Frances Advisories

[spaceisland]

Yes, the bands are impressive... the visible is now available, and the cloud cover is impressive, also the long distance radar out of Miami...

IMHO, the storm may not have the wind punch it once had, but, if anything, the rain potential appears to have increased, not decreased.

[Anonymous]

Yes. My own opinion is still 140 mph at landfall.... only 20 mph of strengthening and some people look at me like that is out of the question.

[tampastorm]

Agreed this can be a soaker for 24 hours or more from South to central to north FL, we must not let are guard down.

[The Big Dog]

Eleuthera's highest elevations are only about 115 feet. Would that really have much effect on Francis, as opposed to an island like Hispanola?

Yeah, Bahamas did nothing to weaken Andrew or Floyd. However, I remember David hit Hispanola as a Cat 5 and came off as a TS.

[LAwxrgal]

Guys and gals we have to remember that this storm is still dangerous, especially in light of the fact that Charley just passed through this same general area 3 weeks ago.

Heck if she were to hit as a tropical storm it would still be dangerous.

[Hyperstorm]

I disagree about the dry air being a factor for the weakening. This system has been ingesting dry air since it came off the African coast and has been able to strengthen gradually. Humidity values are expected to rise as it approaches the Florida coast, so no weakening because of that.

The main reason for the weakening was an outflow restriction initially and some westerly shear since last evening. This shear is expected to abate somewhat just before it's expected to reach the shore, so if it can maintain a well-defined inner core...this could rapidly strengthen the 12 hours before landfall.

There are signs that the inner core has collapsed somewhat so it could take time for it to strengthen...

Dry air indeed played a role. Steve Lyons showed it yesterday and stated it could play a role in some weakening. He was right. Even showed it on his map.

That's not true. (Sometimes I think Steve Lyons shouldn't be a TV person, but that's another story. His forecasts are sometimes the opposite of those from the NHC.)

I can remember last year when Claudette was 24 hours from moving inland over Texas and it was still a strongly sheared tropical storm. He stated that "dry air is moving southward from Oklahoma and Texas into the Gulf of Mexico and it should prevent this system to become a hurricane at landfall". He said that with such a confidence that I was a little surprised. Well, what happened? Everyone woke up the other morning with a strong Category 1 hurricane about to move onshore. He had to eat his own words.

In the case with Frances we know that it has been surrounded by dry air throughout its entire lifetime. I didn't see any signs of weakening (besides ERC) when it was a tropical storm or hurricane until now. Dry air has been slowly diminishing and will not be there when the hurricane approaches the coast, so imagine what can happen. If it has maintained itself and strengthened with dry air since it was born, imagine what it can do when humidity values rise as it approaches land.

Reason for the weakening...westerly shear.

[Tip]

I've seen lesser storms encounter worse shear and not decrease in intensity that quickly. I think there are more than just one factor at work here. Lyons said dry air entrainment. Obviously there is shear. And I believe there may be more to the story.

[cycloneye]

03/1145 UTC 25.3N 76.3W T5.0/6.0 FRANCES -- Atlantic Ocean

Great news it continues to weaken.

[spaceisland]

I already sense some of the folks staying with us here in Brevard County saying, in essence, "WHEW! Glad that's over with!" I just want to shake them! First, the rain may start late tonight, (based on looking t Miami radar) and the projections don't show Frances leaving Florida until Monday! I can already envision the raccoons and armadillos starting to pair up two-by-two!

Also, 100 or 120 mph winds can still take a roof off, especially on an older home. It seems we were so psyched for 150 mph that 100 or 120 seems like "nothing"...

If this had been an 80 mph Erin and suddenly went UP to 120 mph, our mood would be quite different, I am sure!

[Deenac813]

First, the rain may start late tonight, (based on looking t Miami radar) and the projections don't show Frances leaving Florida until Monday! I can already envision the raccoons and armadillos starting to pair up two-by-two!

That was cute!

[LAwxrgal]

^Oh, trust me, 100-120 is a lot of wind, and the potential for enormous amounts of rain continues to increase.

[Guest]

great new now you need to worry about Ivan. This looks like a real threat to PR.

[Hurrilurker]

What did happen or is happening down there? Damage reports? Pictures? Video? How much rain? How big a storm surge?

[LAwxrgal]

Hurrilurker: Check this thread for the latest:

http://www.storm2k.org/phpbb2/viewtopic.php?t=39931

[B-Bear]

I've seen lesser storms encounter worse shear and not decrease in intensity that quickly. I think there are more than just one factor at work here. Lyons said dry air entrainment. Obviously there is shear. And I believe there may be more to the story.

I do believe there was more than a single factor which led to the reduction in intensity.

1. Frances appeared to be trying to go through another EWR yesterday, and, as she has done previously, she looked like she was struggling to get it done. Her eye started looking ragged rather early in the day and that continued for an extended period of time.

2. She encountered light shear at a time when she was already struggling to get her act together.

3. She ran into a patch of dry air, which temporarily cut off some of her feeding source.

4. She butted up against the high pressure system to the north, which inhibited her outflow.

5. She's been going over islands. Normally that may not take a lot out of a storm like Frances, but in a weakened state it might inhibit further development.

Although none of these factors alone may have been enough to cause such rapid storm depletion, I believe it was a culmination of these contributing factors that caused her rapid weakening.

[Hyperstorm]

I've seen lesser storms encounter worse shear and not decrease in intensity that quickly. I think there are more than just one factor at work here. Lyons said dry air entrainment. Obviously there is shear. And I believe there may be more to the story.

Can you tell me which ones? Thanks.

[LAwxrgal]

I don't remember the forecast a few days out mentioning westerly shear. Has Frances' slowdown contributed to the shear affecting her?

[charleston_hugo_veteran]

I've seen lesser storms encounter worse shear and not decrease in intensity that quickly. I think there are more than just one factor at work here. Lyons said dry air entrainment. Obviously there is shear. And I believe there may be more to the story.

I do believe there was more than a single factor which led to the reduction in intensity.

1. Frances appeared to be trying to go through another EWR yesterday, and, as she has done previously, she looked like she was struggling to get it done. Her eye started looking ragged rather early in the day and that continued for an extended period of time.

2. She encountered light shear at a time when she was already struggling to get her act together.

3. She ran into a patch of dry air, which temporarily cut off some of her feeding source.

4. She butted up against the high pressure system to the north, which inhibited her outflow.

5. She's been going over islands. Normally that may not take a lot out of a storm like Frances, but in a weakened state it might inhibit further development.

Although none of these factors alone may have been enough to cause such rapid storm depletion, I believe it was a culmination of these contributing factors that caused her rapid weakening.

Great post...i agree!

[janswizard]

I feel bad for the folks living on the south edge of the Big O. The dikes are 30 ft and the water level is at 13 ft right now. If this produces the 20+ inches of rain the local stations are predicting, Lake Okeechobee is going to spill over - and history has already shown that the last time this happened, there were huge amounts of death involved.

[Hyperstorm]

I don't remember the forecast a few days out mentioning westerly shear. Has Frances' slowdown contributed to the shear affecting her?

Here you have one of them:

ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
HURRICANE FRANCES DISCUSSION NUMBER 26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT TUE AUG 31 2004

SATELLITE AND AIRCRAFT DATA INDICATE THAT FRANCES IS COMPLETING A
CONCENTRIC EYEWALL CYCLE. THE AIR FORCE RESERVE HURRICANE HUNTER
REPORTS A 30-40 NM DIAMETER OUTER EYEWALL WITH MAXIMUM FLIGHT-LEVEL
WINDS OF 121 KT AT 700 MB...ALONG WITH A CENTRAL PRESSURE OF 949
MB. SATELLITE IMAGERY SHOWS THE REMAINS OF THE EARLIER INNER
EYEWALL ARE STILL PRESENT. BASED ON THE AIRCRAFT DATA...THE
MAXIMUM INTENSITY REMAINS 110 KT. THE AIRCRAFT ALSO SHOWS A WIND
MAXIMA OUTSIDE OF THE OUTER EYEWALL.

THE INITIAL MOTION IS NOW 280/13. FRANCES REMAINS ON THE SOUTH SIDE
OF A STRONG RIDGE OVER THE WESTERN ATLANTIC. LARGE-SCALE MODELS
ALL FORECAST THE RIDGE TO WEAKEN DURING THE FORECAST PERIOD...BUT
THERE ARE SIGNIFICANT DIFFERENCES IN THE DETAILS WHICH HAVE MAJOR
IMPLICATIONS FOR WHERE FRANCES WILL END UP. DATA FROM THE RECENT
SYNOPTIC SURVEILLANCE MISSION HAD SOME INTERESTING EFFECTS ON THE
DYNAMICAL MODELS. THE GFS...WHICH HAS BEEN A LEFT OUTLIER MOST OF
THE TIME...HAS SHIFTED WELL TO THE RIGHT AND IS NOW A RIGHT
OUTLIER...MOVING FRANCES NORTHWARD ALONG 77-78W AFTER 72 HR. THE
NOGAPS...WHICH HAS BEEN A RIGHT OUTLIER...IS NOW A LEFT OUTLIER
CALLING FOR LANDFALL IN SOUTHEASTERN FLORIDA. THE GFDL AND UKMET
HAVE BOTH SHIFTED THEIR TRACKS TO THE RIGHT AFTER 72 HR. GIVEN THE
LARGE CHANGES IN JUST ONE CYCLE...THE OFFICIAL FORECAST WILL NOT
CHANGE MUCH AT ALL...BASICALLY BEING AN UPDATE OF THE PREVIOUS
PACKAGE. IT IS DOWN THE CENTER OF THE MODEL GUIDANCE UP TO 72 HR
AND ALONG THE LEFT SIDE THEREAFTER.

WHEN THE CONCENTRIC EYEWALL CYCLE IS FINALLY DONE...FRANCES SHOULD
STRENGTHEN AS INDICATED BY THE SHIPS AND GFDL MODELS. IT WOULD NOT
BE A SURPRISE TO SEE MORE STRENGTHENING THAN CURRENTLY FORECAST.
ALTHOUGH NOT CURRENTLY REFLECTED IN THE INTENSITY FORECAST DUE TO
THE UNCERTAINTY IN THE UPPER-LEVEL WIND PATTERNS...THE SHIPS...
GFDL...AND GFS MODELS SUGGEST CONDITIONS MAY BECOME LESS FAVORABLE
AFTER ABOUT 48 HR. ALSO...THERE REMAINS THE POSSIBILITY OF OTHER
CONCENTRIC EYEWALL CYCLES THAT CANNOT CURRENTLY BE FORECAST.

FORECASTER BEVEN

Are we past 48 hours yet?