Hurricane Calvin

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[Somerset Squall]

03E has been upgraded to Tropical Storm Calvin, with intensity rising to 45kts. Calvin is a healthy looking tropical storm with convection becoming more centralised to the LLC as shear eases. However, Calvin is heading west-northwestwards and is not far away from significantly colder waters south of Baja California. This means Calvin only has about another 24hrs to intensify. NHC peak Calvin at 60kts, but there is a chance the storm could become a hurricane, especially as a central dense overcast seems to be forming. Calvin is of no threat to land.

[Somerset Squall]

Calvin has strengthened quickly this afternoon and intensity is now at 60kts. As I mentioned earlier, Calvin was developing a CDO which has become solid over the last hour or two. Satellite imagery reveals an intermittent eye feature suggesting Calvin is close to becoming a hurricane. Time is running out for Calvin, but the storm should become a minimal hurricane before weakening commences.

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Just might get a hurricane out of it!

[Somerset Squall]

And we have! Intensity has risen to 65kts, making Calvin a cat 1 hurricane. Interestingly, the first three Eastern Pacific TC's this year so far have reached hurricane intensity. The last time this happened was in 1995 (Adolph, Barbara and Cosme). Calvin has developed a large eye in satellite imagery with some good banding flanking the hurricane. Calvin has about another 12hrs to intensify a little more before weakening begins over colder water.

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HURRICANE CALVIN DISCUSSION NUMBER 6

NWS NATIONAL HURRICANE CENTER MIAMI FL EP032011

200 PM PDT FRI JUL 08 2011

ALTHOUGH THE AREA OF CONVECTION IS NOT AS LARGE AS IT WAS ONE OR TWO

HOURS AGO...CONVENTIONAL SATELLITE IMAGES AS WELL AS MICROWAVE DATA

HAVE BEEN SHOWING AN INTERMITTENT EYE FEATURE. BASED ON THE CURRENT

CLOUD PATTERN AND THE INCREASE IN THE DVORAK T-NUMBERS SINCE THIS

MORNING...CALVIN HAS BEEN UPGRADED TO HURRICANE STATUS WITH AN

INITIAL INTENSITY OF 65 KNOTS. THE WESTERN PORTION OF THE

CIRCULATION IS ALREADY OVER COOLER WATER WHERE THE CONVECTION HAS

BEGUN TO WEAKEN. IT APPEARS THAT CALVIN HAS REACHED ITS PEAK

INTENSITY AND ALTHOUGH THERE COULD BE SOME FLUCTUATIONS IN

INTENSITY DURING THE NEXT 6 TO 12 HOURS...THE GENERAL TREND IS FOR

CALVIN TO WEAKEN.

CALVIN HAS SLOWED DOWN A LITTLE AND IS NOW MOVING TOWARD THE WEST OR

275 DEGREES AT 11 KNOTS. THE STEERING CURRENTS ARE NOT FORECAST TO

CHANGE SIGNIFICANTLY AND THE HURRICANE WILL LIKELY CONTINUE ON A

GENERAL WEST OR WEST-NORTHWEST TRACK WITH AN ADDITIONAL DECREASE IN

FORWARD SPEED FOR THE NEXT DAY OR SO. THEREAFTER...CALVIN IS

EXPECTED TO WEAKEN AND BECOME A REMNANT LOW WHICH WILL PROBABLY

BEGIN TO MEANDER EMBEDDED WITHIN A MUCH WEAKER LOW-LEVEL FLOW.

TRACK MODELS ARE IN VERY GOOD AGREEMENT IN MOVING CALVIN ON A

GENERAL WESTWARD TRACK FOR THE NEXT 24 TO 48 HOURS BUT VARY

SIGNIFICANTLY IN FORWARD SPEED THEREAFTER. HOWEVER...BY THEN CALVIN

IS NOT EXPECTED TO BE A SIGNIFICANT WEATHER SYSTEM.

FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 16.3N 108.5W 65 KT 75 MPH

12H 09/0600Z 16.4N 110.2W 60 KT 70 MPH

24H 09/1800Z 17.0N 112.0W 50 KT 60 MPH

36H 10/0600Z 17.5N 113.5W 40 KT 45 MPH

48H 10/1800Z 18.0N 114.5W 30 KT 35 MPH

72H 11/1800Z 19.0N 117.0W 25 KT 30 MPH...POST-TROP/REMNT LOW

96H 12/1800Z 19.5N 118.0W 20 KT 25 MPH...POST-TROP/REMNT LOW

120H 13/1800Z...DISSIPATED

$$

FORECASTER AVILA

[Somerset Squall]

Calvin peaked at 70kts but is now weakening over colder water. Intensity is down to 50kts, the eye has dissapeared and convection is shrinking over the LLC. General westwards motion is expected until dissipation.

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TROPICAL STORM CALVIN DISCUSSION NUMBER 10

NWS NATIONAL HURRICANE CENTER MIAMI FL EP032011

200 PM PDT SAT JUL 09 2011

VISIBLE AND MICROWAVE SATELLITE IMAGERY SHOWS THAT CALVIN CONTINUES

TO WEAKEN QUICKLY...WITH THE CENTER NOW EXPOSED TO THE EAST OF A

DIMINISHING AREA OF CONVECTION. THE INITIAL INTENSITY IS SET AT 40

KT USING A BLEND OF DVORAK CI AND FINAL-T NUMBERS FROM TAFB AND

SAB...AND A 1745 UTC ASCAT PASS THAT SHOWED A SMALL PATCH OF 35-40

KT WINDS EAST OF THE CENTER. CONTINUED WEAKENING IS FORECAST AS THE

CYCLONE MOVES OVER EVEN COLDER WATERS AND THE OFFICIAL FORECAST

SHOWS CALVIN BECOMING A REMNANT LOW BY TOMORROW IN AGREEMENT WITH

THE SHIPS AND LGEM. DISSIPATION IS EXPECTED WITHIN 48 TO 72

HOURS...BUT COULD OCCUR SOONER.

THE CENTER IS LOCATED A LITTLE NORTHEAST OF PREVIOUS ESTIMATES...BUT

THE INITIAL MOTION REMAINS TOWARD THE WEST-NORTHWEST OR 285 DEGREES

AT 8 KNOTS. AS CALVIN CONTINUES TO WEAKEN...IT WILL BE STEERED

GENERALLY WEST-NORTHWESTWARD BY THE LOW-LEVEL FLOW UNTIL

DISSIPATION. THE NEW NHC FORECAST IS ESSENTIALLY AN UPDATE OF THE

PREVIOUS ONE AFTER ADJUSTING FOR THE INITIAL POSITION.

THE 34-KT WIND RADII HAVE BEEN ADJUSTED INWARD BASED ON 09/1734Z

ASCAT SCATTEROMETER DATA.

FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 17.4N 111.7W 40 KT 45 MPH

12H 10/0600Z 17.8N 113.0W 30 KT 35 MPH

24H 10/1800Z 18.3N 114.6W 25 KT 30 MPH...POST-TROP/REMNT LOW

36H 11/0600Z 18.8N 116.2W 20 KT 25 MPH...POST-TROP/REMNT LOW

48H 11/1800Z 19.3N 117.6W 20 KT 25 MPH...POST-TROP/REMNT LOW

72H 12/1800Z...DISSIPATED

$$

FORECASTER BRENNAN/STEWART

[Somerset Squall]

Calvin has degenerated into a remnant low. Regeneration is not expected as the low spins down over cold water.