Model Runs & Discussions of GOM-Bahamas

[LaBreeze]

Our local mets have not mentioned any area east of Florida. They are concentrating more (it seems) on whatever might develop in the Western Carib. and moving into the GOM. They might change their "talk" later today if things are changing.

[skysummit]

I still don't understand where this "potential" Carribean system came
from. The talk (models & NWS discussions) has always been something in upper levels coming across Fl. and moving westward across the GOM and acquiring tropical characteristics.

Wrong....a couple days ago, every model except the Canadian was developing a southern Caribbean system and moved it north into the Gulf. Now, most have jumped ship and are agreeing on the east coast system moving west into the Gulf.

[Stormcenter]

Our local mets have not mentioned any area east of Florida. They are concentrating more (it seems) on whatever might develop in the Western Carib. and moving into the GOM. They might change their "talk" later today if things are changing.

Well I was referring to discussions like this from the NWS in Lake Charles, LA and not local TV mets.

FORECAST FOR THE END OF THE WEEK THROUGH THE WEEKEND REMAINS FRAUGHT
WITH UNCERTAINTY...AS THERE HAS BEEN PRECIOUS LITTLE RUN TO RUN
CONSISTENCY OR AGREEMENT AMONGST THE MEDIUM RANGE MODELS WITH REGARD
TO THE UPPER LOW AND ANY ASSOCIATED SURFACE LOW PRESSURE. THE
GENERAL IDEA IS FOR AN AREA OF SFC LOW PRESSURE TO DEVELOP OVER THE
SE GOMEX THURSDAY MORNING IN ASSOCIATION WITH THE UPPER LOW...THEN
TRACK WESTWARD THROUGH THE GULF FRIDAY AND THROUGH THE WEEKEND. THE
LATEST GFS HAS COME IN A LITTLE SLOWER THAN ITS PREVIOUS RUN...AND
THE ECMWF HAS SHIFTED SOUTH OF ITS PREVIOUS RUN. FOR THE TIME
BEING...WILL MAINTAIN CURRENT FORECAST AS IS. THIS FITS WELL WITH
GFS ENSEMBLE MEAN...WHICH IS CLOSER TO THE ECMWF TIMING AND A
COMPROMISE BETWEEN THE OP GFS AND ECMWF POSITIONS.

[Stormcenter]

I still don't understand where this "potential" Carribean system came
from. The talk (models & NWS discussions) has always been something in upper levels coming across Fl. and moving westward across the GOM and acquiring tropical characteristics.

Wrong....a couple days ago, every model except the Canadian was developing a southern Caribbean system and moved it north into the Gulf. Now, most have jumped ship and are agreeing on the east coast system moving west into the Gulf.

Well I'm sorry if I missed it but everything I've read from NWS discussions acoss the board in the last several days has primarily mentioned the FL to GOM scenario only. Now why they didn't discuss the southern Carribean is not for me to answer.

Now the morning discussion out of N.O., LA. does refer to the Carribean wave after mentioning the FL. to GOM scenario.

LONG TERM...
THE GFS/ECMWF REMAIN FAIRLY CONSISTENT SHOWING THE MID/UPPER LOW
BECOMING STACKED AND BUILDING DOWN TO THE SURFACE AS IT MOVES
SLOWLY WEST ACROSS THE EASTERN GULF OF MEXICO WEDNESDAY THROUGH
EARLY FRIDAY. THIS WOULD NOT NORMALLY BE THE TYPE OF SYSTEM THAT
WOULD DEVELOP INTO A PURE TROPICAL CYCLONE...AT LEAST NOT VERY
FAST...HOWEVER...WILL HAVE TO MONITOR THE WAVE THAT IS MOVING
THROUGH THE CENTRAL CARIBBEAN SEA. SEE THE TROPICAL WEATHER
OUTLOOK FROM NHC/TPC FOR ADDITIONAL DETAILS.

[skysummit]

The 12z NAM shows a low pressure center just off the coast of Jacksonville in 84 hours. Also still showing a little something in the Caribbean...

[southerngale]

Stormcenter, someone asked you last night when you seemed confused to read Jeff's post on page 22 of the other thread. It doesn't seem like you did, so here's the thread:

http://www.storm2k.org/phpbb2/viewtopic.php?f=31&t=97987&st=0&sk=t&sd=a&start=420


Maybe that will help you.




Edit:

Well I'm sorry if I missed it but everything I've read from NWS discussions acoss the board in the last several days has primarily mentioned the FL to GOM scenario only. Now why they didn't discuss the southern Carribean is not for me to answer.

Actually, the "potential" Caribbean system has been mentioned quite a bit.

[MiamiensisWx]

If the model prognosis is correct, I highly doubt any significant development will occur in the E Gulf of Mexico. It's a classic non-tropical cutoff low, and some models have a bias (develop a sfc low too quickly). Upper-level 500 mbar flow is reflective of shear (check the GFS operational run). Personally, I think development is much more probable off the Carolinas. If that is the case, a NE movement (away from the Gulf) is a realistic outcome. A classic "fish" scenario or Carolinas impact (hybrid-type development/transition to a tropical cyclone) should be monitored. The Gulf and Caribbean are not terribly favorable in the model guidance. Ingrid will not regenerate in the Bahamas; its remnant circulation will spin down when it is sheared by the TUTT axis.

Here's the operational GFS 500 mbar pattern (~48 hours).

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/00/images/gfs_500_048l.gif

200 mbar:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/00/images/gfs_300_048l.gif

It doesn't show any significant feature. The Euro follows a similar tune, too. Interestingly, the GFS brings a weak low-level system over south FL. It is unrelated to the Caribbean wave and Ingrid's remnants. It is probably the convection E of the Bahamas - click here for the recent shortwave imagery. The operational suite has been quite consistent about the evolution of this feature in recent runs.

850 mbar heights at ~48 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/00/images/gfs_850_048l.gif

Personally, the mid to upper levels don't look promising for development in the short term. Shear is quite inhibitive over the W Atlantic basin.

[skysummit]

The 12z GFS has begun rolling in if anyone wants to post it.

[Stormcenter]

Stormcenter, someone asked you last night when you seemed confused to read Jeff's post on page 22 of the other thread. It doesn't seem like you did, so here's the thread:

http://www.storm2k.org/phpbb2/viewtopic.php?f=31&t=97987&st=0&sk=t&sd=a&start=420


Maybe that will help you.




Edit:

Well I'm sorry if I missed it but everything I've read from NWS discussions acoss the board in the last several days has primarily mentioned the FL to GOM scenario only. Now why they didn't discuss the southern Carribean is not for me to answer.

Actually, the "potential" Caribbean system has been mentioned quite a bit.

I did read it and after doing so I believe there are way too many intangibles that need to happen for anything of any consequence to form coming from the Carribean and somehow interacting with the FL. disturbance. As a ProMet mentioned the most you will get out of this is a sheared system in the GOM coming across via FL. the way things look now. Yes I know things can change but that is how I see it right now. I'm only stating my opinion.

[Ed Mahmoud]

MiamiensisWx


Not in the short term, no.


But, while I am not suggesting anything like an Humberto situation, would point out that Humberto also started as a disturbed area on an old front near Florida.


So the potential is there for a system, the farther South it starts, the farther West it comes, that starts as a non-tropical system and changes. The Texas thing on models is a product, IMHO, of where they develop the surface low at. Of course, when it develops, is also a factor to where it goes. Later and weaker is farther West.


And if I'm in Louisiana, especially, although Texas and Alabama/Mississippi/Western FLA P'handle should keep an eye open, I'd think what would Humberto have become if it had started development 12 hours earlier. Probably a Cat 2.


Fairly big target area if something develops, because until something does develop, won't know where it does develop.

In my very uneducated and not particularly bold stand, I'll say 60/40 we get an Invest out of this, and 40/60 it will become at least a named or numbered tropical cyclone.

[MiamiensisWx]

Recently, I've been monitoring the model guidance trends, and I've noticed an intriguing persistent feature in the recent GFS runs (short term). Interestingly, the GFS brings a weak low-level system over south FL. It is unrelated to the Caribbean wave and Ingrid's remnants. It is probably the convection E of the Bahamas - click here for the recent shortwave imagery. The operational suite has been quite consistent about the evolution of this feature in recent runs.

850 mbar heights at ~48 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/00/images/gfs_850_048l.gif

I'm starting to wonder about the prospects of Bahamian development off SE Florida, especially when Ingrid's low-level remnants reach the area. Conditions are quite hostile now, and model guidance doesn't show any improvement at the upper levels within the short term. Interestingly, the operational GFS suite, ensembles, and Euro develop a nice 500 mbar ridge over the W Atlantic. If the TUTT-related shear relaxes, things could become more interesting. Most people have been focused on the Caribbean and Gulf, but the Bahamas have been ignored.

Additionally, the 12Z GFS (rolling out) shows the feature E of the Bahamas again:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/12/images/gfs_ten_012l.gif

The Euro shows a weak sfc low over south FL (~72 hours), too:

ECMWF (~72 hours)

What do you think about development prospects in that vicinity?

[southerngale]

Stormcenter, someone asked you last night when you seemed confused to read Jeff's post on page 22 of the other thread. It doesn't seem like you did, so here's the thread:

http://www.storm2k.org/phpbb2/viewtopic.php?f=31&t=97987&st=0&sk=t&sd=a&start=420


Maybe that will help you.




Edit:

Well I'm sorry if I missed it but everything I've read from NWS discussions acoss the board in the last several days has primarily mentioned the FL to GOM scenario only. Now why they didn't discuss the southern Carribean is not for me to answer.

Actually, the "potential" Caribbean system has been mentioned quite a bit.

I did read it and after doing so I believe there are way too many intangibles that need to happen for anything of any consequence to form coming from the Carribean and somehow interacting with the FL. disturbance. As a ProMet mentioned the most you will get out of this is a sheared system in the GOM coming across via FL. the way things look now. Yes I know things can change but that is how I see it right now. I'm only stating my opinion.

I don't see anyone arguing with your opinion on how strong anything that possibly develops could get... that wasn't even what we were talking about. Nobody knows if anything will even develop or how strong it will be if it does. You were saying you didn't know where the "potential" Caribbean system came from, so we were telling you where it came from.

[jdray]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
346 AM EDT MON SEP 17 2007

...LOCAL NOR`EASTER CONDITIONS EXPECTED THROUGH WED...

.SYNOPSIS...MSAS ANALYSIS SHOWS A TIGHT PRESSURE GRADIENT ALONG THE
COAST AS AN INVERTED TROUGH DEVELOPS OFFSHORE AND SFC HIGH PRESSURE
CONTINUES TO WEDGE DOWN THE LEE OF THE APPALACHIANS. OUR GA COASTAL
SITES HAVE BEEN REPORTING SUSTAINED 20 MPH WINDS WITH GUSTS UP TO 30
MPH OUTSIDE OF CONVECTION. BANDS OF CONVECTION ARE IMPACTING OUR
COASTAL WATERS AND COASTAL FL ZONES AS THEY ROTATE SSW AROUND THE
WEST SIDE OF THE INVERTED COASTAL TROUGH. ALOFT WATER VAPOR IMAGERY
SHOWS A VORT CENTER OVER VA/NC AND A DEEPENING ATLANTIC COAST
TROUGH.

.SHORT TERM...TODAY THROUGH WED...
THE UPPER LEVEL VORTEX NOW OVER THE MID-ATLANTIC REGION WILL ADVANCE
SSW AND AMPLIFY THE LOW LEVEL COASTAL TROUGH OFFSHORE OF THE SE
SEABOARD THROUGH LATE WED WHICH WILL CONTINUE LOCAL NOR`EASTER
CONDITIONS. WINDY AND DREARY CONDITIONS WILL AFFECT OUR EASTERN
ZONES FROM ST SIMONS ISLAND SSW TOWARD GAINESVILLE THROUGH MID WEEK
WITH BELOW NORMAL MAX TEMPS AND ABOVE NORMAL MINS DUE TO ABUNDANT
LOW LEVEL MOISTURE. EXPECT A TIGHT POP GRADIENT WITH NEAR NIL ACROSS
OUR NW GA ZONES TO HIGH CHANCE ACROSS OUR SE FL ZONES WERE DEEPER
MOISTURE AND STRONGEST LOW LEVEL CONVERGENCE WILL RESIDE AND BRING
BANDS OF CONVECTION ONSHORE. LAKE WIND ADVISORIES WILL BE NEEDED FOR
AT LEAST THE COAST AND POSSIBLY CLAY AND PUTNAM COUNTIES THROUGH WED
WITH SPEEDS 20-25 MPH AND GUSTS OF 30-35 MPH OUTSIDE OF CONVECTION.

.LONG TERM...THU THROUGH SUN...
INCREASED UPPER LEVEL FORCING AND DEEP MOISTURE WARRANT AT LEAST
LIKELY POPS WED NIGHT-THU AS THE SFC TROUGH ADVANCES INLAND AS THE
UPPER LOW RETROGRADES OVER THE GULF. A FEW STRONG STORMS MAY BE
POSSIBLE THU-THU NIGHT WITH COOLER TEMPS ALOFT AND UPPER LEVEL
FORCING FROM VORTICITY LOBES ROTATING NWD AROUND THE UPPER LOW. FRI
INTO SUN MODELS INDICATE LINGERING MOISTURE AS HIGH PRESSURE BUILDS
TO OUR EAST BRINGING A WARMER SSE FLOW TO OUR AREA. EXPECT MAINLY
DIURNAL CONVECTION AND TEMPS WARMING TO NEAR OR SLIGHTLY ABOVE CLIMO
VALUES IN THE MID-UPPER 80S AND MINS IN THE UPPER 60S TO LOWER 70S.

&&

.AVIATION...MVFR CONDS ARE POSSIBLE DURING FREQUENT SHOWERS
ESPECIALLY AT JAX...CRG AND SSI AS COASTAL SHRA MOVE ONSHORE.
OTHERWISE CIGS WILL BE ABV 3 KFT. WILL INCLUDE VCTS AT GNV FROM
MID TO LATE AFTN. WINDS WILL BE SUSTAINED ABV 12 KT MOST OF THE
DAY WITH FREQUENT GUSTS TO 25 KT.

&&

.MARINE...SEAS ARE RUNNING 8 TO 10 FT IN GA WATERS AND THE SURGE
WILL CONTINUE PUSHING SWD INTO THE FL WATERS. WINDS ARE NE 20-25
KT WITH GUSTS TO 30 KT OFFSHORE AND NEAR 20 KT NEAR THE COAST.
RIPS CURRENTS WILL REMAIN AT HIGH RISK NEXT COUPLE DAYS. BREAKERS
ARE EXPECTED TO BE 5-7 FT AND WILL HOLD OFF ISSUING HIGH SURF ADV
ATTM...BUT WILL MONITOR TODAY FOR PSBL HIGHER BREAKERS. SEE THE
COASTAL HAZARDS STATEMENT.


==================================

Nice ULL right now, Lake Wind advisories due to pressure gradient, this might help it to spin up.

[MiamiensisWx]

The recent consistency in the GFS (ensembles/operational suite) and Euro has been remarkable, in my opinion. These models are generally regarded as the "meat" in the meteorological community, and they have been showing this feature for numerous runs in the same time frame. The 12Z GFS really picks up the prospects of a sfc low developing over the Bahamas. It moves the system W toward FL:

~42 hours

[chadtm80]

Stormcenter, someone asked you last night when you seemed confused to read Jeff's post on page 22 of the other thread. It doesn't seem like you did, so here's the thread:

http://www.storm2k.org/phpbb2/viewtopic.php?f=31&t=97987&st=0&sk=t&sd=a&start=420


Maybe that will help you.




Edit:

Well I'm sorry if I missed it but everything I've read from NWS discussions acoss the board in the last several days has primarily mentioned the FL to GOM scenario only. Now why they didn't discuss the southern Carribean is not for me to answer.

Actually, the "potential" Caribbean system has been mentioned quite a bit.

I did read it and after doing so I believe there are way too many intangibles that need to happen for anything of any consequence to form coming from the Carribean and somehow interacting with the FL. disturbance. As a ProMet mentioned the most you will get out of this is a sheared system in the GOM coming across via FL. the way things look now. Yes I know things can change but that is how I see it right now. I'm only stating my opinion.

No one said they dont understand that opinion.. However you had said that you dont understand why its being discussed when no models or NHC have discussed or shown it.. Well Models did show it, and NHC has mentioned it in the TWO's for the last couple days.. so.. I dunno...

[skysummit]

12z GFS @ 66 Hours....broad low in southeastern gulf.

[MiamiensisWx]

DISCUSSION...
MODELS AGREE OVER THE NEXT 2 DAYS. ALOFT...A BREAK DEVELOPS IN THE
SUBTROPICAL RIDGE WITH FLA IN A COL BETWEEN THE GREAT PLAINS AND
ATLC HIGH PRES CELLS. BY LATE TUES...AN INVERTED TROUGH DEVELOPS
EXTENDING FROM THE CARIB N TO OFF OF THE MID ATLC COAST U.S. COAST
WITH A CLOSED UPPER LOW DEVELOPING E OF CENTRAL FLA OVER THE ATLC.
AT THE SURFACE...THE FRONTAL SYSTEM BECOMES DIFFUSE NEAR LAKE OKEE
WHILE THE BUILDING HIGH PRES RIDGE OVER THE E U.S...COMBINED WITH AN
INVERTED TROUGH FROM THE CARIB NE ACROSS THE BAHAMAS...PRODUCES A
SUSTAINED NE WIND FLOW. THEN THINGS BECOME MUDDLED FROM WED ON. NAM
BRINGS THE CLOSED LOW SLOWLY TOWARD S FLA AND OVER THE S CENTRAL
COAST BY THU MORN WHILE THE GFS MOVES THE UPPER LOW OFF THE SW
COAST. THIS CHANGES STEERING FLOW AND AMOUNT OF MOISTURE
AVAILABLE.

FOR THE SHORT TERM...TODAY THROUGH TUE NIGHT...ENE WIND FLOW IN
MOIST ATMOSPHERE WILL MAINTAIN TYPICAL S FLA PRECIP PATTERN OF
NOCTURNAL ACTIVITY ATLC/E COAST AND OFFSHORE GULF WATERS WITH
DIURNAL MAINLY INTERIOR AND W ACTIVITY.

EXTENDED PERIOD...WED THROUGH SUN...IF GFS RIGHT...UPPER LOW
MOVES INTO GULF AND DEEP TROPICAL MOISTURE PULLED OVER S FLA
LEADING TO COPIUS RAIN POSSIBLE UNTIL UPPER LOW MOVES FAR ENOUGH W
AND HIGH PRES REBUILDS ALOFT OVER S FLA TO MITIGATE RAINFALL. IF
NAM TREND CONTINUES...WITH UPPER LOW OVER S FLA...E COAST MAY SEE
MORE POSSIBILITY OF RAIN WED DUE TO SW FLOW ALOFT WITH LESS W
COAST AS AREA WOULD BE UNDER SUBSIDENT SIDE OF UPPER LOW. WRAP
AROUND MOISTURE WOULD INCREASE POPS W INTO LATTER PART OF WEEK
WITH A DRY SLOT MOVING UP FROM THE CARIB OVER S FLA. AT THIS
JUNCTURE WILL LEAVE EXTENDED POPS ALONE UNTIL UPPER LOW DEVELOPS
AND MOVEMENT DISCERNED.

NWS Miami discussion

[skysummit]

12z GFS @ 78 Hours...low moving west toward central gulf.

[MiamiensisWx]

The operational GFS brings the developing sfc low into the Gulf of Mexico. Note the nice UL ridge and more conducive conditions (low-level convergence and UL support) for development in the W Atlantic and GOM. I think Steve's great post in the main models thread holds some merit here. The setup looks mildly similar to Katrina and Rita (interaction between sfc trough and tropical wave spawns cyclogenesis off SE Florida).

~78 hours

500 mbar heights

The GFS develops this system in the short term, while the Euro brings it over south FL later in the period (~72 hours). Interestingly, the remnants of Ingrid could interact with the sfc trough, while instability and decreasing shear supports slow tropical development moving W through the Bahamas and southern Florida. The GFS deepens the low in the GOM and moves the system toward TX and W LA:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/12/images/gfs_ten_114l.gif

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/12/images/gfs_ten_138l.gif

Wow - this thread has +98 views and no comments from others. What do y'all think?

[Steve]

Some of you people are nuts and apparently just want to have something out there that put you in a super positive or super negative (on development) camp so you can come back and stake some kind of weather-weenie claim. Really.

All you have to do is look for pattern reversal which has pre-indicated several developments this year (as it does almost every year). I don't understand what's so hard to see. You have an upper trough splitting away and behind it, you're going to have a surge coming off south america, a low (possibly mid or upper) cutting across Florida and a wave moving in from a little farther north than the tropical surge. So basically we're going to end up with high pressure aloft sitting atop the interesection of a tropical wave and tropical surge. Either it forms or it doesn't, but the opportunity is there. To say to stick a fork in something that hasn't even started yet is crazy. And for anyone who says, "I don't see anything there", that would be correct. Nothing is. Surge and wave intersection would be Tuesday or Wednesday. Possible landfall might be Friday or Saturday. And this will happen quick if it does. There's not going to be 72 hours of advance warning. It's going to be more like Humberto where people would say, "wow, I didn't see that coming." (That's because they didn't pay attention to the signs or storm2k.) Now we don't know whether something is or isn't going to form, but if it does, look out.

Steve <---- Putting actual thought into the post and leaving the cockiness and absolutes out.