INVEST 90L: Gulf of Mexico : Gone from NRL

['CaneFreak]

This is totally different than the setup for TD 10. There is no massive ULL to the west of this thing. This just might go tropical. For the first time in a while, I really think this might become an issue.

[Stormcenter]

What impresses me most with this system (as opposed to the last one), is the amount of heavy convection that has formed on the WEST side of the system. Could this convection/moisture "shield" the developing surface low near the Keys from the dry air over the Gulf?

BTW, I'm saying surface low near the keys based on this map (click on NWS fronts):
http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html

Also, of note, the above map now shows that the 1006 low has moved further west and has broken off from the front

Agree 100%

[rockyman]

so what's making the BAM models show a NNW movement with this low over the Keys?

http://icons.wunderground.com/data/images/at200790_model.gif

[rockyman]

[srainhoutx]

90L is up on NHC/TPC SAT Floater1 for those that are interested...

http://www.nhc.noaa.gov/satellite.shtml

['CaneFreak]

so what's making the BAM models show a NNW movement with this low over the Keys?

http://icons.wunderground.com/data/images/at200790_model.gif

Well, you have to remember, this model is designed for cyclones a little bit deeper than the low we are dealing with here. This model deals with the mid-to-upper level steering layers and this thing is no where near that deep yet.

[rockyman]

TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1308 UTC TUE OCT 2 2007

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL902007) 20071002 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
071002 1200 071003 0000 071003 1200 071004 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 24.3N 82.6W 25.3N 83.4W 27.0N 84.6W 28.8N 85.8W
BAMD 24.3N 82.6W 26.6N 83.8W 28.5N 85.5W 30.2N 86.9W
BAMM 24.3N 82.6W 26.0N 83.7W 27.8N 85.3W 29.5N 86.8W
LBAR 24.3N 82.6W 25.1N 84.6W 26.1N 86.8W 27.3N 88.7W
SHIP 25KTS 27KTS 31KTS 36KTS
DSHP 25KTS 27KTS 31KTS 36KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
071004 1200 071005 1200 071006 1200 071007 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 30.6N 87.3W 34.8N 89.1W 40.4N 88.3W 44.4N 82.1W
BAMD 31.7N 87.2W 34.0N 85.1W 33.3N 85.4W 34.6N 87.9W
BAMM 31.1N 87.9W 34.4N 87.7W 37.5N 87.3W 41.5N 84.6W
LBAR 28.5N 90.7W 30.9N 93.0W 35.4N 93.3W 42.4N 88.5W
SHIP 39KTS 34KTS 32KTS 31KTS
DSHP 32KTS 27KTS 27KTS 29KTS

...INITIAL CONDITIONS...
LATCUR = 24.3N LONCUR = 82.6W DIRCUR = 260DEG SPDCUR = 12KT
LATM12 = 24.9N LONM12 = 79.6W DIRM12 = 256DEG SPDM12 = 12KT
LATM24 = 25.2N LONM24 = 77.8W
WNDCUR = 25KT RMAXWD = 100NM WNDM12 = 30KT
CENPRS = 1006MB OUTPRS = 1010MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

[Windsurfer_NYC]

Today's Recon cancelled (not a surprise):

NOUS42 KNHC 021415
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1015 AM EDT TUE 02 OCTOBER 2007
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 03/1100Z TO 04/1100Z OCTOBER 2007
TCPOD NUMBER.....07-130

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (GULF OF MEXICO)
FLIGHT ONE --TEAL 70
A. 03/1800Z
B. AFXXX 01KKA INVEST
C. 03/1600Z
D. 24.0N AND 88.0W
E. 03/1700Z TO 2300Z
F. SFC TO 10,000FT

FLIGHT TWO --TEAL 71
A. 04/0600Z,1200Z
B. AFXXX 02KKA CYCLONE
C. 04/0300Z
D. 25.0N AND 90.0W
E. 04/0430Z TO 1200Z
F. SFC TO 10,000FT

2. OUTLOOK FOR SUCCEEDING DAY: CONTINUE 6 HRLY FIXES IF
SYSTEM DEVELOPS.
3. REMARKS: TASKING FOR 02/1800Z AND 03/0600Z ON THIS AREA
CANCELLED AT 02/1225Z.

II.PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
SEF

[Stormcenter]

Today's Recon cancelled (not a surprise):

NOUS42 KNHC 021415
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1015 AM EDT TUE 02 OCTOBER 2007
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 03/1100Z TO 04/1100Z OCTOBER 2007
TCPOD NUMBER.....07-130

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (GULF OF MEXICO)
FLIGHT ONE --TEAL 70
A. 03/1800Z
B. AFXXX 01KKA INVEST
C. 03/1600Z
D. 24.0N AND 88.0W
E. 03/1700Z TO 2300Z
F. SFC TO 10,000FT

FLIGHT TWO --TEAL 71
A. 04/0600Z,1200Z
B. AFXXX 02KKA CYCLONE
C. 04/0300Z
D. 25.0N AND 90.0W
E. 04/0430Z TO 1200Z
F. SFC TO 10,000FT

2. OUTLOOK FOR SUCCEEDING DAY: CONTINUE 6 HRLY FIXES IF
SYSTEM DEVELOPS.
3. REMARKS: TASKING FOR 02/1800Z AND 03/0600Z ON THIS AREA
CANCELLED AT 02/1225Z.

II.PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
SEF

I would have to say that I am surprised considering how poor looking some of the other
Invests have been in the past that they have in fact still sent recons into. This actually has more convection with it then TD10 ever did. IMO

[frederic79]

Good point, Rockyman. Just to add to your comments. 24-hour shear tendency map shows a vertical band of decreasing shear covering the entire eastern GOM. That's prime for development
even if given a limited amount of real estate to work with. We've all seen what can happen, once a bonifide depression forms, under the right conditions. Those include but aren’t limited to a moist environment, warm SST’s, little or no shear and an upper-level anticyclone. That’s not currently the case but as time passes things can change, one way or another.

[tolakram]

http://www.ssd.noaa.gov/goes/flt/t1/loop-wv.html

Looks like an upper air feature to me, why all the excitement?

['CaneFreak]

It may be an upper level feature tolakram but it has a heck of a better chance than 10L did of becoming at least a subtropical storm IMO.

[eaglegirl]

FLUS42 KTBW 020852
HWOTBW

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
452 AM EDT TUE OCT 2 2007

FLZ039-042-043-048>052-055>057-060>062-065-021500-
LEVY-CITRUS-SUMTER-HERNANDO-PASCO-PINELLAS-HILLSBOROUGH-POLK-
MANATEE-HARDEE-HIGHLANDS-SARASOTA-DE SOTO-CHARLOTTE-LEE-
452 AM EDT TUE OCT 2 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST CENTRAL AND SOUTHWEST
FLORIDA.

DAY ONE...TODAY.

..THUNDERSTORM IMPACT...
NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED TODAY AS A
WARM FRONT MOVES ACROSS THE STATE FROM THE EAST. HEAVY RAINS...BRIEF
GUSTY WINDS...AND OCCASIONAL CLOUD TO GROUND LIGHTNING ARE EXPECTED
AS THESE CELLS MOVE TOWARD THE NORTHWEST. IN ADDITION AN ISOLATED
TORNADO IS POSSIBLE NEAR THE FRONTAL BOUNDARY. THIS MORNING THE
FRONT WILL BE FOCUSED OVER THE CENTRAL PENINSULA. LATER THIS
AFTERNOON...EXPECT THE FOCUS TO SHIFT TO THE NATURE COAST COUNTIES.

DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

..THUNDERSTORM IMPACT...
DRY AIR WRAPPING AROUND AN UPPER LEVEL LOW CURRENTLY IN THE
SOUTHEAST GULF WILL LIMIT STORM COVERAGE WEDNESDAY...BUT AREA WILL
STILL SEE SCATTERED SHOWERS GIVEN AMPLE LOW LEVEL MOISTURE. THE
BEST COVERAGE IS EXPECTED ALONG THE WEST COAST FROM TAMPA BAY SOUTH
LATE IN THE AFTERNOON. BRIEF GUSTY WINDS...HEAVY RAINS...AND
OCCASIONAL CLOUD TO GROUND LIGHTNING ARE POSSIBLE AS WELL AS AN
ISOLATED WATERSPOUT OR FUNNEL CLOUD CAUSED BY INTERACTIONS BETWEEN
THE WEST COAST SEABREEZE AND ANY OUTFLOW BOUNDARIES FROM STORMS.

DEEP MOISTURE WILL RETURN THURSDAY THROUGH MONDAY PROVIDING A
SLIGHTLY BETTER CHANCE FOR SHOWERS AND STORMS. THE MAIN THREATS
EACH DAY WILL BE HEAVY RAINS...BRIEF GUSTY WINDS...AND FREQUENT
AND DANGEROUS CLOUD TO GROUND LIGHTNING.

SPOTTER INFORMATION STATEMENT...

SPOTTERS SHOULD MONITOR THE WEATHER AND SELF ACTIVATE IF NEEDED.

$$

SHARP

[rockyman]

http://www.ssd.noaa.gov/goes/flt/t1/loop-wv.html

Looks like an upper air feature to me, why all the excitement?

Because there is also a surface reflection...which means this is not a purely upper level feature...plus, we're just an excitable lot

[chadtm80]

TORNADO WARNING
Issue Date: 1022 AM EDT TUE OCT 02 2007
Expiration: 1100 AM EDT TUE OCT 02 2007

Expires:200710021500;;
WFUS52 KMLB 021420
TORMLB
FLC127-021500-
/O.NEW.KMLB.TO.W.0025.071002T1417Z-071002T1500Z/
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE MELBOURNE FL
1017 AM EDT TUE OCT 2 2007
THE NATIONAL WEATHER SERVICE IN MELBOURNE HAS ISSUED A
* TORNADO WARNING FOR...
NORTH CENTRAL VOLUSIA COUNTY IN EAST CENTRAL FLORIDA...
THIS INCLUDES THE CITIES OF...ORMOND BEACH...HOLLY HILL...
* UNTIL 1100 AM EDT
* AT 1016 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 15 MILES EAST OF
ORMOND BY THE SEA...OR ABOUT 15 MILES EAST OF ORMOND BEACH...
MOVING WEST AT 25 MPH.
* THE TORNADO WILL BE NEAR...
ORMOND BY THE SEA AND ORMOND BEACH BY 1040 AM EDT...
THE SAFEST PLACE TO BE DURING A TORNADO IS IN A STRONG BUILDING ON
THE LOWEST FLOOR...IN AN INTERIOR ROOM SUCH AS A BATHROOM OR CLOSET.
KEEP AWAY FROM WINDOWS. GET UNDER A WORKBENCH OR OTHER PIECE OF
STURDY FURNITURE. USE BLANKETS OR PILLOWS TO COVER YOUR BODY.
EVACUATE MOBILE HOMES OR VEHICLES FOR MORE SUBSTANTIAL SHELTER. IF NO
SHELTER IS AVAILABLE...LIE FLAT IN THE NEAREST DITCH OR OTHER LOW
SPOT AND COVER YOUR HEAD WITH YOUR HANDS. ABANDON YOUR VEHICLE IF THE
TORNADO IS NEARBY.
LAT...LON 2930 8097 2924 8097 2922 8098 2920 8122
2929 8120 2930 8117 2944 8117 2946 8109
TIME...MOT...LOC 1417Z 095DEG 18KT 2938 8080
$$

[Derek Ortt]

I'd watch the area east of the Bahamas. Visible is showing signs of mid level turning and the upper air support appears to be much better there

[Stormcenter]

Hmmmmm interesting comments from Jeff Masters this morning.

Heavy thunderstorms are on the increase over the southeastern Gulf of Mexico, several hundred miles west of Key West, in association with an upper-level low pressure system that is now generating an area of low pressure at the surface. This system is being referred to as "Invest 90L" by NHC. The buoy 262 nm south of Panama City, FL had winds of 36 mph gusting to 45 mph this morning, and there were ship reports this morning of winds of 25-33 knots (29-38 mph) in the eastern Gulf of Mexico. This morning's QuikSCAT pass showed a large area of 30-35 mph winds over the eastern Gulf of Mexico. Satellite loops show a steady increase in heavy thunderstorm activity, but the activity is not well-organized at present.

A surface area of low pressure was over the western Bahamas last night, several hundred miles east of the Gulf of Mexico upper level low. This Bahamas surface low was the initial suspect area we were watching (labeled "Invest 90L" by NHC). This surface low moved westward overnight, and is now underneath the upper low. This is a situation very much like we saw with Tropical Depression Ten last month, which also formed from an upper level low over the Gulf of Mexico. Like TD 10, 90L will probably start off as a subtropical depression. There will be a warm core to the storm at the surface, but the upper low has a cold core aloft. This will make the storm subtropical in nature--a system has to have a warm core all the way from the surface to the upper atmosphere to be truly tropical. 90L will gradually warm up its entire core and become tropical, but this will probably take two days. It took two days for TD 10 to become fully tropical, and it ran out of time to intensify when it moved ashore into the Florida Panhandle as a tropical depression. Until a subtropical system establishes a fully warm core, it cannot undergo rapid intensification. With a landfall expected Thursday or Friday in Louisiana or Texas, this does not give 90L much time to strengthen. There is plenty of warm water in the Gulf of Mexico to aid intensification, but hampering intensification will be dry, continental air from North America that is being pulled southward over the Gulf of Mexico by the counter-clockwise circulation around the upper low. This dry air is readily apparent on water vapor satellite loops (the brown colors). The most likely scenario is that 90L will make landfall as a tropical storm. The Hurricane Hunter mission scheduled for today has been canceled, since 90L is not organized enough to warrant a flight. The mission has been rescheduled for Wednesday afternoon.

[Sanibel]

Yeah, I was telling people on chat last night that this was the center of organization. Another TD10-like event. The overall trough is too dry and pocked with dry pockets - which is part of the 2007 atmosphere that is keeping formation limited. Once again the deep convection wheeled around us and we got nothing here in drought land. Like TD10, the LLC could form more poleward as they tend to do in weak systems like this.

[BigA]

The most likely scenario is that 90L will make landfall as a tropical storm.

I dont want to be a hair-splitter, but I wonder if this means Dr. Masters believes that the system becoming a tropical storm is the most likely of all scenarios, or merely the scenarios if 90L develops.

Looking at TWC online's Key West Radar, it looks like there is a turning west of Key West (unfortunately the radar goes blank)

It's wondrous hard to tell without any close in loops, but I think I do see some turning east northeast of the Bahamas. I wonder if this is what the CMC and GFS latch on to.

[BigA]

This isn't the TWC radar, but it is what I meant when I said there was a spin westnorthwest of Key West. http://www.intellicast.com/National/Rad ... imate=true

Unfortunately, it goes blank

If there is anything significant between this and TD 10, it looks like whatever low is going to form(or perhaps has formed)from this thing is a lot farther south than TD10, which may let it stay longer over water.