ATL: GABRIELLE - Remnants - Discussion

[ozonepete]

When is D-Max?

Diurnal maximum and minimum. During the day it is diurnal minimum over water because, the surrounding air has less specific heat capacity than the sea,and thus warms faster, but cools down faster during the night. During the night time, the water is typically warmer than the surrounding air. Now the air near the surface which is in contact with the water warms by conduction, and then begin to rise. The during the day, the warming of the air which is above the water creates a quasi-capping inversion, inhibiting convection. Keep in mind that air rises from the surface to the higher levels, so when the air warmer than the sea during the day, it acts as a lid.

From weather underground.

I love weather underground but they miss the boat on this one. The most important part is that the tall thunderstorms needed for development are driven by the very large difference between the warm tropical maritime air below the storms and the very cold air high up above at the thunderstorm tops. During the day the incoming solar radiation gradually heats the tops of the clouds and this reduces the difference in temp from bottom to top of the thunderstorms which causes weakening. At night the solar input is lost and the cloud tops grow colder, allowing the thunderstorms to intensify and build even higher.

[ninel conde]

im less convinced of a recurve. i think a recurve is highly dependent on the double low remaining intact which seems unlikely.

[Blown Away]

Nearly all the guidance we see now shows a WNW movement to just north of Hispaniola and then sharp NNE turn...

[SFLcane]

Naked swirl in a few hrs... Please go away

[TJRE]

Cimms -Mid-Level Shear 0000Z


The chart also shows the direction of the shear - so we can see it is a clockwise flow right over the lower to mid-circ right now. That doesn't tell us anything about the upper flow so I would never use this chart to determine if there's a beneficial upper high over it. If you want to know that just use their upper level wind chart, ok?

Thanks O.P.

UNDERSTOOD!!!
TJ

the GOES severe page has some nice Sat coverage here
http://www.goes.noaa.gov/g8severe.html



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[cycloneye]

Updated discussion from the San Juan NWS.


AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
939 PM AST TUE SEP 3 2013

.SYNOPSIS...SUBEQUATORIAL RIDGE WILL BUILD OVER PR BY THU AND
ESTABLISH BETWEEN THE DOM REP AND PR THROUGH THE END OF THE WEEK.
WEAK AREA OF LOW PRES OVR THE ERN CARIB WILL MOVE WNW PASSING
SOUTH OF PR WED NIGHT AND MOVE NORTH OF HISPANIOLA FRI.

&&

.DISCUSSION...GLOBAL MODELS CONTINUE TO PAINT A VERY WET SCENARIO
FOR PR THROUGH THE END OF THE WEEK FIRST ASSOCIATED WITH THE MID
LEVEL CIRCULATION OVER THE ERN CARIB WED-WED NIGHT THEN WITH A
LONG FETCH SE FLOW THU-FRI AS MID LEVEL CIRCULATION LIFTS NORTH
OF HISPANIOLA. HOWEVER...SOME DIFFERENCES STILL SHOW UP ON THE
MODELS WITH RESPECT TO TIMING OF WHEN THE PERIOD OF MOST INTENSE
RAINFALL WILL OCCUR WITH GFS SHOWING WED-WED NIGHT AND ECMWF
INDICATING WED NIGHT-THU. ANYWAY...MOISTURE...LIFT AND
INSTABILITY LOOK PRETTY IMPRESSIVE WED-FRI TO SUSTAIN LONG PERIODS
OF HEAVY RAINFALL AND WHEN YOU ADD TOPOGRAPHY INTO THE MIX
POTENTIAL IS THERE FOR SIGNIFICANT THREE-DAY RAINFALL TOTALS. IS
NOT REALLY UNTIL SAT WHEN LOW-LEVEL CONVERGENCE WEAKENS ENOUGH TO
NOT LONGER SUPPORT LONG PERIODS OF RAIN. BUT EVEN THEN...MOIST
SSE FLOW WILL KEEP SHOWERS IN THE FCST THROUGH EARLY NEXT WEEK. IS
NOT UNTIL LATE MON WHEN TRADES FINALLY ESTABLISH OVER THE REGION
AND ATMOSPHERE RETURNS TO NORMAL.

LOOKING AT SATELLITE TRENDS IT APPEARS TO ME THAT THE GFS TIMING
OF LATE WED THRU WED NIGHT WILL BE THE PERIOD OF MOST INTENSE
RAINFALL. ALSO...SATELLITE BASED RAINFALL ESTIMATES OVER THE PAST
24 HRS SHOW 4-8 INCHES FELL OVER A LARGE AREA TO THE EAST OF THE
ANTILLES. WHEN YOU LOOK AT A THREE-DAY EVENT AVERAGE AMOUNTS
TYPICALLY AVERAGE OUT TO 10 INCHES. WHEN LOOKING AT THE CURRENT
FLOOD WATCH WE ARE CALLING FOR 3-6 INCHES OF RAIN BEFORE FRI
MORNING. I BELIEVE OUR CURR FORECAST IS UNDERDONE AND WILL BE
RAISING TOTALS TO MATCH UP SATELLITE BASED RAINFALL ESTIMATES
WHICH COULD BE CONSERVATIVE.

[WYNweather]

When is D-Max?

Diurnal maximum and minimum. During the day it is diurnal minimum over water because, the surrounding air has less specific heat capacity than the sea,and thus warms faster, but cools down faster during the night. During the night time, the water is typically warmer than the surrounding air. Now the air near the surface which is in contact with the water warms by conduction, and then begin to rise. The during the day, the warming of the air which is above the water creates a quasi-capping inversion, inhibiting convection. Keep in mind that air rises from the surface to the higher levels, so when the air warmer than the sea during the day, it acts as a lid.

From weather underground.

I love weather underground but they miss the boat on this one. The most important part is that the tall thunderstorms needed for development are driven by the very large difference between the warm tropical maritime air below the storms and the very cold air high up above at the thunderstorm tops. During the day the incoming solar radiation gradually heats the tops of the
clouds and this reduces the difference in temp from bottom to top of the thunderstorms which causes weakening. At night the solar input is lost and the cloud tops grow colder, allowing the thunderstorms to intensify and build even higher.

Thanks

[ozonepete]

Well be careful, Luis. Looks like a serious flood threat.

[ozonepete]

I really am puzzled by this whole scenario. More than once in the last 24-48 hours both have started behaving as if they're developing separately, as it looks right now, and I get tempted to think that both could develop into two separate storms. Although that would be a really rare occurrence, it's not unheard of. (So you are asking a good question Hammy. )

[cycloneye]

:uarrow: Well be careful, Luis. Looks like a serious flood threat.

Yes,our main threat regardless of what this turns out to be is the rainfall.Here is one model of rainfall that is forecasting a dire situation.

[ninel conde]

I really am puzzled by this whole scenario. More than once in the last 24-48 hours both have started behaving as if they're developing separately, as it looks right now, and I get tempted to think that both could develop into two separate storms. Although that would be a really rare occurrence, it's not unheard of. (So you are asking a good question Hammy. )

too close together.

[ROCK]

whats to close together? these 2 entities are not that close.

[ozonepete]

I really am puzzled by this whole scenario. More than once in the last 24-48 hours both have started behaving as if they're developing separately, as it looks right now, and I get tempted to think that both could develop into two separate storms. Although that would be a really rare occurrence, it's not unheard of. (So you are asking a good question Hammy. )

too close together.

Not at all. I said it's not unheard of, which means I have actually seen systems this close develop into two separate TCs a number of times, especially over the tropical Pacific where it is more common.

[ozonepete]

whats to close together? these 2 entities are not that close.

thanks, rock. And I'm getting more of a feeling we may be watching that rare event. Now THAT would help make this a season to remember.

[SeGaBob]

Convection seems to be waning a bit but i do see new storms forming near 15.5N 63.5W.

I may be a little bit off though because I'm not so great with coordinates.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

[ninel conde]

I really am puzzled by this whole scenario. More than once in the last 24-48 hours both have started behaving as if they're developing separately, as it looks right now, and I get tempted to think that both could develop into two separate storms. Although that would be a really rare occurrence, it's not unheard of. (So you are asking a good question Hammy. )

too close together.

Not at all. I said it's not unheard of, which means I have actually seen systems this close develop into two separate TCs a number of times, especially over the tropical Pacific where it is more common.

john hope said they need to be at least 600 miles apart for both to develop.

[boca]

If both systems develop into separate systems then how would that affect the track of each one?

[cycloneye]

00z surface analysis tracks low thru Mona Channel.

[baytownwx]

I love reading this forum and learning as much as I can. With that said, for those that post links please use the URL tab and then copy the link in-between. This allows a new window to open. I don't know how many times tonight I have clicked on a link only to accidentally close out of my storm2k session. Thank you and keep up the great discussions!

[ninel conde]

If both systems develop into separate systems then how would that affect the track of each one?

joe bastardi has a theory about that. the trailing low might force the lead low more west. if both did develop i feel they would just march on out to sea, yet one may get left behind under the growing wheel.