Caribbean-On-Line's Caribbean Hurricane Blog



Hurricane Rafael

HURRICANE RAFAEL DISCUSSION NUMBER 17

Published on October 16, 2012 5:36 PM | Comments

HURRICANE RAFAEL DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172012
500 PM AST TUE OCT 16 2012

THE SATELLITE APPEARANCE OF RAFAEL HAS RECENTLY TRANSITIONED FROM A
CENTRAL DENSE OVERCAST TO AN EYE PATTERN...WITH A RECENT MICROWAVE
PASS SHOWING A SOLID INNER CORE. THIS WOULD NORMALLY SUGGEST SOME
STRENGTHENING...BUT THE AIR FORCE RESERVE HURRICANE HUNTERS
REPORTED THAT FLIGHT-LEVEL AND SFMR WINDS HAD COME DOWN A BIT
DURING THE PAST FEW HOURS. THE PLANE DATA SUGGEST AN INITIAL
INTENSITY OF ABOUT 75 KT...WITH A LITTLE HIGHER UNCERTAINTY THAN
AVERAGE GIVEN THE RECENT SATELLITE TREND. A NOAA AIRCRAFT WILL BE
IN THE AREA THIS EVENING FOR ANOTHER LOOK AT THE INTENSITY.
HOWEVER...SLOW WEAKENING SEEMS LIKE THE BEST BET DUE TO GRADUALLY
COOLING WATERS AND INCREASING SHEAR. THE NHC INTENSITY FORECAST IS
AN UPDATE OF THE PREVIOUS ONE...NEAR THE LGEM MODEL BUT A BIT BELOW
THE INTENSITY CONSENSUS. GLOBAL MODELS SUGGESTS EXTRATROPICAL
TRANSITION BETWEEN 24-36H DUE TO INTERACTION OF RAFAEL WITH A COLD
FRONT AND AN UPPER-LEVEL TROUGH.

AIRCRAFT FIXES SHOW THAT RAFAEL HAS RECENTLY BEEN MOVING A BIT LEFT
OF THE PREVIOUS ESTIMATE...BUT A LONGER-TERM ESTIMATE IS 020/23.
THERE HAS BEEN NO CHANGE TO PREDICTED STEERING FLOW WITH THE
HURRICANE MOVING BETWEEN A RIDGE OVER THE CENTRAL ATLANTIC AND A
TROUGH OVER THE NORTHWESTERN ATLANTIC. THIS SHOULD CAUSE RAFAEL TO
TURN TOWARD THE NORTHEAST BY WEDNESDAY AND TO MOVE FASTER. MODEL
GUIDANCE IS WELL CLUSTERED ON THIS TRACK...AND EVEN THE SPEED
DIFFERENCES ARE LESS NOTICEABLE THAN ON THE PREVIOUS FORECAST
CYCLE. THE NHC FORECAST IS ADJUSTED WESTWARD TOWARD THE
CONSENSUS...BUT STILL LIES ON THE SPEEDIER SIDE OF THE GUIDANCE FOR
THE FIRST 48 HOURS OR SO. AFTERWARD...MOST OF THE GLOBAL MODELS
SUGGEST THAT POST-TROPICAL RAFAEL WILL COMPLETE A LARGE CYCLONIC
LOOP OVER THE NORTHEASTERN ATLANTIC.



TROPICAL STORM RAFAEL DISCUSSION NUMBER 2

Published on October 13, 2012 3:54 AM | Comments

Rafael is not well organized, but is a tropical storm and will remain one as it moves north over the Virgin Islands.

TROPICAL STORM RAFAEL DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172012
1100 PM AST FRI OCT 12 2012

RAFAEL HAS A RATHER DISORGANIZED APPEARANCE IN SATELLITE IMAGERY
THIS EVENING. THE BROAD LOW-LEVEL CENTER IS LOCATED TO THE WEST OF
THE MAIN CONVECTIVE MASS DUE TO 20-25 KT OF SOUTHWESTERLY VERTICAL
WIND SHEAR. LESS CONCENTRATED CONVECTION IS OCCURRING TO THE
NORTHWEST OF THE CENTER. THERE HAVE BEEN NO OBSERVATIONS OF
TROPICAL-STORM-FORCE WINDS FROM THE LESSER ANTILLES...BUT IT IS
LIKELY THAT SUCH WINDS ARE LOCATED IN THE CONVECTIVE BAND EAST AND
SOUTHEAST OF THE CENTER. THE INITIAL INTENSITY REMAINS 35 KT IN
AGREEMENT WITH THE SATELLITE INTENSITY ESTIMATE FROM TAFB.

THE INITIAL MOTION IS A RATHER UNCERTAIN 325/9. RAFAEL IS CURRENTLY
SOUTHEAST OF A LARGE BREAK IN THE SUBTROPICAL RIDGE CAUSED BY
TROPICAL DEPRESSION PATTY...A FRONTAL SYSTEM...AND A MID/UPPER-
LEVEL TROUGH. THIS SYNOPTIC PATTERN SHOULD STEER RAFAEL GENERALLY
NORTH-NORTHWESTWARD FOR THE NEXT 24-36 HR...WITH THE CENTER PASSING
NEAR THE VIRGIN ISLANDS IN ABOUT 24 HOURS. THE GLOBAL MODELS
FORECAST A LOW/MID-LEVEL RIDGE TO BRIEFLY BUILD NORTH OF RAFAEL AT
ABOUT 48 HR...WHICH WILL SUBSEQUENTLY BREAK DOWN AS A POWERFUL
DEEP-LAYER TROUGH MOVES INTO THE WESTERN ATLANTIC. THIS TROUGH
SHOULD RECURVE RAFAEL INTO THE WESTERLIES. WHILE THE GLOBAL MODELS
AGREE ON THIS...THEY DIFFER ENOUGH ON THE DETAILS THAT THE GFS AND
CANDIAN SHOW A MUCH FASTER FORWARD MOTION AFTER RECURVATURE THAN
THE ECMWF AND UKMET. THE NEW TRACK FORECAST FOLLOWS THE PREVIOUS
FORECAST IN SPLITTING THE DIFFERENCE BETWEEN THESE EXTREMES.
OVERALL...THE NEW FORECAST TRACK IS CLOSE TO THE OLD TRACK AND NEAR
THE CENTER OF THE GUIDANCE ENVELOPE.

LITTLE CHANGE IN STRENGTH IS EXPECTED DURING THE FIRST 12 HR DUE TO
CONTINUED SHEAR. AFTER THAT...THE GLOBAL MODELS FORECAST A
DECREASE IN SHEAR FROM 24-48 HR...WITH THE INTENSITY GUIDANCE
SHOWING INTENSIFICATION DURING THIS TIME. THE INTENSITY FORECAST
DURING THIS PERIOD IS NEAR THE INTENSITY CONSENSUS. THE GLOBAL
MODELS AGREE ON INCREASING SHEAR AFTER 48 HR. DESPITE THIS...THE
GFDL...HWRF...AND SHIP MODELS FORECAST RAFAEL TO STRENGTHEN INTO A
HURRICANE. THE INTENSITY FORECAST WILL RELY MORE ON THE FORECAST
SHEAR AND SHOW ARRESTED DEVELOPMENT AFTER 48 HR. EXTRATROPICAL
TRANSITION SHOULD BEGIN BY 120 HR AND LIKELY BE COMPLETE SHORTLY
THEREAFTER.