Tropical Storm Lana

[Somerset Squall]

Invest 97E has rapidly consolidated today in the far west of the East Pacific and is now a 30kt tropical depression. 06E looks to be on the verge of TS strength, and I expect it will be upgraded next advisory. As 06E is currently at 138.9W, it is very nearly in the Central Pacific, and it is uncertain whether the system will be upgraded soon enough to become Enrique or later and become Lana (central pac name). 06E has about 36hrs of low shear and warm waters ahead of it on the westward track, and based on the very healthy satellite presentation, I think 06E could well peak at 55-60kts before shear increases. There is a small risk (currently assessed at 14% on the NHC wind probabilty product) of 06E actually developing into a minimal hurricane, but the system would really have to get it's act together quickly. After 36hrs, weakening will commence due to incteased shear. 06E should remain well south of Hawaii.

Edited July 30, 2009 by Somerset Squall

[Somerset Squall]

Although 06E formed in the East Pacific, it became a tropical storm in the Central Pacific, and has been named Lana. Deep convective banding is wrapping around the tight LLC. The forecast is similar to before, but NHC are now being more aggressive with the strengthening. Chances are increasing for Lana to become a hurricane before the shear increases.

Edited July 30, 2009 by Somerset Squall

[MAF]

...SUMMARY OF 1100 AM HST INFORMATION...

LOCATION...12.3N 141.4W

MAXIMUM SUSTAINED WINDS...40 MPH

PRESENT MOVEMENT...WEST OR 280 DEGREES AT 18 MPH

MINIMUM CENTRAL PRESSURE...1005 MB

[kold weather]

Got a good circulation right now though we do need to see some deeper convection re-develop over the center if we are going to get a hurricane out of this. However its got a pretty decent circulation and thus depsite its convection weakening over the last few hours the system should still slowly weaken after having rapidly organised in the 12hrs between 9am-9pm. I personally don't think this will reach hurricane status, shear from the ULL to its NW should eventually cause some shear though of course with ULL's they often are nowcasting type features as they often are very poorly forecasted over the open ocean.

[MAF]

yep, just checking out Satty images. NHC seem to think it may strengthen

AT 1100 AM HST...2100 UTC...THE CENTER OF TROPICAL STORM LANA WAS

LOCATED NEAR LATITUDE 12.3 NORTH...LONGITUDE 141.4 WEST OR ABOUT

1045 MILES...1680 KM...EAST-SOUTHEAST OF HILO HAWAII.

LANA IS MOVING TOWARD THE WEST NEAR 18 MPH...30 KM/HR...AND THIS

GENERAL MOTION IS EXPECTED TO CONTINUE OVER THE NEXT COUPLE OF

DAYS.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 40 MPH...65

KM/HR...WITH HIGHER GUSTS. ADDITIONAL STRENGTHENING IS FORECAST

DURING THE NEXT 48 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM

FROM THE CENTER.

Edited July 31, 2009 by MAF

[Cookie]

so we have Lana, nice to see you in this area MAF

[kold weather]

Lana continues to look good right now, I'd be quite happy to go higher then the 50kts the NHC have got Lana at, I'd suspect its closer to 55-60kts right now but its hard to tell. It continues to have good conditions as the upper flow aloft is still helping the outflow quite a lot. The ULL is still sitting where it was before causing a solid wall of shear further to the NW where Lana. Odds f Lana becoming a hurricane have also increased quite a lot overnight as it has organised very well.

ps, I had a typo in my last post, I said it would weaken steadily when in fact I meant that it would get stronger, as in the context of the sentence that makes no sense, oooppps!

Edited July 31, 2009 by kold weather

[Cookie]

shes not looking to bad atm

[Somerset Squall]

Indeed Cookie, Lana weakened to 45kts earlier but is now back up at a new official peak of 55kts. Deep convection is persisting over the well defined LLC. However, outflow seems poor in most quadrants, and this signifies that shear is increasing, as expected. This could well mean that Lana will not get any stronger and will gradually weaken over the next day or so before dissipation occurs as a weakened Lana finally succumbs to shear.

[Cookie]

STEADY

WEAKENING IS FORECAST FROM 24 HOURS AND BEYOND DUE TO THE EFFECTS

OF INCREASING VERTICAL SHEAR ALONG LANA/S PROJECTED TRACK. THE

FORECAST IS FOR LANA TO BE A REMNANT LOW BY 96 HOURS AND POTENTIALLY

SOONER.

[Cookie]

time is running out for Lana

[Somerset Squall]

Indeed Cookie, as expected- shear is tearing Lana apart. CPHC have kept the intensity at 45kts but this could be a little generous. The LLC is losing definition and the convection is patchy and not persistant. Although waters will remain warm, shear is expected to remain on the high side so Lana could degenerate into a remnant low pretty soon.

Seems my guess of a peak of 55-60kts was pretty good, for once!

[Cookie]

did she make hurricane stautes at all?

[Somerset Squall]

No she didn't Cookie, official peak was 55kts. If the shear held off a little longer then Lana probably would have made it to hurricane status but this did not occur.

Strong shear continues to adversely affect Lana. Bursts of deep convection, probably down to continued warm waters, have allowed Lana to remain a tropical storm despite the high shear. However, convection is not persistant, and indeed Lana has very little convection near the LLC at present. Unless another flare up occurs, Lana could soon weaken to a tropical depression. Lana's future intensity will almost be entirely governed by the shear as other factors remain favourable. Lana is becoming a little too reliant on convectional flare ups to maintain itself and is at risk of dissipation at any time. However, as waters are set to become warmer near the dateline in a couple days, there is a small chane Lana could make it into the West Pacific. Shear is set to remain high over the next few days, so the most reasonable option as forecast by the CPHC is gradual weakening until dissipation in a few days time.

[Cookie]

thanks mate.

[Cookie]

good night Lana

Last advisory written

TROPICAL DEPRESSION LANA DISCUSSION NUMBER 17

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP062009

500 AM HST MON AUG 03 2009

THE STRONG VERTICAL WIND SHEAR CONTINUES TO TAKE ITS TOLL ON

TROPICAL DEPRESSION LANA. THE LATEST UW-CIMSS ENVIRONMENTAL VERTICAL

WIND SHEAR ANALYSIS INDICATED VALUES OF 25 KT FROM 230 DEG. THE

CENTER OF THE LOW LEVEL CIRCULATION CENTER...WHICH HAS BEEN DEVOID

OF DEEP CONVECTION SINCE SUNDAY...WAS DIFFICULT TO LOCATE AT 200 AM

HST...1200 UTC...THIS MORNING. FIXES FROM PHFO...JTWC AND SAB WERE

RATHER TIGHTLY CLUSTERED...EVEN THOUGH THE ACTUAL CIRCULATION HAS

BECOME MUCH LESS DEFINED IN INFRARED IMAGERY DURING THE PAST 6

HOURS. BASED ON THE LATEST INITIAL POSITION...LANA IS MOVING 280/14.

ALL OF THE SATELLITE AGENCIES INDICATED THE SYSTEM WAS TOO WEAK TO

CLASSIFY...WITH PHFO GIVING A T-NUMBER OF 1.5 BASED ON MET. THE

CURRENT UW-CIMSS INTENSITY ANALYSIS INDICATED A CI OF 1.0.

THEREFORE...THE INITIAL INTENSITY IS REDUCED TO 25 KT.

THE STEERING OF TROPICAL DEPRESSION LANA...WHICH IS BEING CARRIED BY

THE LOW-LEVEL FLOW DUE TO ITS LACK OF DEEP CONVECTION...IS BEING

CONTROLLED BY THE SUBTROPICAL RIDGE LOCATED TO THE NORTH OF THE

SYSTEM NEAR LATITUDE 28N. THIS RIDGING IS FORECAST TO REMAIN IN

PLACE FOR AT LEAST THE NEXT FEW DAYS...SO NO MAJOR CHANGES TO THE

FORECAST TRACK WERE MADE FOR THIS PACKAGE. HOWEVER...THE FORECAST

TRACK FOR LANA...OR ITS REMNANTS...WAS NUDGED SLIGHTLY TO THE RIGHT

IN DEFERENCE TO BAMS/BAMM...AS WELL AS THE TRACK CONSENSUS.

IN REGARD TO THE INTENSITY FORECAST...DESPITE WARM SSTS AND

INCREASINGLY FAVORABLE OCEAN HEAT CONTENT BASED ON THE LATEST CIRA

ANALYSIS...THE STRONG VERTICAL WIND SHEAR WILL BE THE LIMITING

FACTOR FOR LANA AS A VIABLE TROPICAL CYCLONE. THE LATEST SHIPS

FORECAST INDICATES SHEAR WILL BE INCREASING TO 30 KT OR GREATER

LATER TODAY. THIS FORECAST APPEARS TO BE REASONABLE SINCE WATER

VAPOR IMAGERY DEPICTS AN UPPER TROPOSPHERIC LOW CENTERED NEAR 17N

168W...OR ABOUT 350 NM NORTHWEST OF LANA. THE GFS MODEL INDICATES

THIS LOW WILL TRAVEL WESTWARD AS A COMPANION OF LANA DURING THE NEXT

FEW DAYS. THERE DOES NOT APPEAR TO BE A CHANCE FOR THE SYSTEM TO

EVER RECOVER FROM THIS HOSTILE ENVIRONMENT. THEREFORE...THIS WILL BE

THE LAST ADVISORY FOR TROPICAL DEPRESSION LANA ISSUED BY THE CENTRAL

PACIFIC HURRICANE CENTER.

FORECAST POSITIONS AND MAX WINDS

INITIAL 03/1500Z 14.9N 163.6W 25 KT...DISSIPATING

12HR VT 04/0000Z 15.3N 165.8W 20 KT...REMNANT LOW

24HR VT 04/1200Z 15.8N 168.7W 20 KT...REMNANT LOW

36HR VT 05/0000Z 16.3N 171.6W 20 KT...REMNANT LOW

48HR VT 05/1200Z 16.8N 174.5W 20 KT...REMNANT LOW

$$

FORECASTER HOUSTON