Pouch PGI50L in NW Carribean - Code Orange - (Is Invest 96L)

[Vortex]

18Z GFS H168 ensembles over SFL....



http://raleighwx.easternuswx.com/models ... cal168.gif

[Vortex]

GFS 18Z GFS ensmbles at H180 over SE FL and the adjacent waters..



http://raleighwx.easternuswx.com/models ... cal180.gif

[Ivanhater]

As soon as I posted it, the image went blank

[Ivanhater]

[gatorcane]

GFS 18Z GFS ensmbles at H180 over SE FL and the adjacent waters..



http://raleighwx.easternuswx.com/models ... cal180.gif

That trough is unbelievable. Will it really dig into the central gom? Wow.

[Vortex]

18Z Nogaps just sits down there over the NW carribean very slowly moving NNE...notice the vorticity it spins off to the N...I wonder if thats what the GFS was doing and leaving the main low behind then moving out of the carribean late next weekend???


https://www.fnmoc.navy.mil/wxmap_cgi/cg ... t=Tropical

[Vortex]

Im starting to think this circulation is very large(monsoon low) and takes longer to develop a core and sits in place basically down there this upcoming week...while at the same time multipe vorticities spin around the larger circulation....

[ronjon]

Whatever forms down there, the long range models show a ton of moisture getting pulled over the peninsula. Wouldn't be surprised to see 10+ inches rain over a large portion of the peninsula over the next week.

[hurricaneCW]

I have a feeling that this system won't be completely tropical due to its very large circulation, especially if it really gets involved with that huge trough. Could have some baroclinic enhancement like Wilma did. The upcoming week will be very interesting indeed.

[otowntiger]

18Z GFS H168 ensembles over SFL....



http://raleighwx.easternuswx.com/models ... cal168.gif

Yeah, but extremely weak. 1006mb? That's a depression at best.

[jlauderdal]

notice on the ecm ensembles at 12Z H120...folks when you see the ensembles with pressures under 1000mb there is going to be something ready for lift off..


http://raleighwx.easternuswx.com/models ... SLP120.gif

how about the squeeze play between the low in the carib and that little high in the atl

[psyclone]

well i am defintely cheering on a big rain producer for florida. let 'er dump. a good 5 to 10 inches over the peninsula over a couple of days would be a benefit.

[sfwx]

http://www.accuweather.com/blogs/news/s ... ential.asp

Gulf Coast Tropical Potential Late Next WeekBy Brian Edwards, Meteorologist

Sep 25, 2010; 2:05 |
AccuWeather.com meteorologists are monitoring the potential for additional tropical development in the northwestern Caribbean, which may impact a portion of the Gulf Coast late next week.

Recently weakened Tropical Depression Matthew continues to track through Belize and Guatemala. Matthew will continue to bring heavy rain and breezy conditions from Belize into southern Mexico the remainder of the weekend into early next week before the feature dissipates over southern Mexico.

A separate feature currently located over the central Caribbean will slowly track eastward through early next week. The feature will be in an area favorable for tropical development, as sea surface temperatures are running between 1 and 2 degrees Celsius above normal.

Along with the warm waters, light winds aloft will promote very slow movement of this feature into the middle of next week, which will allow for gradual tropical development to occur.

Long-range forecast models show that a potential tropical storm or hurricane, which would be named Nicole, could track northward late next week toward the Gulf Coast region.

According to AccuWeather.com Hurricane Expert Joe Bastardi, "Whether it is Matthew, or a reformed version of it, perhaps with the name Nicole, a hit is coming for Florida later next week, then the storm could move north into the Southeast and mid-Atlantic states."


The storm would be steered in between two areas of high pressure, one located over the southern Plains and another over the central and eastern Atlantic. Depending on the location of the high pressure systems, this storm could take a northward track toward the Gulf Coast or Florida.

Bastardi states, "This pattern is now akin to something one sees off Africa, but in the Caribbean, where one storm is followed by another."

Tropical moisture associated with this potential feature may be drawn even farther northward next week, helping to produce more substantial rainfall totals in the remainder of the East during the first part of "Troptober."

[johngaltfla]

18Z GFS ensembles at H144..near SW FL..I must be looking at the wrong thing Ivan




http://raleighwx.easternuswx.com/models ... cal144.gif

Gee thanks. 5 years without boarding up and now I've got this nagging sense......

[Vortex]

Irene in 1999 appears to be an excellent analog for this storm.

Exerpt from wikipedia on Irene:


A broad area of low pressure formed over the western Caribbean Sea on October 8, and it persisted until October 11, when a tropical wave reached the area and caused the convection to organize, resulting in the development of a low-level circulation. Convection increased and organized around the circulation's center late on October 12, and the system organized into Tropical Depression Thirteen on October 13 off the north coast of Honduras. The depression continued to organize over the favorable conditions present in the Caribbean Sea, and attained tropical storm status later on the 13th, when it was assigned the name Irene.[1] Operationally, the system remained a tropical wave until it already reached tropical storm strength.[3]

Tropical Storm Irene strengthened as it moved northward, and reached maximum sustained winds of 70 mph (115 km/h) early on October 14. Operationally, Irene was upgraded to a hurricane on the 14th, although later analysis after the hurricane season indicated it remained a tropical storm until later. Irene continued to move towards the north-northeast, crossed over the western portion of the Isla de la Juventud as a strong tropical storm, and hours later, it struck mainland Cuba near Batabano. The storm was able to strengthen further over the Florida Straits, and Irene attained hurricane status on October 15. It passed over Key West, turned more to the north-northeast, and struck mainland Florida at Cape Sable as an 80 mph (130 km/h) hurricane.[1]


Hurricane Irene at peak intensityIrene entered the Atlantic Ocean near Jupiter, Florida early on October 16, still as a Category 1 hurricane. It turned to the north, remained a hurricane despite little convection, then turned to the northeast in response to an approaching upper-level trough. Just offshore, Irene moved parallel to the coastlines of South Carolina and North Carolina on October 17. On October 18, as it interacted with very warm ocean waters and the upper level trough, Irene rapidly intensified, reaching peak winds of 110 mph (175 km/h) with a pressure of 952 mbar, a Category 2 hurricane. Despite its strength, the circulation was very asymmetrical, and the convection was not particularly organized. The hurricane continued to accelerate to the northeast, steadily weakening until becoming extratropical on October 19 to the south of Newfoundland. The extratropical storm continued to the northeast until becoming absorbed by another, larger extratropical storm late that same d

[otowntiger]

18Z GFS ensembles at H144..near SW FL..I must be looking at the wrong thing Ivan




http://raleighwx.easternuswx.com/models ... cal144.gif

Gee thanks. 5 years without boarding up and now I've got this nagging sense......

I don't think you'll need to board up for a 1007 mb low pressure area. Of course intensity forecasting is really just guessing I know but many of the models are only turning this event into a large almost subtropical low pressure system affecting a large area mostly in the form of clouds and rain.

[AJC3]

18Z GFS H168 ensembles over SFL....

http://raleighwx.easternuswx.com/models ... cal168.gif

Yeah, but extremely weak. 1006mb? That's a depression at best.

EEK! You're totally misinterpreting what an ensemble forecast mean is! Do not...I repeat...do NOT try and mistake an ensemble forecast mean for a deterministic model forecast!!!

What you're looking at is an AVERAGE of several deterministic model runs. Variations within the ensemble members of not only in the strength, but also placement of a surface low center, is going to "water down" the presentation of the surface pressure field in the ensemble mean, and often to a significant extent. An ensemble mean of surface pressure (and any other parameter for that matter) will invariably be both WEAKER and have a BROADER presentation than the great majority of it's ensemble members.

[Vortex]

Irene in 1999 appears to be an excellent analog for this storm.

Exerpt from wikipedia on Irene:


A broad area of low pressure formed over the western Caribbean Sea on October 8, and it persisted until October 11, when a tropical wave reached the area and caused the convection to organize, resulting in the development of a low-level circulation. Convection increased and organized around the circulation's center late on October 12, and the system organized into Tropical Depression Thirteen on October 13 off the north coast of Honduras. The depression continued to organize over the favorable conditions present in the Caribbean Sea, and attained tropical storm status later on the 13th, when it was assigned the name Irene.[1] Operationally, the system remained a tropical wave until it already reached tropical storm strength.[3]

Tropical Storm Irene strengthened as it moved northward, and reached maximum sustained winds of 70 mph (115 km/h) early on October 14. Operationally, Irene was upgraded to a hurricane on the 14th, although later analysis after the hurricane season indicated it remained a tropical storm until later. Irene continued to move towards the north-northeast, crossed over the western portion of the Isla de la Juventud as a strong tropical storm, and hours later, it struck mainland Cuba near Batabano. The storm was able to strengthen further over the Florida Straits, and Irene attained hurricane status on October 15. It passed over Key West, turned more to the north-northeast, and struck mainland Florida at Cape Sable as an 80 mph (130 km/h) hurricane.[1]


Hurricane Irene at peak intensityIrene entered the Atlantic Ocean near Jupiter, Florida early on October 16, still as a Category 1 hurricane. It turned to the north, remained a hurricane despite little convection, then turned to the northeast in response to an approaching upper-level trough. Just offshore, Irene moved parallel to the coastlines of South Carolina and North Carolina on October 17. On October 18, as it interacted with very warm ocean waters and the upper level trough, Irene rapidly intensified, reaching peak winds of 110 mph (175 km/h) with a pressure of 952 mbar, a Category 2 hurricane. Despite its strength, the circulation was very asymmetrical, and the convection was not particularly organized. The hurricane continued to accelerate to the northeast, steadily weakening until becoming extratropical on October 19 to the south of Newfoundland. The extratropical storm continued to the northeast until becoming absorbed by another, larger extratropical storm late that same d

this is what KWT was referring to and I agree should the 18Z GFS pan out in similar fashion with a digging trough/shear...





On October 18, as it interacted with very warm ocean waters and the upper level trough, Irene rapidly intensified, reaching peak winds of 110 mph (175 km/h) with a pressure of 952 mbar, a Category 2 hurricane

[sfwx]

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
146 PM EDT SAT SEP 25 2010

VALID 12Z TUE SEP 28 2010 - 12Z SAT OCT 02 2010


MID LEVEL CUT OFF LOW DEVELOPMENT AND LOCATION IN THE SHORT RANGE
STILL LEAVES SOME FORECAST PROBLEMS BUT OVERALL MODELS AND
ENSEMBLES ARE IN GOOD AGREEMENT WITH THE PATTERN EVOLTUION AS SEEN
BY SUBJECTIVE COMPARISON AND OBJECTIVE COMPARISON OF LAGGED
AVERAGE FORECASTS AND RELATIVE MEASURE OF PREDICTABILITY OF GFS
ENSEMBLES. RIDGING BUILDS BACK OVER WRN CONUS WHILE THE DOWNSTREAM
ERN CONUS CUT OFF LOW LIFTS OUT IN PIECES DAYS 3 AND 4 TUES/WED
BUT LEAVES BEHIND A MEAN TROF AXIS ALONG 85W. CLOSED MID LEVEL
HIGH UNDER WRN RIDGING SHIFTS ITS CENTER TO EAST OF THE FOUR
CORNERS REGION LATE WEEK. BY DAYS 6-8 FRI/SUN MODEL AND ENSEMBLES
AGREE ON THE OVERALL PATTERN OF SIGNIFICANT WRN CONUS RIDGING AND
A CONTINUED MEAN DOWNSTEAM ERN CONUS TROF. THE 00Z ECMWF IN
PARTICULAR LATE PERIOD DROPS ANOTHER DIGGING SHORTWAVE INTO THE
DOWNSTREAM MEAN TROF RESULTING IN HT ANOMALIES THAT EXCEED 5
STANDARD DEVIATIONS BELOW NORMAL. THIS IS EXCESSIVE AND A
PERSISTENT MODEL BIAS OF OVER AMPLIFICATION OF ERN CONUS TROFS. A
BETTER AGREED UPON ENSMBLES MEAN SOLUTION PREFERRED WITH AGAIN
TODAY THE 00Z ECMWF ENS MEAN PREFERENCE USED AS A BASE FOR PROG
CHARTS AND H500S.

WHILE THE ENS MEANS OF GFS AND ECMWF ARE SIMILAR AND EITHER COULD
BE USED AFTER DAY 5 OVER CONUS THE HPC PREFERENCE IS TOWARDS THE
00Z ECMWF ENS MEAN BASED ON ITS HANDLING OF THE TROPICAL LOW
FORMATION IN THE WRN CARIBBEAN AND ITS SLOWER AND MORE WWD LIFT
NORTHWARD BY THE END OF THE PERIOD. CMC HAS BEEN CONSISTENTLY FAST
WITH ITS EJECTION INTO FL DAYS 4 AND 5 WITH THE 00Z ECMWF PICKING
IT UP BY DAY 5 AND RUNNING IT UP OFF THE ERN SEABOARD DAY 7 SAT.
UKMET HOLDS THE CIRCULATION BACK NEAR YUCATAN THURSDAY NIGHT WITH
GFS OVER CENTRAL CUBA WHERE IT ONLY SLOWLY MOVES BEFORE IT IS
PICKED UP BY LATE SATURDAY AND EJECTED NEWD. BOTH GFS AND ECMWF
ENS MEANS KEEP THE CIRCULATION CENTER IN THE ERN GLFMEX NEAR THE
WRN FL COAST BY DAY 7. WHILE HIGHLY UNCERTAIN THIS IS A BETTER
MATCH TOWARDS THE LAGGED AVERAGE FORECAST LOCATION AND THE
TENDENCY FOR MODELS TO EJECT CARIBBEAN/LOWER GLFMEX SYSTEMS TOO
FAST.

06Z/12Z GFS RUNS HANDLING THE WRN CARIBBEAN SYSTEM HAVE A LARGE
SPREAD IN TRACK AND TIMING YIELDING A LOW CONFIDENCE HIGH
UNCERTAINTY FORECAST. LATEST 12Z CMC MUCH SLOWER THAN ITS PRIOR
RUN WHILE THE UKMET CONTINUES TO KEEP THE CIRCULATION NEAR
YUCATAN. THIS CONTINUED WIDE ARRAY OF SOLUTIONS WILL KEEP THE HPC
SOLUTION NEAR THE SLOWER ECMWF AND GFS ENS MEANS. AGAIN A LOW
CONFIDENCE FORECAST.

[SouthFloridawx]

Just looked at the 18z GFS. Looks like multiple Lows being shot up through Florida, huh?