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East Pacific Hurricane Season 2013


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Henriette looks awesome now, I hesitate to use the word but she looks annular.  She's just a donut of convection.  Might have a bit too much banding to actually be annular but the presentation on infrared looks awesome.  Also looking at water vapor it seems like she's headed into a pretty moist environment so while she's probably peaked I'm curious to see how quickly she will fall apart.

 

The eye would have to be much clearer for the system to be considered annular... minus 30-20C temperatures won't cut it, you typically need +10C and beyond. Its appearance is more akin to a midget TC currently. 

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I'm not a big student of the East Pac, but it seems an unusual number of storms have survived to the CPHC area of responsibility.  Henriette disco even holds out chance it crosses the dateline as an intact TC, although dissipation is forecast.

 

When was the last season with a similar seasonal ENSO state to have so many low latitude long lived East Pac systems?

 

Also a small amount of weeniesm for September when there is a better chance for a trough to capture a system well South of Hawaii ala Iniki.

 

20.jpg

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I'm not a big student of the East Pac, but it seems an unusual number of storms have survived to the CPHC area of responsibility.  Henriette disco even holds out chance it crosses the dateline as an intact TC, although dissipation is forecast.

 

When was the last season with a similar seasonal ENSO state to have so many low latitude long lived East Pac systems?

 

Also a small amount of weeniesm for September when there is a better chance for a trough to capture a system well South of Hawaii ala Iniki.

 

20.jpg

 

2000.

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90C in the Central Pacific near Pewa has been given a Dvorak T number of 2.5 by SSD, which is equivalent to a tropical storm, but in the latest tropical weather outlook, CPHC gives it a 10% chance of developing. On the satellite, it certainly looks better than a '10% system'.

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90C in the Central Pacific near Pewa has been given a Dvorak T number of 2.5 by SSD, which is equivalent to a tropical storm, but in the latest tropical weather outlook, CPHC gives it a 10% chance of developing. On the satellite, it certainly looks better than a '10% system'.

 

90C has vigorous convection, fairly strong surface winds, and even a well-defined mid-level circulation, but the surface circulation is not closed:

 

post-378-0-43871500-1376790218_thumb.png

 

See TS Pewa, also in the central Pacific, by comparison (far lower-left corner):

 

post-378-0-45748800-1376790314_thumb.png

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90C has vigorous convection, fairly strong surface winds, and even a well-defined mid-level circulation, but the surface circulation is not closed:

 

attachicon.gifWMBas4.png

 

See TS Pewa, also in the central Pacific, by comparison (far lower-left corner):

 

attachicon.gifWMBas4_2.png

 

Interesting that ASCAT doesn't depict a closed circulation, because it was definately closed yesterday when the convection was more poorly organized, and there are some rather suggestive 37 GHz Microwave Imagery with some hints of a mid-level eye on some of the 85 Ghz scans... 

 

I get concerned with using ASCAT imagery when there is a bunch of convection ongoing (directional contamination is just as big of a problem as magnitude contamination) and I think this might be one of those times the ASCAT might not be seeing the full picture. Note that you also see this with Pewa somewhat (there are some easterly wind vectors that seem to be clearly south of the llc... there's the rain contamination)

 

In any event, 90C certainly deserves more than the negligent 20% that the CPHC is giving it currently. 

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Interesting that ASCAT doesn't depict a closed circulation, because it was definately closed yesterday when the convection was more poorly organized, and there are some rather suggestive 37 GHz Microwave Imagery with some hints of a mid-level eye on some of the 85 Ghz scans... 

 

I get concerned with using ASCAT imagery when there is a bunch of convection ongoing (directional contamination is just as big of a problem as magnitude contamination) and I think this might be one of those times the ASCAT might not be seeing the full picture. Note that you also see this with Pewa somewhat (there are some easterly wind vectors that seem to be clearly south of the llc... there's the rain contamination)

 

In any event, 90C certainly deserves more than the negligent 20% that the CPHC is giving it currently. 

 

Yeah, good points about the possible rain contamination. 

 

Even if there wasn't a closed surface circulation, vigorous convection symmetrically-located about a robust mid-level circulation and vertically stacked over a surface trough should warrant more than a 20%.

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Talk about an impressive signature for a disturbance with a 20% chance of development. I'm stunned ASCAT continues to depict a trough axis. 

 

2hwi3w1.jpg

 

1. Showers and thunderstorms associated with a surface trough located about 1120 miles west southwest of Lihue, Hawaii are moving westward at 10 to 15 mph. Little significant development of this system is expected due to its close proximity to the outflow from tropical storm Pewa, which crossed the dateline yesterday and has been creating unfavorable winds aloft above the system. This system has a low chance, 20 percent, of becoming a tropical cyclone during the next 48 hours.

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Well, apprently, per the ATCF, we have Unala, though I find it hard to belive.

 

Looks like ASCAT didn't do a very well job depicting the tight llc that was underneath the convection earlier.

 

CPHC basically saying D'oh!

 

 

 

WTPA45 PHFO 190300

TCDCP5

TROPICAL STORM UNALA DISCUSSION NUMBER 1

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP022013

500 PM HST SUN AUG 18 2013

GOES VISIBLE IMAGERY AT 2330Z AND A 0020Z ASCAT PASS DEMONSTRATED

THAT THE SUSPECT AREA FORMERLY KNOWN AS INVEST 90C WAS ACTUALLY

TROPICAL STORM UNALA. ASCAT SHOWED A SHARP TROUGH WITH A RAGGED 30

NM SWATH OF TROPICAL STORM FORCE WINDS ACROSS NORTHEAST AND

NORTHWEST SECTIONS...BUT NO CLOSED CIRCULATION CENTER.

HOWEVER...GOES VISIBLE IMAGERY AT 2330Z SHOWED A LOW LEVEL

CIRCULATION CENTER...LLCC...POPPING OUT TO THE WEST SOUTHWEST OF

DEEP CONVECTION. THE COMBINATION OF THE TWO DATA SETS COMPELLED US

TO UPGRADE THIS SYSTEM IN SHORT ORDER.

INITIAL STRENGTH IS SET AT 35 KT BASED MAINLY ON SCATTEROMETER DATA.

FIXES FROM CPHC AND JTWC INDICATED 30 KT STRENGTH...WHILE SAB ALONE

HAD THIS SYSTEM STRONGER AT 35 KT. THERE WERE A FEW STRONGER WIND

BARBS WITHIN THE ASCAT PASS...BUT WITH THE EMERGENCE OF THE LLCC IT

IS LIKELY THIS SYSTEM IS ACTUALLY PAST ITS PEAK...MAKING 35 KT SEEM

REASONABLE. SHIPS SLOWLY STRENGTHENS UNALA THROUGH 120

HOURS...MAKING IT A 50 KT TROPICAL STORM AT THE END OF 5 DAYS.

HOWEVER...INTERFERENCE FROM TROPICAL STORM PEWA OR ITS REMNANTS

SHOULD HINDER DEVELOPMENT. SHIPS SEEMS TO PARAMETERIZE THIS BY

HAVING UNALA PASS THROUGH RATHER BRUTAL SHEAR BEYOND 12 HOURS...BUT

FAILS TO WEAKEN THE SYSTEM APPROPRIATELY. WE WILL KEEP UNALA AT

MARGINAL TROPICAL STORM STRENGTH THROUGH 48 HOURS...THEN WEAKEN IT

AFTERWARD AS A NOD TO THE FORECAST SHEAR.

INITIAL MOTION IS TOWARD THE WEST AT 18 KT ALONG THE SOUTH SIDE OF A

BROAD SUBTROPICAL RIDGE. THIS TRACK WILL GRADUALLY BECOME

NORTHWESTERLY IN THE 36 TO 48 HOUR TIMEFRAME AS UNALA BEGINS TO

GAIN LATITUDE ALONG THE WESTERN LIMB OF THE RIDGE. TRACK GUIDANCE

IS TIGHTLY PACKED IN A SIMILAR MANNER...BUT WITH A QUICKER SWING TO

THE NORTH. INITIAL MOTION AND THE PROXIMITY OF PEWA KEEPS THE

FORECAST TRACK WITHIN THE LEFT HALF OF THE TRACK GUIDANCE ENVELOPE.

FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 17.1N 178.3W 35 KT 40 MPH

12H 19/1200Z 17.2N 178.9E 35 KT 40 MPH

24H 20/0000Z 17.6N 175.3E 35 KT 40 MPH

36H 20/1200Z 18.4N 172.1E 35 KT 40 MPH

48H 21/0000Z 19.9N 169.0E 35 KT 40 MPH

72H 22/0000Z 24.0N 163.9E 30 KT 35 MPH

96H 23/0000Z 29.5N 160.6E 30 KT 35 MPH

120H 24/0000Z 34.9N 158.8E 30 KT 35 MPH...POST-TROP/REMNT LOW

$

FORECASTER POWELL

 
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90C in the Central Pacific near Pewa has been given a Dvorak T number of 2.5 by SSD, which is equivalent to a tropical storm, but in the latest tropical weather outlook, CPHC gives it a 10% chance of developing. On the satellite, it certainly looks better than a '10% system'.

I guess I was right after all.

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