Tropical Depression LORENZO: Discussions & Images

[HURAKAN]

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 AM EDT TUE SEP 25 2007

FOR THE GULF OF MEXICO...

SHOWER ACTIVITY WITH THE AREA OF LOW PRESSURE IN THE SOUTHWESTERN
GULF OF MEXICO IS CURRENTLY DISORGANIZED...AND SURFACE OBSERVATIONS
SHOW NO DEVELOPMENT HAS OCCURRED DURING THE NIGHT. HOWEVER...UPPER
LEVEL WINDS ARE BECOMING MORE FAVORABLE...AND THIS SYSTEM COULD
BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS IT DRIFTS
SLOWLY AND ERRATICALLY. AN AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT IS SCHEDULE TO INVESTIGATE THE SYSTEM LATER TODAY...IF
NECESSARY.


ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$

FORECASTER BEVEN

[HURAKAN]

LATEST:

[wxman57]

It hasn't moved any northward overnight. Surface obs show it's just west of that SW Gulf buoy now. Heaviest convection is near the low center, though it's not very heavy yet. Shear continues to drop off. Look for gradual development today. No TD at 10am CDT, maybe by 4pm after recon investigates. I don't think they'll cancel this recon.

[HURAKAN]

LATEST:

[cycloneye]

A. 25/1600Z
B. AFXXX 01KKA INVEST
C. 25/1345Z
D. 22.0N 94.0W
E. 25/1530Z TO 25/1930Z
F. SFC TO 10,000 FT

If they go today,plane departs at 9:15 AM EDT.I agree with wxman57,they will go.

[HURAKAN]

LATEST:

[Terry]

A 1009 MB LOW IS OVER THE SW GULF OF MEXICO NEAR 22N94W. A SFC
TROUGH EXTENDS THROUGH THE LOW FROM NEAR BROWNSVILLE TO THE
YUCATAN ALONG 26N97W 22N94W 20N92W. DISORGANIZED SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ARE FROM 21N-27N BETWEEN
90W-96W. UPPER LEVEL WINDS ARE BECOMING MORE FAVORABLE...AND
THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY
OR SO AS IT DRIFTS SLOWLY AND ERRATICALLY. AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT IS SCHEDULE TO INVESTIGATE THE SYSTEM
LATER TODAY...IF NECESSARY.

...
DISCUSSION...

GULF OF MEXICO...
THE MAIN WEATHER FEATURE ACROSS THE GULF IS THE AREA OF LOW
PRES LOCATED OVER THE SW GULF WHICH COULD BECOME A TROPICAL
CYCLONE OVER THE NEXT COUPLE OF DAYS. SEE SPECIAL FEATURES
ABOVE. ABUNDANT DEEP LAYER MOISTURE IS OVER THE BASIN BETWEEN
87W-95W. THIS IS ASSOCIATED WITH THE SPECIAL FEATURE IN THE SW
GULF IN ADDITION TO LIFT AHEAD OF AN UPPER TROUGH OVER THE FAR
WRN GULF. AN UPPER RIDGE CONTINUES TO DOMINATE MUCH OF THE
CENTRAL GULF...WITH THE AXIS NOW EXTENDING NE BETWEEN THE BAY OF
CAMPECHE TO SE LOUISIANA. VERY DRY MID TO UPPER AIR IS BEING
ADVECTED INTO THE NE GULF AROUND AN UPPER TROUGH EXTENDING INTO
THE AREA FROM THE WRN ATLC...WHILE MOISTURE AND SCATTERED SHOWER
ACTIVITY PERSISTS OVER THE SE GULF...FL KEYS...AND STRAITS OF
FLORIDA. ELSEWHERE AT THE SFC...RIDGING EXTENDS INTO THE NE GULF
AROUND HIGH PRES CENTERED NEAR MID ATLANTIC COAST. RIDGING WILL
PERSIST OVER THE NRN GULF THROUGH WED WHILE LOW PRES MEANDERS IN
THE SW PORTION.

[Thunder44]

It looks like convection is diminishing around the center again. If it doesn't refire soon, they may cancel recon for today again.

[HURAKAN]

It looks like convection is diminishing around the center again. If it doesn't refire soon, they may cancel recon for today again.

It seems to be increasing: http://www.ssd.noaa.gov/goes/flt/t4/sloop-avn.html

[HURAKAN]

Latest:

[Extremeweatherguy]

The convection appears to be decreasing around the center and increasing further north. I still think there is a chance that we will see a center reformation or relocation today.

[Thunder44]

It looks like convection is diminishing around the center again. If it doesn't refire soon, they may cancel recon for today again.

It seems to be increasing: http://www.ssd.noaa.gov/goes/flt/t4/sloop-avn.html

That convection is well north of the center. The center is around 22N 94W and the convection earlier over it, has diminished.

[xironman]

The loss of convection to the north is absolutely striking in the SWIR loop http://www.ssd.noaa.gov/goes/flt/t4/sloop-ir2.html. I have been bullish on this system, but it just can't seem to stay together. Maybe today's decrease in shear will assist it.

[wxman57]

I see convection increasing about 60 miles north of the center and building slowly southward toward the center. Good chance it'll b declared a TD this afternoon when recon checks it out. Good chance it'll become a TS tomorrow. With wind shear low Thu-Sat before it moves inland into Mexico, it could well become a hurricane.

[Johnny]

wxman, send that son of a gun up our way. I'm in need of some good ol tropical type weather..say a strong tropical storm. I think everyone here wouldn't mind feeling some nice breezy conditions with tropical downpours....AWWWWWWWWWWWWWWWW.

[Portastorm]

Yeah Wxman57 ... I'm with Johnny on this. You need to do your job a little better and get us a little rain and some nice breeze. This Mexico landfall business won't work! Besides, you don't have any plans for this weekend now do you?

[xironman]

Your right, from the first couple of visuals http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20CONUS&lat=23&lon=-94.5&zoom=1&type=Animation&info=vis&numframes=4 it looks ready to go.

[wxman57]

Sorry, I have bicycling plans for the weekend (like every weekend). I'm not sending "Lorenzo-to-be" here. Just snapped a GARP image. You can see the LLC very clearly near 22N/95W. Heavy convection is about 60 miles NNE of the center and slowly building southward. Also note the recent blow-up of storms south of the center. TD by 4pm CDT today as recon will confirm.

[jasons2k]

From Jeff Lindner:

IR images and surface observations over the western Gulf of Mexico suggest an area of low pressure remains this morning about 300 miles SE of Brownsville. Upper air winds remain strong from the SW and dry air is being entrained from TX and MX keeping thunderstorms at a minimum with this system. The upper air pattern is expected to become more favorable over the next 24-36 hours allowing deeper convection to fire over the center.

Track:

Building high pressure over TX should result in a weak NE to N steering flow over the system resulting in a rare SW to S movement. Upper air pattern setup is similar to powerful hurricane Roxanne in 1995 which sat over the Bay of Campeche for several days during October. If the system develops it will likely drift to the SW and possibly S over the next 3-5 days and may still be in the Bay of Campeche late this weekend. High pressure over TX will begin to move eastward this weekend however the system should be buried far enough south to not feel the approach of the next trough/weakness over TX by late this weekend.

Intensity:

Once the shear relaxes there is little to keep this system from ramping up. It is interesting to note that really none of the global models show much development of this system…maybe dry air entrainment from the N as a front drops down off the TX coast this weekend. However, past experience with slow moving late season storms in the Bay of Campeche suggest significant intensification is possible and I am leaning more toward this solution than the lack of intensification. In fact we could very well have a hurricane by late Thursday or Friday and I would not rule out a major hurricane as long as the system maintains enough forward motion to prevent significant upwelling.

Recon mission is planned for this afternoon.

[wxman57]

Jeff's assessment looks good. Here's a McICAS shot showing the center. Note the increasing squalls south of the center now, a sign of decreasing shear. No doubt this will be TD 13 this afternoon if the trend continues. May have time to reach hurricane intensity before it moves inland into Mexico to the WSW-SW by late Friday or Saturday.

For those of you who've forgotten Roxanne from 1995:
http://weather.unisys.com/hurricane/atlantic/1995/ROXANNE/track.gif