Disturbance 90L brings heavy rain to Puerto Rico; major pollution in California

By: Dr. Jeff Masters , 2:05 PM GMT on October 25, 2007

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A surface low pressure system (90L) just east of Puerto Rico is moving to the west at 5-10 mph. This low is entangled with an upper-level low pressure system that is bringing about 30 knots of wind shear, so no development is likely today. Long range radar out of Puerto Rico shows bands of heavy rain hitting the islands and surrounding waters, but these bands are not well-organized. Satellite loops show most of the heavy thunderstorm activity is to the northeast of the low's center of circulation, and high wind shear is keeping this thunderstorm activity disorganized. This morning's QuikSCAT pass missed 90L.


Figure 1. Latest satellite image of 90L. Image credit: NOAA.

The surface low is expected to separate from the upper level low tonight and move west-southwest or southwest across Puerto Rico, bringing the threat of heavy rain and flooding to the island. Recent rains have left large areas of interior and western Puerto Rico at or near saturation, and mudslides were reported yesterday in Utuado. Flooding problems and mudslides are likely across Puerto Rico and the Virgin Islands Friday and Saturday, and this is shaping up to be the most significant rain event of the fall wet season thus far for Puerto Rico.

On Friday and Saturday, 90L will move westward along or just south of Hispaniola, bringing heavy rain, flash flooding, and possible mudslides to that island. The ECMWF and NOGAPS models predict that wind shear will drop to 10-20 knots by Friday night, which may allow some slow development of the disturbance if the center remains over water. The GFS model keeps wind shear 20-30 knots through the period, and does not develop 90L. By Saturday, the storm will near Jamaica, and the ECMWF and NOGAPS models predict a tropical depression will form by Sunday. Steering currents grow weak on Monday, and the storm could stall out for many days in the Western Caribbean, in an area of low wind shear and high heat content waters. This may allow the system to intensify into a hurricane. The eventual fate of this system is highly uncertain, since steering currents will be so weak. Those of you planning to travel to the Western Caribbean next week should keep a close watch on this system. NHC has not scheduled any flights into 90L yet.

It is possible that wind shear and passage over the islands will sufficiently disrupt this disturbance so that it does not develop. However, surface pressures have fallen 2-3 mb over most of the Western Caribbean the past two days, and there is a good chance that a new area of disturbed weather will develop. One such disturbance formed yesterday south of Haiti, but has since dissipated. Unsettled rainy weather can be expected to affect much of the Western Caribbean over the coming week.

California's fires
Surface maps show that the high pressure system that brought this week's strong Santa Ana winds to Southern California has now moved east and is over Colorado. The Santa Ana winds have ceased over California, and only light winds with afternoon sea breezes are expected today and for the next seven days. No precipitation is expected for at least the next week. The combination of light winds and lack of rain will make for a serious air pollution hazard in the region, until the fires are extinguished. There is still plenty of smoke over the ocean waters (Figure 2) that will get blown back over land by afternoon sea breezes over the next week.


Figure 2. Visible satellite image at 1:45 pm PDT Wednesday October 24, showing a huge area of smoke over the Pacific Ocean. Some of this smoke is being blown northward (top of image), and is expected to move over northern California and northern Nevada over next two days. This northward-moving smoke is being lifted by the flow around an approaching low pressure system, and is not expected to affect air quality near the surface. However, the smoke just offshore San Diego and Los Angeles will remain near the surface, and some of it will be pushed back over land by afternoon sea breezes. Image credit: NASA.

Jeff Masters

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October moon (mauidave)
with all the smoke in the air the moon last night was looking like holloween.
October moon

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591. kmanislander
2:24 AM GMT on October 26, 2007
Gnite Drak

I suspect something will be there tomorrow.
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590. MrSea
2:21 AM GMT on October 26, 2007
Thank you Justcoasting too its good to know that there are some compassionate people on tonight
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588. TheCaneWhisperer
2:19 AM GMT on October 26, 2007
TD Folks!
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587. cattlebaroness
2:23 AM GMT on October 26, 2007
evenin yall.
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586. Drakoen
2:21 AM GMT on October 26, 2007
Anways, i'm out for the night. Hopefully things will be cleared up tomorrow if there is still something there.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
585. MrSea
2:19 AM GMT on October 26, 2007
THANK YOU TROPICSDUDE you're my new best friend!! Good night to all.
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584. JUSTCOASTING
2:20 AM GMT on October 26, 2007
mrsea with that gpa of yours and tops in your class a have a daughter i would like to introduce you to LOL
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583. JLPR
2:19 AM GMT on October 26, 2007


OMG i think i will rent a boat
look the heavy convection is moving directly to m e
Member Since: September 4, 2007 Posts: 36 Comments: 5223
582. Patrap
9:20 PM CDT on October 25, 2007
Im Okay. Thanx,..
Relaxing and watching that Lil Invest. Late October and Early November still can bite one good. Will be one to watch maybe.
Juan in 85 was a slow beginner.But a strong finisher too.

Wiki on Juan 1985 Link

Member Since: July 3, 2005 Posts: 428 Comments: 129844
580. MrSea
2:15 AM GMT on October 26, 2007
Now that thats oover with, I will have to admit that there is a nice flareup of convection, but due to a hostile environment (much like this chat tonight) I do not think it will develop. I will go now. Hopefully none of this will be mentioned tomorrow I liked it for the past 3 months when it was nice weather talk.
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579. Weather456
10:12 PM AST on October 25, 2007
560. InTheCone 10:07 PM AST on October 25, 2007 Hide this comment.
Hmm 456 -

0.2 not too bad - mountains could make a problem?? Hopefully not!


That image is an instant measure so 0.2 inches an hr was at one moment in time. Alot more can fall and accumulate over time since those are only satellite estimates and not actual obs.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
578. Drakoen
2:16 AM GMT on October 26, 2007
actually i think the Cimss might be right on the money. Zoom in on the 850mb the strongest region of vorticity maximum in the deep red is just ENE to NE of Puerto Rico. Matches with the night time visible imagery.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
577. InTheCone
10:16 PM EDT on October 25, 2007
Thanks Pat -

Glad you're back!!
Member Since: September 1, 2007 Posts: 0 Comments: 1990
576. JUSTCOASTING
2:15 AM GMT on October 26, 2007
thanks Pat how have you been feeling ?
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575. kmanislander
2:13 AM GMT on October 26, 2007
Hey Pat

My first chance to welcome you back

What do you make of the 850 mb placement of vorticity given the surface obs ?
One would not expect the 850 mb center to be N of PR with 90L would you ?
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573. MrSea
2:10 AM GMT on October 26, 2007
So now that you know about me, please call me immature and tell me to leave again. Whoever starts to bicker with someone else on this site is the immature one. Administration, if you are reading, please note that I am not the bickerer but the bickeree just trying to defend himself from a guy who apparently cant pick on someone his own size. Please dont ban me!!
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572. JUSTCOASTING
2:08 AM GMT on October 26, 2007
MRSEA LET IT GO ,you are entiteled to your opion ,but some times the more expericed here take a off the cuff prediction kinda hard ,back it up with your reasons they will respect you a lot more
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571. zoomiami
2:12 AM GMT on October 26, 2007
JFV - don't feed the trolls or you will get banned too.
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570. Drakoen
2:10 AM GMT on October 26, 2007
yea i noticed that Kman. With all this shear is hard to depict a decent well defined circulation center.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
568. kmanislander
2:11 AM GMT on October 26, 2007
Not quite sure what to make of this given the IR image

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567. Patrap
9:09 PM CDT on October 25, 2007
GOES-12 Channel 3 (WV) False Color Image
Atlantic Basin 1:45 UTC

Link



Member Since: July 3, 2005 Posts: 428 Comments: 129844
566. Weather456
10:10 PM AST on October 25, 2007
I'm thinking this report needs quality fix

Member Since: July 24, 2005 Posts: 407 Comments: 19076
565. kmanislander
2:08 AM GMT on October 26, 2007
Drak

I know the feeling LOL

But here is another curve ball for you ( and for me )

The 850 mb vorticity graphic shows the strongest turning to the N of PR !!

Go figure
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564. InTheCone
10:08 PM EDT on October 25, 2007
Yeah Drak. - Nice to know you're human like the rest of us - lol!!! You're work is GREAT!
Thanx!
Member Since: September 1, 2007 Posts: 0 Comments: 1990
563. zoomiami
2:07 AM GMT on October 26, 2007
Hi Tigger - not much - been in and out of the rain tonight. We had beautiful weather this morning - all the way down to 70! lol
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561. Drakoen
2:06 AM GMT on October 26, 2007
i meant east lol. I'm staring at imagery and its late here. I don't function well. Drak is subject to errors LMAO.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
560. InTheCone
10:04 PM EDT on October 25, 2007
Hmm 456 -

0.2 not too bad - mountains could make a problem?? Hopefully not!
Member Since: September 1, 2007 Posts: 0 Comments: 1990
559. raggpr
2:00 AM GMT on October 26, 2007
Im looking at the news right know and they are advertising know that it can be a dangerous event. I think most people should know right know. but this event have already been a deadly one because two men died this afternoon after a car accident caused by a mudslide.
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558. kmanislander
2:05 AM GMT on October 26, 2007
Drak

I would have expected the mid level center to be off to the NE of the surface low given the extent to which the system is sheared
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556. tiggeriffic
2:04 AM GMT on October 26, 2007
hey zoo, what's up?
Member Since: September 16, 2007 Posts: 0 Comments: 3666
555. Drakoen
2:02 AM GMT on October 26, 2007
Shortwave night visible imagery shows a definite WSW motion of the system. The system appears to have a titled circulation with the mid level center slightly to the west of the low level center.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
554. zoomiami
2:02 AM GMT on October 26, 2007
Seems strange to be looking at tropical anything a few days before Halloween.

Especially since the whole month was so quiet.

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553. kmanislander
2:02 AM GMT on October 26, 2007
Well quikscat has missed 90L as expected but there is a well defined surface trough of low pressure stretching all the way from the NW Caribbean to just N of Panama.

This will keep pressures low in the area for now
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552. Weather456
10:03 PM AST on October 25, 2007
I don't think PR will get much wind, but the potential for tremendous rainfall is looking, well, BIG. You agree????

Yeah..not really a wind event in the near term good rainfall

Satellite Estimated Rainfall Rate



Member Since: July 24, 2005 Posts: 407 Comments: 19076
551. Weather456
9:59 PM AST on October 25, 2007
90L
25 Knots
1005 mb

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550. Drakoen
1:59 AM GMT on October 26, 2007
Long range radar. The low may skirt or slip south Puerto Rico.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
549. InTheCone
9:54 PM EDT on October 25, 2007
Thanks 456 -

I worry about the people who don't have access to info. such as we have here. Especially when it could be a really big event.

I don't think PR will get much wind, but the potential for tremendous rainfall is looking, well, BIG. You agree????
Member Since: September 1, 2007 Posts: 0 Comments: 1990
548. cchsweatherman
1:42 AM GMT on October 26, 2007
WOW! Invest 90L starting to look more impressive with each passing image. Convection starting to consolidate around the center and has begun to move WSW. TD 16 tomorrow in my opinion.

Referring to the questions of the monster ULL, the ULL is helping ventilate the system as the wind shear is not associated with the ULL. But, I agree it needs to move away from it since it will likely start to come closer.

This will be an interesting system to watch. Maybe the last for 2007.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
547. raggpr
1:55 AM GMT on October 26, 2007
kmanislander. Ok i understand and yes pr comes from Puerto Rico
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545. kmanislander
1:53 AM GMT on October 26, 2007
raggpr

I assume the " pr" in your handle means Puerto Rico. If so you have several hours before the worst of the weather ( which is on the E side of 90L ) impacts you. However, the rain will come before the wind as is usually the case with a sheared system
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544. weatherblog
1:53 AM GMT on October 26, 2007
My latest blog entry about 90L and...

Everything I have to say about it is there...
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543. raggpr
1:49 AM GMT on October 26, 2007
kmanislander you are right, i might report tomorrow how wind was here. but still right know is a little breaze coming from the Northeast higher than normal
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542. kmanislander
1:51 AM GMT on October 26, 2007
A reminder to those of you who have started to bicker

Admin will not hesitate to issue a 24 hr ban to discourage anti social behaviour

Lighten up guys
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541. Weather456
9:51 PM AST on October 25, 2007
Do you think they should be concerned about flooding/mudslides??

Yes...100% concern. Of all the flooding events that occur in my island almost all occurred in October and November which are the two wettest months and the culprits are tropical waves and tropical disturbances like 90L. Flooding will most likely occur as 90L moves west, we had a very heavy downpour just ended minutes ago.

__________________________________________

I graphic i made:

Member Since: July 24, 2005 Posts: 407 Comments: 19076

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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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