Tropical Depression Greg At EPAC

[cycloneye]

TROPICAL STORM GREG DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT SAT AUG 13 2005

INFRARED AND SHORTWAVE IR IMAGERY OF GREG SHOW AN INTERMITTENTLY
EXPOSED CENTER AND FLARE UPS OF CONVECTION IN THE SOUTHERN
QUADRANT. NORTHERLY SHEAR IS STILL IMPINGING ON THE SYSTEM AND GREG
CONTINUES TO STRUGGLE IN ITS CURRENT ENVIRONMENT. DVORAK INTENSITY
ESTIMATES FROM TAFB AND SAB ARE 2.5 RESPECTIVELY GIVING AN
INTENSITY ESTIMATE OF 35 KT... WHILE AFWA ESTIMATES ARE SLIGHTLY
LOWER. THE INTENSITY FOR GREG REMAINS AT 35 KT.

THE INTENSITY FORECAST DOES DEVIATE SLIGHTLY FROM THE PREVIOUS. THE
SHORT TERM TREND HOLDS GREG AT 35 KT AND SLOWLY WORKS THE INTENSITY
UP TO 60 KT BY 72 HOURS WHICH IS SIMILAR TO SHIPS. HOWEVER...
BEYOND 72 HOURS SHIPS KEEPS GREG AT TROPICAL STORM STRENGTH
WHILE THE GFDL INCREASES GREG TO A HURRICANE AT 48 HOURS. THE
OFFICIAL INTENSITY FORECAST TAKES A CONSERVATIVE APPROACH BY
KEEPING GREG AS A TROPICAL STORM IN THE MIDDLE OF THE FORECAST
PERIOD AND NUDGING IT TO HURRICANE STATUS IN THE EXTENDED PERIODS.
THIS FORECAST MOSTLY FOLLOWS SHIPS... HOWEVER IT DOES TAKE INTO
ACCOUNT THE GFDL SOLUTION LATER ON IN THE PERIOD.

THE INITIAL MOTION ESTIMATE IS 315/3. GIVEN THAT THE CENTER IS
PARTIALLY EXPOSED...THE SHORT TERM MOTION WILL CONTINUE A SLOW
MOVEMENT IN THE NORTHWESTWARD DIRECTION... AND IS CONSISTENT WITH
THE SHALLOW BETA ADVECTION MODEL. THE DYNAMICAL MODEL SUITE QUICKLY
MOVES GREG TO THE SOUTHWEST IN THE SHORT TERM WHICH GIVEN ITS
PRESENT MOTION MAY BE UNLIKELY. CONSEQUENTLY... THE OFFICIAL TRACK
LEANS MORE TOWARD THE BAMS AND SLOWLY TRENDS BACK TOWARD THE MODEL
CONSENSUS LATER ON IN THE FORECAST.

FORECASTER SISKO/AVILA


FORECAST POSITIONS AND MAX WINDS

INITIAL 13/1500Z 15.4N 114.3W 35 KT
12HR VT 14/0000Z 15.6N 114.8W 35 KT
24HR VT 14/1200Z 15.4N 115.7W 40 KT
36HR VT 15/0000Z 15.0N 116.5W 45 KT
48HR VT 15/1200Z 15.0N 118.0W 50 KT
72HR VT 16/1200Z 15.0N 120.5W 60 KT
96HR VT 17/1200Z 15.0N 123.5W 65 KT
120HR VT 18/1200Z 15.5N 126.0W 65 KT

[cycloneye]

948
WTPZ42 KNHC 132037
TCDEP2
TROPICAL STORM GREG DISCUSSION NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT SAT AUG 13 2005

VISIBLE IMAGERY OF GREG STILL SHOWS A BURST OF CONVECTION IN THE
SOUTHERN QUADRANT AS NORTHERLY SHEAR IMPINGES ON THE SYSTEM. THE
CENTER WAS FULLY EXPOSED...BUT THE CONVECTION CONTINUES TO
INTERMITTENTLY FLARE UP NEAR THE CENTER. DVORAK INTENSITY ESTIMATES
FROM TAFB ARE 2.5 AND FROM SAB ARE 2.0 SO THE SYSTEM IS A
BORDERLINE TROPICAL STORM. A RECENT QUIKSCAT OVERPASS OVER THE
EASTERN PORTION OF THE CYCLONE DOES HAVE 35 KT WINDS...SO THE
INITIAL INTENSITY ESTIMATE IS HELD AT 35 KT FOR THIS ADVISORY. WIND
RADII WERE ALSO ADJUSTED BASED ON THIS SAME QUIKSCAT OVERPASS
INFORMATION.

THE SHORT TERM INTENSITY FORECAST HOLDS GREG AT 35 KT AND SLOWLY
WORKS THE INTENSITY UP TO 60 KT BY 72 HOURS. THIS FORECAST IS VERY
SIMILAR TO THE FSSE AND SHIPS GUIDANCE. ON THE OTHER HAND...THE
GFDL DEPICTS A MORE AGGRESSIVE INTENSITY SCENARIO BY DEVELOPING
GREG TO HURRICANE STRENGTH IN 36 HRS. THE OFFICIAL FORECAST CALLS
FOR SLOW DEVELOPMENT IN THE MEANTIME. BY THE EXTENDED FORECAST
PERIOD... THE OFFICIAL FORECAST DOES BRING GREG TO HURRICANE
STRENGTH BEYOND 96 HRS...THIS IS CONSERVATIVE APPROACH COMPARED TO
THE GFDL.

THE INITIAL MOTION ESTIMATE IS 290/5. MOST OF THE SHORT TERM TRACK
GUIDANCE QUICKLY DIVES GREG SOUTHWESTWARD. THE GFS IS THE SOUTHERN
MOST OUTLIER IN THE GROUP. BEYOND 36 HRS...THE TRACK TURNS WEST AND
REMAINS SO UNTIL THE END OF THE FORECAST PERIOD. THE FORECAST TRACK
REMAINS JUST NORTH OF THE MODEL CONSENSUS CONU...GUNS AND GUNA. THE
LARGE SPREAD IN THE MODELS EARLY IN THE FORECAST YIELD A BIT OF
UNCERTAINTY BUT A GENERAL LONG TERM WEST MOTION IS ANTICIPATED.

FORECASTER SISKO/AVILA


FORECAST POSITIONS AND MAX WINDS

INITIAL 13/2100Z 15.5N 114.9W 35 KT
12HR VT 14/0600Z 15.3N 115.6W 35 KT
24HR VT 14/1800Z 14.7N 116.4W 35 KT
36HR VT 15/0600Z 14.0N 117.5W 40 KT
48HR VT 15/1800Z 14.0N 119.0W 45 KT
72HR VT 16/1800Z 14.0N 122.5W 55 KT
96HR VT 17/1800Z 14.5N 125.0W 65 KT
120HR VT 18/1800Z 15.5N 127.5W 65 KT

[cycloneye]

564
WTPZ22 KNHC 140235
TCMEP2
TROPICAL STORM GREG FORECAST/ADVISORY NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP072005
0300Z SUN AUG 14 2005

TROPICAL STORM CENTER LOCATED NEAR 15.3N 115.6W AT 14/0300Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE WEST OR 260 DEGREES AT 6 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1002 MB
MAX SUSTAINED WINDS 40 KT WITH GUSTS TO 50 KT.
34 KT....... 30NE 70SE 70SW 30NW.
12 FT SEAS.. 60NE 60SE 60SW 60NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 15.3N 115.6W AT 14/0300Z
AT 14/0000Z CENTER WAS LOCATED NEAR 15.4N 115.4W

FORECAST VALID 14/1200Z 15.1N 116.2W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 50NE 70SE 70SW 50NW.

FORECAST VALID 15/0000Z 14.7N 117.2W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 50NE 70SE 70SW 50NW.

FORECAST VALID 15/1200Z 14.3N 118.5W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 20NE 20SE 20SW 20NW.
34 KT... 70NE 70SE 70SW 70NW.

FORECAST VALID 16/0000Z 14.2N 120.0W
MAX WIND 55 KT...GUSTS 65 KT.
50 KT... 30NE 30SE 30SW 30NW.
34 KT... 80NE 80SE 80SW 80NW.

FORECAST VALID 17/0000Z 14.3N 122.6W
MAX WIND 60 KT...GUSTS 75 KT.
50 KT... 30NE 30SE 30SW 30NW.
34 KT... 80NE 80SE 80SW 80NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 200 NM
ON DAY 4 AND 250 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 18/0000Z 14.5N 125.0W
MAX WIND 65 KT...GUSTS 80 KT.

OUTLOOK VALID 19/0000Z 15.0N 127.5W
MAX WIND 65 KT...GUSTS 80 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 15.3N 115.6W

NEXT ADVISORY AT 14/0900Z

FORECASTER ROBERTS/STEWART

[cycloneye]

000
WTPZ42 KNHC 140850
TCDEP2
TROPICAL STORM GREG DISCUSSION NUMBER 13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT SUN AUG 14 2005

A 14/0447Z TRMM OVERPASS HAS HELPED IMMENSELY IN LOCATING THE
EXPOSED CIRCULATION CENTER. THE TRMM IMAGE AND A 14/0123Z QUIKSCAT
PASS SUPPORT THE INITIAL MOTION. THE QUIKSCAT DATA WAS ALSO USED
TO ADJUST THE WIND RADII. MODERATE NORTHEASTERLY SHEAR CONTINUES
TO HINDER DEVELOPMENT...BUT THE DYNAMICAL MODELS SUGGEST THAT THE
SHEAR WILL WEAKEN AND SHIFT SOUTHEAST. DVORAK CLASSIFICATIONS HAVE
NOT CHANGED FROM THE PREVIOUS PACKAGE...THEREFORE THE INITIAL
INTENSITY WILL REMAIN AT 40 KT. THE GFDL BRINGS GREG TO HURRICANE
STRENGTH IN 24 HOURS...HOWEVER...EARLIER GFDL RUN INTENSITY
VERIFICATION INDICATES A HIGH BIAS IN THE MODEL. THE INTENSITY
FORECAST AGAIN WILL BE BASED OFF OF THE SHIPS AND FSU SUPERENSEMBLE
MODELS...FOLLOWING THE PREVIOUS PACKAGE.

THE INITIAL MOTION IS 245/5. TROPICAL STORM GREG SHOULD CONTINUE ON
A GENERALLY WEST-SOUTHWESTWARD TRACK WITHIN THE BUILDING MID-LEVEL
RIDGE EXTENDING WESTWARD FROM CENTRAL MEXICO. THE GFS AND THE
CANADIAN ARE SOUTHERN OUTLIERS...ERRONEOUSLY MERGING GREG WITH A
TROPICAL WAVE WELL TO THE EAST. THE ECMWF SUGGESTS A VERY STRONG
RIDGE...DRIVING THE TROPICAL CYCLONE QUICKLY TO THE SOUTHWEST
BEFORE TURNING THE SYSTEM SHARPLY INTO THE RIDGE TO THE NORTH LATE
IN THE PERIOD. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS
ADVISORY AND IS BASED ON A NOGAPS...GFDL AND UKMET BLEND.

FORECASTER ROBERTS/KNABB


FORECAST POSITIONS AND MAX WINDS

INITIAL 14/0900Z 15.2N 116.1W 40 KT
12HR VT 14/1800Z 15.0N 116.8W 45 KT
24HR VT 15/0600Z 14.6N 118.0W 45 KT
36HR VT 15/1800Z 14.3N 119.2W 50 KT
48HR VT 16/0600Z 14.3N 120.9W 55 KT
72HR VT 17/0600Z 14.1N 124.0W 60 KT
96HR VT 18/0600Z 14.0N 127.0W 65 KT
120HR VT 19/0600Z 14.0N 130.0W 65 KT

[P.K.]

WTPZ42 KNHC 142029
TCDEP2
TROPICAL DEPRESSION GREG DISCUSSION NUMBER 15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT SUN AUG 14 2005

SATELLITE IMAGES INDICATE THAT A PORTION OF THE LOW-LEVEL
CIRCULATION OF GREG IS GRADUALLY BEING PULLED EASTWARD BY A MUCH
LARGER CYCLONIC GYRE CENTERED SOUTH OF MANZANILLO MEXICO. THERE IS
STILL CONVECTION WEST OF THE CENTER AND A WELL DEFINED CYCLONICALLY
CURVED BAND. THE CURRENT DETERIORATION OF THE CLOUD PATTERN
SUGGESTS THAT GREG HAS WEAKENED TO TROPICAL DEPRESSION STATUS.

THE CENTER OF GREG HAS BEEN MEANDERING FOR THE PAST FEW HOURS. SINCE
THE SYSTEM HAS BECOME SHALLOW AND THE DOMINANT STEERING APPEARS TO
BE THE NORTHWESTERLY FLOW ASSOCIATED WITH THE LARGER GYRE TO THE
EAST....THE BEST OPTION AT THIS TIME IS SHOW LITTLE MOTION AND NO
CHANGE IN INTENSITY THROUGH THE FORECAST PERIOD. HOWEVER...BECAUSE
THE DEPRESSION STILL HAS A LARGE CIRCULATION OVER WARM WATER...A
REFORMATION OR SOME RE-INTENSIFICATION WOULD NOT BE OUT OF THE
QUESTION. IN FACT...THIS IS THE SOLUTION OF THE GFDL AND SHIPS
MODELS.


FORECASTER AVILA


FORECAST POSITIONS AND MAX WINDS

INITIAL 14/2100Z 14.3N 115.5W 30 KT
12HR VT 15/0600Z 14.0N 115.5W 30 KT
24HR VT 15/1800Z 14.5N 115.5W 30 KT
36HR VT 16/0600Z 14.5N 115.5W 30 KT
48HR VT 16/1800Z 14.5N 115.5W 30 KT
72HR VT 17/1800Z 14.5N 115.5W 30 KT
96HR VT 18/1800Z 14.5N 115.5W 30 KT
120HR VT 19/1800Z 14.5N 115.5W 30 KT

[P.K.]

WTPZ42 KNHC 150900
TCDEP2
TROPICAL DEPRESSION GREG DISCUSSION NUMBER 17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT MON AUG 15 2005

GOES SHORTWAVE INFRARED IMAGERY... AND A 0226Z SSMI OVERPASS...
CONTINUE TO REVEAL AN EXPOSED LOW LEVEL CIRCULATION. THE NEAREST
CONVECTION... WHICH IS EXTREMELY LIMITED... IS ABOUT 50 N MI TO THE
WEST... SO EASTERLY SHEAR MAINTAINS ITS GRIP ON THE SYSTEM. DVORAK
INTENSITY ESTIMATES REMAIN 30 KT... AS DOES THE ADVISORY INTENSITY.

PERHAPS IN PART BECAUSE IT IS BEING DRAGGED ALONG BY THE CONVECTION
TO ITS WEST... THE CENTER OF GREG APPEARS TO HAVE RESUMED A VERY
SLOW WESTWARD MOTION... ESTIMATED AT 270/2. THE FORECAST SOLUTIONS
FROM THE VARIOUS DYNAMICAL MODELS ARE ALL OVER THE MAP...
LITERALLY... BUT AT LEAST THEY ARE UNANIMOUS IN FORECASTING A
GENERAL WESTWARD TREND. THE GFDL FORECASTS A SLOW SOUTHWESTWARD
DRIFT AS A STRENGTHENING TROPICAL STORM FOR THE NEXT THREE DAYS...
FOLLOWED BY A TURN TO THE NORTH AND FURTHER INTENSIFICATION INTO A
HURRICANE. THE OTHER DYNAMICAL MODELS ALSO SHOW THIS SOUTHWESTWARD
MOTION... APPARENTLY DUE TO JUST ENOUGH NARROW LOW-LEVEL RIDGING
WEST OF THE BAJA CALIFORNIA PENINSULA. THE OFFICIAL FORECAST WILL
INDICATE VERY SLOW WESTWARD MOTION AT ABOUT 5 KNOTS THROUGHOUT THE
FORECAST PERIOD... WHICH IS NOT AS FAST OR AS FAR SOUTHWEST AS THE
MODELS. DUE TO THE CURRENT DISORGANIZATION OF THE DEPRESSION... AND
SINCE UPPER-LEVEL WINDS ARE NOT EXPECTED TO BECOME VERY FAVORABLE
FOR INTENSIFICATION ALONG THE OFFICIAL FORECAST TRACK... NO
INTENSITY CHANGE IS INDICATED... DESPITE THE AGGRESSIVE GFDL
FORECAST. IT IS SAFE TO SAY THAT BOTH THE TRACK AND INTENSITY
FORECASTS ARE LOW CONFIDENCE... ESPECIALLY SINCE THE DEPRESSION
MIGHT NOT EVEN SURVIVE MUCH LONGER.

FORECASTER KNABB


FORECAST POSITIONS AND MAX WINDS

INITIAL 15/0900Z 14.4N 115.9W 30 KT
12HR VT 15/1800Z 14.4N 116.2W 30 KT
24HR VT 16/0600Z 14.2N 117.0W 30 KT
36HR VT 16/1800Z 14.0N 117.9W 30 KT
48HR VT 17/0600Z 13.7N 118.9W 30 KT
72HR VT 18/0600Z 13.5N 121.0W 30 KT
96HR VT 19/0600Z 13.5N 122.5W 30 KT
120HR VT 20/0600Z 13.5N 124.0W 30 KT

[cycloneye]

000
WTPZ42 KNHC 151447
TCDEP2
TROPICAL DEPRESSION GREG DISCUSSION NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT MON AUG 15 2005

GOES SHORTWAVE INFRARED IMAGERY CONTINUES TO REVEAL AN EXPOSED LOW-
LEVEL CIRCULATION WITH THE NEAREST CONVECTION ABOUT 40-45 NM
SOUTHWEST OF THE LOW LEVEL CENTER. EASTERLY SHEAR MAINTAINS ITS
GRIP ON THE SYSTEM. DVORAK INTENSITY ESTIMATES REMAIN
30 KT...AS DOES THE ADVISORY INTENSITY. DUE TO THE CURRENT
DISORGANIZATION OF THE DEPRESSION...AND SINCE THE SHEAR IS NOT
FORECAST TO RELAX...NO INTENSITY CHANGE IS INDICATED...DESPITE THE
AGGRESSIVE GFDL AND OPTIMISTIC SHIPS FORECASTS.

THE MOTION OVER THE PAST 6 HOURS HAS OSCILLATED BETWEEN SOUTHWEST
AND WEST-SOUTHWEST WITH A MEAN INITIAL MOTION OF 245/4. THE
FORECAST SOLUTIONS FROM THE VARIOUS DYNAMICAL MODELS ARE IN BETTER
AGREEMENT AT LEAST THROUGH 72 HOURS AND ARE UNANIMOUS IN
FORECASTING A GENERAL WESTWARD TREND. THE MODELS DIVERGE
SIGNIFICANTLY AFTER 72 HOURS WITH THE NOGAPS/UKMET AND THE
GUNS...GUNA AND CONU DYNAMICAL CONCENSUS FORECASTING A TURN TOWARD
THE NORTHWEST. ONCE AGAIN THE GFDL FORECASTS A SLOW WEST-
SOUTHWESTWARD DRIFT AS A STRENGTHENING TROPICAL STORM FOR THE
NEXT THREE DAYS...FOLLOWED BY AN ABRUPT TURN TO THE NORTH-NORTHEAST.
THE GFS IS FORECASTING A FAIRLY SIGNIFICANT MID LEVEL CIRCULATION
SOUTH OF BAJA CALIFORNIA...WHICH IS LIKELY DUE TO POOR
INITIALIZATION. THEREFORE THAT MODEL'S TRACK...WHICH MOVES GREG IN
A CLOCKWISE LOOP...DOES NOT APPEAR TO BE REALISTIC. THE OFFICIAL
FORECAST IS SIMILAR TO THE PREVIOUS AND INDICATES A VERY SLOW
WESTWARD MOTION AT ABOUT 5 KNOTS THROUGHOUT THE FORECAST PERIOD.

FORECASTER COBB/PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL 15/1500Z 14.0N 116.4W 30 KT
12HR VT 16/0000Z 13.7N 117.0W 30 KT
24HR VT 16/1200Z 13.4N 117.7W 30 KT
36HR VT 17/0000Z 13.1N 118.6W 30 KT
48HR VT 17/1200Z 12.7N 120.0W 30 KT
72HR VT 18/1200Z 12.5N 122.0W 30 KT
96HR VT 19/1200Z 12.5N 124.0W 30 KT
120HR VT 20/1200Z 12.5N 126.0W 30 KT

[P.K.]

WTPZ42 KNHC 152032
TCDEP2
TROPICAL DEPRESSION GREG DISCUSSION NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT MON AUG 15 2005

A 1342 UTC QUIKSCAT PASS INDICATED ONLY 15-20 KT WINDS IN THE
RAIN-FREE AREAS OF THE CIRCULATION OF GREG. IN ADDITION VISIBLE
SATELLITE IMAGERY INDICATES THAT THE CONVECTION IN THE VICINITY OF
THE EXPOSED LOW LEVEL CENTER IS BECOMING INCREASINGLY SPARSE AND
STILL UNDERGOING STRONG EASTERLY SHEAR...ALL SIGNS THAT GREG IS IN
THE PROCESS OF DISSIPATING. THEREFORE THIS IS THE LAST ADVISORY ON
GREG UNLESS REGENERATION OCCURS. GREG WILL BE CARRIED AS A REMNANT
LOW THROUGH 48 HOURS IN THE FORECAST.

THE MOTION OVER THE PAST 12 HOURS HAS BEEN 245/4. GREG IS
EXPECTED TO CONTINUE WEST-SOUTHWESTWARD AT 5 KNOTS OR SO OVER THE
NEXT COUPLE OF DAYS.

INFORMATION ON THE REMNANT LOW OF GREG CAN BE FOUND IN THE HIGH SEAS
FORECASTS ISSUED BY THE TROPICAL ANALYSIS AND FORECAST BRANCH OF THE
TROPICAL PREDICTION CENTER UNDER AWIPS/WMO HEADERS MIAHSFEP2/FZPN03
KNHC.

FORECASTER COBB/PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL 15/2100Z 13.8N 116.7W 25 KT...DISSIPATING
12HR VT 16/0600Z 13.6N 117.2W 25 KT...REMNANT LOW
24HR VT 16/1800Z 13.1N 118.2W 20 KT...REMNANT LOW
36HR VT 17/0600Z 12.7N 119.2W 20 KT...REMNANT LOW
48HR VT 17/1800Z 12.3N 120.5W 20 KT...REMNANT LOW
72HR VT 18/1800Z...DISSIPATED

[Andrew92]

Greg, And don't let it hit you on the way outta here! See ya in 2011.