Skip Navigation Links
NOAA NOAA United States Department of Commerce

Hurricane HUMBERTO


ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
 
HURRICANE HUMBERTO DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092013
500 AM AST THU SEP 12 2013
 
THE CLOUD PATTERN OF HUMBERTO REMAINS WELL ORGANIZED...WITH THE
CYCLONE MAINTAINING A WELL-DEFINED CENTRAL DENSE OVERCAST COMPRISED
OF COLD CLOUD TOPS AND OCCASIONAL HINTS OF A WARM SPOT OR EYE.  THE
OUTER CIRCULATION OF THE CYCLONE CONSISTS OF SEVERAL WELL-DEFINED
BANDS...AND THE OUTFLOW REMAINS GOOD TO EXCELLENT IN ALL QUADRANTS. 
HOWEVER...SATELLITE DATA IN THE LAST FEW HOURS SUGGEST THAT THE
STRUCTURE OF THE INNER CORE CONVECTION HAS BECOME LESS SYMMETRIC
AND THERE HAS BEEN SOME DETERIORATION OF THE EYEWALL JUST RECENTLY. 
THESE DEVELOPMENTS SUGGEST THAT HUMBERTO MAY HAVE PEAKED IN
INTENSITY.  DVORAK INTENSITY ESTIMATES ARE A CONSENSUS T4.5 FROM
TAFB AND SAB...AND ADT VALUES ARE RUNNING AROUND 4.5.  ON THIS
BASIS...THE INITIAL INTENSITY IS KEPT AT 75 KT.
 
HUMBERTO HAS BEEN MOVING STEADILY NORTHWARD...005/12....AND A
NORTHWARD OR NORTH-NORTHWESTWARD MOTION INTO A SIGNIFICANT WEAKNESS
IN THE SUBTROPICAL RIDGE SHOULD CONTINUE FOR ANOTHER DAY OR SO.
AFTER THAT...A WEAKENING HUMBERTO SHOULD TURN NORTHWESTWARD AND
THEN WEST-NORTHWESTWARD IN BETWEEN A BLOCKING LOW- TO MID-LEVEL
RIDGE OVER THE NORTHEAST ATLANTIC AND A MID- TO UPPER-LEVEL LOW TO
THE WEST UNTIL ABOUT DAY 4. BY DAY 5...HUMBERTO SHOULD REACH A
REGION OF WEAK STEERING AND SLOW DOWN WHILE IT TURNS NORTHWARD OR
PERHAPS EVEN NORTHEASTWARD AHEAD OF A STRONG MID-LATITUDE TROUGH
ADVANCING ACROSS ATLANTIC CANADA.  THE GUIDANCE HAS SHIFTED TO THE
RIGHT THIS CYCLE...ESPECIALLY BEYOND 48 HOURS...AND THE OFFICIAL
FORECAST IS ADJUSTED IN THAT DIRECTION. HOW FAST AND IN WHAT
DIRECTION THE CYCLONE IS STEERED LATE IN THE PERIOD WILL LIKELY BE
DEPENDENT ON THE STRENGTH OF THE CYCLONE...WHICH IS MORE UNCERTAIN
THAN NORMAL AT THE MOMENT.
 
EVEN THOUGH HUMBERTO IS ALREADY OVER WATERS LESS THAN 26C...
SUFFICIENT MID-LEVEL MOISTURE AND INSTABILITY HAVE ALLOWED THE
CYCLONE TO MAINTAIN ITSELF. HOWEVER...WEAKENING IS EXPECTED SOON AS
A RESULT OF INCREASING SHEAR ASSOCIATED WITH A LARGE AMPLITUDE
UPPER-LEVEL TROUGH OVER THE EAST-CENTRAL ATLANTIC AND THE
ENTRAINMENT OF DRIER AIR. SHIPS MODEL OUTPUT SHOWS THE WEST-
SOUTHWESTERLY SHEAR INCREASING TO GREATER THAN 40 KT IN 2-3 DAYS
WHILE HUMBERTO IS STILL OVER COOL WATERS...WHICH COULD RESULT IN
THE CYCLONE DEGENERATING INTO A REMNANT LOW. HOWEVER...GLOBAL
MODELS SHOW A RESILIENT HUMBERTO...PERHAPS BECAUSE OF THE LARGE
SIZE OF ITS CIRCULATION...SURVIVING TO REACH WARMER WATERS BY DAY
4. SOME DECREASE IN THE SHEAR LATE IN THE PERIOD AND POTENTIAL
INTERACTION WITH THE APPROACHING MID-LATITUDE TROUGH MIGHT ALLOW
FOR SOME RE-STRENGTHENING...ALTHOUGH THIS IS NOT EXPLICITLY SHOWN
IN THE FORECAST.  THE OFFICIAL INTENSITY FORECAST IS ADJUSTED
DOWNWARD AND LIES IN BETWEEN THE LOWER SHIPS MODEL GUIDANCE AND THE
INTENSITY CONSENSUS AIDS AND FLORIDA STATE SUPERENSMBLE OUTPUT.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/0900Z 20.5N  28.7W   75 KT  85 MPH
 12H  12/1800Z 22.0N  29.4W   70 KT  80 MPH
 24H  13/0600Z 23.5N  30.3W   65 KT  75 MPH
 36H  13/1800Z 24.5N  31.9W   55 KT  65 MPH
 48H  14/0600Z 25.1N  33.7W   45 KT  50 MPH
 72H  15/0600Z 26.1N  38.5W   35 KT  40 MPH
 96H  16/0600Z 27.3N  42.5W   30 KT  35 MPH
120H  17/0600Z 28.5N  45.0W   30 KT  35 MPH
 
$$
FORECASTER KIMBERLAIN
 
NNNN