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Hurricane Linda

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I don't think it will be to long till we have Linda

96e200909070600.jpg

ep200915.gif

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Indeed, 96E has acquired enough convection near the well defined circulation to be designated a tropical depression. 15E is located in marginally warm waters, and low shear. However, the air is fairly dry in the area which is supressing convection at the moment which is stopping the system becoming a tropical storm. 15E is forecast to modestly intensify over the next 48hrs in the marginal environment and then beging to rapidly weaken as waters cool and shear increases. 15E is currently moving westwards and will soon be approaching a weakness in the steering ridge to the north. It's not certain just how much 15E will feel this weakness but if it becomes more vertically deep (eg. a moderate tropical storm) then 15E will turn more towards the north. The sooner this occurs, the sooner 15E would be over cooler waters which may initiate weakening prior to the 48hr time frame. 15E is not expected to affect land.

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Against all expectations and in at best, marginal conditions, 15E has rapidly intensified into Tropical Storm Linda and intensity has increased to 50kts. Convection has exploded over the last few hours and a possible eye like feature is appearing on latest satellite imagery. This is somewhat surprising given that waters are only just about warm enough to support slow intensification and the airmass is fairly stable. Linda appears to be undergoing some rapid intensification at the moment, but it is unclear how long this will last. The official forecast from NHC now brings Linda to minimal hurricane status before the cyclone reaches cooler waters and higher shear. If current trends continue however, Linda could become stronger than the 65kt peak forecast by the NHC. I really wouldn't like to say how strong Linda will get as it is very uncertain.

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Linda is now behaving more typically of storm in a marginal environment, and has maintained an intensity of 50kts over the last 12hrs. The fleeting eye feature has not appeared recently and convection has flared and waned over the last 12hrs, but is currently looking quite impressive. Westerly shear has increased and this has brought some of the dry and stable air I mentioned earlier in towards the core of Linda. With continued westerly shear, dry and stable air, and eventually colder waters, it is hard to see Linda intensifying much more, if at all. But as we all know, predicting future intensity of tropical cyclones is still immensely difficult and as Linda showed yesterday, she could still intensify more than expected in the face of the mediocre environment. Linda still has a brief window of opportunity to become a minimal hurricane.

Linda is still heading westwards. A northward turn is still forecast, though the timing of this is uncertain. The longer it delays turning north, the longer Linda has over warmer waters as sea temps shelve off steeply to the north.

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Linda looks like she has resumed intensifying, just like this time yesterday. An eye has quite clearly appeared in latest satellite imagery and Linda may be upgraded to a hurricane in the next advisory (in about 45 mins):

post-1820-12524406441688_thumb.jpg

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Linda wasn't quite as strong as I thought, and shows that satellite appearances can be deceptive. Intensity has increased modestly to 55kts since I last updated. Linda, though exhibiting an eye like feature, lacked significant central convection for the upgrade. Dry air continues to be a significant problem for Linda, prohibiting significant intensification. Waters will cool on the northward heading which will cause a weakening trend to begin soon. Linda still does have a small shot at hurricane status but she really must do this sooner rather than later. Linda's slow motion currently is keeping her over warmer waters for longer so this could still occur if Linda manages to mix out the dry air.

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Linda has intensified a little more this evening with a narrow ring of convection wrapping around what looks like a developing eye. Intensity has increased to 60kts, and NHC now officially forecast again for Linda to briefly become a hurricane before shear increases and waters cool later tomorrow.

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funny

000

WTPZ45 KNHC 090834

TCDEP5

TROPICAL STORM LINDA DISCUSSION NUMBER 9

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152009

200 AM PDT WED SEP 09 2009

THE OVERALL SATELLITE PRESENTATION OF LINDA HAS CHANGED LITTLE

DURING THE PAST SEVERAL HOURS. CURRENT SATELLITE INTENSITY

ESTIMATES FROM BOTH AGENCIES REMAIN T3.5 OR 55 KT...WHICH IS THE

INITIAL INTENSITY FOR THIS ADVISORY. THE CIRRUS OUTFLOW OF LINDA

REMAINS RESTRICTED OVER THE WESTERN SEMICIRCLE...BUT QUITE

EXPANSIVE OVER THE NORTHEASTERN QUADRANT. RECENT MICROWAVE IMAGERY

SUGGEST THAT THE CYCLONE IS NOT VERTICALLY ALIGNED AS THE LOW-LEVEL

CENTER IS DISPLACED A LITTLE TO THE SOUTHWEST OF THE MID-LEVEL

CENTER.

DESPITE THE LIGHT TO MODERATE SOUTHWESTERLY SHEAR...THE INTENSITY

GUIDANCE PREDICTS SOME MODEST STRENGTHENING DURING THE NEXT 12-24

HOURS. THE OFFICIAL FORECAST SHOWS SLIGHT INTENSIFICATION...BUT IS

BELOW THE MORE AGGRESSIVE GFDL AND HWRF MODELS WHICH BRING THE

CYCLONE TO HURRICANE STRENGTH. IN 24-36 HOURS...THE SHEAR IS

FORECAST TO INCREASE AND LINDA IS EXPECTED TO BE MOVING OVER

SLIGHTLY COOLER WATER. THESE FACTORS SHOULD INDUCE WEAKENING.

THEREAFTER...LINDA IS EXPECTED TO WEAKEN AT A FASTER RATE AS IT

MOVES OVER PROGRESSIVELY COOLER WATERS...AND INTO A MORE HOSTILE

UPPER-LEVEL ENVIRONMENT. THE NEW INTENSITY FORECAST IS UNCHANGED

FROM THE PREVIOUS ADVISORY AND SHOWS LINDA BECOMING A REMNANT LOW

IN ABOUT 4 DAYS.

THE INITIAL MOTION ESTIMATE IS 340/2. THE GLOBAL MODELS INDICATE

THAT A STRONG MID-LEVEL RIDGE TO THE NORTHWEST OF THE CYCLONE WILL

WEAKEN DURING THE NEXT DAY OR SO. AT THE SAME TIME...A MID-LEVEL

RIDGE IS FORECAST TO BUILD TO THE EAST OF THE CYCLONE...WHICH

SHOULD ALLOW LINDA TO BEGIN MOVING NORTH-NORTHWESTWARD AT A FASTER

FORWARD SPEED. THE TRACK GUIDANCE IS IN GOOD AGREEMENT DURING THE

FIRST 2-3 DAYS OF THE FORECAST PERIOD...AND THE NEW NHC FORECAST

SHOWS VERY LITTLE CHANGE FROM THE PREVIOUS ADVISORY. THEREAFTER...

THERE IS SOME SPREAD IN THE GUIDANCE WITH A FEW OF THE MODELS

TURNING LINDA WESTWARD AS IT WEAKENS AND BECOMES A SHALLOW SYSTEM.

THE NHC TRACK AT DAYS 4 AND 5 KEEPS LINDA ON A SLOW NORTHWARD

MOTION...IN GOOD AGREEMENT WITH THE GFDL...HWRF...GFS...AND BAMS

SOLUTIONS. HOWEVER...THE NEW TRACK IS A LITTLE SLOWER THAN THE

PREVIOUS FORECAST AT 96 AND 120 HOURS.

IT SEEMS THAT NINES MUST BE WILD THIS MORNING...AS THIS HAPPENS TO

BE THE 9TH ADVISORY ON LINDA AT 0900 UTC ON 9/9/09.

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off subject slightly, I have tided up my Sig a bit, is all the information correct?

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Yeah, all looks correct apart from Linda was named on the 7th Sept, and is now a hurricane!

HURRICANE LINDA DISCUSSION NUMBER 12

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152009

800 PM PDT WED SEP 09 2009

LINDA HAS BECOME BETTER ORGANIZED DURING THE EVENING. AN EYE HAS

BECOME APPARENT IN CONVENTIONAL SATELLITE IMAGERY...AND AN AMSU

OVERPASS AT 0030 UTC SHOWED A BETTER DEFINED EYEWALL THAN A FEW

HOURS AGO. SATELLITE INTENSITY ESTIMATES ARE 77 KT FROM TAFB AND

65 KT FROM SAB...AND THERE HAVE BEEN SEVERAL AMSU ESTIMATES OF

65 KT OR GREATER. BASED ON THIS...LINDA IS UPGRADED TO A HURRICANE

WITH 70 KT WINDS.

THE INITIAL MOTION IS 320/5. LINDA IS SOUTH OF A LOW-LEVEL RIDGE...

WITH WATER VAPOR IMAGERY SHOWING A MID/UPPER-LEVEL TROUGH WEST OF

THE HURRICANE AND A MID/UPPER-LEVEL RIDGE EAST OF IT. THE

MID/UPPER-LEVEL FEATURES ARE TRYING TO STEER THE CYCLONE

NORTHWARD...WHILE THE LOW-LEVEL RIDGE IS TRYING TO STEER IT MORE

WESTWARD. THIS IS RESULTING IN A SLOW NORTHWESTWARD MOTION...

WHICH SHOULD CONTINUE AS LONG AS LINDA KEEPS ITS VERTICALLY DEEP

STRUCTURE. THE LARGE-SCALE GUIDANCE SUGGESTS THIS WILL BE FOR ABOUT

48-72 HR...AND THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS

TRACK THROUGH THAT TIME. AFTER THAT TIME...THE ECMWF...GFDN...

NOGAPS...AND UKMET SHOW THE LOW-LEVEL CENTER OF LINDA TURNING MORE

WESTWARD...WHILE THE GFS...HWRF...AND GFDL SHOW A GENERALLY

NORTHWARD MOTION. THIS SPREAD SUGGESTS THAT THE MOTION SHOULD BE

SLOW...AND THE NEW FORECAST TRACK COMPROMISES BETWEEN THESE

EXTREMES BY SHOWING A SLOW NORTHWARD MOTION.

ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SHOW 20 KT OF

SOUTHERLY VERTICAL WIND SHEAR OVER LINDA...AND SIMILAR SHEAR IS

EXPECTED THROUGH THE REST OF THE FORECAST PERIOD. IN ADDITION...

THE CYCLONE IS MOVING OVER SEA SURFACE TEMPERATURES OF 27C AND

COLDER. THESE FACTORS SUGGEST THE CURRENT INTENSIFICATION SHOULD

END SOON...AND THAT LINDA SHOULD STEADILY WEAKEN AFTER 12-24 HR.

THE NEW INTENSITY FORECAST IS AN UPDATE OF THE PREVIOUS ADVISORY...

AND CALLS FOR LINDA TO WEAKEN TO A TROPICAL STORM IN ABOUT 24

HR...A TROPICAL DEPRESSION IN ABOUT 72 HR...AND A REMNANT LOW IN

ABOUT 96 HR. THE SHEAR IS FORECAST TO BE STRONG ON THE FORECAST

TRACKS OF THE ECMWF AND THE OTHER WESTWARD-MOTION MODELS...SO EVEN

IF LINDA AVOIDS THE COLD WATERS NORTH OF 20N IT IS STILL LIKELY TO

WEAKEN TO A REMNANT LOW BEFORE 120 HR.

FORECAST POSITIONS AND MAX WINDS

INITIAL 10/0300Z 17.1N 129.4W 70 KT

12HR VT 10/1200Z 18.1N 130.1W 70 KT

24HR VT 11/0000Z 19.3N 131.0W 65 KT

36HR VT 11/1200Z 20.2N 131.7W 55 KT

48HR VT 12/0000Z 21.2N 132.5W 45 KT

72HR VT 13/0000Z 22.5N 133.5W 30 KT

96HR VT 14/0000Z 23.5N 133.5W 20 KT...REMNANT LOW

120HR VT 15/0000Z 24.0N 133.5W 20 KT...REMNANT LOW

$$

FORECASTER BEVEN

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Linda has continued to intensify and intensity is now at 75kts, a mid range cat 1 hurricane. Linda has managed to mix out the abundant dry air through an outflow channel. Shear is moderate, but not enough to stop this slow intensfication. Linda continues to move generally northwards along the western periphery of a ridge to the east, at a faster speed than before. In time, the models show this ridge weakening which will force Linda to slow down again. By this time, Linda will be over cooler waters and higher shear which should cause weakening. Linda is likely to hang on to hurricane status for about another 24hrs before weakening to a remnant low, currently thought to occur within 4 days.

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Conditions have deteriorated fast for Linda this morning, and strong shear has removed almost all convection from the increasingly distorted LLC. NHC have lowered the intensity to 45kts, and this may be generous. Sea temps are sharply declining, and Linda could well dissipate later today if convection doesn't make a comeback.

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Linda degenerated into a remnant low this morning. Cold waters will ensure the low won't re-develop, and the low itself will dissipate within the next day or two.

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gone

Last Advisory

000

WTPZ35 KNHC 120230

TCPEP5

BULLETIN

TROPICAL DEPRESSION LINDA ADVISORY NUMBER 20

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152009

800 PM PDT FRI SEP 11 2009

...LINDA NO LONGER A TROPICAL CYCLONE...

AT 800 PM PDT...0300 UTC...THE CENTER OF LINDA WAS LOCATED NEAR

LATITUDE 20.9 NORTH...LONGITUDE 131.7 WEST OR ABOUT 1405 MILES

...2260 KM...WEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA.

THE REMNANT LOW IS MOVING TOWARD THE WEST-NORTHWEST NEAR 5 MPH...8

KM/HR...AND A SLOW MOTION TO THE WEST-NORTHWEST IS EXPECTED OVER

THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER

GUSTS. THE LOW IS EXPECTED TO WEAKEN FURTHER DURING THE NEXT DAY OR

SO.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB...29.74 INCHES.

...SUMMARY OF 800 PM PDT INFORMATION...

LOCATION...20.9N 131.7W

MAXIMUM SUSTAINED WINDS...35 MPH

PRESENT MOVEMENT...WEST-NORTHWEST OR 300 DEGREES AT 5 MPH

MINIMUM CENTRAL PRESSURE...1007 MB

THIS IS THE LAST PUBLIC ADVISORY ISSUED BY THE NATIONAL HURRICANE

CENTER ON LINDA. FOR ADDITIONAL INFORMATION ON THE REMNANT LOW

PLEASE SEE HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER

SERVICE...UNDER AWIPS HEADER NFDHSFEPI AND WMO HEADER FZPN02 KWBC.

$$

FORECASTER ROBERTS/BRENNAN

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