97L a threat to become a tropical depression on Wednesday

By: Dr. Jeff Masters , 1:31 PM GMT on July 20, 2010

Share this Blog
3
+

A tropical wave (Invest 97L) near the east coast of Puerto Rico has become more organized overnight and is a threat to develop into a tropical depression as early as Wednesday. The disturbance has brought heavy rains of 8+ inches to Culebra and Vieques islands over the past day (Figure 1), and all of Puerto Rico and the Virgin Islands are under flash flood watches today. The storm could bring an additional 3 - 6 inches of rain to the islands over the next two days. The upper level low centered a few hundred miles north of the Dominican Republic is no longer bringing high levels of wind shear to 97L; wind shear has fallen to the moderate range, 10 - 20 knots, which may allow 97L to continue to develop today. Satellite images of 97L show a moderate area of disorganized thunderstorms, but no signs of a surface circulation, no low-level spiral banding, and no upper-level outflow. There is a large amount of dry air to the northwest of Puerto Rico that will interfere with development of 97L. Surface observations show only light winds over Puerto Rico, with no signs of a surface circulation. The Hurricane Hunters are on call to investigate 97L this afternoon, if necessary.


Figure 1. Total radar-estimated rainfall from Invest 97L.

Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of flooding to the Dominican Republic today and Wednesday, and to Haiti on Wednesday and Thursday. Heavy rains from 97L will begin moving into eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas on Wednesday, and South Florida can expect heavy rains to arrive as early as Thursday night. We do have several models developing 97L into a tropical depression or tropical storm. The GFS and HWRF both take 97L to tropical storm status over the Bahamas by Thursday, with the storm then tracking over South Florida on Friday and entering the Gulf of Mexico on Saturday. The NOGAPS is similar, but portrays a weaker system. All of these models foresee a threat to the oil spill region by Saturday night or Sunday, with the storm making a second landfall somewhere between the Florida Panhandle and Louisiana. One factor potentially aiding the storm will be the Madden-Julian oscillation, which currently favors upward motion over the Gulf of Mexico and Caribbean. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. Also in favor of development are the warm ocean temperatures of 29°C. The SHIPS model predicts shear will remain moderate, 10 - 20 knots, over the next 4 - 5 days, and I believe the primary detriment to development of 97L over the next two days will be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. NHC is giving 97L a 40% chance of developing into a tropical depression by Thursday, which is a reasonable forecast. I think there is a 60% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development today or on Wednesday is unlikely, due to the dry air over the Bahamas, and I put the odds of 97L making it to hurricane strength before reaching Florida at 10%. There is a better chance that 97L could attain hurricane strength in the Gulf of Mexico, perhaps 20%. These probabilities will depend heavily upon how long 97L (or Bonnie) spends over land or interacting with land over the next four days, which is very uncertain.

Time to cut the forecast numbers for the coming hurricane season?
Here are the number of Atlantic named storms, hurricanes, and intense hurricanes predicted by the various forecast groups in their late May or early June forecasts:

23 named storms: PSU statistical model
20 named storms: UKMET GloSea dynamical model
18.5 named storms, 11 hurricanes, 5 major hurricanes: NOAA hybrid statistical/dynamical model technique
18 named storms, 10 hurricanes, 5 intense hurricanes: CSU statistical model (Phil Klotzbach/Bill Gray)
17.7 named storms, 9.5 hurricanes, 4.4 intense hurricanes: Tropical Storm Risk (TSR), hybrid statistical/dynamical model technique (Note: TSR increased their numbers to 19.1, 10.4, and 4.8 with their July 6 forecast)
17 named storms, 10 hurricanes: FSU dynamical model
10 named storms, 6 hurricanes, 2 intense hurricanes: climatology

The group forecasting the lowest activity was the Florida State University group led by Dr. Tim LaRow. They use a new dynamical forecast model called COAPS, which is funded by a 5-year, $6.2 million grant from NOAA. This year's June forecast by the COAPS model called for 17 named storms and 10 hurricanes. However, Dr. LaRow emailed me yesterday to say that the COAPS model is now calling for reduced activity. Using the state of the atmosphere and ocean as of July 15, a new run of the COAPS model was performed over the weekend. The new forecast is now calling for two fewer hurricanes--a total of 15 named storms and 8 hurricanes (including Alex.) The COAPS model generated an "ensemble" of five different forecasts, done by varying the initial sea surface temperatures by a few percent at the beginning of the model run. These five forecasts came up with a range of 12 - 16 named storms (including Alex), and 7 - 10 hurricanes. It will be interesting to see when CSU issues its August 4 forecast if they also cut their numbers. With only one named storm (Alex) thus far this year, it's getting pretty hard to have a season with 19 or 20 named storms. Only four hurricane seasons since 1851 have had as many as nineteen named storms. These four seasons--1887, 1933, 1995, and 2005--all had at least three named storms by July 20.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Invest 97
2) A look ahead at the coming two weeks

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 788 - 738

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

Member Since: July 15, 2006 Posts: 165 Comments: 52343
Quoting xcool:
i think hwrf based on GFS .


no GFDL.
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting MiamiHurricanes09:
The HWRF initialization point looks to be too far east and south.




Looks right on the mark to me?

AL, 97, 2010072012, , BEST, 0, 190N, 658W, 30, 1013, DB,
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting flwthrfan:


Wish I had a like button right now! Thanks Storm!


Couldnt agree more. I like storm and his post are very helpful. Cmon, lets show some respect, get along with everyone, and put everything else on the backburner ok?
Member Since: Posts: Comments:
where is Weather456? he always does a great analysis of the systems we have out there..he is always cool and calm with the bloggers even with they critized him..interested to know if 97L wont even cross florida but hug the east coast of Fl, GA, SC and NC?
Member Since: Posts: Comments:
Something to consider with that Beer guy's.....

Member Since: July 3, 2007 Posts: 0 Comments: 524
offical track has 97L about 100 miles west of st pete fl at 120 hrs!!!,this could be setting up for a SWFL event IMO...
Member Since: Posts: Comments:
another problem with this run of the model

this is in 6 hours from now.... 72 knts

Member Since: Posts: Comments:
Quoting Prgal:


I even mentioned earlier about the circulation south of Vieques and I was mostly ignored. Ada Monzon said that there was a huge drop in pressure in the Fajardo area with the wind comming from the west. What does that tells us? We all know...
I read that also I am wondering how the folks elsewhere in Turks and Caicos, Bahamas, DR, Cuba will fare.
Member Since: Posts: Comments:
778. xcool
i think hwrf based on GFS .
Member Since: September 26, 2009 Posts: 2 Comments: 15603
776. 7544
hawf went further north this run and stronger right over so fla too stay tuned
Member Since: May 6, 2007 Posts: 0 Comments: 6618
The HWRF initialization point looks to be too far east and south IMO.

Member Since: September 2, 2009 Posts: 130 Comments: 21032
If 97L does not get in gear and move I'm going to have a beach front lot...

I have no doubts this will develop soon as it moves away from the islands a bit. There is basically a feeder band going straight over me right now and has been for the last 24 hours.
Pressure at
http://www.ndbc.noaa.gov/show_plot.php?station=41043&meas=wdpr&uom=E&time_diff=-3&time_label=ADT
Will start to drop soon....
Again as I said yesterday and especially since it has really slowed down T&C, Bahamas get ready and SFL as well...its to late when it is on you..
Member Since: Posts: Comments:


this shows a hurricane with winds around 75 mph and the very next image is landfall with winds of 65 mph... something is wrong there
Member Since: Posts: Comments:
It seems that landfall in inevitable at this point. Whether a TD or TS. The question is will it landfall in SFL or CFL?
Member Since: Posts: Comments:
769. Prgal
Quoting Prgal:


Hi Serial. With all due respect I think that most people here pay attention when there is a chance it will hit the CONUS but forget that people in the islands take the hit first. Just my opinion and obviously I agree with you.


I even mentioned earlier about the circulation south of Vieques and I was mostly ignored. Ada Monzon said that there was a huge drop in pressure in the Fajardo area with the wind comming from the west. What does that tells us? We all know...
Member Since: Posts: Comments:
Quoting Floodman:


But considerably less powerful...


Intensity is unknown. Remember Andrew?
The Gulf Stream and Herbert's Box is notorious.

although im not suggesting anything of the sort.
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting StormW:


Well, you do that! Be my guest! Ya know, if some of ya folks that have nothin' to do but come on and give us mets a hard time, would zip it up and actually read, think, and understand the synopses, ya might learn somethin'


Wish I had a like button right now! Thanks Storm!
Member Since: Posts: Comments:
729 Good suggestion Storm!
Member Since: Posts: Comments:
Quoting StormW:


Well, you do that! Be my guest! Ya know, if some of ya folks that have nothin' to do but come on and give us mets a hard time, would zip it up and actually read, think, and understand the synopses, ya might learn somethin'


Sorry for the constructive criticism. Geez
Member Since: Posts: Comments:
763. xcool
TropicalNonsense lol
Member Since: September 26, 2009 Posts: 2 Comments: 15603
762. Prgal
Quoting serialteg:
i was talking about 97l when it passed thru puerto rico and no one paid attention.


Hi Serial. With all due respect I think that most people here pay attention when there is a chance it will hit the CONUS but forget that people in the islands take the hit first. Just my opinion and obviously I agree with you.
Member Since: Posts: Comments:
761. unf97
Quoting Floodman:


But considerably less powerful...


Let's really hope that is the case!!
Member Since: Posts: Comments:
Quoting xcool:
i need a Canadian beer


I need another shot of Beam........
Member Since: September 1, 2007 Posts: 0 Comments: 1793
Quoting xcool:
i need a Canadian beer


Moosehead is great! ... Here have one XCool. LOL
Member Since: July 3, 2007 Posts: 0 Comments: 524
Quoting DestinJeff:
change in 12Z HWRF
A shift to the north in the forecast?
Member Since: July 20, 2010 Posts: 0 Comments: 225
Quoting nrtiwlnvragn:
12Z HWRF further northward, although hard to tell with this graphic.




Strong tropical storm. Similar track to the 12Z TCVN
Member Since: January 30, 2010 Posts: 0 Comments: 3259
754. 7544
gfs

Link
Member Since: May 6, 2007 Posts: 0 Comments: 6618


HWRF model
Member Since: July 20, 2010 Posts: 0 Comments: 225
.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

A PERSISTENT BREEZY ONSHORE WIND FLOW ALONG THE ATLANTIC COAST WILL
CONTINUE TO RESULT IN STRONG, DANGEROUS RIP CURRENTS AT THE ATLANTIC
BEACHES OVER THE NEXT SEVERAL DAYS.

THE NATIONAL HURRICANE CENTER IS MONITORING THE VIGOROUS TROPICAL
WAVE NEAR PUERTO RICO FOR POSSIBLE TROPICAL CYCLONE DEVELOPMENT.
REGARDLESS OF DEVELOPMENT, THIS FEATURE HAS THE POTENTIAL TO BRING
HEAVY RAIN AND GUSTY WINDS TO SOUTH FLORIDA FROM EARLY FRIDAY
MORNING THROUGH SATURDAY. STAY TUNED TO THE LATEST FORECASTS FOR
POSSIBLE DETERIORATING WEATHER CONDITIONS LATE THIS WEEK.


From the Miami NWS
Member Since: September 2, 2009 Posts: 130 Comments: 21032
750. xcool
i need a Canadian beer
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting MiamiHurricanes09:
Lol...probably not although I would certainly like it to be that way. StormW thinking that we will see a small shift to the left.


Cone-caster
Member Since: Posts: Comments:
Quoting TropicalNonsense:


ALL of SOUTH/CENTRAL Florida should be keeping an eye out.

Don't get alarmed but stay informed and ahead of the game.
could be a track similar to Jean/Frances maybe slightly south.


But considerably less powerful...
Member Since: Posts: Comments:
12Z HWRF further northward, although hard to tell with this graphic.


Member Since: Posts: Comments:
Quoting mcluvincane:


Well being u were more interested in the Jamaica wave yesterday and now is not much I will take your forecast with a grain of salt. Not even these so called experts can forecast mother nature its just a guessing game.


Mistake. Boy BIG mistake.
Member Since: July 3, 2007 Posts: 0 Comments: 524
Did it squeak when you fell??? LOL
Quoting Patrap:


More of a stumble on the dogs chew toy paper thingee.

Never leave dog toys on the Stairs I tell the Dog all the time, But she listens Like tropical Bloggers..


Sparsely

..LOL

Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
Right.


If it can't organize by the time it get close to Florida, it shouldn't be that much of a threat tropically.
Member Since: Posts: Comments:
743. 7544
new cmc makes it stronger this run and now the cmc and the new gfs shows two whatttttttttt a one two punch for so fla?

Link
Member Since: May 6, 2007 Posts: 0 Comments: 6618
Quoting Patrap:


More of a stumble on the dogs chew toy paper thingee.

Never leave dog toys on the Stairs I tell the Dog all the time, But she listens Like tropical Bloggers..


Sparsely

..LOL

What did you say, I wasn't listening....LOL
Member Since: Posts: Comments:
Quoting Patrap:
IKE is a Guy..


Now I'm messing with you. I'm a Martian.....
Member Since: September 1, 2007 Posts: 0 Comments: 1793
Quoting P451:


Uh oh, the waters ahead of it are enough to support a Cat 5. Thank goodness for shear and dry air.
Member Since: Posts: Comments:
Quoting CyclonicVoyage:


It's going to be a matter of where the center develops how quickly it can organize.
Right.
Member Since: September 2, 2009 Posts: 130 Comments: 21032

Viewing: 788 - 738

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.