95L growing more organized; Pakistan's Indus River flood peaking downstream

By: Dr. Jeff Masters , 2:23 PM GMT on August 21, 2010

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A tropical wave (Invest 95L) in the far eastern Atlantic about 350 miles southwest of the Cape Verdes Islands has become more organized this morning. Satellite loops show that the wave has some rotation, and heavy thunderstorm activity has increased in recent hours, after a period overnight with little change. Water vapor satellite loops show that there is some dry air to the north of 95L, but this dry air currently appears to be too far away to significantly interfere with development. The main impediment to development is the moderate 10 - 20 knots of wind shear over the system. The shear is forecast to remain in the moderate range through Monday, then decrease. This should allow 95L to develop into a tropical depression Monday or Tuesday. NHC is giving 95L a 30% chance of developing into a tropical depression by Monday morning. With 95L's recent increase in organization, these odds should probably be 50%.


Figure 1. Morning satellite image of 95L.

Forecast for 95L
A ridge of high pressure will force 95L to the west or west-northwest for the next five days, and the system should increase its forward speed from its current 5 - 10 mph to 15 - 20 mph by Monday. A series of two powerful troughs of low pressure are predicted to move off the U.S. East Coast next week and cross the Atlantic; these troughs should be able to pull 95L far enough to the northwest so that it will miss the Lesser Antilles Islands. If 95L stays weak or does not develop in the next five days, as predicted by the NOGAPS model, it has a chance of eventually threatening Bermuda. If 95L develops into a hurricane, as predicted by most of the computer models, it will probably recurve to the east of Bermuda and not threaten any land areas.

Elsewhere in the tropics
The ECMWF model is predicting formation of a tropical depression in the western Gulf of Mexico off the coast of Texas 6 - 7 days from now.

Pakistan's monsoon rains diminish; Indus River flood crest nears the coast
The flooding on Pakistan's largest river, the Indus, has slowly eased along the upper and middle stretches where most of the heavy monsoon rains fell in late July and early August. However, a pulse of flood waters from these heavy rains is headed southwards towards the coast, and flood heights have risen to near all-time record levels today at the Indus River gauge station nearest to the coast, Kotri (Figure 2.) The new flooding has forced the evacuation of an additional 150,000 people in Pakistan today. Flood heights at every monitoring station along the Indus have been the highest or almost the highest since records began in 1947. Fortunately, the monsoon has entered a weak to moderate phase, and heavy rain is not expected over the flood region over the next few days, according to the Pakistan Meteorological Department.


Figure 2. August flow rates along the Indus River, courtesy of the Pakistan Meteorology Department.

Some aid agencies helping with humanitarian crisis in Pakistan:

Doctors Without Borders

The International Red Cross

MERLIN medical relief charity

The mobile giving service mGive allows one to text the word "SWAT" to 50555. The text will result in a $10 donation to the UN Refugee Agency (UNHCR) Pakistan Flood Relief Effort.

Jeff Masters

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Quoting Vero1:
I remember~~



Is something like this possible with this system?
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As for TD6 right now...

Still some easterly shear which should slowly diminish as the LLC starts accelerating to the west, allowing the center to become vertically stacked and some intensification to begin. Looks like late tonight or tomorrow seems like a good bet for this to occur.

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1582. xcool


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Quoting smuldy:
It is either much more land based diurnal convection or it's much further south than td5 was. I'm here in miami beach and not a rain drop these last 2 days. Td5 genesis brought some wicked storms the first few days cause the bands wrapped over from its central convection off of key west. Wouldn't expect this to become much of a threat for anyone.


Yea i thought i read somewhere about this being forcasted to travel accross the GOMEX
into S Tx next week isnt supposed to do anything But with the way things been going this year Im not turning my back
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Quoting stormhank:
evening did any of you notice the hwrf 18z run? toward the end of the loop it juts back to the west??


Link please
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1578. aquak9
plenty of lightning up here too, eyewall, but barely a drizzle. Thanks for the update.
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Afternoon WRF model shows something that I had mentioned earlier today... If TD6 doesn't get far enough north it could get trapped by the rebuilding ridge and head much further west.

The probability still favors a recurve not threatening land, but this definitetly bears watching.

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evening did any of you notice the hwrf 18z run? toward the end of the loop it juts back to the west??
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Quoting fishcop:
is the XTRP model ever right??


Its always right.
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1573. Vero1
I remember~~

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1572. fishcop
I know - its a straight line
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Quoting Hurricanes101:
18Z GFS shows TD 6 much further west and a weakness that is closing, look at that ridge by the east coast?

Fish you say?

I say not so fast


I have to agree...not so fast on it being a Fish.
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Quoting Hurricanes101:
18Z GFS shows TD 6 much further west and a weakness that is closing, look at that ridge by the east coast?

Fish you say?

I say not so fast



yup this may not be a fish storm



sorry for the fishcaster
Member Since: May 21, 2006 Posts: 5091 Comments: 114719
yes it does
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1568. scott39
I think TD6 will hit somewhere West of where it is now!
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1567. smuldy
Quoting MrstormX:


You bring up a good point, Florida looks exactly like it did before TD-5 formed. Literally to a tee.
It is either much more land based diurnal convection or it's much further south than td5 was. I'm here in miami beach and not a rain drop these last 2 days. Td5 genesis brought some wicked storms the first few days cause the bands wrapped over from its central convection off of key west. Wouldn't expect this to become much of a threat for anyone.
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Quoting blsealevel:


might want to pay some attention to this to


You bring up a good point, Florida looks exactly like it did before TD-5 formed. Literally to a tee.
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18Z GFS shows TD 6 much further west and a weakness that is closing, look at that ridge by the east coast?

Fish you say?

I say not so fast
Member Since: March 10, 2010 Posts: 1 Comments: 7367
1563. scott39
TD 6 will be a monster!
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might want to pay some attention to this to
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Quoting markot:
its not moving wnw look at loops maybe slightly south of west.


So you are saying that the NHC doesn't know what they are talking about?
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1559. Vero1
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Quoting fishcop:
is the XTRP model ever right??


It is not a model.
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Quoting Tazmanian:
i think the new track at 11pm will be more too too the W


i excpect them to also.
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If there's a pissibility that the Bermuda's High Pressure can rebuild itself stronger and this TD move eventually to the west/west-northwest as H Georges did?

please someone answerme that because I live in Puerto Rico and I don't wanna get surprise by this system!!!
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Quoting aquak9:


hi eyewall. Dau is watching it at a sports bar here in Jax, wearing a dolphins jersey. Has it started yet?


No, delayed because of lightning.
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1553. aquak9
Quoting nrtiwlnvragn:


You've been wishing for rain, but did it have to be thunderstorms? Holding up my Fins game.


hi eyewall. Dau is watching it at a sports bar here in Jax, wearing a dolphins jersey. Has it started yet?
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i think the new track at 11pm will be more too too the W
Member Since: May 21, 2006 Posts: 5091 Comments: 114719
1551. bappit
Interesting how the circulation center is further south than yesterday. It is like the whole circulation from yesterday--elongated east/west--has tilted or rotated. There are two vorticity maximums, yesterday and today. I wonder if there is a Fujiwakarakahawara effect going on. (Heck, I don't know how it is spelled.)
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1550. Vero1
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 21 2010

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION SIX IS CENTERED NEAR 11.0N 32.1W AT 21/2100
UTC OR 500 NM WSW OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING
W-NW AT 08 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB.
MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT.
STRENGTHENING IS FORECAST OVER THE NEXT FEW DAYS AS THE CYCLONE
RESIDES ON THE SOUTHWESTERN PERIPHERY OF AN UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERED NEAR 21N20W WITH AN UPPER
LEVEL RIDGE AXIS EXTENDING SW FROM THE CENTER TO 15N39W. THIS IS
EXPECTED TO PROVIDE AN OVERALL FAVORABLE UPPER LEVEL DIFFLUENT
ENVIRONMENT FOR THE SYSTEM TO MAINTAIN ORGANIZED CONVECTION AND
PROVIDE FOR MINIMAL WIND SHEAR. SCATTERED MODERATE AND ISOLATED
STRONG CONVECTION COVERS A BROAD AREA FROM 06N-16N BETWEEN
25W-41W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

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Quoting aquak9:


oh my, oh my, oh my....


You've been wishing for rain, but did it have to be thunderstorms? Holding up my Fins game.
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Quoting aquak9:


oh my, oh my, oh my....


lol
Member Since: July 6, 2010 Posts: 113 Comments: 31456
Quoting fishcop:
is the XTRP model ever right??


Two parts: A) It's not a model; B) yes.
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Quoting atmoaggie:
No prob.

I neglected to also bold the last portion: When the TC size is large, the beta effect may have a major impact on the motion.

This is a larger system.


might ought to keep a eye out on this,
it just might come into play here.
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1545. aquak9
Quoting fishcop:
is the XTRP model ever right??


oh my, oh my, oh my....
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Quoting GeoffreyWPB:
This is a portion of the third Discussion on TD6, future Frances. They are already noticing a shift, some major, in some of the models. So current TD6 has two more opportunities to be compared to Frances...afterwards, the end of that story:

THE INITIAL MOTION IS NOW 275/15. THE CYCLONE IS CURRENTLY SOUTH OF
A SUBTROPICAL RIDGE. LARGE-SCALE MODELS INDICATE THAT A MID/
UPPER-LEVEL LEVEL LOW CURRENTLY SEEN IN WATER VAPOR IMAGERY JUST
SOUTHEAST OF NOVA SCOTIA WILL DIVE SOUTHEASTWARD AND WEAKEN THE
RIDGE FROM 48-96 HR AND THEN LIFT OUT TO THE NORTHEAST. IF THIS
VERIFIES...IT WOULD ALLOW THE TROPICAL DEPRESSION TO TURN
NORTHWESTWARD AFTER 24-36 HR...AND THEN POSSIBLY TURNING MORE
WESTWARD BY 120 HR AS THE RIDGE REBUILDS TO THE NORTH. THE
DYNAMICAL MODELS GENERALLY AGREE WITH THIS SCENARIO. HOWEVER...THE
GFS HAS SHIFTED ITS TRACK CONSIDERABLY TO THE SOUTH AND WEST OF THE
GFDL...UKMET...AND NOGAPS. THE OFFICIAL FORECAST TRACK ALSO SHIFTS
TO THE LEFT OF THE PREVIOUS TRACK...BUT NOT AS FAR AS THE GFS. THE
NEW TRACK IS ALONG THE WESTERN EDGE OF THE OTHER DYNAMICAL MODELS
IN BEST AGREEMENT WITH THE GFDL AND THE CONSENSUS MODELS.



that old and new mode runs have come out so we be seeing some in new with the new forcast update for TD 6

Member Since: May 21, 2006 Posts: 5091 Comments: 114719
This is a portion of the third Discussion on TD6, future Frances. They are already noticing a shift, some major, in some of the models. So current TD6 has two more opportunities to be compared to Frances...afterwards, the end of that story:

THE INITIAL MOTION IS NOW 275/15. THE CYCLONE IS CURRENTLY SOUTH OF
A SUBTROPICAL RIDGE. LARGE-SCALE MODELS INDICATE THAT A MID/
UPPER-LEVEL LEVEL LOW CURRENTLY SEEN IN WATER VAPOR IMAGERY JUST
SOUTHEAST OF NOVA SCOTIA WILL DIVE SOUTHEASTWARD AND WEAKEN THE
RIDGE FROM 48-96 HR AND THEN LIFT OUT TO THE NORTHEAST. IF THIS
VERIFIES...IT WOULD ALLOW THE TROPICAL DEPRESSION TO TURN
NORTHWESTWARD AFTER 24-36 HR...AND THEN POSSIBLY TURNING MORE
WESTWARD BY 120 HR AS THE RIDGE REBUILDS TO THE NORTH. THE
DYNAMICAL MODELS GENERALLY AGREE WITH THIS SCENARIO. HOWEVER...THE
GFS HAS SHIFTED ITS TRACK CONSIDERABLY TO THE SOUTH AND WEST OF THE
GFDL...UKMET...AND NOGAPS. THE OFFICIAL FORECAST TRACK ALSO SHIFTS
TO THE LEFT OF THE PREVIOUS TRACK...BUT NOT AS FAR AS THE GFS. THE
NEW TRACK IS ALONG THE WESTERN EDGE OF THE OTHER DYNAMICAL MODELS
IN BEST AGREEMENT WITH THE GFDL AND THE CONSENSUS MODELS.
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1541. xcool
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1540. fishcop
is the XTRP model ever right??
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00
WTPZ34 KNHC 212349
TCPEP4
BULLETIN
TROPICAL DEPRESSION NINE-E INTERMEDIATE ADVISORY NUMBER 1A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092010
500 PM PDT SAT AUG 21 2010

...DEPRESSION GETTING BETTER ORGANIZED...


SUMMARY OF 500 PM PDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...13.7N 93.5W
ABOUT 205 MI...330 KM SE OF SALINA CRUZ MEXICO
ABOUT 280 MI...450 KM ESE OF PUERTO ESCONDIDO MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/HR
PRESENT MOVEMENT...WSW OR 255 DEGREES AT 2 MPH...4 KM/HR
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF MEXICO HAS ISSUED A TROPICAL STORM WATCH FOR THE
SOUTHERN COAST OF MEXICO FROM SALINA CRUZ WESTWARD TO LAGUNAS DE
CHACAHUA.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* THE COAST OF MEXICO FROM SALINA CRUZ WESTWARD TO LAGUNAS DE
CHACAHUA

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM PDT...0000 UTC...THE CENTER OF TROPICAL DEPRESSION NINE-E
WAS LOCATED NEAR LATITUDE 13.7 NORTH...LONGITUDE 93.5 WEST. THE
DEPRESSION IS MOVING SLOWLY TOWARD THE WEST-SOUTHWEST NEAR 2 MPH...
4 KM/HR. A SLOW WESTWARD MOTION IS EXPECTED FOR THE NEXT COUPLE OF
DAYS...AND ON THE FORECAST TRACK THE DEPRESSION WILL BE MOVING
PARALLEL TO THE COAST OF SOUTHERN MEXICO.

MAXIMUM SUSTAINED WINDS ARE NOW NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS...
AND THE DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT OR SUNDAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH
AREA BY LATE SUNDAY OR MONDAY.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...800 PM PDT.

$$
FORECASTER BEVEN
Member Since: May 21, 2006 Posts: 5091 Comments: 114719
Since steering is being brought up, I thought I'd post this little bit of wisdom from a 2003 article by Steve Lyons:

  • "Steering currents are defined as the vertically averaged (and pressure weighted) wind that pushes a tropical cyclone (tropical depression, tropical storm or hurricane) along. It is very difficult if not impossible to determine the exact contributions a specific layer of winds has for that motion, but we can estimate "steering" IF we know what the winds are surrounding a tropical cyclone at some levels in the atmosphere.

  • "We routinely know surrounding winds in the low levels (about 1,500 to 2,000 feet) and near the surface, and in the upper levels about 30,000-45,000 feet. Buoys, ships, satellites and occasionally aircraft provide these observations. Obviously, knowing how "steering" will change in time is critically important to forecasting the track of a tropical cyclone.

  • "There are occasions when low-level and upper-level winds are very different in direction and speed (a "shearing/sheared" environment). It turns out weak tropical cyclones routinely are steered by lower-level winds than are hurricanes and strong hurricanes which are typically deep and hence steered by deep layer averaged winds. Upper level wind steering (from about 25,000-50,000 feet) becomes very important in strong hurricanes.

  • "In "steering" situations where wind changes speed and direction with height (sheared environment), it becomes impossible to forecast "steering" change without forecasting tropical cyclone depth/strength/intensity change!

  • "There are many situations, then, where a tropical cyclone will move in one direction if it is weak and remains weak, though it could move in a different direction--with possibly a different speed--if it were stronger and deeper.


"Therefore any statement about track MUST be tied to intensity and intensity change in sheared environments. A few classic recent examples of sheared environments are Hurricane Lenny and Tropical Storm Allison. There are others: 2003's Mindy and Kate come to mind as a few examples...look at their track changes (right or left turns) relative to how their intensity changed (weakening or strengthening)

"Therefore it is my forecast method to always realize that, in sheared environments one cannot forecast track without forecasting intensity."
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1537. bappit
Here's the CIMSS MIMIC.

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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.