Tropical Development at Bahamas / GOM in comming days?

[cycloneye]

[Tampa Bay Hurricane]

all that's needed is some convection directly north of the center and directly
south to fill those blank spots and then folks the real development
may begin...

[Ed Mahmoud]

Still not runnin SHIPs on this.

[Tampa Bay Hurricane]

In order to get the SHIPS run and invest I think
convection has to just fill up all around it...notice
those two areas about north and then another about
south that are lacking in convection accoridng to the picture
that cycloneye posted.

I think we should have an invest tomorrow after the
convection surrounds the low fully and then it should
be upgraded to a subtropical storm tuesday or wednesday
since the winds according to the tropical weather discussion
are a Pressure Gradient Enhanced 30 knots...right now, and will
likely strengthen to 34 kts or perhaps even 40 kts as a subtropical
hybrid low.

[Ed Mahmoud]

Again, 100% on topic, while Euro shows something near TexMex border, HPC model discussion notes Euro initial surface low a couple of hundred miles too far South, and as we say in the world of petroleum engineering, where computer models are vital to assisting us in design "garbage in, garbage out."


just relevant part quoted...

DEEP CYCLONE FORMING IN THE CENTRAL BAHAMAS EXPECTED TO RETROGRADE
ACROSS THE FLORIDA STRAITS...
THE 12Z NAM/CANADIAN ARE NORTHEAST OF THE REMAINDER OF THE
GUIDANCE WITH THIS POTENTIAL SUBTROPICAL/TROPICAL LOW. THE
ECMWF/UKMET SOLUTIONS ARE THE MOST SOUTHERLY...BUT THE ECMWF
POSITION OF THIS LOW OVER THE NEXT 24 HOURS IS LIKELY HUNDREDS OF
MILES TOO FAR TO THE SOUTHWEST. THE 09Z COMBINED SREF
MEMBERS...AND 7 OF THE 12Z NCEP ENSEMBLE MEMBERS...ACTUALLY
SUPPORT THE NAM AND CANADIAN SOLUTIONS...ENOUGH SUPPORT THAT THEIR
FORECAST CANNOT BE DISCOUNTED. ANOTHER TROUBLING ASPECT OF THE
FORECAST IS THAT THE MODELS MOVE THE SYSTEM TOWARDS A
COL/SADDLEPOINT IN THE STEERING FLOW BY WEDNESDAY
MORNING...ARGUING AGAINST ANY FAST PROGRESSION BY MID-WEEK. THE
CANADIAN/NAM/GFS SOLUTIONS ARE SLOWLY TRENDING TOGETHER...WHICH
HAVE BOTH INITIALIZED THE LOW REASONABLY WELL AT 12Z. PREFER A
COMPROMISE SOLUTION BETWEEN THE NAM AND GFS FOR ITS TRACK AND
DEPTH OVER THE NEXT FEW DAYS.

ROTH

MODEL BIASES AT http://WWW.HPC.NCEP.NOAA.GOV

*edited by southerngale to add quotes Ed tried to add with edit, but hit quote instead

[ROCK]

Around 26N and 74W was where that LLC was spotted before night fall hauling SW. If its still there, I expect to see sheared convection over night sw to ne of those coordinates.....

[cpdaman]

with ull moving rather swiftly westward (already in easter gulf) and low pressure possibly taking shape further east then initialized will the upper level enviornment be any more favorable for development before florida impact

ACJ3 i would like your take if possible (when you get the chance)

[ROCK]

with ull moving rather swiftly westward (already in easter gulf) and low pressure possibly taking shape further east then initialized will the upper level enviornment be any more favorable for development before florida impact

ACJ3 i would like your take if possible (when you get the chance)

I agree.....ULL moving away rather quickly wsw. Maybe it could aid in development rather than hinder it as its doing now......

http://www.opc.ncep.noaa.gov/UA/Mexico.gif

[Dean4Storms]

I should clarify, I meant to say the 18z GFS loses a closed low over the central Gulf. It does not show a closed low moving inland.

[wxman57]

Way too much shear, and I see the upper low over SE Florida not the eastern Gulf. Come back in a few days.

[AJC3]

with ull moving rather swiftly westward (already in easter gulf) and low pressure possibly taking shape further east then initialized will the upper level environment be any more favorable for development before florida impact

AJC3 i would like your take if possible (when you get the chance)

My take is pretty much the same as before. Similar to what occurred with TD 10, the initial mechanism for any surface low development will be upward vertical motion caused by UL jet forcing (i.e. divergence aloft - a baroclinic process). I think we'll likely be looking at a rather broad, convectively "sloppy", sheared mess.

Based upon the consensus of global model guidance (see Chris's post/graphics earlier in this thread) It seems pretty dubious that any low that forms would ever wind up in a very favorable environment for true TC-genesis to take place. It may eventually, but I think IF that occurs it won't be for several days, since the best pressure falls are likely to follow the strongest divergence, and underneath a H25 jetstreak is not the best place to have a TC develop.

Still, much like TD 10, these processes will be occurring in the subtropics, over warm water, so when and if a closed low forms, it may acquire some tropical characteristics - perhaps enough to be eventually labelled as a STC or TC.

Bottom line...conditions strongly favor development of a non-tropical surface low, and any transition toward a STC or TC will be slow, if it happens at all.

[BigA]

Wherever the ULL is right now (and it does look like it is over Florida) it appears to be hauling westward at a good clip.

[Extremeweatherguy]

As wxman57 just pointed out..shear is way too high for any kind of development tonight or tomorrow. IMO, it looks like Tuesday or Wednesday will be the earliest for something to really get going. Once it starts spinning up though, then we will need to watch it closely.

[cycloneye]

ABNT20 KNHC 010230
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1030 PM EDT SUN SEP 30 2007

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A LARGE BUT DISORGANIZED AREA OF CLOUDINESS AND A FEW THUNDERSTORMS
IS LOCATED OVER THE WESTERN ATLANTIC...BAHAMA ISLANDS...AND
PORTIONS OF SOUTH FLORIDA. THIS ACTIVITY IS ASSOCIATED WITH AN
UPPER-LEVEL TROUGH AND A WEAK SURFACE LOW. SOME SLOW
DEVELOPMENT...PERHAPS OF A SUBTROPICAL NATURE...IS POSSIBLE DURING
THE NEXT COUPLE OF DAYS AS THIS SYSTEM MOVES SLOWLY WESTWARD OR
WEST-SOUTHWESTWARD.

$$

FORECASTER KNABB

[ROCK]

FWIW......NAM rolling in....


54hrs...

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _054.shtml

[ROCK]

72hrs.....FL panhandle it seems...


http://www.nco.ncep.noaa.gov/pmb/nwprod ... p0_072.sht
ml

78hrs....still sitting there off of FL....stall?

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _078.shtml


84hrs....and still sitting there off of FL.....

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _084.shtml

[hiflyer]

FXUS62 KMFL 010138
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
938 PM EDT SUN SEP 30 2007

.UPDATE...DEEP NORTHEASTERLY FLOW CONTINUES TO AFFECT S FLA WITH
SFC WIND GUSTS UP TO 40 MPH ALONG THE COAST. EARLIER CONVECTION
HAS DECREASED IN BOTH COVERAGE AND INTENSITY AND NOW IS ALL WELL
OFF THE SE CST. THE WRF MODEL SHOWS THE CONVECTION REMAINING
OFFSHORE BUT ONLY UP THROUGH ABOUT MIDNIGHT AND THEN ONCE AGAIN
DEVELOPS ANOTHER ROUND RIGHT ALONG THE IMMEDIATE COAST. THE 00Z
MFL SOUNDING SHOWS THE PWAT STILL HOVERING TWO INCHES WITH NE FLOW
UP THROUGH 50H SO IT NOT AT ALL OUT OF THE QUESTION FOR THE
REDEVELOPING CONVECTION NEARER THE COAST LATER TONIGHT. THEREFORE,
DO NOT PLAN TO MAKE ANY CHANGES TO EVENING UPDATES. THE MARINE
ZONES LOOK TO BE IN GOOD SHAPE AS WELL WITH THE STRONG NE WINDS
CONTINUING THIS WILL CERTAINLY CONTINUE THE THREAT FOR HIGH SURF
CONDITIONS ALONG PALM BEACH COAST AND HIGH RISK OF RIPS ATLC
BEACHES. 30/KOB


&&

.AVIATION...BASED ON CURRENT DATA FROM KAMX 88-D...IT APPEARS
THAT THERE MAY BE A SHORT BREAK IN THE SHRA ACTIVITY FOR MUCH OF
THE AREA EARLY THIS EVENING...WITH CURRENT SHRA/TSRA CONFINED TO
TERMINALS BETWEEN KHWO-KHST. CONVECTIVE ACTIVITY SHOULD BEGIN TO
REDEVELOP OVER THE ATLANTIC WATERS LATER THIS EVENING...AS STRONG
NORTHEAST FLOW CONTINUES ALONG NW PERIPHERY OF DEVELOPING LOW TO
MID-LEVEL CYCLONE OVER THE BAHAMAS. HIGHEST CHANCES FOR TSRA
APPEAR TO COME ROUGHLY FROM 01/11-22Z...BUT WILL ONLY MENTION
VCTS/CB AND LOWER CIGS AT THIS POINT. CONDITIONS MAY BEGIN TO
GRADUALLY IMPROVE EARLY MONDAY EVENING. AT KAPF...THERE ARE FEW
WEATHER-RELATED CONCERNS...WITH VFR CONDITIONS EXPECTED THROUGH AT
LEAST MID-MORNING ON MONDAY... WHEN TSRA CHANCES WILL BEGIN TO
INCREASE AS ACTIVITY APPROACHES FROM THE EAST. GUSTY NE WINDS WILL
CONTINUE AT ALL TERMINALS ON MONDAY... AND WILL PERSIST THROUGHOUT
THE FORECAST PERIOD FOR TERMINALS ALONG THE IMMEDIATE ATLANTIC
COAST. 70/DD

[MiamiensisWx]

Winds have been quite gusty along the east coast of Florida. Some SHRA should be moving toward the coast per Miami radar. The station at Fowey Rocks (off Key Biscayne, FL) is reporting gusts to 33 kts! Winds are lower at my location (still very breezy) W of Federal Highway and the Intracoastal when compared to the conditions over Atlantic coastal waters. It will be interesting if the adjacent upper low's baroclinic influence can spark another sfc low in the Bahamas (ala TD 10) - see WV imagery. Aviation interests should monitor those overnight NE cross winds at KMIA, KFLL, and KPBI (in addition to FLL Executive/KBCT).

http://www.ndbc.noaa.gov/station_page.php?station=FWYF1

[RL3AO]

They said the "s" word.

[Sanibel]

I just got an e-mail from the computer in my brain saying it sees a WV scenario in the west Atlantic/Caribbean that says if conditions suddenly became less hostile the area is ripe for development.