ATL: INVEST 95L - Discussion

[wxman57]

Question is, will this system/storm be already inland near Tampico by Friday evening and will that trof dig far enough south before then? I don't think the trof will be quick enough, but the system could move inland then stall and moisture be drawn NE up the front Sat PM/Sun. Complex situation - more so than Ingrid.

[Riptide]

On the 12z GFS 95L appears frontal while being a distinct low pressure system, could be a book-end developement. The trough is rather shallow and barely manages to carry 95L from the Bay of Campeche. Shear would not be very strong and the gradients help developement.

Will keep an eye on this one especially for Gulf Coast.

[wxman57]

Yeah, on the 12Z GFS it looks like 95L merges with the front on Saturday and its moisture is pulled NE.

[jconsor]

The GFS is likely overdoing the amplitude of the southern portion of the trough moving through the eastern US this weekend. It's had a persistent bias of doing this past 10 days and it's also a known model bias:

http://www.hpc.ncep.noaa.gov/mdlbias/
http://www.hpc.ncep.noaa.gov/mdlbias/biastext.shtml#GFS

IMHO the most likely outcome is that 95L gets within 50-75 miles of the Mexican coast before getting nudged eastward by the trough but not picked up. It would then have a chance to intensify in the southwest/south-central Gulf of Mexico as upper level winds become more favorable once the trough lifts out. The FIM and UKMET models have been consistently been showing this type of scenario, as have some ECMWF runs (not the most recent one).

[Riptide]

The GFS is likely overdoing the amplitude of the southern portion of the trough moving through the eastern US this weekend. It's had a persistent bias of doing this past 10 days and it's also a known model bias:

http://www.hpc.ncep.noaa.gov/mdlbias/
http://www.hpc.ncep.noaa.gov/mdlbias/biastext.shtml#GFS

IMHO the most likely outcome is that 95L gets within 50-75 miles of the Mexican coast before getting nudged eastward by the trough but not picked up. It would then have a chance to intensify in the southwest/south-central Gulf of Mexico as upper level winds become more favorable once the trough lifts out. The FIM and UKMET models have been consistently been showing this type of scenario, as have some ECMWF runs (not the most recent one).

It appears the 12z GFS is now developing two seperate systems; one in the Gulf and the other off the East Coast. Looks like convective feedback to be honest and a subtle move towards the Euro.

[Tireman4]

Yeah, on the 12Z GFS it looks like 95L merges with the front on Saturday and its moisture is pulled NE.

So, this is looking good for us (Houston) as a rainmaker?

[floridasun78]

Yeah, on the 12Z GFS it looks like 95L merges with the front on Saturday and its moisture is pulled NE.

So, this is looking good for us (Houston) as a rainmaker?

it be moving alway from Texas more toward florida and northern gulf

[cycloneye]

First mission will be on Wednesday afternoon.

Code: Select all

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1100 AM EDT TUE 17 SEPTEMBER 2013
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
         VALID 18/1100Z TO 19/1100Z SEPTEMBER 2013
         TCPOD NUMBER.....13-108

I.  ATLANTIC REQUIREMENTS
    1. SUSPECT AREA (BAY OF CAMPECHE)
       FLIGHT ONE -- TEAL 70          FLIGHT TWO -- TEAL 71
       A. 18/2000Z                    A. 19/1200Z
       B. AFXXX 01GGA INVEST          B. AFXXX 0211A CYCLONE
       C. 18/1700Z                    C. 19/0830Z
       D. 20.0N 91.5W                 D. 20.5N 94.0W
       E. 18/1630Z TO 18/2100Z        E. 19/1130Z TO 19/1530Z
       F. SURFACE TO 10,000 FT        F. SURFACE TO 10,000 FT

    2. SUCCEEDING DAY OUTLOOK:  CONTINUE 12 HOURLIES WHILE SYSTEM
       REMAINS A THREAT.


[Tireman4]

Yeah, on the 12Z GFS it looks like 95L merges with the front on Saturday and its moisture is pulled NE.

So, this is looking good for us (Houston) as a rainmaker?

it be moving alway from Texas more toward florida and northern gulf

Interaction with the front coming our way with the moisture is what I was aiming the question to be....

[storm4u]

im guessing they go 40/70 at 2pm

[SeGaBob]

If the Florida path verified would Georgia and South Carolina get rain from it or would it likely be in Southern Florida?

And I mean IF it went to Florida...answers are appreciated.

[Aric Dunn]

im guessing they go 40/70 at 2pm

I think they will up it.. but not sure they will go 70..

[gatorcane]

Not moving very fast, very slowly WNW:

Information as of the most recent model cycle

At 1200 UTC, 17 September 2013, LOW INVEST (AL95) was located in the North Atlantic basin at 18.0°N and 88°W. The current intensity was 25 kt and the center was moving at 3 kt at a bearing of 285 degrees. The minimum central pressure was 1006 mb.

http://www.ral.ucar.edu/guidance/realtime/plots/northatlantic/2013/al952013/

[chaser1]

Not sure who mentioned it (may have been from the 95L Discussion thread), but I would agree with a prior observation made this a.m., that 95L just doesn't look like its moving all that quickly. That, and its increasing organization might be causing pressures to further drop a bit and thus potentially aiding a temporary slow down or stall. That all said, I'd throw out all of the dynamic models at the moment at least until they might get a somewhat better handle of this system after a few runs. I might guess that a somewhat deeper and more organized system that perhaps exits the W. Yucatan Penninsula a few degrees further north might cause the dynamic modeling to better (or at least differently) analyze how this might gain more latitude in light of the possible breaking down of the ridging in the Northern Gulf. Timing IS everything, and if 95L were somehow able to sit and simmer for an additional day with not too much westward advance, than I could easily see a forming storm just entering the S.W. Gulf potentially moving towards the N.W. or even NNW.

Such a scenario could be a potential hurricane threat to the Central Texas coast, and perhaps depending on the timing of the trough that will be swinging through, could well even "push" the storm suddenly off to the East or ENE. I'm trying to remember such instances from the past but seem to think that those few circumstances that I remember something like that, there were also increasing upper level westerlies that impacted some shear (unless the system was negating that shear by its own changed forward motion). I recall other later season storms that responded to an approaching trough that just started to become baroclinic...but that was likely end of Oct. or Nov.

Bottom line, any near term increasing development along with a stall, slower WNW motion than anticipated, or simply a formation a little further north than earlier anticipated might make a significant impact in what comes out of this. How 95L develops might also prove out why some models were more robust on developing one single system that eventually threatens some part of the Conus, verses other models seeing a weaker and more southern forming system that follows Ingrid's path just to have yet another area of residual vorticity to then slide north along or ahead of the Eastward front over Florida.

Hey Mod's....sorry, this was meant for the 95L Models discussion and realized I somehow "parked" it here; feel free to delete or move

[cycloneye]

Uo to 40%-60%

AN AREA OF LOW PRESSURE LOCATED OVER BELIZE AND THE SOUTHERN YUCATAN
PENINSULA IS ACCOMPANIED BY CLOUDINESS AND THUNDERSTORMS. THIS
SYSTEM IS FORECAST TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND
EMERGE OVER THE BAY OF CAMPECHE ON WEDNESDAY. SURFACE PRESSURES ARE
LOW IN THIS AREA...AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE
FAVORABLE FOR DEVELOPMENT DURING THE NEXT DAY OR TWO. THIS LOW HAS
A MEDIUM CHANCE...40 PERCENT...OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS. ENVIRONMENTAL CONDITIONS SHOULD CONTINUE
TO BE GENERALLY CONDUCIVE FOR SOME ADDITIONAL DEVELOPMENT DURING
THE NEXT SEVERAL DAYS AS THE DISTURBANCE MOVES SLOWLY ACROSS THE
SOUTHERN GULF OF MEXICO. THIS SYSTEM HAS A HIGH CHANCE...60
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.
REGARDLESS OF TROPICAL CYCLONE FORMATION...THIS DISTURBANCE WILL
LIKELY SPREAD HEAVY RAINS OVER EASTERN MEXICO. THESE RAINS COULD
CAUSE LIFE-THREATENING FLOODS AND MUD SLIDES OVER AREAS ALREADY
IMPACTED BY THE TORRENTIAL RAINS ASSOCIATED WITH INGRID AND MANUEL.

[wxman57]

I don't see any scenario where this is a hurricane threat to the TX coast. The jet stream will be reaching the TX coast Friday night and strong westerly winds aloft will dominate the western Gulf through early next week.

[ronjon]

Yeah I'm thinking another sheared TS mess that is lopsided with all the weather on the east side. If this trof is as deep as the GFS predicts, then shear will probably be screaming out of the SW or W. Probably just a big rainmaker.

[stormlover2013]

might not be hurricane but could see this affect texas coast though..

[Alyono]

wonder why NHC is going with the southern Gulf solution. Looking more like a more northerly track now

[cycloneye]

Long Special Feature discussion:

A SURFACE TROUGH IS ALONG THE COAST OF THE NORTHWESTERN CORNER
OF THE CARIBBEAN SEA...FROM THE YUCATAN PENINSULA...THROUGH THE
GULF OF HONDURAS...INTO EL SALVADOR. A 1007 MB LOW PRESSURE
CENTER IS ALONG THE TROUGH NEAR 18N88W. CONVECTIVE
PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM HONDURAS AND
GUATEMALA ALONG 15N TO 19N IN THE YUCATAN PENINSULA BETWEEN 86W
AND 89W. NUMEROUS STRONG ALSO IN THE NORTHWESTERN CARIBBEAN SEA
FROM 18N TO 20N BETWEEN 79W AND 84W. SCATTERED STRONG IS
DEVELOPING FROM 14N TO 15N BETWEEN 81W AND 82W. THIS SYSTEM IS
FORECAST TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND EMERGE
OVER THE BAY OF CAMPECHE ON WEDNESDAY. SURFACE PRESSURES ARE LOW
IN THIS AREA...AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE
FAVORABLE FOR DEVELOPMENT DURING THE NEXT DAY OR TWO. THIS LOW
HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS. ENVIRONMENTAL CONDITIONS SHOULD CONTINUE TO BE
GENERALLY CONDUCIVE FOR SOME ADDITIONAL DEVELOPMENT DURING THE
NEXT SEVERAL DAYS AS THE DISTURBANCE MOVES SLOWLY ACROSS THE
SOUTHERN GULF OF MEXICO. THIS SYSTEM HAS A HIGH CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. THIS
DISTURBANCE WILL LIKELY SPREAD HEAVY RAINS OVER EASTERN MEXICO.
THESE RAINS MAY CAUSE LIFE-THREATENING FLOODS AND MUD SLIDES IN
AREAS THAT ALREADY HAVE BEEN IMPACTED BY THE TORRENTIAL RAINS
THAT HAVE BEEN ASSOCIATED WITH INGRID AND MANUEL...REGARDLESS OF
TROPICAL CYCLONE FORMATION. THE 24-HOUR RAINFALL TOTAL IN INCHES
FOR THE PERIOD ENDING AT 17/1200 UTC...ACCORDING TO THE PAN
AMERICAN TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN...IS
0.07 IN MERIDA IN MEXICO.