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Major flooding in Austin from Hermine

By: Dr. Jeff Masters, 1:24 PM GMT on September 08, 2010

Major flooding is occurring in the Austin, Texas region after Tropical Storm Hermine dumped an estimated 10 - 15 inches of rain over the past 24 hours. The flash flood warning for Austin from the National Weather Service at 4am this morning summarized the danger:

"Areas along I-35 and the Balcones Escarpment in and around the Austin Metro area will continue to experience a very dangerous flash flood event over the next few hours. Numerous evacuations and high water rescues have already been reported by the media and law enforcement personnel."

As wunderground's Dr. Rob Carver reports in his blog this morning, hardest hit was the area ten miles north-northwest of Austin, where an NWS cooperative station measured 10.11" of rain yesterday. The rains have swollen the South Fork of the San Gabriel River at Georgetown, Texas to 50-year flood heights.

Hermine has dissipated, but its heavy rains live on, and are now affecting the Dallas/Fort Worth region, where 1 - 3 inch rainfall amounts have been common. Hermine's rains are still lingering over the hard-hit Austin area, but should remain under one inch for the remainder of the morning. However, this afternoon, additional significant rains are possible near Austin as the sun's heat drives thunderstorm development in the very moist airmass over Central Texas.


Figure 1. Radar estimated rainfall for the Austin, Texas area shows that over fifteen inches of rain may have fallen in the region ten miles north-northwest of the city.

Gaston's remains no longer a threat
Dry air has significantly disrupted the remains of Tropical Storm Gaston, which are now over the Dominican Republic. NHC is now giving Gaston a 0% chance of developing, and no models are calling for development. It appears Gaston is finally dead.

Invest 91 off the coast of Africa
A large, well-organized tropical wave (91L) is just off the coast of Africa, near the Cape Verdes Islands, and is bringing sustained winds of 30 mph this morning to Praia in the southeast Cape Verdes. 91L is under a high 20 - 30 knots of wind shear, but this shear will decline to the moderate range, 10 - 20 knots, by Thursday. Water temperatures are warm, 28°C, and 91L has plenty of spin. The Saharan Air Layer (SAL) is well north of 91L, and should not be an impediment to development over the next few days. The models are pretty unanimous about developing 91L into Tropical Storm Igor sometime in the next 1 - 3 days. NHC is giving 91L a 70% chance of developing into a tropical depression by Friday. The GFDL model predicts 91L will be Hurricane Igor five days from now. The storm will track west to west-northwest over the next week, with long range forecasts from the GFS and ECMWF models putting 91L several hundred miles northeast of the Lesser Antilles Islands 7 - 10 days from now. History shows that about 20% of all tropical cyclones that have existed at 91L's current position have gone on to hit the U.S. East Coast; these odds are 10% for the U.S. Gulf Coast, 5% for Puerto Rico, and 10% for Canada. The forecast steering pattern for the coming two weeks from the GFS model shows a continuation of the pattern we've seen all hurricane season, with regular strong troughs of low pressure moving off the U.S. East Coast. This pattern favors a continuation of the sort of tracks we saw for Danielle, Earl, and Fiona, with threats to the northern Lesser Antilles, Bermuda, the U.S. East Coast, and Canada.


Figure 2. Morning satellite image of Invest 91L (Igor?)

Elsewhere in the tropics
The GFS and ECMWF models are predicting the development of a new tropical wave off the coast of Africa 5 - 6 days from now.

Death toll in Guatemala from Tropical Depression 11E rises to 54
In the Eastern Pacific, heavy rains from Tropical Depression 11E have killed at least 54 people in Guatemala, with many more missing and feared dead. The heavy rains triggered nearly 200 landslides and collapses, causing damages near $500 million. Fifteen landslides hit portions of the Inter-American Highway, burying a number of vehicles and a bus. Tropical Depression 11E formed on September 3, moved over Mexico and Guatemala, and dissipated by the next day. Remnants from the depression may have played a role in the formation of Tropical Storm Hermine in the Gulf of Mexico on September 5.

Guatemala is still recovering from the impacts of Tropical Storm Agatha, which killed 287 people in the country and did over $1 billion in damage in May. This September's heavy rains in Guatemala come on the heels of the rainiest August in Guatemala's history, according to preliminary data from the National Institute of Seismology, Volcanology, Meteorology and Hydrology (INSIVUMEH). Rain was more than 100% above average in many parts of the country, and more than 200% above average in some regions. September and October are historically Guatemala's rainiest months, and any additional tropical cyclones which affect the country can be expected to cause more serious flooding.


Figure 3. Satellite image from Friday, September 3, 2010, showing Tropical Depression 11E over Mexico and Guatemala. Image credit: NASA.

Next post
I'll have an update Thursday morning.

Jeff Masters

Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Quoting Cotillion:


Yes.


where
Pottery... just because I tracked it.. does not mean its my fault....



AOI

AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
3004. scott39
Quoting Cotillion:


Yes.
Wrong!!
Quoting cat5hurricane:
Cat 5 is very unlikely, but a strong cat 3 or cat 4 could be in the cards.


Really ?. You have obviously not seen how many storms have undergone RI in the NW Caribbean.
I think the CV season will soon end 10 days or so but thats when the western Caribbean & GOM will heat up. JMO
Quoting RecordSeason:
2976:

So, you're saying it's going to be Wilma 2.0, at least in terms of track?


Conditions aloft look very favorable and that combined with extreme ocean heat content should bode well for this disturbance. Ridge will force this baby westward.
3008. NASA101
Typical...., people on here are already talking about Cat5 from 92L - it's not even a TD yet...Wait and see! SHIPS intensity is over the top it seems to me...!!
Quoting StormW:


Morning kman!


Hi Storm. 92L is sitting just outside the Eastern Caribbean where it can avoid the John Hope Rule ! LOL

It is also far enough N from the SA continent to avoid ingesting dry continental air. The signs are not good.
With the exeception of a TUTT cell currently centered over the Yucatan Channel, there will be no ULL interference in the short term for 92L thus there does not appear to be any major impediment for continued development over the next few days.
3011. scott39
Quoting gulfbreeze:
I think the CV season will soon end 10 days or so but thats when the western Caribbean & GOM will heat up. JMO
It aint waitin on the CV season to end its heating up now!
Quoting pipelines:
wow, I've never seen so much wish casting over an ITCZ embedded low before. It's almost like a lot of you want this to turn into a destructive hurricane.

A lot of these low pressure systems do not develop and even the hottest water temps in the world won't make it that much more likely.

I'll be interested once 92L breaks off from the ITCZ and develops a closed low level circulation.
That's the vibe I seem to be getting...

And good point regarding the water temps.
Quoting scott39:
Wrong!!


No, it is correct.

It hit the British Virgin Islands as a Category Three Major Hurricane.
i would like everyone to take a moment of silence for my pet that just died

rip sir reginald poopums iii
3016. NASA101
Quoting NASA101:
Typical...., people on here are already talking about Cat5 from 92L - it's not even a TD yet...Wait and see! SHIPS intensity is over the top it seems to me...!!


However saying all that, 06Z GFS does have 92L as a Cat 2 hurricane off the eastern coast of Yucatan!!
Ridge protects the Gulf and the trof catches the long CV trackers.
Quoting Cotillion:


No, it is correct.

It hit the British Virgin Islands as a Category Three Major Hurricane.


do little islands really count as landfall though
3020. shawn26
Anyone think 92L could be a problem for Florida?
PR NWS :


FEATURE OF INTEREST IS NOW A WEAK AREA OF LOW PRES EAST OF
TRINIDAD WHICH MODELS HAVE INDICATED SOME SORT OF WEAK TC
DEVELOPMENT OVR THE PAST COUPLE OF DAYS. THE RELIABLE MODELS ECMWF
AND GFS KEEP THIS SYSTEM JUST SOUTH OF THE AREA WITH THE ECMWF A
BIT FURTHER NORTH THAN THE GFS. PRIMARY THREAT FROM THIS SYSTEM
LOOKS TO BE HEAVY RAINFALL DUE TO ITS EXPECTED SLOW MOVEMENT.
TIMING UNCERTAINTIES NOTED BETWEEN THE MODELS WITH THE ECWMF
FASTER THAN THE GFS. HAVE SIDED WITH THE ECWMF BRINGING SOME GOOD
RAINS SAT AND SAT NIGHT AS THIS MODEL HAS OUTPERFORMED THE REST OF
THE OTHER GLOBAL MODELS THIS HURRICANE SEASON. MODELS HAVE ALSO
LAG BEHIND WITH OTHER TROPICAL CYCLONES AS WAS THE CASE WITH FAST
MOVING STORMS LIKE GASTON...COLIN AND FIONA. PEOPLE ARE ENCOURAGED
TO MONITOR LATEST FORECASTS OVR THE NEXT 48 HRS AS WE ARE VERY NEAR
THE CLIMATOLOGICAL PEAK OF THE HURRICANE SEASON AND TC DEVELOPMENT
CAN TAKE PLACE ABOUT ANYWHERE AND VERY QUICKLY. OF NOTE IS THE
UNRELIABLE MODELS CANADIAN GLOBAL AND NAM INDICATE THIS SYSTEM
ACTUALLY MOVING ACROSS PR ON SUN. GIVEN THAT THE H25 HIGH IS
EXPECTED TO WEAKEN AND UPPER LVL TROUGH XPCD TO CONTINUE TO DIG
SOUTH IS NOT OUT THE REALM OF POSSIBILITIES THAT THIS SYSTEM COULD
END UP FURTHER NORTH THAT WHAT IS SUGGESTED BY THE GFS/ECMWF
MODELS.
3022. FLdewey
It's all fun and games until someone sees an eye.
Quoting NASA101:


However saying all that, 06Z GFS does have 92L as a Cat 2 hurricane off the eastern coast of Yucatan!!
MUCH more likely to see a cat 2 (or even low-end cat 3) than a cat 5....if this system even materializes in the first place!! We'll see.
Quoting shawn26:
Anyone think 92L could be a problem for Florida?


No this system as of now should stay to our south.
3025. KBH
Quoting StormW:


It will...guess this pretty much sums up the surface low:

THE ITCZ AXIS IS ANALYZED ALONG 10N26W 9N40W 10N52W 12N57W THEN
RESUMES IN THE S CARIBBEAN NEAR 12N65W 12N73W 10N78W ACROSS
COSTA RICA INTO THE E PACIFIC REGION NEAR 10N84W. A 1009 MB LOW
IS EMBEDDED WITHIN THE ITCZ
NEAR 12N60W WITH A SURFACE TROUGH
ALONG 60W BETWEEN 10N-15N. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 5N-10N BETWEEN 35W-46W...
S OF 13N TO INLAND OVER SOUTH AMERICA BETWEEN 51W-55W... AND S
OF 13N TO THE COAST OF SOUTH AMERICA BETWEEN 56W-64W INCLUDING
THE WINDWARD ISLANDS/TRINIDADA AND TOBAGO.


Right now in Barbados there is lots of heavy heavy rains, very litle wind, so circulation from this system seems low,
3027. scott39
Quoting Cotillion:


No, it is correct.

It hit the British Virgin Islands as a Category Three Major Hurricane.
No it didnt! It went by it. They never received any Cat 3 winds or higher!Look, I would never take away from any land mass being affected by any TC. I simply stated that there could be the potiential From 92L, to be the first MAJOR hurricane to hit land for this season.
Quoting cat5hurricane:
MUCH more likely to see a cat 2 (or even low-end cat 3) than a cat 5....if this system even materializes in the first place!! We'll see.


That statement is true for every tropical system, not just this one.
Quoting pipelines:
wow, I've never seen so much wish casting over an ITCZ embedded low before. It's almost like a lot of you want this to turn into a destructive hurricane.

A lot of these low pressure systems do not develop and even the hottest water temps in the world won't make it that much more likely.

I'll be interested once 92L breaks off from the ITCZ and develops a closed low level circulation.


it has to move N to detach
At this point no, but you can never be too sure. It definitely merits further attention. It'll have to be watched closely.
Quoting FloridaHeat:


do little islands really count as landfall though


What? There are people and property on these islands, right? Of course it counts.
Quoting StormW:


Or until the eye sees you, as it passes overhead!
lol. good one
3018.

Do people live on them?

Then yes.
And speaking of heavy convection, 92L is firing some in the area of the disturbance which is headed towards the Grenadines passing between Grenada and St. Vincent.
3035. angiest
Quoting kmanislander:


Really ?. You have obviously not seen how many storms have undergone RI in the NW Caribbean.


Let's see. Not necessarily cat 5s, but these storms exploded in the northern and NW Caribbean: Gustav (2008), maybe Dennis (2005), maybe Emily (2005), Ivan (2004, re-intensified to cat 5), Isidore (2002), Camille (1969, intensification cut-off by landfall in Cuba).
Quoting rmbjoe1954:


What? There are people and property on these islands, right? Of course it counts.


ok i wasnt sure but that makes sense
Quoting scott39:
No it didnt! It went by it. They never received any Cat 3 winds or higher!Look, I would never take away from any land mass being affected by any TC. I simply stated that there could be the potiential From 92L, to be the first MAJOR hurricane to hit land for this season.


It's still a major. Whether it had the winds or not, I do not know, but the northern most island was in the eyewall when it was a Category 3, intensifying into a Category 4. The waves were bad enough.
3039. WxLogic
Quoting hurricane23:
Ridge protects the Gulf and the trof catches the long CV trackers.


Indeed... being noticing a deep Ridge getting established across the C GOM. In my current thinking if 92L was to group deep enough and the E CONUS TROF was to delay on lifting out or dig S far enough it could bring the possibility of a farther N track like NOGAPS, CMC, NAM are showing. Else, if the ridge builds further enough E to the extreme W ATL then we'll definitely see 92L threatening C America.

Like always is a wait and see deal until 92L organizes enough and to see how steering patterns start to shape up over the weekend.
Quoting FloridaHeat:


do little islands really count as landfall though


Yes they do. Millions of people live on "little islands" and are affected badly and sometimes are killed when hurricanes make landfall there.
Quoting kmanislander:


That statement is true for every tropical system, not just this one.
Yep. I'm an equal opportunity tropical system forecaster.
3042. FLdewey
Quoting StormW:


Or until the eye sees you, as it passes overhead!

LOL... that'll ruin your day.
Radar 92L

Tobago Crown Point, TD (Airport)
Updated: 32 min 55 sec ago
26 °C
Overcast
Humidity: 83%
Dew Point: 23 °C
Wind: 24 km/h / 6.7 m/s from the West
Pressure: 1013 hPa (Rising)
Visibility: 9.0 kilometers
UV: 3 out of 16
Clouds: Few 213 m


Storm,

good morning. couple of quick questions for you. First, with the forward speed of Igor slowing and now moving north, when the high builds back in in a few days, do you see a potential pick up in forward speed enough where it could miss the strong trough at 60W?

Second, when wunderground posts Invest systems, why does it now show models like the GFS, EMCWF, UKMET, NOGAPS, etc..? thanks
3046. A4Guy
Quoting FLdewey:
It's all fun and games until someone sees an eye.


Best post I have read in a while. Thank you!
Can anyone enlighten me as to what the John Hope Rule is? I tried googling it, but was directed to this blog, where it is mentioned but never explained.
Thanks!
Back later
Wow could 92 do a Charley track?? I see a front coming across the country
Quoting Amanda44:
Can anyone enlighten me as to what the John Hope Rule is? I tried googling it, but was directed to this blog, where it is mentioned but never explained.
Thanks!


Simply put, John Hope often stated that if a tropical system did not develop before reaching the Eastern Caribbean it would most likely not do so until reaching the Western Caribbean.
Well, we're talking about 'hits', not landfall. Landfall is slightly different (when the centre of the centre crosses land).

Many islands do not get technical landfall, but 'direct hits'. In other words, it's close enough and the people on those islands are getting basically the same conditions anyway.
3047:

The John Hope Rule is something that John Hope used to say a lot on the Weather Channel.

"If it hasn't developed by the time it reaches the eastern caribbean it probably won't develop until it reaches the western caribbean."

It's a bit "fuzzy" for a rule, but there have not been very many historical exceptions.
Quoting Cotillion:
Well, we're talking about 'hits', not landfall. Landfall is slightly different (when the centre of the centre crosses land).

Many islands do not get technical landfall, but 'direct hits'. In other words, it's close enough and the people on those islands are getting basically the same conditions anyway.


can you elaborate this is what i was trying to ask earlier when i asked it islands counted as landfall
Quoting FloridaHeat:
i just had a burial at toilet for my poor fishy

rip sir reginald poopums iii


I sorry for your loss, RIP fishy.
Thank you kmanislander!
Quoting Cotillion:
Well, we're talking about 'hits', not landfall. Landfall is slightly different (when the centre of the centre crosses landfall).

Many islands do not get technical landfall, but 'direct hits'. In other words, it's close enough and the people on those islands are getting basically the same conditions anyway.


The eye of Ivan passed 25 miles South of us but the hurricane did US$3 billion dollars worth of damage here including submerging about 70% of Grand Cayman, destroyed about 80% of all motor vehicles on the island and damaged or destroyed close to 80% of all buildings as well.

The technical definition of landfall may need revisiting.
Quoting rmbjoe1954:


I sorry for your loss, RIP fishy.


he was 6 years old and i think that is old for a fish
Quoting cat5hurricane:
MUCH more likely to see a cat 2 (or even low-end cat 3) than a cat 5....if this system even materializes in the first place!! We'll see.
as long as it dont come to S.Texas Im starting to mildew
Out now
If 92L really gets going and sneaks past Hispaniola-- this has a great chance to be a big cyclone. The waters are so ridiculously warm and warm at depth-- with the right vortex, rapid intensification is so much more likely than normal.
3066. bayeloi
Quoting FLdewey:
It's all fun and games until someone sees an eye.


That's hilarious!!
Good Morning Senior Chief!!

Semper Paratus

Dave
3068. Patrap
Dr. Masters has Posted a NEW Entry Sports Fans..

ya gonna wear out dem F 5 key's..

New Blog.
Quoting ackee:
How strong will 92L get

A strong TS
B CAT ONE HURRICAE
C major hurricane
D TD


My vote for C in about 4-5 days.....
The technical definition of landfall may need revisiting.

===

While we were on the subject of the John Hope rule...

Back when John Hope was still alive and on the weather channel, they used to actually draw the windfield radius on the screen and show people ahead of time what the conditions the could expect even if the eye missed them.

I do not believe there was enough of that done in the 2004 and 2005 hurricane seasons, especially not by TWC and the local mets.

There were too many people who were like, "Oh well, the eye is going to miss me 50 or 100 miles east." They did not seem to realize that storms like Ivan, Katrina, or Ike are just in a different category and you have to consider the whole thing a serious threat, not just the eye wall or the landfall location.
New blog...
Quoting kmanislander:


If it develops into a storm the likelihood of attaining Cat 5 status in the Caribbean is very high, especially if it moves to the WNW. Anyway, let's see what it does in the next 24 hours first. This year has seen several systems fail to achieve their true potential, let's hope 92L is also one of them, although I have a bad feeling about this one.



I listen when Kman gets bad feelings. The force is strong in this one.
3076. Jax82
good morning CONUS
3052.

Since I apparently can't quote today...

WHO DAT DEY SAY GONNA BEAT DEM SAINTS?
Quoting angiest:


Everyone in the Caribbean and on the Gulf Coast needs to watch it closely.


isnt there a deal where a cat five cant stay a cat five for longer than so many days? Excuse me if its an ignorant questiojn... but that could save us.... it getting big so early off the coast of africa?
Definitions from the NHC's glossary - some interesting reading:

Direct Hit:
A close approach of a tropical cyclone to a particular location. For locations on the left-hand side of a tropical cyclone's track (looking in the direction of motion), a direct hit occurs when the cyclone passes to within a distance equal to the cyclone's radius of maximum wind. For locations on the right-hand side of the track, a direct hit occurs when the cyclone passes to within a distance equal to twice the radius of maximum wind. Compare indirect hit, strike.

Indirect Hit:
Generally refers to locations that do not experience a direct hit from a tropical cyclone, but do experience hurricane force winds (either sustained or gusts) or tides of at least 4 feet above normal.

Landfall:
The intersection of the surface center of a tropical cyclone with a coastline. Because the strongest winds in a tropical cyclone are not located precisely at the center, it is possible for a cyclone's strongest winds to be experienced over land even if landfall does not occur. Similarly, it is possible for a tropical cyclone to make landfall and have its strongest winds remain over the water. Compare direct hit, indirect hit, and strike.

Strike:
For any particular location, a hurricane strike occurs if that location passes within the hurricane's strike circle, a circle of 125 n mi diameter, centered 12.5 n mi to the right of the hurricane center (looking in the direction of motion). This circle is meant to depict the typical extent of hurricane force winds, which are approximately 75 n mi to the right of the center and 50 n mi to the left.

Quoting ackee:
How strong will 92L get

A strong TS
B CAT ONE HURRICAE
C major hurricane
D TD

C
Quoting Vero1:
DestinJeff -- on 10 Sept which side of the Peak is IGOR on?

AS I understand September 10 is an arbitrary average date and the peak of hurricane can either occur between late August to the first week of October, but speaking arbitrarily Igor would be on the down side which is neither here nor there!