EPAC: GUILLERMO - Post-Tropical

[Kingarabian]

ECMWF kills it within 24 hours.

[Kingarabian]

Multiple wind shifts.

Movement still 300 like the CPHC says?

[Chris_in_Tampa]

It depends where the center is.

About 12 hour movement noted. Center is somewhere between that using flight level data:

[Chris_in_Tampa]

Wind was from the SSE at the surface in the sonde. If there is only one surface center, and not something like multiple swirls, it would be around 283 degrees for approximately twelve hour movement.

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[Chris_in_Tampa]

On second thought, it's around 286 or 287 degrees. (maybe they will go with 290) The two dropsondes noted are about twelve hours apart. Both sondes coincidentally had winds from the SSE at 9 knots. The first 997mb vortex from the previous mission was located a little far north.

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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[Kingarabian]

Wind was from the SSE at the surface in the sonde. If there is only one surface center, and not something like multiple swirls, it would be around 283 degrees for approximately twelve hour movement.

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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

So if we only factor in the past 6 hours, the heading would be between 270-280.

[Chris_in_Tampa]

Over approximately seven hours below. The vortex message was well placed for the 998mb icon. The sonde above it had east wind.

A. Time of Center Fix: 5th day of the month at 5:58:00Z
A. Time of Center Fix: 4th day of the month at 23:11:00Z

[Kingarabian]

They went with 295.

[wxman57]

Looks like it's falling apart. No more convection. No significant impact on Hawaii.

[wxman57]

Recon found a pressure of 1002mb. FL winds to 62 kts. Rain-contaminated SFMR to 58kts but generally in the 45-48kt range. Convection is minimal.

[Yellow Evan]

There's still convection just north of the center.

62 knt FL even using a conservative 80% reduction factor still supports 50 knots.

[wxman57]

There's still convection just north of the center.

62 knt FL even using a conservative 80% reduction factor still supports 50 knots.

I'm measuring nearest convection at 90 miles NNE of the center. Shear is taking its toll.

[Kingarabian]

So the end is here and Hawaii is spared once again. Thank you all for your posts and taking part in discussions. I learned a lot.

On to Invest 92E.

[Yellow Evan]

WTPA44 PHFO 052054
TCDCP4

TROPICAL STORM GUILLERMO DISCUSSION NUMBER 28
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092015
1100 AM HST WED AUG 05 2015


THE CENTER OF GUILLERMO HAS BECOME EXPOSED DUE TO STRONG VERTICAL
WIND SHEAR. A U.S. AIR FORCE HURRICANE HUNTER AIRCRAFT FOUND
PERSISTENT FLIGHT LEVEL WINDS OF UP TO 62 KT WITHIN THE NORTHEAST
QUADRANT...WHERE DEEP CONVECTION IS NOW CONFINED...AND CONVERSION OF
THE FLIGHT LEVEL WINDS TO THE SURFACE YIELDS 50 KT. THE SFMR
REPORTED WINDS WERE UP TO 55 KT...BUT GIVEN COLLOCATED RAIN RATES...
THE FLIGHT LEVEL DATA HAVE BEEN USED FOR THE CURRENT INTENSITY OF 50
KT.

STEADY WEAKENING IS EXPECTED TO RESUME TODAY. VERTICAL WIND SHEAR
ACCORDING CIMSS IS NEARLY 45 KT...AND WITH AN UPPER LEVEL TROUGH
OVERHEAD...WIND SHEAR IS FORECAST TO INCREASE FURTHER DURING THE
NEXT 24 HOURS. THIS WILL LEAD TO STEADY WEAKENING AS THE WARM CORE
ALOFT BECOMES FURTHER DISRUPTED AND INCREASINGLY TILTED. THE
INTENSITY FORECAST IS SIMILAR TO THE PRIOR ADVISORY...WEAKENING
GUILLERMO INTO A TROPICAL DEPRESSION BY THURSDAY NIGHT WITH
DEGENERATION INTO A REMNANT LOW BY SATURDAY. THE FORECAST CLOSELY
FOLLOWS ICON. SHIPS IS MORE AGGRESSIVELY WEAKENING THE SYSTEM AND
FORECASTS DEGENERATION INTO A REMNANT LOW BY FRIDAY.

AIRCRAFT RECONNAISSANCE FOUND THE CENTER OF GUILLERMO TO BE
SLIGHTLY NORTH OF ITS EXPECTED POSITION THIS MORNING...AND
SUBSEQUENT VISIBLE SATELLITE IMAGERY SUPPORT THIS LOCATION...GIVING
AN INITIAL MOTION TOWARD THE WEST-NORTHWEST...295 DEGREES...AT 10
KT. THE NORTHWARD JOG IN THE INITIAL POSITION SUGGESTS THAT THE
CIRCULATION...THOUGH TILTED...IS STILL COUPLED AT THE LOWER LEVELS
AND ALOFT. UNDER THE INFLUENCE OF INCREASING VERTICAL WIND
SHEAR...THE LOW LEVEL CENTER COULD BECOME DECOUPLED...CAUSING THE
STEERING FLOW AFFECTING GUILLERMO TO BECOME INCREASINGLY DOMINATED
BY THE LOW LEVEL RIDGE THAT WILL REMAIN FAR TO THE NORTH-NORTHEAST.
WITH THIS IN MIND...THE TRACK FORECAST HAS BEEN CHANGED LITTLE FROM
THE LAST ADVISORY AND IS ALONG THE SOUTHERN EDGE OF THE GUIDANCE
ENVELOPE.

TROPICAL STORM WATCHES FOR MAUI COUNTY AND THE BIG ISLAND OF HAWAII
HAVE BEEN DISCONTINUED WITH THIS ADVISORY. THIS DECISION WAS MADE
GIVEN THE HIGH CONFIDENCE IN THE FORECAST FOR WEAKENING AND THE
DECREASE IN WIND PROBABILITIES OVER THE ISLANDS.



FORECAST POSITIONS AND MAX WINDS

INIT 05/2100Z 21.4N 151.7W 50 KT 60 MPH
12H 06/0600Z 22.0N 153.1W 45 KT 50 MPH
24H 06/1800Z 22.6N 155.3W 35 KT 40 MPH
36H 07/0600Z 23.1N 157.6W 30 KT 35 MPH
48H 07/1800Z 23.8N 159.8W 30 KT 35 MPH
72H 08/1800Z 25.5N 164.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 09/1800Z 27.4N 168.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 10/1800Z...DISSIPATED

$$
FORECASTER WROE

[Yellow Evan]

WTPA44 PHFO 060237
TCDCP4

TROPICAL STORM GUILLERMO DISCUSSION NUMBER 29
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092015
500 PM HST WED AUG 05 2015

THE SATELLITE PRESENTATION OF GUILLERMO CONTINUES TO DEGRADE AS
VERTICAL WIND SHEAR EXACTS A GREATER TOLL. A LONE CLUSTER OF DEEP
CONVECTION IS PERSISTING WITHIN THE NORTHEAST QUADRANT AS STRONG
UPPER LEVEL WEST-SOUTHWEST WINDS PRODUCE VERTICAL WIND SHEAR OF OVER
40 KT ACCORDING TO CIMSS. AS A RESULT...THE LOW LEVEL CIRCULATION
CENTER IS COMPLETELY EXPOSED. WATER VAPOR IMAGERY REVEALS AN AREA OF
DRY AIR ALOFT DIRECTLY OVER THE CENTER...WHICH SUGGESTS THAT THE
UPPER LEVEL WARM CORE IS LIKELY DESTROYED. CURRENT INTENSITY
ESTIMATES FROM HFO AND SAB CAME IN AT 2.0...AND JTWC AND ADT WERE
LOWER...YIELDING AN ESTIMATE OF 30 KT. MORNING RECONNAISSANCE DATA
AND A 1930 UTC ASCAT PASS SUPPORTED MUCH HIGHER WINDS...SO THE
INITIAL INTENSITY FOR THIS ADVISORY WILL BE LOWERED TO 45 KT.

STEADY WEAKENING IS EXPECTED TO CONTINUE DURING THE NEXT FEW DAYS.
AN UPPER LEVEL TROUGH WILL FLATTEN AS IT REMAINS IN PLACE NORTH OF
THE ISLANDS THROUGH THE WEEKEND...IMPARTING STRONG VERTICAL WIND
SHEAR. DEEP CONVECTION IS EXPECTED TO BECOME LESS PERSISTENT AS THE
UPPER LEVELS OF THE SYSTEM BECOME INCREASINGLY DECOUPLED...CAUSING
GUILLERMO TO STEADILY WEAKEN. THE INTENSITY FORECAST IS SIMILAR TO
THE PRIOR ADVISORY...WEAKENING GUILLERMO TO A TROPICAL DEPRESSION
BY THURSDAY NIGHT WITH DEGENERATION INTO A REMNANT LOW BY SATURDAY.
THE FORECAST CLOSELY FOLLOWS ICON AND IS LESS AGGRESSIVE THAN
SHIPS...WHICH DISSIPATES GUILLERMO ON FRIDAY.

THE INITIAL MOTION IS TOWARD THE WEST-NORTHWEST...OR 295 DEGREES...
AT 9 KT...WITH THE LOW LEVEL CENTER COMPLETELY EXPOSED. THE FORWARD
MOTION OF THE SYSTEM IS A BIT SLOWER DUE TO WOBBLES OF THE LOW
LEVEL CENTER AS IT WAS BECOMING EXPOSED EARLIER TODAY. AS THE UPPER
LEVELS OF THE SYSTEM BECOME DECOUPLED...THE STEERING SHOULD BECOME
DOMINATED BY A LOWER LEVEL RIDGE FAR TO THE NORTH...WITH A GENERAL
WEST-NORTHWEST MOTION IMPARTED BY A WEAKNESS IN THE MID LEVEL RIDGE
TO THE NORTH. THE TRACK FORECAST HAS CHANGED LITTLE FROM THE LAST
ADVISORY AND REMAINS ALONG THE SOUTHERN EDGE OF A RATHER TIGHTLY
CLUSTERED GUIDANCE ENVELOPE THROUGH 48 HOURS...THEN IN THE MIDDLE OF
THE ENVELOPE THEREAFTER.



FORECAST POSITIONS AND MAX WINDS

INIT 06/0300Z 21.6N 152.3W 45 KT 50 MPH
12H 06/1200Z 22.1N 153.8W 40 KT 45 MPH
24H 07/0000Z 22.7N 155.8W 35 KT 40 MPH
36H 07/1200Z 23.3N 158.2W 30 KT 35 MPH
48H 08/0000Z 24.0N 160.6W 30 KT 35 MPH
72H 09/0000Z 25.9N 165.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 10/0000Z...DISSIPATED

$$
FORECASTER WROE

[Yellow Evan]

Probs still 45 based on Recon.

[AbcdeerHI]

Product: Air Force Vortex Message (URPN12 KNHC)
Transmitted: 6th day of the month at 7:21Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5305
Storm Number & Year: 09 in 2015
Storm Name: Guillermo (flight in the Northeast Pacific basin)
Mission Number: 10
Observation Number: 08
A. Time of Center Fix: 6th day of the month at 6:56:10Z
B. Center Fix Coordinates: 21°42'N 152°44'W (21.7N 152.7333W)
C. Minimum Height at Standard Level: 1,474m (4,836ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 51kts (~ 58.7mph)
E. Location of the Estimated Maximum Surface Wind: 82 nautical miles (94 statute miles) to the NE (44°) of center fix
F. Maximum Flight Level Wind Inbound: From 117° at 52kts (From the ESE at ~ 59.8mph)
G. Location of Maximum Flight Level Wind Inbound: 72 nautical miles (83 statute miles) to the NE (44°) of center fix
H. Minimum Sea Level Pressure: 1005mb (29.68 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 1,520m (4,987ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,523m (4,997ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind and Pressure
N. Fix Level: 850mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile

Remarks Section:
Maximum Flight Level Wind: 52kts (~ 59.8mph) which was observed 72 nautical miles (83 statute miles) to the NE (44°) from the flight level center at 6:34:30Z
Dropsonde Surface Wind at Center: From 110° at 10kts (From the ESE at 12mph)

[Chris_in_Tampa]

From completed mission:





11pm HST track. 8:30Z satellite.

[Yellow Evan]

If SFMR said 40, this should be 40....

WTPA44 PHFO 061511
TCDCP4

TROPICAL STORM GUILLERMO DISCUSSION NUMBER 31
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092015
500 AM HST THU AUG 06 2015

THE LOW LEVEL CIRCULATION CENTER...LLCC...OF GUILLERMO HAS BECOME
COMPLETELY DECOUPLED FROM ITS MID AND UPPER LEVEL CIRCULATION. THIS
IS DUE TO THE VERY STRONG VERTICAL WIND SHEAR AND THE ENTRAINMENT OF
DRIER AIR ALOFT INTO THE SYSTEM DURING THE PAST 12 TO 18 HOURS.
THESE CONDITIONS CONTINUE TO PRODUCE VERY HOSTILE CONDITIONS FOR THE
INNER CORE OF THE TROPICAL STORM. AFTER CAREFUL REANALYSIS OF THE
DATA REPORTED BY THE U.S. 53RD WEATHER RECONNAISSANCE SQUADRON
AIRCRAFT FLYING INTO GUILLERMO LAST EVENING...THIS DECOUPLING OF THE
LLCC HAS ALREADY BEGUN TO DISRUPT THE LOW LEVEL WINDS NEAR THE STORM
CENTER. EVEN THOUGH THERE WERE SFMR ESTIMATED SURFACE WINDS OF AT
LEAST 45 KNOTS...THESE WERE ASSOCIATED WITH THE DEEP CONVECTION...
WHICH WAS ABOUT 75 NM FROM THE CENTER. CLOSER TO THE STORM CENTER...
THE SFMR WINDS WERE APPROXIMATELY 40 KNOTS. AS A RESULT...GUILLERMO
IS WEAKENING MUCH FASTER THAN ANTICIPATED. THERE IS CURRENTLY A
SMALL CLUSTER OF ISOLATED THUNDERSTORMS WITH TOPS TO NEAR 50
THOUSAND FEET ABOUT 55 NM NORTH OF THE CENTER. THE SATELLITE FIX
AGENCIES INDICATE THAT GUILLERMO HAS WEAKENED BELOW TROPICAL STORM
INTENSITY...WITH JTWC AND SAB INDICATING IT WAS TOO WEAK TO
CLASSIFY. BASED ON ALL OF THE AVAILABLE INFORMATION FROM THE
AIRCRAFT AND SATELLITE BASED GUIDANCE...WE HAVE MADE GUILLERMO A
MINIMAL TROPICAL STORM WITH 35 KNOTS AS THE INITIAL INTENSITY.

BASED ON THE LATEST SATELLITE FIXES AND IMAGERY...THE INITIAL MOTION
IS JUST NORTH OF DUE WEST...OR 275 DEGREES...AT 10 KT. ONCE THE LLCC
BECAME DECOUPLED...IT HAS BEEN DRIVEN BY THE LOW LEVEL TRADE WIND
FLOW SOUTHWEST OF THE SUBTROPICAL RIDGE LOCATED FAR NORTH OF THE
AREA. THE FORECAST TRACK HAS BEEN ADJUSTED MORE TO THE SOUTH TO
ACCOUNT FOR THIS NEW STEERING MECHANISM. NOTE THAT THE TRACK IS TO
THE LEFT OF THE ECMWF GUIDANCE...WHICH IS THE LEFT-MOST RELIABLE
TRACK AVAILABLE.

WITH NO SIGNS OF DECREASING VERTICAL WIND SHEAR OR ABATEMENT OF THE
ENTRAINMENT OF DRY AIR ALOFT...ADDITIONAL RAPID WEAKENING IS
EXPECTED TO CONTINUE TODAY. THE INTENSITY FORECAST NOW WEAKENS
GUILLERMO TO A TROPICAL DEPRESSION LATER THIS MORNING OR THIS
AFTERNOON. THE DEPRESSION IS THEN FORECAST TO MAINTAIN ITSELF FOR
THE NEXT 12 TO 36 HOURS...BUT THIS MAY BE GENEROUS GIVEN THE CURRENT
RAPID RATE OF DECAY. IT IS POSSIBLE THAT GUILLERMO COULD BECOME A
POST-TROPICAL/REMNANT LOW MUCH SOONER THAN ANTICIPATED...WHICH IS
DAY 2 FOR THIS FORECAST.

THE FINAL ANALYSIS OF THE WIND RADII FOUND BY THE RECONNAISSANCE
AIRCRAFT LAST EVENING WERE USED TO MAKE ADJUSTMENTS TO THE SIZE OF
THE STORM FOR THIS ADVISORY. NOTE THAT THERE WERE NO GALE FORCE
WINDS IN THE SOUTHWEST QUADRANT LAST EVENING. GUILLERMO IS A VERY
ASYMMETRIC TROPICAL CYCLONE...SO THE PRIMARY THREAT TO MARINERS
REMAINS IN THE NORTHERN SEMICIRCLE.


FORECAST POSITIONS AND MAX WINDS

INIT 06/1500Z 21.7N 154.4W 35 KT 40 MPH
12H 07/0000Z 22.0N 156.1W 30 KT 35 MPH
24H 07/1200Z 22.4N 158.7W 30 KT 35 MPH
36H 08/0000Z 22.9N 161.5W 25 KT 30 MPH
48H 08/1200Z 23.4N 164.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 09/1200Z 24.5N 170.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 10/1200Z...DISSIPATED

$$
FORECASTER HOUSTON

[Alyono]

may end up with a landfall out of this