000
WTPZ45 KNHC 251431
TCDEP5
HURRICANE DARBY DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
800 AM PDT FRI JUN 25 2010

DARBY IS A SMALL BUT INTENSE HURRICANE.  SATELLITE IMAGES AND
MICROWAVE DATA REVEAL AN EYE SURROUNDED BY A RING OF VERY DEEP
CONVECTION. T-NUMBERS FROM TAFB AND SAB HAVE INCREASED TO 5.5 ON
THE DVORAK SCALE AND THE INITIAL INTENSITY HAS BEEN ADJUSTED UPWARD
TO 100 KNOTS. THE HURRICANE HAS AN OPPORTUNITY TO STRENGTHEN A
LITTLE MORE BEFORE THE UPPER-LEVEL ENVIRONMENT BECOMES UNFAVORABLE
IN A DAY OR TWO. THEREFORE...A GRADUAL WEAKENING IS INDICATED.

DARBY HAS CONTINUED TO MOVE TOWARD THE WEST-NORTHWEST OR 285 DEGREES
AT 6 KNOTS.  HOWEVER...AS THE RIDGE TO THE NORTH WEAKENS AND THE
STEERING CURRENTS COLLAPSE...THE HURRICANE SHOULD BEGIN TO MEANDER
AS INDICATED IN THE OFFICIAL FORECAST. GLOBAL MODELS ARE NOT IN GOOD
AGREEMENT ON THE TRACK OF DARBY...BUT MOST OF THEM WEAKEN THE
CYCLONE AS IT BECOMES EMBEDDED WITHIN A LOW-LEVEL WESTERLY FLOW.


FORECAST POSITIONS AND MAX WINDS

INITIAL      25/1500Z 13.6N 101.2W   100 KT
 12HR VT     26/0000Z 13.9N 102.0W   105 KT
 24HR VT     26/1200Z 13.9N 103.2W   100 KT
 36HR VT     27/0000Z 13.5N 103.5W    90 KT
 48HR VT     27/1200Z 13.5N 104.0W    80 KT
 72HR VT     28/1200Z 13.8N 104.0W    70 KT
 96HR VT     29/1200Z 14.0N 103.3W    60 KT
120HR VT     30/1200Z 14.5N 102.5W    50 KT

$$
FORECASTER AVILA

000
WTPZ45 KNHC 252044
TCDEP5
HURRICANE DARBY DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
200 PM PDT FRI JUN 25 2010

DARBY REMAINS A WELL-ORGANIZED HURRICANE WITH VISIBLE IMAGERY
SHOWING A DISTINCT EYE AND AN IMPRESSIVE OUTFLOW PATTERN. DVORAK
SATELLITE CLASSIFICATIONS FROM TAFB AND SAB AT 1800 UTC WERE
T5.5...102 KT.  SINCE THAT TIME...THE SYSTEM HAS BECOME BETTER
ORGANIZED WITH DEEPER CONVECTION IN THE EYEWALL. THUS...THE INITIAL
INTENSITY IS NUDGED UPWARD TO 105 KT.  EASTERLY SHEAR IS FORECAST
BY ALL OF THE GLOBAL MODELS TO INCREASE OVERNIGHT WHICH SHOULD
LIMIT FUTURE STRENGTHENING.  THIS SHEAR WILL LIKELY PERSIST FOR
SEVERAL DAYS AND CAUSE DARBY TO GRADUALLY WEAKEN.  MOST OF THE
INTENSITY GUIDANCE IS IN REASONABLE AGREEMENT ON THIS SCENARIO...
AND THE NHC FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS
ADVISORY.

THE INITIAL MOTION OF THE TROPICAL CYCLONE IS TOWARD THE
WEST-NORTHWEST OR 285/5.  A MID-TROPOSPHERIC RIDGE OVER MEXICO IS
FORECAST BY ALL OF THE GLOBAL MODELS TO WEAKEN DURING THE NEXT 24
HOURS...WHICH SHOULD CAUSE DARBY TO SLOW DOWN AND BECOME NEARLY
STATIONARY.  THEREAFTER...THE MODELS HAVE WILDLY DIVERGENT
SOLUTIONS...WITH THE HWRF CONTINUING A WESTWARD MOTION OF DARBY AND
THE ECMWF/UKMET SHOWING AN EASTWARD MOTION.  MOST OF THIS
DISAGREEMENT IS CAUSED BY THE HANDLING OF THE SYSTEM OVER THE
NORTHWESTERN CARIBBEAN...AND WHETHER THE MUCH-SMALLER DARBY GETS
CAUGHT UP IN WESTERLY FLOW SOUTH OF MEXICO.  IT IS BEST TO STAY
CLOSE TO THE MODEL CONSENSUS FOR NOW...AND THE NHC FORECAST IS
CLOSE TO THE PREVIOUS ONE...A LITTLE WEST OF THE DYNAMICAL MODEL
CONSENSUS.

DARBY IS THE EARLIEST SECOND MAJOR HURRICANE FORMATION IN THE
EASTERN PACIFIC SINCE RELIABLE RECORDS BEGAN IN 1971...ECLIPSING OF
THE PREVIOUS RECORD OF HURRICANE DANIEL ON JUNE 30 1978.


FORECAST POSITIONS AND MAX WINDS

INITIAL      25/2100Z 13.6N 101.5W   105 KT
 12HR VT     26/0600Z 13.7N 102.3W   105 KT
 24HR VT     26/1800Z 13.5N 103.3W   100 KT
 36HR VT     27/0600Z 13.4N 103.8W    90 KT
 48HR VT     27/1800Z 13.5N 104.2W    80 KT
 72HR VT     28/1800Z 14.0N 103.5W    65 KT
 96HR VT     29/1800Z 14.3N 102.7W    55 KT
120HR VT     30/1800Z 14.6N 102.0W    45 KT

$$
FORECASTER BLAKE

000
WTPZ45 KNHC 260850
TCDEP5
HURRICANE DARBY DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
200 AM PDT SAT JUN 26 2010

DARBY IS AN INCREDIBLY SMALL HURRICANE.  AN ASCAT PASS AROUND 0345
UTC INDICATED THAT TROPICAL STORM FORCE WINDS DO NOT EXTEND ANY
FARTHER THAN ABOUT 35 N MI FROM THE CENTER.  THE HURRICANE HAD BEEN
MAINTAINING A SMALL 10-N MI WIDE EYE SURROUNDED BY DEEP
CONVECTION...WHICH SUPPORTED 0600 UTC DVORAK ESTIMATES OF T5.5 FROM
BOTH TAFB AND SAB.  HOWEVER...THE EYE HAS RECENTLY BECOME
OBSCURED...AND THE MOST RECENT ADT ESTIMATE FROM UW-CIMSS IS T5.1.
THE INITIAL INTENSITY IS THEREFORE LOWERED TO 95 KT.  VERTICAL
SHEAR IS EXPECTED TO INCREASE OVER DARBY OVER THE NEXT SEVERAL
DAYS...WHICH IS EXPECTED TO INDUCE GRADUAL WEAKENING.  THE
WEAKENING IS EXPECTED TO BE MORE RAPID FROM 72-120 HOURS AS A
STRONG UPPER RIDGE BUILDS OVER MEXICO...CREATING FAIRLY STRONG
UPPER-LEVEL EASTERLY WINDS NEAR THE CYCLONE.  THE NEW OFFICIAL
FORECAST CLOSELY FOLLOWS THE SHIPS AND LGEM INTENSITY
GUIDANCE...AND IS NOT TOO DIFFERENT FROM THE PREVIOUS ADVISORY.

DARBY HAS BEEN MOVING ALMOST WEST-SOUTHWESTWARD OVER THE PAST FEW
HOURS...AND THE INITIAL MOTION IS 260/5.  THE STEERING CURRENTS
AROUND THE HURRICANE ARE STILL EXPECTED TO COLLAPSE THROUGH THE
FORECAST PERIOD...AND DARBY SHOULD BEGIN TO MOVE VERY SLOWLY
WESTWARD OVER THE NEXT 24-36 HOURS.  THEREAFTER...THE CYCLONE IS
EXPECTED TO BEGIN FEELING THE INFLUENCE OF NEWLY-NAMED TROPICAL
STORM ALEX IN THE WESTERN CARIBBEAN.  THE OFFICIAL FORECAST
INDICATES A SLOW NORTHEASTWARD MOTION BETWEEN DAYS 3 AND 5...BUT IT
SHOULD BE NOTED THAT THE GUIDANCE ENVELOPE IS STILL RATHER
DIVERGENT AND DARBY COULD DRIFT OR MEANDER IN PLACE FOR SEVERAL
DAYS.  THE ECMWF SHOWS A QUICK NORTHEASTWARD MOTION AND BRINGS
DARBY TO THE MEXICAN COAST IN 3 DAYS...BUT THIS SOLUTION IS
DISCOUNTED AT THIS TIME.


FORECAST POSITIONS AND MAX WINDS

INITIAL      26/0900Z 13.5N 102.7W    95 KT
 12HR VT     26/1800Z 13.4N 103.4W    90 KT
 24HR VT     27/0600Z 13.4N 104.1W    85 KT
 36HR VT     27/1800Z 13.6N 104.4W    75 KT
 48HR VT     28/0600Z 13.9N 104.1W    70 KT
 72HR VT     29/0600Z 14.3N 103.3W    55 KT
 96HR VT     30/0600Z 14.7N 102.8W    45 KT
120HR VT     01/0600Z 15.0N 102.5W    35 KT

$$
FORECASTER BERG