE EASTERN CARIBBEAN ISLANDS.
Member Since: September 23, 2005 Posts: 14 Comments: 11212
566. CycloneBoy 6:43 PM GMT on August 31, 2009
amateur afternoon kind of has new meaning today....I've never understood how people can make entries on this blog without first reading the update from Dr. Masters. It would almost be funny if it didn't take up so much space.


Don't be sooo quick to judge. An amateur may not completely understand. Since when did it become problematic for "anyone" to ask a question and take up space. Last I looked, this was WU space. I'll certainly keep asking, whether it offends you or not.
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Quoting SCwannabe:
We don't even have a TD and people are already making predictions??

lol people, including myself, were calling this one Erika 3 days ago...
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Quoting mikatnight:
Hey, quick poll -

Favorite Satellite Link site?

NWS-NHC or?


GHCC site. First link under imagery here.
Member Since: August 17, 2005 Posts: 26 Comments: 16859

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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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