Felicia... a Pacific hurricane

[*Mach*]

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hurricane felicia discussion number 7

nws tpc/national hurricane center miami fl ep082009

200 am pdt wed aug 05 2009

 

satellite intensity estimates at 0600 utc from tafb and sab were

t4.5 and t4.0...respectively...but since that time the satellite

presentation has continued to improve. The eye has now persisted

for several hours and continues to warm with the deepest convection

located in the eastern and southeastern semicircles. An analysis

would now yield a average data t-number of 5.0 on the dvorak

scale...and the initial intensity is being raised to 90 kt.

 

Now that felicia is a deeper system...it is being pulled a little

more to the north by a large mid- to upper-level trough located off

the u.s. West coast. The initial motion is 300/10...and little

change to this heading is expected over the next 48 hours while the

mid-latitude trough remains nearly stationary. By days 4 and 5...

Two factors will cause felicia to turn to the west. First...the

trough will move eastward over western north america and will be

replaced by a mid-level high currently located north of hawaii.

Second...felicia will likely be weakening by that time and will be

influenced more strongly by the lower-level trade wind flow. There

has been a noticeable northward shift in the tightly-clustered

guidance envelope for this package...and the official forecast is

shifted northward towards the model consensus.

 

The environment around felicia remains conducive for further

strengthening. The mid-level cut-off low near california is

inducing diffluence aloft to the north of felicia...and it appears

that an outflow jet may be forming. Vertical shear is expected to

remain light over the next five days...and oceanic heat content

should remain sufficient for at least the next 36 hours. The

northward shift in the track forecast puts felicia over 24-25

degrees celsius water after 48 hours...and the new official

intensity forecast accounts for this by showing faster weakening

than was indicated in the previous forecast. If felicia stays a

little farther south...it might be able to maintain its intensity

for a longer period of time.

 

Forecast positions and max winds

 

initial 05/0900z 13.4n 128.2w 90 kt

12hr vt 05/1800z 14.1n 129.5w 100 kt

24hr vt 06/0600z 15.1n 131.2w 105 kt

36hr vt 06/1800z 16.1n 132.8w 100 kt

48hr vt 07/0600z 17.1n 134.6w 90 kt

72hr vt 08/0600z 18.5n 139.0w 75 kt

96hr vt 09/0600z 19.0n 144.5w 65 kt

120hr vt 10/0600z 19.0n 150.0w 50 kt

 

$$

forecaster berg

[*Mach*]

The current 5 day forecast track has Felicia headed toward Hawaii. Fortunately, the shear is forecast to slow considerably prior to arriving at the islands...

 

 

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HURRICANE FELICIA DISCUSSION NUMBER 11

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP082009

200 AM PDT THU AUG 06 2009

 

FELICIA APPEARS TO HAVE LEVELED OFF IN INTENSITY. THE EYE HAS BEEN

WARMING AND HAS BECOME MORE WELL-DEFINED OVER THE PAST FEW HOURS...

BUT AT THE SAME TIME THE COLD CLOUD TOPS AROUND THE EYE HAVE ALSO

BEEN WARMING. FINAL T-NUMBERS ARE UNCHANGED FROM SIX HOURS AGO...

AND THIS ADVISORY MAINTAINS 120-KT AS THE INTENSITY. FELICIA MAY

HAVE PEAKED NEAR 125 KT AROUND 0200-0300 UTC WHEN A WHITE RING

COMPLETELY SURROUNDED THE EYE ON THE DVORAK BD ENHANCEMENT CURVE.

 

THE FORWARD SPEED HAS SLOWED DOWN A BIT...AND THE INITIAL MOTION IS

300 DEGREES AT 9 KT. FELICIA CONTINUES TO MOVE WEST-NORTHWESTWARD

DUE TO A WEAKNESS IN THE SUBTROPICAL RIDGE...AND THE HURRICANE

COULD TURN A LITTLE MORE TO THE NORTHWEST DURING THE NEXT 24 HOURS

AS THE RIDGE RETREATS FARTHER EAST OVER MEXICO. THE GLOBAL MODELS

AGREE THAT ANOTHER MID-LEVEL RIDGE CURRENTLY NORTH OF HAWAII WILL

SHIFT EASTWARD AND CAUSE FELICIA TO TURN BACK TO WEST-NORTHWEST AND

THEN WEST BY DAYS 2 AND 3. THE GUIDANCE ENVELOPE HAS SHIFTED A

LITTLE FARTHER SOUTH FROM THE PREVIOUS PACKAGE...AND THE NEW

OFFICIAL FORECAST NOW LIES NEAR THE NORTHERN EDGE OF THE SOLUTIONS.

FELICIA IS EXPECTED TO BE STEERED WESTWARD BY DAYS 3 THROUGH 5 AS

IT WEAKENS AND BECOMES EMBEDDED IN THE TRADE WIND FLOW.

 

FLUCTUATIONS IN INTENSITY COULD OCCUR DURING THE NEXT DAY OR SO AS

FELICIA REMAINS OVER WARM WATERS. THEREAFTER...THE HURRICANE

SHOULD BE OVER SEA SURFACE TEMPERATURES LESS THAN 26C AND HEADING

TOWARD INCREASING WESTERLY SHEAR. STEADY WEAKENING IS INDICATED IN

THE FORECAST AT THAT TIME. ALL THE GLOBAL MODELS SHOW A MUCH

WEAKER VORTEX AS THE CYCLONE APPROACHES THE HAWAIIAN ISLANDS...AND

THE SHIPS MODEL EVEN DISSIPATES THE SYSTEM BY THAT TIME. ONLY THE

HWRF AND GFDL STILL HAVE THE CYCLONE AS A MINIMAL TROPICAL STORM ON

DAY 5. THE OFFICIAL FORECAST IS A COMPROMISE BY NOT INDICATING

DISSIPATION BUT WEAKENING FELICIA TO A TROPICAL DEPRESSION AT THE

END OF THE FORECAST PERIOD.

 

FORECAST POSITIONS AND MAX WINDS

 

INITIAL 06/0900Z 15.5N 131.2W 120 KT

12HR VT 06/1800Z 16.2N 132.3W 115 KT

24HR VT 07/0600Z 17.4N 133.9W 105 KT

36HR VT 07/1800Z 18.5N 135.8W 90 KT

48HR VT 08/0600Z 19.4N 138.1W 75 KT

72HR VT 09/0600Z 20.0N 143.0W 55 KT

96HR VT 10/0600Z 20.0N 148.5W 35 KT

120HR VT 11/0600Z 20.0N 154.0W 30 KT

 

$$

FORECASTER BERG

[LilNik]

I'm heading to the Mex Riviera this weekend. What can I expect? Is Felicia going to affect the waters at all do you think?

 

Thanks!!

[Hurricane Expert]

Felicia is almost dead east of the Big Island of Hawaii. As for the Mexican Riviera, this is hurricane season. Typically tropical cyclones form offshore and head west northwest or northwest. Sometimes the brush the coast with rain. Only rarely do they make landfall. Remember during the summer thundershowers build many days into the overnight hours.