ATL: Tropical Depression Fay

[xironman]

I don't know. I have been watching this all day. A little bit after noon the southern center gave out and things started spinning where ExtremeWeatherGuy pointed out. That is the same area that the maps have been saying that convergence was happening. Convergence was the last ingredient in the TC secret sauce that was missing, once that and the LLC got together it is off to the races. Right now I can see very cold cloud tops at the minimum.

as always

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[Recurve]

Wxman, thanks for your input as always.

If 92L did develop, a recurve certainly seems likely with a trough out ahead of it as on the chart. Not a prediction or forecast.

I was more bullish on this system than pre-Dolly. I thought I was seeing perfect inflow pattern. At one time there was a good mid-level spin, I think, with no Low center. There was nice outflow and divergence (diffluence?) aloft, a good moist envelope, but no convergence, needed centered convection to get the chimney started. We were seeing the convection on the west of a broad cyclonic flow. There were some opposite winds around the elongated low, but it was more like easterlies on the back pushing the wave forward, not concentrating on a center.

And this is about what we have. All to my untrained eye of course.

[Recurve]

Convergence was the last ingredient in the TC secret sauce that was missing, once that and the LLC got together it is off to the races

Chicken and egg? Low pressure, convergence and concentrated convection.

[xironman]

Chicken and egg? Low pressure, convergence and concentrated convection

Yeah Recurve I got you. But yesterday we had plenty of convection and no convergence, hence it gave out. Today we have both.

[Recurve]

Convection blooming -- and flowing north rapidly on rainbow:




The movement and tops show well on RGB loop:

http://www.ssd.noaa.gov/goes/flt/t1/loop-rgb.html

[HURAKAN]

Could you define "rapidly"? I don't see it racing to the north or anything like that.

[Honeyko]

Prediction: Great Red Spot on IR over LLC by midnight. Declared TD by 2am or 5am; declared TS by 11am.

I haven't been following this much today, but didn't you call this dead last night?

I forecast death around 2PMish yesterday -- and it then proceeded to croak to virtually nothing under harsh subsidence. It squeaked by, however, and refired around noon today.

[tolakram]

Missed it, but I think you can see evidence of a closed low to the right of the dead space. I'm not convinced that the LLC dissipated but if it did then I have to agree with wxman. At this point I just don't know.



Here is the previous pass for comparison:

[cycloneye]

That pass was at 4:14 AM EDT early this morning.Lets see of a new pass occurs later tonight or early tommorow morning.

[Honeyko]

It's always the same question. Does it have a well-defined LLC? Only QuickSCAT and RECON can confirm that if it's present under the convection.

Well, you can reasonable assumptions based upon the curvature of the banding and where surface cu streaks are darting in the fastest.

[tolakram]

:uarrow: That pass was at 4:14 AM EDT early this morning.Lets see of a new pass occurs later tonight or early tommorow morning.

Well sure, but if we wait we'll be looking at todays data tomorrow and we'll know by then. That's no fun.

[Recurve]

Could you define "rapidly"? I don't see it racing to the north or anything like that.

The clouds tops as the convection bloomed seemed to surge north to me. Look at the rainbow loop and the RGB loop.


And is that a black pixel or two on the center tops?

[KWT]

Convection surging northwards may be something to do with the shear that is probably still present I reckon?

[Scorpion]

There is little to no shear over the system.

[AtlanticWind]

Seems to me this still has a llc on the south side of the convection.

[perk]

Could you define "rapidly"? I don't see it racing to the north or anything like that.

Me either.

[Vortex]

Seems to me this still has a llc on the south side of the convection.

LLC looks to be on the extrme SE side of convection..Also convection is beging to "ball" and may see the LLC tighten and form underneath the deep convection as 92L becomes more symetrical overnight.

[HURAKAN]

Great Loop: http://rammb.cira.colostate.edu/ramsdis ... _floater_1

[Blown Away]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
254 PM EDT MON AUG 11 2008

.DISCUSSION...

...INCREASED STORM CHANCES AGAIN HEADING INTO TUESDAY...

.CURRENT-TONIGHT...DEWPOINT VALUES IN THE LOWER/MIDDLES 60S
TELLING THE STORY AGAIN ACROSS MUCH OF OUR NORTH AS THE CU FIELDS
ARE RATHER POOR. FURTHER SOUTH ACROSS ST. LUCIE...OKEECHOBEE AND
MARTIN COUNTIES CU FIELDS ARE A BIT BETTER AS MOISTURE IS DEEPER.
WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE BEGUN TO
DEVELOP AND EXPECT A BIT HIGHER COVERAGE OVER THE SOUTH THROUGH
THE REST OF THE AFTERNOON. REMAINS TO BE SEEN IF THE EAST COAST
SEA BREEZE CAN MAKE AN APPEARANCE LATER THIS AFTERNOON TO HELP
ENHANCE CONVECTION ALONG THE TREASURE COAST. IN THE MEANTIME...THE
GFS IS STILL ADAMANT ON BRINGING A SHORTWAVE FEATURE SOUTH DOWN
THE PENINSULA LATE THIS AFTERNOON/EARLY EVENING. NOT CONFIDENT
THAT NORTHERN AREAS WILL BE ABLE TO TAP THIS ENERGY BUT AREAS
SOUTHWARD MAY BE ABLE TO HARNESS IT LATER DOWN THE ROAD. IN THE
ZONES WILL LEAVE SCHC POPS (SHRAS) NORTH AND CHC POPS (TSRA) SOUTH
THROUGH SUNSET. INTERESTING ENOUGH THE GFS...THROUGH RECENT FLIP-
FLOPS IN ARRIVAL OF DEEPER MOISTURE TIMING...IS NOW BRINGING SOME
OF IT INTO OUR NORTHERN AREAS OVERNIGHT AND WILL KEEP CURRENT SCHC
POPS (SHRAS) LATE FOR THIS AREA. LOWS CONTINUE IN THE LOWER/MIDDLE
70S.

.TUE...UPPER TROUGH AXIS SITUATED ALONG THE EAST COAST TO FINALLY
PUSH EASTWARD DURING THE DAY. THIS WILL ALLOW SOUTHWEST FLOW TO
RETURN ONCE AGAIN TO THE MID-LEVELS AS ANOTHER SHORTWAVE WITH
ASSOCIATED UPPER ENERGY DIVES SOUTHEASTWARD ACROSS THE GULF COAST
STATES. AT THE SURFACE...RIDGING WILL REMAIN SUPPRESSED ACROSS THE
SOUTHERN PENINSULA. SHORT RANGE MODELS SUGGEST POOLING MOISTURE OVER
CENTRAL FLORIDA WITH LOW PRESSURE DEEPENING JUST NORTH OF FLORIDA.
EXPECT AN ABOVE NORMAL COVERAGE OF SHOWERS AND THUNDERSTORMS DURING
THE AFTERNOON HOURS TOMORROW WITH 60% POPS NORTH AND 50% POPS SOUTH.
SHORT TERM MODELS PROGGING MORE CLOUD COVER AROUND DURING THIS DAY
SO WILL HIGHLIGHT PARTLY CLOUDY EARLY AND CONSIDERABLE CLOUDINESS
MOST AREAS...ESPECIALLY NORTHERN 2/3RDS...FOR THE AFTERNOON. WILL KEEP
TEMPERATURES IN THE UPPER 80S TO AROUND 90 DEGREES NEAR THE COAST
AND AROUND 90 DEGREES TO LOWER 90S INLAND.

.WED-THU...PERIOD FORECAST FINDS LOWERING PRESSURE OVER THE DEEP
SOUTH WITH ASSOCIATED CONCENTRATED MOISTURE (FRONTAL TROUGH) PUSHING
DOWN INTO NORTH FLORIDA. SURFACE RIDGE AXIS STAYS WELL SOUTH
KEEPING PREVAILING LOW LEVEL WESTERLIES IN PLACE FOR CENTRAL
FLORIDA. THE EFFECT WILL SUPPORT AN INCREASE IN CONVECTIVE
ACTIVITY. HOWEVER...NOT A SIGNIFICANT EXTENT OF MID LEVEL COOLING
OR MID LEVEL INSTABILITY...EVEN THOUGH THE UPPER TROUGH DIGS
TOWARD THE NORTH GULF AND INCHES EASTWARD.

.FRI-SUN (EXTENDED)...FROM PREVIOUS MORNING AFD...PRECIP CHANCES
BEGIN TO DECREASE SLIGHTLY BY THE END OF THE WEEK INTO THE WEEKEND
AS UPPER LEVEL RIDGING BEGINS TO TAKE FORM OVER THE EAST COAST AND
HIGH PRESSURE RIDGE BEGINS TO MOVE NORTH AND SETTLE BACK OVER
CENTRAL FLORIDA. THIS WILL GENERATE DEEPER SUBSIDENCE ACROSS THE
CWA. MOISTURE WILL STILL BE GREAT ENOUGH HOWEVER TO KEEP LOW END
SCATTERED POPS IN THE FORECAST.

NWS Melbourne, some clues that may help determine the path of 92L. The timing
of the ridge building is consistent with the models and what Jeff Master's was
talking about. If 92L speeds up then the trough may catch 92L. Again it's all
about the timing.

[KWT]

There is little to no shear over the system.

Maybe I'm not totally sure, the convection still seems to be on the northern side of any circulation. LLC was last seen on the Vis imagery to the SE of the deep convection, only slightly mind you but it became difficult to track as the sun went down, either because it was tucking into the convection or it was opening back up again.