EPAC: Tropical Storm Hernan

[Chacor]

WTPZ24 KNHC 091445
TCMEP4
HURRICANE HERNAN FORECAST/ADVISORY NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
1500 UTC SAT AUG 09 2008

HURRICANE CENTER LOCATED NEAR 15.7N 123.3W AT 09/1500Z
POSITION ACCURATE WITHIN 10 NM

PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT 8 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 956 MB
EYE DIAMETER 15 NM
MAX SUSTAINED WINDS 105 KT WITH GUSTS TO 130 KT.
64 KT....... 20NE 20SE 20SW 20NW.
50 KT....... 45NE 45SE 35SW 45NW.
34 KT....... 90NE 90SE 75SW 90NW.
12 FT SEAS..180NE 180SE 90SW 150NW.
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 15.7N 123.3W AT 09/1500Z
AT 09/1200Z CENTER WAS LOCATED NEAR 15.5N 122.8W

FORECAST VALID 10/0000Z 16.2N 124.4W
MAX WIND 105 KT...GUSTS 130 KT.
64 KT... 20NE 20SE 20SW 20NW.
50 KT... 45NE 45SE 35SW 45NW.
34 KT... 90NE 90SE 75SW 90NW.

FORECAST VALID 10/1200Z 16.8N 125.9W
MAX WIND 95 KT...GUSTS 115 KT.
64 KT... 20NE 20SE 20SW 20NW.
50 KT... 45NE 45SE 35SW 45NW.
34 KT... 90NE 90SE 75SW 90NW.

FORECAST VALID 11/0000Z 17.3N 127.3W
MAX WIND 80 KT...GUSTS 100 KT.
64 KT... 20NE 20SE 20SW 20NW.
50 KT... 45NE 45SE 35SW 45NW.
34 KT... 90NE 90SE 75SW 90NW.

FORECAST VALID 11/1200Z 17.6N 128.7W
MAX WIND 65 KT...GUSTS 80 KT.
50 KT... 45NE 30SE 30SW 45NW.
34 KT... 90NE 75SE 75SW 90NW.

FORECAST VALID 12/1200Z 18.0N 131.0W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 75NE 50SE 50SW 75NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 200 NM
ON DAY 4 AND 225 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 13/1200Z 17.5N 133.5W
MAX WIND 35 KT...GUSTS 45 KT.

OUTLOOK VALID 14/1200Z 16.5N 136.0W
MAX WIND 30 KT...GUSTS 40 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 15.7N 123.3W

NEXT ADVISORY AT 09/2100Z

$$
FORECASTER KNABB

105 kts.

[Chacor]

268
WTPZ34 KNHC 091446
TCPEP4
BULLETIN
HURRICANE HERNAN ADVISORY NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
800 AM PDT SAT AUG 09 2008

...HERNAN BECOMES THE FIRST MAJOR HURRICANE OF THE 2008 EASTERN
NORTH PACIFIC SEASON...

AT 800 AM PDT...1500 UTC...THE CENTER OF HURRICANE HERNAN WAS
LOCATED NEAR LATITUDE 15.7 NORTH...LONGITUDE 123.3 WEST OR ABOUT
1005 MILES...1615 KM...WEST-SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.

HERNAN IS MOVING TOWARD THE WEST-NORTHWEST NEAR 9 MPH...15 KM/HR...
AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE
OF DAYS.

MAXIMUM SUSTAINED HAVE INCREASED AND ARE NOW NEAR 120 MPH...195
KM/HR...WITH HIGHER GUSTS. HERNAN IS A CATEGORY THREE HURRICANE ON
THE SAFFIR-SIMPSON HURRICANE SCALE. LITTLE CHANGE IN STRENGTH IS
EXPECTED TODAY...BUT A GRADUAL WEAKENING TREND IS EXPECTED TO BEGIN
TONIGHT OR SUNDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 25 MILES...35 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 105
MILES...165 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 956 MB...28.23 INCHES.

REPEATING THE 800 AM PDT POSITION...15.7 N...123.3 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 9 MPH. MAXIMUM SUSTAINED WINDS...120
MPH. MINIMUM CENTRAL PRESSURE...956 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
200 PM PDT.

$$
FORECASTER KNABB

[Chacor]

WTPZ44 KNHC 091457
TCDEP4
HURRICANE HERNAN DISCUSSION NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
800 AM PDT SAT AUG 09 2008

THE EYE OF HERNAN HAS BECOME DRAMATICALLY MORE DISTINCT IN GOES
INFRARED IMAGERY DURING THE PAST SEVERAL HOURS...AND IT IS NOW
SURROUNDED BY A SOLID RING OF CLOUD TOPS COLDER THAN -70C. AMSR-E
MICROWAVE IMAGERY AT 0937 UTC DEPICTED A SINGLE COMPLETE EYEWALL
AND AN EYE DIAMETER OF 20-25 N MI. THERE SEEMS LITTLE DOUBT THAT
HERNAN HAS BECOME A MAJOR HURRICANE... HAVING UNDERGONE RAPID
INTENSIFICATION SINCE YESTERDAY. THIS PROVIDES YET ANOTHER EXAMPLE
OF THE INABILITY OF MODEL GUIDANCE...AND THEREFORE THE HUMAN
FORECASTER...TO CAPTURE AND CONVEY THE TIMING AND MAGNITUDE OF THESE
EPISODES WITH A DETERMINISTIC INTENSITY FORECAST. THE EXACT
INITIAL INTENSITY IS A LITTLE UNCERTAIN. SUBJECTIVE DVORAK
ESTIMATES AT 12Z FROM TAFB AND SAB WERE BOTH 102 KT...WHILE
OBJECTIVE ESTIMATES ARE ABOUT 115 KT. THE ADVISORY INTENSITY
COMPROMISES AT 105 KT...BUT WITHOUT ACTUAL WIND DATA TO KNOW ANY
BETTER...IT IS POSSIBLE HERNAN IS A LITTLE STRONGER THAN THIS
ESTIMATE. UNDERLYING SEA-SURFACE TEMPERATURES ARE ABOUT 27 CELSIUS
NOW...AND ALONG THE FORECAST TRACK THE HURRICANE WILL CROSS THE 26
CELSIUS ISOTHERM IN ROUGHLY 24 HOURS...SO A GRADUAL WEAKENING TREND
IS FORECAST TO BEGIN AROUND THAT TIME. A FASTER DECLINE IS
FORECAST IN A COUPLE OF DAYS ONCE THE CYCLONE REACHES SUBSTANTIALLY
COOLER WATERS. THE OFFICIAL FORECAST IS ABOVE THE OBJECTIVE
GUIDANCE FOR THE NEXT DAY OR TWO...THEN SHOWS A FASTER WEAKENING
THAN THE MODELS DUE TO THE SMALL SIZE OF THE CYCLONE.

HERNAN HAS TURNED A LITTLE MORE TO THE RIGHT...AND ONE MUST GIVE
SOME OF THE MODELS CREDIT FOR CORRECTLY FORECASTING THIS BEND
YESTERDAY. THE INITIAL MOTION ESTIMATE IS 295/8...BUT A GRADUAL
TURN BACK TO THE LEFT IS FORECAST BY ALL OF THE DYNAMICAL MODELS AS
THE SUBTROPICAL RIDGE BUILDS WESTWARD OVER THE EASTERN PACIFIC
DURING THE NEXT COUPLE OF DAYS. BEYOND THAT TIME...A WEAKENING
HERNAN IS EXPECTED TO BECOME A MORE SHALLOW SYSTEM AND TURN
WESTWARD AND EVENTUALLY WEST-SOUTHWESTWARD IN THE LOW- TO MID-LEVEL
FLOW. THE NEW OFFICIAL TRACK FORECAST IS ALMOST IDENTICAL TO THE
PREVIOUS ONE AND IS CLOSE TO THE MODEL CONSENSUS.



FORECAST POSITIONS AND MAX WINDS

INITIAL 09/1500Z 15.7N 123.3W 105 KT
12HR VT 10/0000Z 16.2N 124.4W 105 KT
24HR VT 10/1200Z 16.8N 125.9W 95 KT
36HR VT 11/0000Z 17.3N 127.3W 80 KT
48HR VT 11/1200Z 17.6N 128.7W 65 KT
72HR VT 12/1200Z 18.0N 131.0W 45 KT
96HR VT 13/1200Z 17.5N 133.5W 35 KT
120HR VT 14/1200Z 16.5N 136.0W 30 KT

$$
FORECASTER KNABB

[CrazyC83]

They mention it could possibly be stronger due to lack of observations. I wouldn't be surprised if it is as strong as 115 kt.

[CrazyC83]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 09 AUG 2008 Time : 133000 UTC
Lat : 15:36:45 N Lon : 123:04:08 W


CI# /Pressure/ Vmax
6.1 / 948.0mb/117.4kt


Final T# Adj T# Raw T#
(3hr avg)
6.1 6.1 6.1

Latitude bias adjustment to MSLP : +2.6mb

Estimated radius of max. wind based on IR : 11 km

Center Temp : -23.8C Cloud Region Temp : -68.4C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

[chadtm80]

http://www.storm2k.org/weather/hw3.php? ... d=15&size=

[HURAKAN]

09/1800 UTC 16.0N 123.6W T5.5/5.5 HERNAN -- East Pacific Ocean

102 knots.

[HURAKAN]

.

[HURAKAN]

916
WTPZ44 KNHC 092034
TCDEP4
HURRICANE HERNAN DISCUSSION NUMBER 13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
200 PM PDT SAT AUG 09 2008

VISIBLE SATELLITE IMAGERY CONTINUES TO DEPICT A WELL-DEFINED EYE...
BUT INFRARED IMAGERY INDICATES THAT THE CLOUD TOPS SURROUNDING THE
EYE HAVE WARMED A LITTLE THIS AFTERNOON. OBJECTIVE DVORAK
T-NUMBERS FROM UW-CIMSS APPEAR TO HAVE PEAKED AROUND T6.2 LATE THIS
MORNING. A BLEND OF THE SUBJECTIVE AND OBJECTIVE DVORAK ESTIMATES
SUGGEST THAT HERNAN'S PEAK INTENSITY COULD HAVE BEEN AROUND 110 KT.
THE LATEST SUBJECTIVE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 102
KT. SINCE THE RAW OBJECTIVE T-NUMBERS HAVE DECREASED THE INITIAL
INTENSITY REMAINS 105 KT.

VERTICAL SHEAR IS FORECAST TO REMAIN LOW DURING THE NEXT SEVERAL
DAYS SO COOLER SSTS ALONG THE FORECAST TRACK AND A MORE STABLE
ENVIRONMENT WILL DETERMINE HOW FAST HERNAN WEAKENS. THE HURRICANE
IS EXPECTED TO MOVE OVER THE 26 DEGREE CELSIUS ISOTHERM IN ABOUT 12
HOURS SO WEAKENING SHOULD BEGIN SOON. THERE IS A LARGE SPREAD IN
GUIDANCE AS TO HOW FAST HERNAN WILL SPIN DOWN...IN FACT...THE HWRF
MODEL KEEPS HERNAN AS A FORMIDABLE TROPICAL STORM THROUGH THE
FORECAST PERIOD. THE NEW INTENSITY PREDICTION SHOWS A LITTLE MORE
WEAKENING DURING THE FIRST 48 HOURS OF THE FORECAST THAN THE
PREVIOUS ADVISORY INDICATED...BUT IT IS CLOSE TO THE PREVIOUS
FORECAST AND THE LGEM MODEL THEREAFTER.

THE HURRICANE IS MOVING WEST-NORTHWESTWARD OR 300 DEGREES AT 9 KT.
THE MODELS ARE IN GOOD AGREEMENT ON A WEST-NORTHWESTWARD HEADING
WITH SOME DECREASE IN FORWARD SPEED DURING THE 12-24 HOURS. BEYOND
24 HOURS...THE MODELS PREDICT A MORE WESTWARD TRACK FOR A
COUPLE OF DAYS....FOLLOWED BY A WEST-SOUTHWEST TURN AS THE CYCLONE
BECOMES A SHALLOWER SYSTEM. THE NEW FORECAST IS A LITTLE SLOWER AND
SLIGHTLY NORTH OF THE PREVIOUS TRACK THROUGH 36 HOURS...BUT IS
NEARLY IDENTICAL THEREAFTER.

FORECAST POSITIONS AND MAX WINDS

INITIAL 09/2100Z 16.2N 124.0W 105 KT
12HR VT 10/0600Z 16.8N 125.2W 100 KT
24HR VT 10/1800Z 17.4N 126.7W 85 KT
36HR VT 11/0600Z 17.7N 128.0W 70 KT
48HR VT 11/1800Z 17.8N 129.3W 60 KT
72HR VT 12/1800Z 17.8N 131.5W 45 KT
96HR VT 13/1800Z 17.5N 133.5W 35 KT
120HR VT 14/1800Z 16.5N 136.5W 30 KT

$$
FORECASTER BROWN

112
WTPZ34 KNHC 092033
TCPEP4
BULLETIN
HURRICANE HERNAN ADVISORY NUMBER 13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
200 PM PDT SAT AUG 09 2008

AT 200 PM PDT...2100 UTC...THE CENTER OF HURRICANE HERNAN WAS
LOCATED NEAR LATITUDE 16.2 NORTH...LONGITUDE 124.0 WEST OR ABOUT
1025 MILES...1655 KM...WEST-SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.

HERNAN IS MOVING TOWARD THE WEST-NORTHWEST NEAR 10 MPH...17 KM/HR.
A WEST-NORTHWESTWARD MOTION WITH SOME DECREASE IN FORWARD SPEED IS
EXPECTED OVER THE NEXT DAY OR TWO.

MAXIMUM SUSTAINED WINDS ARE NEAR 120 MPH...195 KM/HR...WITH HIGHER
GUSTS. HERNAN IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE SCALE. GRADUAL WEAKENING IS FORECAST DURING THE NEXT
COUPLE OF DAYS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES...45 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 115
MILES...185 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 956 MB...28.23 INCHES.

REPEATING THE 200 PM PDT POSITION...16.2 N...124.0 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 10 MPH. MAXIMUM SUSTAINED WINDS...120
MPH. MINIMUM CENTRAL PRESSURE...956 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
800 PM PDT.

$$
FORECASTER BROWN

[HURAKAN]

[KWT]

Wow Hernan is our first major EPAC hurricane of the season, pretty impressive stuff and it does look a pretty impressive system right now as well with a good southern side and eye evident as well.

[Chacor]

Wow.

[HURAKAN]

252
WTPZ34 KNHC 100233
TCPEP4
BULLETIN
HURRICANE HERNAN ADVISORY NUMBER 14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
800 PM PDT SAT AUG 09 2008

...HERNAN STARTING TO WEAKEN...

AT 800 PM PDT...0300 UTC...THE CENTER OF HURRICANE HERNAN WAS
LOCATED NEAR LATITUDE 16.7 NORTH...LONGITUDE 124.9 WEST OR ABOUT
1065 MILES...1715 KM...WEST-SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.

HERNAN IS MOVING TOWARD THE WEST-NORTHWEST NEAR 12 MPH...19 KM/HR.
A GRADUAL TURN TOWARD THE WEST AND A DECREASE IN FORWARD SPEED ARE
EXPECTED DURING THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 115 MPH...185
KM/HR...WITH HIGHER GUSTS. HERNAN IS A CATEGORY THREE HURRICANE
ON THE SAFFIR-SIMPSON HURRICANE SCALE. FURTHER WEAKENING IS
EXPECTED DURING THE NEXT COUPLE OF DAYS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES...45 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
115 MILES...185 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 961 MB...28.38 INCHES.

REPEATING THE 800 PM PDT POSITION...16.7 N...124.9 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 12 MPH. MAXIMUM SUSTAINED WINDS...115
MPH. MINIMUM CENTRAL PRESSURE...961 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
200 AM PDT.

$$
FORECASTER BEVEN

253
WTPZ44 KNHC 100233
TCDEP4
HURRICANE HERNAN DISCUSSION NUMBER 14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
800 PM PDT SAT AUG 09 2008

HERNAN CONTINUES TO SHOW A WELL-DEFINED 20 N MI WIDE EYE IN
SATELLITE IMAGERY. HOWEVER...THE CLOUD TOPS IN THE EYEWALL HAVE
WARMED AS THE HURRICANE MOVES OVER COOLER SEA SURFACE TEMPERATURES.
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN 102 KT...
ALTHOUGH THE FINAL DVORAK T-NUMBERS HAVE DECREASED. BASED ON THESE
DATA...THE INITIAL INTENSITY IS LOWERED TO 100 KT. THE CIRRUS
OUTFLOW IS GOOD IN THE SOUTHWESTERN SEMICIRCLE AND POOR ELSEWHERE.

THE INITIAL MOTION IS 300/10. MID-LEVEL RIDGING TO THE NORTHEAST OF
THE HURRICANE IS STEERING IT TOWARD AN UPPER-LEVEL TROUGH SEEN IN
WATER VAPOR IMAGERY NEAR 30N140W. THE LARGE-SCALE MODELS FORECAST
THIS TROUGH TO WEAKEN AND BE REPLACED BY A WEAK RIDGE DURING THE
NEXT 36-48 HR...WHICH SHOULD RESULT IN HERNAN TURNING MORE
WESTWARD. ALL TRACK GUIDANCE AGREES WITH THIS SCENARIO...AND THE
NEW FORECAST TRACK FOLLOWS THE MODEL CONSENSUS. AFTER 72 HR...A
WEAKENING HERNAN SHOULD TURN MORE SOUTHWESTWARD IN THE
NORTHEASTERLY LOW/MID-LEVEL FLOW. THERE IS SOME SPREAD IN THE
GUIDANCE AT THIS POINT...WITH THE BAM MODELS AND THE NOGAPS CALLING
FOR A MORE WESTERLY MOTION...AND THE UKMET AND ECMWF CALLING FOR A
SOUTHWESTERLY MOTION. THE FORECAST TRACK IS BETWEEN THESE TWO
EXTREMES AND NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE.

HERNAN SHOULD STEADILY WEAKEN OVER COOLER SSTS DURING AT LEAST THE
NEXT 72 HR....WITH THE SYSTEM BECOMING A TROPICAL STORM IN ABOUT 36
HR. WHILE THE FORECAST TRACK DOES BRING THE CENTER OVER SLIGHTLY
WARMER...25C...WATER AFTER 72 HR...THE INTENSITY GUIDANCE CONTINUES
TO SHOW A WEAKENING TREND. THUS...THE INTENSITY FORECAST ALSO
CALLS FOR CONTINUED WEAKENING...BUT NOT A DECAY INTO A
NON-CONVECTIVE REMNANT LOW. HOWEVER...IF THE CYCLONE MOVES NORTH
OF THE FORECAST TRACK...IT COULD DISSIPATE OVER THE COLD WATER.

FORECAST POSITIONS AND MAX WINDS

INITIAL 10/0300Z 16.7N 124.9W 100 KT
12HR VT 10/1200Z 17.2N 126.1W 90 KT
24HR VT 11/0000Z 17.7N 127.5W 75 KT
36HR VT 11/1200Z 17.9N 128.8W 60 KT
48HR VT 12/0000Z 18.0N 130.0W 50 KT
72HR VT 13/0000Z 17.5N 132.0W 40 KT
96HR VT 14/0000Z 17.0N 134.0W 30 KT
120HR VT 15/0000Z 16.0N 136.5W 25 KT

$$
FORECASTER BEVEN

[Mecklenburg]

has a good chance of becoming the first EPac major hurricane...

Anything to back that up, seeing how this is only 75 kt right now?

i was right, it did became the first EPac major, i'm guessing that it will be now downgraded to a cat. 2 next advisory due to cooler waters... by the way, the 2 areas that seemed probable to become a storm system around it's vicinity suddenly vanished...

[Chacor]

The fact that you were right does not change the fact that you had no backing data for your claim, or if you did, did not present it. You require the personal forecast disclaimer in such a case.

[HURAKAN]

947
WTPZ44 KNHC 100840
TCDEP4

HURRICANE HERNAN DISCUSSION NUMBER 15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
200 AM PDT SUN AUG 10 2008

HERNAN CONTINUES TO WEAKEN AS IT MOVES OVER COOLER SSTS AND THE
INITIAL INTENSITY IS LOWERED TO 85 KT BASED ON A BLEND OF THE
SUBJECTIVE DVORAK FINAL T AND CI NUMBERS. ADDITIONAL WEAKENING IS
ANTICIPATED AND HERNAN COULD DROP BELOW HURRICANE STRENGTH WITHIN
THE NEXT 24 HOURS. SSTS LEVEL OFF IN ABOUT 2 DAYS THEN BEGIN TO
RISE SO A SLOWER RATE OF DECAY IS SHOWN AT THE EXTENDED FORECAST
TIMES...AND HERNAN COULD CLING TO ITS STATUS AS A TROPICAL CYCLONE
FOR SEVERAL DAYS.

THE INITIAL MOTION ESTIMATE IS ESSENTIALLY UNCHANGED 305/09. AN
UPPER-LEVEL TROUGH TO THE NORTHWEST OF HERNAN IS FORECAST TO BE
REPLACED BY A WEAK RIDGE DURING THE NEXT DAY OR SO RESULTING IN A
GRADUAL TURN TOWARDS THE WEST. BEYOND 48 HOURS...A TURN MORE
SOUTHWESTWARD IS FORECAST AS THE WEAKENING CYCLONE IS STEERED BY
THE NORTHEASTERLY LOW/MID-LEVEL FLOW. THERE REMAINS SPREAD IN THE
TRACK GUIDANCE...WITH THE BAM MODELS AND THE HWRF CALLING FOR A
SLOWER WESTWARD TURN RESULTING IN THOSE MODELS LYING ALONG THE
NORTHERN EDGE OF THE GUIDANCE ENVELOPE. CONVERSELY...THE GFS AND
UKMET MODELS SHOW A MUCH SHARPER WESTWARD AND SOUTHWESTWARD TURN
WITH THOSE MODELS LYING ALONG THE SOUTHERN EDGE OF THE GUIDANCE
ENVELOPE. THE OFFICIAL TRACK FORECAST IS A LITTLE NORTH OF THE
MODEL CONSENSUS AND CLOSE TO THE GFDL MODEL THROUGH ABOUT 48
HOURS...THEN ALONG BUT A LITTLE SLOWER THAN THE MODEL CONSENSUS
THEREAFTER.

FORECAST POSITIONS AND MAX WINDS

INITIAL 10/0900Z 17.3N 125.7W 85 KT
12HR VT 10/1800Z 17.7N 126.7W 70 KT
24HR VT 11/0600Z 18.0N 128.1W 60 KT
36HR VT 11/1800Z 18.1N 129.4W 50 KT
48HR VT 12/0600Z 18.0N 130.5W 45 KT
72HR VT 13/0600Z 17.0N 133.0W 40 KT
96HR VT 14/0600Z 16.5N 135.0W 35 KT
120HR VT 15/0600Z 16.0N 138.0W 30 KT

$$
FORECASTER RHOME

[Chacor]

Down to 80 kts in ATCF. Looks like some dry air earlier on today but the convection on the northern side is making a comeback.

[Chacor]

856
WTPZ44 KNHC 101434
TCDEP4
HURRICANE HERNAN DISCUSSION NUMBER 16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092008
800 AM PDT SUN AUG 10 2008

HERNAN CONTINUES ITS SLOW WEAKENING TREND AS IT MOVES OVER MODESTLY
COOLER WATERS. ENHANCED INFRARED IMAGERY SHOWS AN EROSION OF THE
WESTERN PORTION OF THE EYEWALL. DVORAK CURRENT INTENSITY ESTIMATES
AVERAGE ABOUT 80 KT...WHICH IS USED FOR THE ADVISORY WIND SPEED.
DYNAMICAL MODEL PREDICTIONS INDICATE THAT VERTICAL SHEAR WILL
REMAIN VERY WEAK OVER HERNAN OVER THE NEXT FEW DAYS SO THE MAIN
CONTRIBUTION TO WEAKENING SHOULD COME FROM THERMODYNAMIC FACTORS.
NEAR THE END OF THE FORECAST PERIOD...SEA SURFACE TEMPERATURES MAY
ACTUALLY BECOME A LITTLE WARMER. BY THAT TIME...HOWEVER...THE
TROPICAL CYCLONE WILL PROBABLY HAVE WEAKENED CONSIDERABLY. THE NHC
INTENSITY FORECAST IS SIMILAR TO THE SHIPS PREDICTION.

INITIAL MOTION IS ABOUT 300/8. THE HURRICANE HAD BEEN TRACKING
NORTHWESTWARD TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE BUT NOW
APPEARS TO HAVE TURNED TOWARD THE WEST-NORTHWEST. GLOBAL MODELS
INDICATE THAT A MID-LEVEL RIDGE WILL BUILD TO THE NORTHWEST OF
HERNAN DURING THE NEXT SEVERAL DAYS...WHICH WOULD LIKELY FORCE A
CONTINUED TURN TOWARD THE LEFT. THIS IS ALSO INDICATED BY THE
DYNAMICAL TRACK MODELS WHICH ARE IN FAIRLY GOOD AGREEMENT ABOUT A
TURN TOWARD THE WEST AND WEST-SOUTHWEST IN 48 HOURS. THE OFFICIAL
TRACK FORECAST IS SOMEWHAT FASTER THAN THE PREVIOUS ONE AND QUITE
CLOSE TO THE MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 10/1500Z 17.7N 126.6W 80 KT
12HR VT 11/0000Z 18.2N 127.6W 70 KT
24HR VT 11/1200Z 18.5N 129.1W 60 KT
36HR VT 12/0000Z 18.4N 130.4W 50 KT
48HR VT 12/1200Z 18.0N 131.7W 45 KT
72HR VT 13/1200Z 17.2N 134.0W 40 KT
96HR VT 14/1200Z 16.5N 136.5W 35 KT
120HR VT 15/1200Z 16.0N 140.0W 30 KT

$$
FORECASTER PASCH

[Mecklenburg]

down to 80 kts. now

[KWT]

It doesn't look bad but the northern eyewall does seem to be having a fairly hard time still at the moment.