Tropical Depression Isaac:

[srainhoutx]

TROPICAL STORM ISAAC DISCUSSION NUMBER 29
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
400 AM CDT TUE AUG 28 2012

REPORTS FROM THE AIR FORCE HURRICANE HUNTER AIRCRAFT INDICATE THAT
THE CENTRAL PRESSURE HAS DROPPED A LITTLE MORE...BUT SO FAR...THE
MAXIMUM FLIGHT-LEVEL AND SFMR-OBSERVED SURFACE WINDS STILL DO NOT
QUITE SUPPORT HURRICANE INTENSITY. THE CURRENT INTENSITY IS HELD
AT 60 KT PENDING ADDITIONAL OBSERVATIONS FROM THE HURRICANE
HUNTERS. ALTHOUGH THE WIND FIELD REMAINS RATHER BROAD AND
RELATIVELY FLAT...RECENT AIRCRAFT DATA SUGGEST THAT THE MAXIMUM
WINDS ARE NOW OCCURRING SOMEWHAT CLOSER TO THE CENTER OVER THE
NORTHERN SEMICIRCLE OF THE CYCLONE. THIS WOULD SUGGEST THAT THE
INNER CORE CIRCULATION IS BECOMING BETTER DEFINED...AND
STRENGTHENING MIGHT BE IMMINENT. UPPER-LEVEL OUTFLOW IS
WELL-ESTABLISHED OVER THE SOUTHERN SEMICIRCLE OF THE SYSTEM...BUT
CENTRAL CONVECTION CONTINUES TO FLUCTUATE. THE LATTER IS
PRESUMABLY DUE TO A CONTINUED INTRUSION OF DRY AIR INTO THE CORE
REGION. THE STATISTICAL-DYNAMICAL GUIDANCE IS A LITTLE LOWER THAN
IN PREVIOUS RUNS...AND THE STORM HAS ONLY ABOUT 12-24 HOURS BEFORE
MOVING INLAND. THE OFFICIAL INTENSITY FORECAST IS JUST SLIGHTLY
LOWER THAN THE PREVIOUS ONE.

CENTER FIXES FROM THE AIRCRAFT INDICATE THAT THE STORM HAS WOBBLED
ON A GENERALLY WESTWARD COURSE OVER THE PAST FEW HOURS. THIS IS
BELIEVED TO BE TEMPORARY...HOWEVER...AND THE LONGER-TERM MOTION
ESTIMATE IS ABOUT 305/10. THE CURRENT AND FORECAST STEERING REGIME
ARE BASICALLY THE SAME AS IN THE PREVIOUS PACKAGE. ISAAC IS
EXPECTED TO MOVE INTO A WEAKNESS IN THE SUBTROPICAL RIDGE NEAR THE
NORTH-CENTRAL GULF COAST...WITH SOME SLOWING OF FORWARD SPEED
DURING THE NEXT COUPLE OF DAYS AS A RIDGE BUILDS A LITTLE TO THE
NORTHWEST OF THE CYCLONE. LATER ON...THE SYSTEM SHOULD TURN
NORTHWARD AND NORTHEASTWARD INTO THE OHIO VALLEY REGION AS IT MOVES
AROUND THE WESTERN PERIPHERY OF A MID-LEVEL ANTICYCLONE.

ISAAC IS A LARGE TROPICAL CYCLONE. A DANGEROUS STORM SURGE...HEAVY
RAINFALL...AND STRONG WINDS EXTEND WELL AWAY FROM THE CENTER AND
ARE EXPECTED TO AFFECT A LARGE PORTION OF THE NORTHERN GULF COAST.
FOR THIS REASON...IT IS IMPORTANT NOT TO FOCUS ON THE EXACT CENTER
LOCATION. THE THREAT OF HEAVY RAINFALL AND FLOODING IS ALSO
EXPECTED TO SPREAD INLAND OVER THE LOWER MISSISSIPPI VALLEY REGION
DURING THE NEXT FEW DAYS.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 27.5N 88.1W 60 KT 70 MPH
12H 28/1800Z 28.5N 89.1W 70 KT 80 MPH
24H 29/0600Z 29.5N 90.1W 75 KT 85 MPH...NEAR THE COAST
36H 29/1800Z 30.3N 90.9W 55 KT 65 MPH...INLAND
48H 30/0600Z 31.4N 91.5W 45 KT 50 MPH...INLAND
72H 31/0600Z 34.5N 92.5W 25 KT 30 MPH...INLAND
96H 01/0600Z 38.0N 91.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0600Z 40.5N 87.0W 15 KT 15 MPH...POST-TROP/REMNT LOW

$$
FORECASTER PASCH

[MRG93415]

WOW~~~~~ Ok soo now what? I already went and got propane and ice on Sunday just to be cautious because that stuff can always be used but now should we be rethinking anything or is he still gonna smack NO...I can see that he did some major change movement by the way everyone was talking...

[srainhoutx]

The latest surface analysis suggests that the trough has retreat back N overnight as High Pressure builds in the Mid Mississippi Valley. Isaac appears to have slowed and may become trapped under the building Ridge to the N which would tend to favor a drift of stalling for the next 12-24 hours. RECON is enroute and there will be additional data coming shortly. Stay tuned as things continue to develop and may change in the hours ahead.

[wxman57]

WOW~~~~~ Ok soo now what? I already went and got propane and ice on Sunday just to be cautious because that stuff can always be used but now should we be rethinking anything or is he still gonna smack NO...I can see that he did some major change movement by the way everyone was talking...

I still see no threat to Texas. Isaac is heading for southeast Louisiana.

[srainhoutx]

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 09:25Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 29
Observation Number: 22
A. Time of Center Fix: 28th day of the month at 8:43:20Z
B. Center Fix Coordinates: 27°26'N 87°58'W (27.4333N 87.9667W)
B. Center Fix Location: 213 miles (342 km) to the SSW (192°) from Pensacola, FL, USA.
C. Minimum Height at Standard Level: 1,239m (4,065ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 50kts (~ 57.5mph)
E. Location of the Estimated Maximum Surface Wind: 78 nautical miles (90 statute miles) to the NE (45°) of center fix
F. Maximum Flight Level Wind Inbound: From 143° at 71kts (From the SE at ~ 81.7mph)
G. Location of Maximum Flight Level Wind Inbound: 83 nautical miles (96 statute miles) to the NE (46°) of center fix
H. Minimum Sea Level Pressure: 977mb (28.85 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,526m (5,007ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 21°C (70°F) at a pressure alt. of 1,525m (5,003ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 21°C (70°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the southwest
M. Eye Shape & Diameter: Circular with a diameter of 32 nautical miles (37 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 2 nautical miles
Remarks Section:
Maximum Flight Level Wind: 78kts (~ 89.8mph) in the east quadrant at 7:52:00Z

[srainhoutx]

The 06Z GFS is looking eerily similar to what the 00Z Euro suggested...

[srainhoutx]

AF HH C-130 enroute from Ellington. Should arrive within an hour or so.

[srainhoutx]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
451 AM CDT TUE AUG 28 2012

.DISCUSSION...
A RELATIVELY QUIET EARLY MORNING ACROSS SOUTHEAST TEXAS TODAY
WITH LIGHT NORTHERLY WINDS AND JUST A FEW HIGH CLOUDS ACROSS THE
REGION COURTESY OF TROPICAL STORM ISAAC. FORECAST FOR TODAY
REMAINS RELATIVELY UNCHANGED AS DRIER MID LEVEL AIR IS EXPECTED TO
WORK INTO THE REGION. THIS WILL ALLOW TEMPERATURES TO WARM INTO
THE MID TO UPPER 90S ACROSS MOST OF SOUTHEAST TEXAS THIS
AFTERNOON. HAVE KEPT SLIGHT CHANCE POPS IN PLACE AS LOW LEVEL
MOISTURE REMAINS PRESENT BUT COVERAGE IS EXPECTED TO BE FAIRLY LOW
ACROSS THE REGION.

THE FORECAST FOR THE NEXT SEVERAL DAYS REMAINS RELATIVELY
UNCHANGED AS TROPICAL STORM ISAAC IS EXPECTED TO MOVE INLAND
ACROSS SOUTHERN LOUISIANA EITHER LATE TONIGHT OR EARLY WEDNESDAY
AND TRACK TO THE NORTH NORTHWEST. THE 00Z GFS REMAINS RELATIVELY
UNCHANGED FROM ITS PREVIOUS TRACK ALTHOUGH THE ECMWF NOW BRINGS
THE SYSTEM A BIT FURTHER TO THE WEST...SIMILAR TO PREVIOUS GFS
RUNS. FURTHERMORE...DATA FROM AN AIR FORCE HURRICANE HUNTER
AIRCRAFT SHOW THAT THE CENTER OF ISAAC HAS WOBBLED TO THE WEST
OVER THE LAST SIX HOURS. THIS WESTWARD SHIFT IS EXPECTED TO BE
TEMPORARY BUT BASED UPON THIS MOTION THE TROPICAL STORM WATCH HAS
BEEN EXTENDED WESTWARD TO INCLUDE PORTIONS OF THE UPPER TEXAS
COASTLINE EAST OF HIGH ISLAND. WITH THE LATEST ECMWF TRACK AND
THIS WESTWARD JOG HAVE DECIDED TO INCREASE POPS SLIGHTLY ACROSS
OUR FAR EASTERN COUNTIES FOR THE NEXT SEVERAL DAYS AND ALSO LOWER
MAX TEMPS GENERALLY ACROSS AREAS ALONG AND EAST OF INTERSTATE 45.
WHILE ISAAC IS NOT EXPECTED TO DIRECTLY THREATEN OUR CWA...ANY
FURTHER SHIFT WESTWARD IN TRACK WOULD NECESSITATE ADDITIONAL
CHANGES TO POPS AND TEMPS LATER TODAY OR TONIGHT BEFORE THE SYSTEM
MOVES INLAND.

IN THE EXTENDED...THE REMNANTS OF ISAAC WILL MOVE INTO THE CENTRAL
UNITED STATES OVER THE WEEKEND FORCING THE MID LEVEL RIDGE INTO
THE MID ATLANTIC STATES. WITH THE HIGH OFF TO OUR EAST WE WILL SEE
ONSHORE FLOW RESUME AND A SLIGHT CHANCE FOR AFTERNOON SHOWERS AND
THUNDERSTORMS ON SATURDAY AND SUNDAY. 38

[srainhoutx]

10Z IR Imagery:

[biggerbyte]

WOW! They just do not want to admit that we have a problem. Okay! I really hope they are right. There are going to be some mighty upset people if preparation times are shortened due to foolishness. Really? With the trough moving away, and the ridge building in? REALLY? Well, okay then. I'm off to bed.

[srainhoutx]

Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 28th day of the month at 10:21Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 30
Observation Number: 09
A. Time of Center Fix: 28th day of the month at 9:31:45Z
B. Center Fix Coordinates: 27°30'N 87°59'W (27.5N 87.9833W)
B. Center Fix Location: 208 miles (336 km) to the SSW (193°) from Pensacola, FL, USA.
C. Minimum Height at Standard Level (Undecoded): NA NA
D. Estimated (by SFMR or visually) Maximum Surface Wind: 62kts (~ 71.3mph)
E. Location of the Estimated Maximum Surface Wind: 47 nautical miles (54 statute miles) to the E (99°) of center fix
F. Maximum Flight Level Wind Inbound: From 180° at 75kts (From the S at ~ 86.3mph)
G. Location of Maximum Flight Level Wind Inbound: 66 nautical miles (76 statute miles) to the E (94°) of center fix
H. Minimum Sea Level Pressure: 977mb (28.85 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14°C (57°F) at a pressure alt. of 2,437m (7,995ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 18°C (64°F) at a pressure alt. of 2,440m (8,005ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 15°C (59°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Poorly Defined
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: Other - Not surface, 1500ft, 925mb (if vortex is newer than about mid 90's; see note for more), 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
Remarks Section:
Maximum Flight Level Wind: 75kts (~ 86.3mph) in the east quadrant at 9:14:32Z
Maximum Flight Level Wind Outbound: 60kts (~ 69.0mph) in the west quadrant at 9:52:27Z

[sambucol]

Just got up and am hearing tropical storm watch has been extended to high island. What happened to the track? Tv met said its been moving west for the last couple of hours. Is this supposed to change back to the NW? Thanks.

[srainhoutx]

Just got up and am hearing tropical storm watch has been extended to high island. What happened to the track? Tv met said its been moving west for the last couple of hours. Is this supposed to change back to the NW? Thanks.

Isaac has been wobbling around for about the past 6 hours. There was a Westward drift via RECON center fixes. The Euro shift way W toward Central Louisiana. Other than that, it's a wait and see what the day brings. Louisiana still looks likely for landfall at this time. Edit to add: AF HH C-130 that left Ellington an hour ago is arriving now.

[sambucol]

Thanks, Steve.

BTW, I am not a rocket scientist lol!

[srainhoutx]

Thanks, Steve.

BTW, I am not a rocket scientist lol!

No problem...

[srainhoutx]

AF HH RECON suggest we may have a Hurricane. We will see... Edit to add: that reading was W of the center S of Morgan City or there abouts

URNT15 KNHC 281053
AF306 3109A ISAAC HDOB 08 20120828
104430 2907N 09101W 8259 01697 0032 +180 +140 020035 035 028 000 00
104500 2906N 09059W 8349 01600 0028 +186 +130 021036 038 028 000 00
104530 2906N 09057W 8417 01528 0027 +186 +120 026039 039 028 000 03
104600 2905N 09055W 8429 01513 0023 +189 +120 025039 040 028 000 00
104630 2904N 09053W 8429 01513 0023 +185 +133 024038 039 029 000 00
104700 2903N 09051W 8429 01511 0021 +185 +146 026039 039 032 000 03
104730 2903N 09049W 8433 01508 0023 +179 +157 028039 039 071 011 00
104800 2902N 09047W 8427 01512 0019 +184 +156 027040 040 031 000 00
104830 2901N 09045W 8428 01511 0020 +181 +160 023040 041 033 002 03
104900 2900N 09043W 8430 01508 0022 +176 +164 020039 040 038 002 00
104930 2900N 09041W 8433 01505 0021 +175 +167 023040 040 037 000 00
105000 2900N 09039W 8429 01510 0019 +179 +164 023040 041 034 000 00
105030 2900N 09037W 8429 01507 0017 +179 +162 022038 039 034 000 00
105100 2900N 09037W 8429 01507 0017 +180 +156 026035 036 033 000 00
105130 2859N 09033W 8428 01507 0017 +179 +155 026033 035 034 000 03
105200 2859N 09031W 8430 01502 0020 +170 +163 028034 035 035 000 00
105230 2858N 09029W 8428 01506 0021 +170 +164 027035 036 035 001 00
105300 2858N 09027W 8428 01503 0017 +174 +163 031033 035 036 001 03
105330 2858N 09025W 8431 01500 0014 +176 +162 037035 035 036 000 00
105400 2857N 09023W 8430 01497 0011 +176 +171 039037 037 036 000 03

[cperk]

What's is going on,i wake up and the Euro has shifted west.

[cisa]

Is he opening his eye a little?

[srainhoutx]

Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 28th day of the month at 11:37Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number & Year: 09L in 2012
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 30
Observation Number: 13
A. Time of Center Fix: 28th day of the month at 11:03:52Z
B. Center Fix Coordinates: 27°47'N 88°08'W (27.7833N 88.1333W)
B. Center Fix Location: 190 miles (306 km) to the SSE (163°) from Gulfport, MS, USA.
C. Minimum Height at Standard Level (Undecoded): NA NA
D. Estimated (by SFMR or visually) Maximum Surface Wind: 59kts (~ 67.9mph)
E. Location of the Estimated Maximum Surface Wind: 79 nautical miles (91 statute miles) to the S (174°) of center fix
F. Maximum Flight Level Wind Inbound: From 257° at 69kts (From the WSW at ~ 79.4mph)
G. Location of Maximum Flight Level Wind Inbound: 74 nautical miles (85 statute miles) to the S (174°) of center fix
H. Minimum Sea Level Pressure: 981mb (28.97 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14°C (57°F) at a pressure alt. of 2,425m (7,956ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 18°C (64°F) at a pressure alt. of 2,437m (7,995ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 15°C (59°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Poorly Defined
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: Other - Not surface, 1500ft, 925mb (if vortex is newer than about mid 90's; see note for more), 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
Remarks Section - Remarks That Were Decoded...
Maximum Flight Level Wind: 75kts (~ 86.3mph) in the east quadrant at 9:14:32Z
Maximum Flight Level Wind Outbound: 63kts (~ 72.5mph) in the north quadrant at 11:24:40Z
Remarks Section - Additional Remarks...
SEC MAX FL WIND 66 KT BRNG:175 deg RNG:103 nm
SLP EXTRAP FROM 8K FT

[Rip76]

Appears to be back to heading NW.