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: 688 - 638

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

688. wayfaringstranger
4:50 PM GMT on July 20, 2010
Dookie, lovin the squirell. Can you send that pic?
Member Since: July 12, 2010 Posts: 0 Comments: 235
686. TropicalNonsense
4:49 PM GMT on July 20, 2010
Quoting MiamiHurricanes09:
Monitor the situation. I think there is a good chance for a minimal hurricane as it has many things going in its favor with the exception of dry air. Hot SSTs and a favorable upper level environment will really help 97L when it's over the Bahamas.


It's called the "Gulf Stream"
Member Since: July 3, 2007 Posts: 0 Comments: 524
685. xcool
4:49 PM GMT on July 20, 2010
Member Since: September 26, 2009 Posts: 2 Comments: 15648
684. MiamiHurricanes09
4:49 PM GMT on July 20, 2010
Quoting gator23:

hey Miami, Miami-Dade doesnt look like it will take a direct hit, looks more Palm Beach maybe Melbourne?
Ehhh, I'm not thinking that far north. Looking at steering this looks like it will be a southern Florida event. However, this can change very quickly.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
683. Floodman
4:49 PM GMT on July 20, 2010
Quoting wayfaringstranger:
starting to see upper level rotation now?


Been seeing it...waiting for lower level circulation and veertical alignment...


Breathe, relax and wait...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
682. Patrap
4:48 PM GMT on July 20, 2010
A G-4 Sniff is in the Cue..

FLIGHT TWO -- NOAA 49
A. 22/0000Z
B. NOAA9 02BBA SURV
C. 21/1730Z
D. NA
E. NA
F. 41,000 TO 45,000 FT
Member Since: July 3, 2005 Posts: 423 Comments: 127804
681. TropicalNonsense
4:48 PM GMT on July 20, 2010
Quoting jurakantaino:
Looks is going paralleling the north coast of PR, once it reaches the hot mona canal it will intensify, historically that's what happened with most Puerto Rican storms. Not a scientific source, just previous experiences.


good observation Jurak. Im a believer.
Member Since: July 3, 2007 Posts: 0 Comments: 524
680. KEEPEROFTHEGATE (Mod)
4:48 PM GMT on July 20, 2010
Quoting CaribbeanIslandStorm:
I think that invest 97 has some serious organization issues, there seems to be several centers forming, one right off the east coast of puerto rico and another about 175 miles north of the island. Will it be a depression soon? Maybe some time thursday or friday, i think SE florida needs to keep an eye on it.
its heading into high octane it will purrr like a kitty
Member Since: July 15, 2006 Posts: 170 Comments: 53505
679. Patrap
4:48 PM GMT on July 20, 2010
Plan of the Day

000
NOUS42 KNHC 201445
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT TUE 20 JULY 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 21/1100Z TO 22/1100Z JULY 2010
TCPOD NUMBER.....10-050

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (NORTH OF HISPANIOLA)
FLIGHT ONE -- TEAL 70
A. 21/1800Z
B. AFXXX 01BBA INVEST
C. 21/1400Z
D. 21.0N 70.0W
E. 21/1700Z TO 21/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO -- NOAA 49
A. 22/0000Z
B. NOAA9 02BBA SURV
C. 21/1730Z
D. NA
E. NA
F. 41,000 TO 45,000 FT

FLIGHT THREE -- TEAL 71
A. 22/0600Z, 1200Z
B. AFXXX 0303A CYCLONE
C. 22/0400Z
D. 22.0N 72.0W
E. 22/0500Z TO 22/1200Z
F. SFC TO 15,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF
SYSTEM REMAINS A THREAT. A POSSIBLE G-IV
MISSION FOR 23/0000Z.
Member Since: July 3, 2005 Posts: 423 Comments: 127804
678. MiamiHurricanes09
4:48 PM GMT on July 20, 2010
Quoting unf97:


Right. We just need to watch it consolidate more and its forward speed. All of this we should have a clearer understanding of hopefully in the next 24 hours or so once the LLC fully develops.
Exactly.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
676. minorLeague
4:48 PM GMT on July 20, 2010
Why does WU always show the SHIPS intensity on the main page summary graph with the models? It seems like the forecast intensity is highest for SHIPS at least early in development. For 97L, Dr.M gives fairly low percentage to become a hurricane, but the main page plot makes it seem like a certainty.
Member Since: November 12, 2009 Posts: 0 Comments: 48
675. CyclonicVoyage
4:47 PM GMT on July 20, 2010
Quoting connie1976:
....ok....I live in South Florida next to the everglades....is this something people are exaggerating....or is there really a possibility that this could be a hurricane that visits South Florida?


Very real possibility, albeit low at this time. Keep tabs next 24 hours, it will be the tell tale.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
674. gator23
4:47 PM GMT on July 20, 2010
Quoting MiamiHurricanes09:
Late Wednesday or early Thursday. Doesn't matter right now.

hey Miami, Miami-Dade doesnt look like it will take a direct hit, looks more Palm Beach maybe Melbourne?
Member Since: August 26, 2008 Posts: 0 Comments: 2165
673. Patrap
4:47 PM GMT on July 20, 2010
Quoting connie1976:
....ok....I live in South Florida next to the everglades....is this something people are exaggerating....or is there really a possibility that this could be a hurricane that visits South Florida?


Watch and be ready..

No Guidance as of now develops a Hurricane till 3 days out.

So stay informed. Ignore rumor

Member Since: July 3, 2005 Posts: 423 Comments: 127804
672. unf97
4:47 PM GMT on July 20, 2010
Quoting MiamiHurricanes09:
Late Wednesday or early Thursday. Doesn't matter right now.


Right. We just need to watch it consolidate more and its forward speed. All of this we should have a clearer understanding of hopefully in the next 24 hours or so once the LLC fully develops.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
671. TropicalNonsense
4:47 PM GMT on July 20, 2010
Quoting connie1976:
....ok....I live in South Florida next to the everglades....is this something people are exaggerating....or is there really a possibility that this could be a hurricane that visits South Florida?


very possible. atleast a strong TS impacting south central
Florida satpm-sun as of right now.
Member Since: July 3, 2007 Posts: 0 Comments: 524
670. MiamiHurricanes09
4:47 PM GMT on July 20, 2010
Quoting connie1976:
....ok....I live in South Florida next to the everglades....is this something people are exaggerating....or is there really a possibility that this could be a hurricane that visits South Florida?
Monitor the situation. I think there is a good chance for a minimal hurricane as it has many things going in its favor with the exception of dry air. Hot SSTs and a favorable upper level environment will really help 97L when it's over the Bahamas.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
669. extreme236
4:47 PM GMT on July 20, 2010
Quoting CaribbeanIslandStorm:
I think that invest 97 has some serious organization issues, there seems to be several centers forming, one right off the east coast of puerto rico and another about 175 miles north of the island. Will it be a depression soon? Maybe some time thursday or friday, i think SE florida needs to keep an eye on it.


The vorticity is not focused east of PR. Probably just a mid-level circulation of some kind, if there is one there at all.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
668. DookiePBC
4:46 PM GMT on July 20, 2010
I apologize to my fellow PB County residents...I have jinxed us. Before looking at the tropics, I filled my pool this morning because we haven't had rain in so long. Nothing guarantees copious amounts of rain like filling your pool. My bad! :(
Member Since: September 1, 2009 Posts: 0 Comments: 447
667. KEEPEROFTHEGATE (Mod)
4:46 PM GMT on July 20, 2010
Quoting StormW:


Based on the current steering layer mean, visible and RGB satellite loop imagery, forecast steering layers, and the fact we could have a LLC developing further to the west (as in where it may be forming right now).

This is why I believe a slight shift in model guidance.
i think its to knock on someones front door
Member Since: July 15, 2006 Posts: 170 Comments: 53505
665. connie1976
4:45 PM GMT on July 20, 2010
....ok....I live in South Florida next to the everglades....is this something people are exaggerating....or is there really a possibility that this could be a hurricane that visits South Florida?
Member Since: September 1, 2008 Posts: 0 Comments: 672
664. MiamiHurricanes09
4:45 PM GMT on July 20, 2010
Quoting CaribbeanIslandStorm:
I think that invest 97 has some serious organization issues, there seems to be several centers forming, one right off the east coast of puerto rico and another about 175 miles north of the island. Will it be a depression soon? Maybe some time thursday or friday, i think SE florida needs to keep an eye on it.
97L only has 1 center that is near the eastern tip of the Dominican Republic. Here in Miami we really aren't watching it at this point, if and when 97L becomes Bonnie is when we will pay a little more attention to it.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
662. 69Viking
4:45 PM GMT on July 20, 2010
Quoting StormSurgeon:
By the way IKE, did I mention this?

Hoopdy Loop


Not a track I'm liking at all, I'm South of IKE along the coast in Fort Walton Beach right about where that Hoopdy Loop of yours makes it's second landfall! Good thing it's early and it will most likely change!
Member Since: August 25, 2006 Posts: 1 Comments: 3022
661. jurakantaino
4:44 PM GMT on July 20, 2010
Quoting TropicalNonsense:
NWS Radar shows 97L very Clearly trying to wind up.

Looks is going paralleling the north coast of PR, once it reaches the hot mona canal it will intensify, historically that's what happened with most Puerto Rican storms. Not a scientific source, just previous experiences.
Member Since: July 31, 2008 Posts: 0 Comments: 730
660. moonlightcowboy
4:44 PM GMT on July 20, 2010
Quoting CosmicEvents:
Don't get me started, but it should have been RED last night. Certainly today. As the models continue to verify, just with the passage of time, we'll have RED this evening. Then it's in the "official" 48 hour window.
.
.
The thing is, we have a system where there's near 100% agreement amongst the models of at least a small TS hitting somewhere from Cuba up to south central Florida in 4 days. Shouldn't the people get that RED alert right now. The sooner the better. RED does not mean Cat5. It simply signifies that there's a good probability of a TD. If somebody needs to trim their trees, or pick up supplies, what's wrong with giving them an extra day instead of going by the official COLOR book?



Precisely. Might even save a life or two. :) Completely agree with this thinking. I just don't agree with the mindset or budgeting that doesn't exhaust all available resources an opportunities to create as much awareness and preparedness caution as possible.
Member Since: July 9, 2006 Posts: 184 Comments: 29596
659. CaribbeanIslandStorm
4:43 PM GMT on July 20, 2010
I think that invest 97 has some serious organization issues, there seems to be several centers forming, one right off the east coast of puerto rico and another about 175 miles north of the island. Will it be a depression soon? Maybe some time thursday or friday, i think SE florida needs to keep an eye on it.
658. Patrap
4:43 PM GMT on July 20, 2010
Member Since: July 3, 2005 Posts: 423 Comments: 127804
657. wayfaringstranger
4:43 PM GMT on July 20, 2010
starting to see upper level rotation now?
Member Since: July 12, 2010 Posts: 0 Comments: 235
656. MiamiHurricanes09
4:43 PM GMT on July 20, 2010
Quoting unf97:


If 97L is designated as a TD in the next 24 hours, the earliest NHC would post watches for portions of South FL coast would be sometime on Thursday.
Late Wednesday or early Thursday. Doesn't matter right now.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
655. southernbell72
4:43 PM GMT on July 20, 2010
im sorry , didnt say i was the best speller, lol
Member Since: July 19, 2010 Posts: 0 Comments: 72
654. wayfaringstranger
4:42 PM GMT on July 20, 2010
What are the possibilities (%) that this becomes a hurricane 1 within 36 hrs?

Possibility of three hurricanes by Saturday?
Member Since: July 12, 2010 Posts: 0 Comments: 235
653. CosmicEvents
4:41 PM GMT on July 20, 2010
Don't get me started, but it should have been RED last night. Certainly today. As the models continue to verify, just with the passage of time, we'll have RED this evening. Then it's in the "official" 48 hour window.
.
.
The thing is, we have a system where there's near 100% agreement amongst the models of at least a small TS hitting somewhere from Cuba up to south central Florida in 4 days. Shouldn't the people get that RED alert right now. The sooner the better. RED does not mean Cat5. It simply signifies that there's a good probability of a TD. If somebody needs to trim their trees, or pick up supplies, what's wrong with giving them an extra day instead of going by the official COLOR book?
Member Since: August 3, 2005 Posts: 10 Comments: 5557
652. MiamiHurricanes09
4:41 PM GMT on July 20, 2010
I counted 38 points on the TCFA checklist, I was being far from conservative though.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
651. Patrap
4:41 PM GMT on July 20, 2010
NEXRAD Radar
San Juan, Base Reflectivity 0.50 Degree Elevation Range 124 NMI


Member Since: July 3, 2005 Posts: 423 Comments: 127804
NWS Radar shows 97L very clearly trying to wind up.

Member Since: July 3, 2007 Posts: 0 Comments: 524
I really hope that at worse 97L is a "shot across the bow" for florida, and will hopefully get some folks moving if they have not already done so for the season. Regardless of where they live on the coast.

I have been building my kit for years now, it is pretty extensive and almost everything I had laid in was used during or after Ike sent his kid over to tear up my house. :)
Member Since: Posts: Comments:
Quoting P451:
12HR WV Loop ending 1115am et.



Seems to be consolidation north of the eastern tip of PR.

If that's the dominant feature all it needs to do is to gain some latitude away from PR and the DR.
Agree it hasn't move much since last night and its been consolidating but interaction with land has kept it in check. I've live in PR and the eastern parts, including Vieques and Culebra have been pound with *8 TO 10 inches of rain so far.
Member Since: July 31, 2008 Posts: 0 Comments: 730
644. unf97
Quoting MiamiHurricanes09:
LOL, watches are warranted when conditions will be felt in 48 hours or less. So if it becomes a tropical depression tomorrow, watches should be warranted for the Florida coast either tomorrow or Thursday depending on speed (looks like it will be affecting Florida in 96 hours).


If 97L is designated as a TD in the next 24 hours, the earliest NHC would post watches for portions of South FL coast would be sometime on Thursday.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
We are becoming pros at this (shrugg)
Quoting Ameister12:
Good afternoon.

You guys in Florida ready for your first storm of the season.
Member Since: Posts: Comments:
Quoting StormW:
Model guidance should shift slightly left next run.
why? thanks in advance:)
Member Since: Posts: Comments:
Quoting DestinJeff:


Hey I broke the seal with the first Rainbow image awhile back ... thought they'd really be pouring in by now.



My Left hand is sprained from a Lil incident with my Stairs this am.

Ice and meds.
Member Since: July 3, 2005 Posts: 423 Comments: 127804
639. 7544
97l is joining forces with the blob that was south this am and getting larger in size now you can see it on the vis
Member Since: May 6, 2007 Posts: 0 Comments: 6749
638. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5696

Viewing: 688 - 638

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.