ATL: TROPICAL STORM BILL (03L)

[Emmett_Brown]

Just viewing the IR loop; is it me, or is Bill accelerating?

[GeneratorPower]

Mike, where do these models get info about the environment from? Are they getting it from aircraft observations or what?

[scogor]

Mike:

What's your blog site address?

[cycloneye]

Just viewing the IR loop; is it me, or is Bill accelerating?

Yes,it has increased its foward speed.Its moving WNW at 17kts per 00 UTC ship.

[Dean4Storms]

I believe we see the eye of Bill tomorrow!

[AtlanticWind]

Just viewing the IR loop; is it me, or is Bill accelerating?

Yes,it has increased its foward speed.Its moving WNW at 17kts per 00 UTC ship.

Mets, A question , If Bill does indeed move faster what likely be the outcome , would he pulled up sooner or miss the weakness or neither

[The Eye Wall]

Just viewing the IR loop; is it me, or is Bill accelerating?

Yes,it has increased its foward speed.Its moving WNW at 17kts per 00 UTC ship.

Mets, A question , If Bill does indeed move faster what likely be the outcome , would he pulled up sooner or miss the weakness or neither

It would likely push a bit further west but not to the point of affecting Florida or the E. Coast, IMO. The weakness in the H5 ridge is not expected to develop for another few days.

[Emmett_Brown]

Mike:

What's your blog site address?

I googled it, and found it at http://www.hurricanetrack.com/watkins/watkins.htm. Doesn't look like it has been updated yet, has yesterday's post on it, so Mike must still be working on it.

[scogor]

Thanks, I was just about to do that myself!

[cpdaman]

I'm putting this in my blog tonight, but here's a preview.

Essentially, the 12z and 18Z GFS drop a mid level weakness into the heart of the 588 ridge at roughly 30N and 60W at t+72.

This weakness acts as a magnet to draw Bill up out of the MDR so that when the east coast ridge does break down, Bill is already far enough north to get scooped up.

However, I don't see the same solution from 12/18z NOGAPS. It shows the little hole there at 30/60 but it isn't nearly as strong as the GFS solution.

The euro just wipes out the east coast ridge and grabs Bill, which may be more likely. But the GFS (and dependent models like HWRF and GFDL) and Euro don't agree, it's two totally different solutions with the same answer. Both could be wrong, which would explain why the 12z NOGAPS and UKMET models get further west with Bill before the turn starts.

I don't see that mid/upper low on the map and until I do, I can't totally buy the GFS (and the GFS background models) solutions. To me it's the UKMET vs. Euro right now.

MW

thank you for this post.....and please keep us updated with your interpretations

[RL3AO]

It would likely push a bit further west but not to the point of affecting Florida or the E. Coast, IMO. The weakness in the H5 ridge is not expected to develop for another few days.

The weakness is already there. Its being caused by an upper level low north of the storm.

[gatorcane]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Model consensus is tightly clustered around a recurve that is now at least 800+ miles away from the CONUS (Florida). Even the UKMET is recurving now albeit a bit farther west but still far enough away from FL to not cause any issues. We still need to watch Bermuda but the threat to the CONUS is about NIL at this point.

[Emmett_Brown]

It would likely push a bit further west but not to the point of affecting Florida or the E. Coast, IMO. The weakness in the H5 ridge is not expected to develop for another few days.

The weakness is already there. Its being caused by an upper level low north of the storm.

That weakness is pulling out the NE. The weakness that draws him north is a different one. Here is the most recent 300 mb GFS:



And here is in 48 hrs, notice the ULL lifting out to the NE:

[gatorcane]

Here is a snippet from NWS Miami:

BY THE FIRST PART OF NEXT
WEEKEND...A LARGE TROUGH SHOULD DEVELOP OVER THE ERN CONUS...WITH
THE ECMWF BEING STRONGER/DEEPER AND CREATING SW STEERING FLOW
ACROSS THE REGION

http://forecast.weather.gov/product.php ... glossary=1

We have seen this pattern nearly the entire summer except for the past 2 weeks or so. In fact I can't remember summer where such a trough has lingered around for weeks on end. There was a window this past two weeks for something tropical to squeeze through with some Bermuda ridging finally developing but that window is going to close before Bill makes it anywhere near Florida or the CONUS, according to latest model guidance.

In fact that trough is going to hang around for a while looking at the latest ECMWF 500MB flow. That means its good news for the Eastern seaboard of the US for the next couple of weeks as this trough should block any Cape Verde system from the east. Beyond that its too early to say and there is still alot of the season left....so can't rule out the possiblity the synoptics change to more Bermuda ridging for September.

[jinftl]

Such a pattern with a deep trough is not a friend to florida late season....that's how we get storms with tracks from the south like irene and wilma. We may not see a Cape Verde system....but there is a reason that October is the #2 month for frequency of hurricanes in south florida.....troughs pick them up from areas to our south.

Here is a snippet from NWS Miami:

BY THE FIRST PART OF NEXT
WEEKEND...A LARGE TROUGH SHOULD DEVELOP OVER THE ERN CONUS...WITH
THE ECMWF BEING STRONGER/DEEPER AND CREATING SW STEERING FLOW
ACROSS THE REGION

http://forecast.weather.gov/product.php ... glossary=1

We have seen this pattern nearly the entire summer except for the past 2 weeks or so. In fact I can't remember summer where such a trough has lingered around for weeks on end. There was a window for something tropical to squeeze through with some Bermuda ridging finally developing but that window is going to close before Bill makes it anywhere near Florida or the CONUS, according to latest model guidance.

In fact that trough is going to hang around for a while looking at the latest ECMWF 500MB flow. That means its good news for the Eastern seaboard of the US for the next couple of weeks as this trough should block any Cape Verde system from the east. Beyond that its too early to say and there is still alot of the season left....so can't rule out the possiblity the synoptics change to more Bermuda ridging for September.

[gatorcane]

Indeed that is something that has been on my mind, but usually its more of an October phenomenon, still we must watch that possibility. If a system is not there to begin with it won't matter. Still September and October are months that can create some problems.....plenty of season left still Bill and Ana should be out of the picture by next weekend and we will be able to look for new possibilities out there.

[jinftl]

Yes, a deep trough in october and a system to our south is why October ranks 2nd for hurricane frequency in south florida after sept.

:uarrow:
Indeed that is something that has been on my mind, but usually its more of an October phenomenon, still we must watch that possibility.

[cycloneye]

60kts at 11 PM advisory

[Brent]

BULLETIN
TROPICAL STORM BILL ADVISORY NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
1100 PM AST SUN AUG 16 2009

...BILL NEARING HURRICANE STRENGTH...

AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM BILL WAS
LOCATED NEAR LATITUDE 13.4 NORTH...LONGITUDE 41.7 WEST OR ABOUT 1320
MILES...2120 KM...EAST OF THE LESSER ANTILLES.

BILL IS MOVING SLIGHTLY FASTER TOWARD THE WEST-NORTHWEST NEAR 20
MPH...32 KM/HR...AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE
FOR THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 70 MPH...110
KM/HR...WITH HIGHER GUSTS. STRENGTHENING IS FORECAST DURING THE
NEXT DAY OR TWO...AND BILL IS FORECAST TO BECOME A HURRICANE ON
MONDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES...220 KM
FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB...29.23 INCHES.

...SUMMARY OF 1100 PM AST INFORMATION...
LOCATION...13.4N 41.7W
MAXIMUM SUSTAINED WINDS...70 MPH
PRESENT MOVEMENT...WEST-NORTHWEST OR 290 DEGREES AT 20 MPH
MINIMUM CENTRAL PRESSURE...990 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM AST.

$$
FORECASTER KIMBERLAIN/PASCH

TROPICAL STORM BILL DISCUSSION NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
1100 PM AST SUN AUG 16 2009

INFRARED SATELLITE IMAGERY REVEALS AN IMPRESSIVE MASS OF DEEP
CONVECTIVE TOPS TO -80C WITHIN A CENTRAL DENSE OVERCAST...ALONG
WITH AN EXPANDING UPPER-LEVEL OUTFLOW. A LONG...WELL-DEFINED BAND
CONNECTED TO THE ITCZ IS NOTED IN THE SOUTHERN SEMICIRCLE...WHILE
LESSER BANDING COILS AROUND THE NORTHERN HALF OF THE CIRCULATION.
DVORAK T-NUMBERS ARE 3.5 AND 4.0 FROM SAB AND TAFB...RESPECTIVELY.
TAKING THE MEAN OF THESE INTENSITY ESTIMATES...THE ADVISORY WIND
SPEED IS SET AT 60 KT.

RECENT SATELLITE CENTER FIXES ARE SOMEWHAT UNCERTAIN BUT YIELD AN
INITIAL MOTION ESTIMATE OF 290/17...REPRESENTING A SLIGHTLY FASTER
FORWARD SPEED THAN BEFORE. UNDER THE INFLUENCE OF SUBTROPICAL
RIDGING TO THE NORTH...BILL IS EXPECTED TO MAINTAIN A GENERAL
WEST-NORTHWEST HEADING FOR THE NEXT 48-72 HOURS. WITH LITTLE
SPREAD IN THE CURRENT MODEL CYCLE THROUGH THIS TIME...THE OFFICIAL
TRACK DEVIATES LITTLE FROM THE PREVIOUS ADVISORY. THEREAFTER...
MODEL GUIDANCE IS IN GOOD AGREEMENT THAT A RATHER SUBSTANTIAL BREAK
IN THE SUBTROPICAL RIDGE SHOULD DEVELOP ROUGHLY ALONG 60W...WHICH
SHOULD RESULT IN A MORE NORTHWESTWARD COURSE. MOST OF THE MODEL
SOLUTIONS HAVE SHIFTED FARTHER NORTH FROM THE PREVIOUS RUNS...AND
SO HAS THE MODEL CONSENSUS. ONLY THE UKMET FAVORS A MORE
WEST-NORTHWESTWARD PATH AND APPEARS AS THE LONE...SOUTHERN OUTLIER
AMONGST THE REMAINDER OF THE GLOBAL MODELS. THE OFFICIAL FORECAST
IS ADJUSTED NORTH OF THE PREVIOUS ONE...ESPECIALLY BEYOND 96
HOURS...BASED ON THE LATEST GUIDANCE.

EVEN THOUGH ENVIRONMENTAL SHEAR IS QUITE LOW...BILL HAS BEEN
TRACKING OVER MARGINAL SEA SURFACE TEMPERATURES AND WATERS ARE NOT
FORECAST TO WARM FURTHER UNTIL AFTER 24 HOURS. INTERESTINGLY...THE
GFDL/HWRF SHOW A NEARLY FLAT INTENSIFICATION RATE FOR THE NEXT DAY
OR TWO...PERHAPS UNDERSCORING THE TEPID THERMODYNAMIC CONDITIONS. IT
SHOULD BE NOTED...HOWEVER...THAT THE SHIPS RAPID INTENSITY INDEX
SHOWS A 41% CHANCE OF A 30 KT INTENSITY INCREASE DURING THE NEXT 24
HOURS. THEREAFTER...THE GUIDANCE IS IN GOOD AGREEMENT THAT LOW
SHEAR AND WARMING WATERS SHOULD PREVAIL FOR BILL...ALLOWING THE
CYCLONE TO EVOLVE INTO A MAJOR HURRICANE OVER THE FORECAST PERIOD.
THE OFFICIAL FORECAST IS CLOSEST TO THE SHIPS MODEL GUIDANCE...
WHICH PREDICTS A FAIRLY STEADY RATE OF DEVELOPMENT OVER THE NEXT
FEW DAYS. TOWARD THE END OF THE FORECAST PERIOD...THE GLOBAL
MODELS HAVE BEEN HINTING AT INCREASING WESTERLY SHEAR AS BILL
OUTRUNS FAVORABLE ANTICYCLONIC FLOW TO THE SOUTHEAST.
ACCORDINGLY...THE OFFICIAL INTENSITY FORECAST SHOWS SLIGHT
WEAKENING NEAR THE END OF THE PERIOD.

FORECAST POSITIONS AND MAX WINDS

INITIAL 17/0300Z 13.4N 41.7W 60 KT
12HR VT 17/1200Z 14.1N 43.7W 70 KT
24HR VT 18/0000Z 14.9N 46.5W 80 KT
36HR VT 18/1200Z 15.8N 49.2W 85 KT
48HR VT 19/0000Z 16.8N 51.8W 95 KT
72HR VT 20/0000Z 19.7N 56.8W 105 KT
96HR VT 21/0000Z 23.5N 61.5W 105 KT
120HR VT 22/0000Z 28.1N 65.5W 100 KT

$$
FORECASTER KIMBERLAIN/PASCH

[cpdaman]

so is it the dang East coast trough that is supposed to be deep and digging by SAT that turns Bill or is a weakness or both

in the GFS 300 mb map above i couldn't really tell if the weakness will have lifted far enough NE to not effect bill (or only for a short time)

seems he could go WNW and miss the weakness then be pulled up by the trough...the furthest west i think he could get is ???? but i will just be hoping that we don't have to wait for the east coast trough on Fri/Sat for bill to turn and curve