| HOME | ARCHIVES | FORECASTS | IMAGERY | ABOUT NHC | RECONNAISSANCE |

---

Tropical Storm DARBY (Text)

ZCZC MIATCDEP5 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM DARBY DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
200 AM PDT THU JUN 24 2010
 
ACCORDING TO A 0156 UTC TRMM PASS...A PINHOLE EYE FEATURE APPEARED
TO HAVE DEVELOPED IN THE MIDDLE OF THE SMALL CENTRAL DENSE OVERCAST
OVER DARBY.  THIS TINY FEATURE HAS NOT BEEN EVIDENT IN INFRARED
SATELLITE IMAGERY...AND DVORAK CLASSIFICATIONS FROM TAFB AND SAB
REMAIN AT T3.5...55 KT.  HOWEVER...THE SAB CLASSIFICATION DID YIELD
A DATA T-NUMBER OF 4.5...77 KT...USING THE EMBEDDED CENTER PATTERN. 
IT IS NOT OUT OF THE ORDINARY FOR SMALL TROPICAL CYCLONES TO BE
STRONGER THAN THE DVORAK TECHNIQUE WILL ALLOW...AND IT IS ASSUMED
THAT DARBY MAY HAVE STRENGTHENED A LITTLE.  MORE RECENTLY...THE
CENTRAL DENSE OVERCAST HAS BECOME SOMEWHAT RAGGED...BUT A CURVED
BAND HAS DEVELOPED AND IS NOW CONNECTED TO THE CENTRAL CONVECTION. 
THE INITIAL INTENSITY IS SET AT 60 KT.

THE INITIAL MOTION REMAINS 285/10 AS DARBY IS STEERED TO THE WEST BY
A LOW/MID-LEVEL RIDGE OVER MEXICO.  THE RIDGE IS EXPECTED TO WEAKEN
WITHIN THE NEXT 48 HOURS OR SO DUE TO THE COMBINED EFFECTS OF A
DISTURBANCE OVER THE WESTERN CARIBBEAN AND A DEEP MID/UPPER-LEVEL
TROUGH MOVING INTO CALIFORNIA.  AS A RESULT...DARBY IS FORECAST TO
SLOW DOWN CONSIDERABLY AND MAY ATTAIN SOME EASTWARD MOTION BY DAY 5
WITH THE DEVELOPMENT OF LOW-LEVEL SOUTHWESTERLY FLOW.  THE TRACK
GUIDANCE IS IN FAIRLY GOOD AGREEMENT OVER THE NEXT 36 HOURS BUT
THEN DIVERGES...AND HAS ALSO SHIFTED A LITTLE BIT TO THE WEST
COMPARED TO THE PREVIOUS PACKAGE.  THE NHC FORECAST FOLLOWS
THIS JOG TO THE WEST AND INDICATES A SLOW TURN TOWARD THE NORTHEAST
BY DAY 5. 

THE TRACK AND INTENSITY FORECASTS ARE BOTH COMPLICATED BY THE FACT
THAT MOST OF THE GLOBAL MODELS DISSIPATE DARBY BY DAYS 4 AND 5 DUE
TO A DECOUPLING OF THE LOW- AND MID-LEVEL CIRCULATIONS.  THE
HURRICANE MODELS DO HOLD ON TO THE CYCLONE THROUGH THE FORECAST
PERIOD...BUT BOTH WEAKEN DARBY TO ABOUT 20-30 KT IN 120 HOURS.  THE
STATISTICAL SHIPS AND LGEM MODELS ARE THE ONLY ONES TO KEEP DARBY
AS A SIGNIFICANT TROPICAL CYCLONE AT THAT TIME.  REGARDLESS OF THE
MODEL...ALL ARE SIGNIFICANTLY LOWER AT DAYS 4 AND 5 COMPARED TO THE
PREVIOUS FORECAST...AND THE NEW OFFICIAL FORECAST INDICATES MORE
RAPID WEAKENING AT THE END OF THE FORECAST PERIOD...ENDING CLOSE TO
THE UPPER END OF THE INTENSITY GUIDANCE.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/0900Z 12.6N  98.0W    60 KT
 12HR VT     24/1800Z 12.9N  99.2W    65 KT
 24HR VT     25/0600Z 13.2N 100.6W    70 KT
 36HR VT     25/1800Z 13.4N 101.7W    80 KT
 48HR VT     26/0600Z 13.6N 102.6W    80 KT
 72HR VT     27/0600Z 14.0N 103.5W    70 KT
 96HR VT     28/0600Z 14.5N 103.5W    65 KT
120HR VT     29/0600Z 15.0N 103.0W    55 KT
 
$$
FORECASTER BERG
 
NNNN