000
WTPZ45 KNHC 230231
TCDEP5
TROPICAL DEPRESSION FIVE-E DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
800 PM PDT TUE JUN 22 2010

THE THUNDERSTORM ACTIVITY HAS BECOME A LITTLE MORE CONSOLIDATED
DURING THE PAST FEW HOURS AND THE CLOUD PATTERN NOW CONSISTS OF A
CYCLONICALLY CURVED CONVECTIVE BAND ON THE WESTERN PORTION OF THE
CIRCULATION AND A FEW PATCHES OF DEEP CONVECTION NEAR THE CENTER.
T-NUMBERS FROM BOTH TAFB AND SAB INCREASED TO 2.0 ON THE DVORAK
SCALE SUPPORTING TROPICAL DEPRESSION STATUS AT THIS TIME. THE
ENVIRONMENT IS NOT EXPECTED TO BE FAVORABLE FOR SIGNIFICANT
INTENSIFICATION DURING THE NEXT FEW DAYS DUE TO SHEAR. IN
FACT...MOST OF THE GLOBAL MODELS WEAKEN THE CYCLONE AS A LOW-LEVEL
SOUTHWEST FLOW BECOMES PREDOMINANT IN THE AREA SOUTH OF MEXICO OVER
THE NEXT FEW DAYS. THE OFFICIAL FORECAST ONLY CALLS FOR A MODEST
STRENGTHENING AS SUGGESTED BY THE SHIPS MODEL.

THE BEST ESTIMATE OF THE INITIAL MOTION IS 295 DEGREES AT 8 KNOTS.
THIS GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE NEXT 2 TO 3
DAYS WHILE THE CYCLONE IS EMBEDDED WITHIN THE EASTERLY FLOW SOUTH OF
A WEAK TO MODERATE RIDGE. THEREAFTER...STEERING CURRENTS ARE
FORECAST TO COLLAPSE AND THE CYCLONE SHOULD BEGIN TO MEANDER.  THIS
IS CONSISTENT WITH MOST OF THE GLOBAL MODELS AS WELL AS THE
GFDL/HWRF MODEL PAIR WHICH KEEP THE CYCLONE LOOPING WELL OFFSHORE
SOUTH OF MEXICO BY THE END OF THE FORECAST PERIOD.    


FORECAST POSITIONS AND MAX WINDS

INITIAL      23/0300Z 11.0N  93.4W    30 KT
 12HR VT     23/1200Z 11.5N  94.5W    35 KT
 24HR VT     24/0000Z 12.0N  96.0W    40 KT
 36HR VT     24/1200Z 12.8N  97.5W    45 KT
 48HR VT     25/0000Z 13.5N  99.0W    50 KT
 72HR VT     26/0000Z 14.0N 101.0W    50 KT
 96HR VT     27/0000Z 15.0N 102.0W    45 KT
120HR VT     28/0000Z 15.5N 102.5W    40 KT

$$
FORECASTER AVILA

000
WTPZ45 KNHC 230849
TCDEP5
TROPICAL STORM DARBY DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
200 AM PDT WED JUN 23 2010

THE OVERALL CONVECTIVE STRUCTURE OF THE TROPICAL CYCLONE HAS
CONTINUED TO BECOME MORE ORGANIZED.  ALTHOUGH THE CIRCULATION
CENTER APPEARS TO BE LOCATED ON THE WESTERN EDGE OF THE DEEP
CONVECTION DUE TO SOME EASTERLY SHEAR...DVORAK T-NUMBERS ARE 2.5
FROM TAFB AND 2.0 FROM SAB.  ASCAT DATA...WHICH IS KNOWN TO HAVE A
LOW BIAS...SHOWED A MAXIMUM OF 30 KT OUTSIDE OF THE DEEP CONVECTION
AT 0306 UTC.  SINCE THE CLOUD PATTERN HAS IMPROVED OVER THE PAST
FEW HOURS AND STRONGER WINDS ARE LIKELY OCCURRING IN THE DEEP
CONVECTION...THE DEPRESSION IS UPGRADED TO TROPICAL STORM DARBY.

THE ASCAT PASS HELPED IN LOCATING THE LOW-LEVEL CENTER...AND IT IS
ESTIMATED THAT DARBY IS MOVING 305 DEGREES AT 8 KNOTS.  A MID-LEVEL
RIDGE LOCATED OVER THE SOUTHERN UNITED STATES AND MEXICO SHOULD
STEER DARBY GENERALLY TOWARD THE WEST-NORTHWEST OVER THE NEXT 2
DAYS.  THEREAFTER...STEERING CURRENTS ARE EXPECTED TO WEAKEN AS THE
RIDGE BREAKS DOWN.  IN FACT...SEVERAL GLOBAL MODELS SUGGEST THAT
DARBY COULD STOP ALTOGETHER AND ATTAIN SOME EASTWARD MOTION WITHIN
LOW-LEVEL SOUTHWESTERLY FLOW DURING THAT TIME.  THE GLOBAL MODEL
SOLUTIONS ARE COUNTER TO THAT OF THE GFDL AND HWRF...WHICH MAINTAIN
A SLOW WEST-NORTHWESTWARD MOTION THROUGH THE FORECAST PERIOD.  THIS
UNCERTAINTY SUPPORTS THE NEGLIGIBLE MOTION SHOWN IN THE OFFICIAL
FORECAST BY DAY 5.

THE SHIPS MODEL INDICATES THAT THE EASTERLY SHEAR OVER DARBY SHOULD
ABATE OVER THE NEXT 2 DAYS...GIVING THE SYSTEM A CHANCE TO
INTENSIFY.  THE NEW OFFICIAL FORECAST SHOWS A LITTLE MORE
STRENGTHENING THAN THE PREVIOUS FORECAST...BUT THIS STILL MIGHT BE
ON THE CONSERVATIVE SIDE SINCE THE SHIPS RI INDEX INDICATES A 1 IN
4 CHANCE OF RAPID INTENSIFICATION OVER THE NEXT 24 HOURS.  WHATEVER
THE MAXIMUM INTENSITY...INCREASED VERTICAL SHEAR AFTER DAY 3 IS
EXPECTED TO INDUCE WEAKENING...ESPECIALLY IF DARBY BEGINS TO ATTAIN
AN EASTERLY MOTION.


FORECAST POSITIONS AND MAX WINDS

INITIAL      23/0900Z 11.5N  94.0W    35 KT
 12HR VT     23/1800Z 11.9N  95.1W    40 KT
 24HR VT     24/0600Z 12.4N  96.6W    45 KT
 36HR VT     24/1800Z 12.8N  98.2W    50 KT
 48HR VT     25/0600Z 13.0N  99.4W    55 KT
 72HR VT     26/0600Z 13.5N 101.0W    55 KT
 96HR VT     27/0600Z 14.0N 101.5W    50 KT
120HR VT     28/0600Z 14.5N 101.5W    45 KT

$$
FORECASTER BERG