WTNT45 KNHC 231445
TCDAT5
 
TROPICAL STORM JOYCE DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL102012
1100 AM AST THU AUG 23 2012
 
THE CLOUD PATTERN ASSOCIATED WITH THE DEPRESSION HAS INCREASED IN
ORGANIZATION THIS MORNING.  ANIMATION OF VISIBLE SATELLITE IMAGERY
SUGGESTS THAT THE LOW-LEVEL CENTER IS ON THE SOUTH SIDE OF A FAIRLY
CIRCULAR MASS OF COLD-TOPPED CONVECTION.  DVORAK T-NUMBERS FROM
TAFB AND SAB HAVE INCREASED TO A CONSENSUS 2.5...AND THE DEPRESSION
IS UPGRADED TO A TROPICAL STORM WITH 35 KT WINDS.
 
THE INITIAL MOTION ESTIMATE IS A STEADY 295/14.  GLOBAL MODELS SHOW
JOYCE CONTINUING ON A WEST-NORTHWESTWARD COURSE DURING THE NEXT
COUPLE OF DAYS...ON THE SOUTH SIDE OF A SUBTROPICAL RIDGE OVER THE
CENTRAL ATLANTIC.  IN 3-4 DAYS...JOYCE SHOULD REACH THE WESTERN
PERIPHERY OF THE RIDGE WHICH SHOULD CAUSE THE STORM TO TURN
NORTHWESTWARD AND NORTHWARD.  LATE IN THE FORECAST PERIOD...AN
AMPLIFYING SHORTWAVE TROUGH MOVING THROUGH THE GREAT LAKES SHOULD
ERODE THE WESTERN EXTENSION OF THE RIDGE OVER THE WESTERN
ATLANTIC...ALLOWING JOYCE TO RECURVE INTO THE WESTERLIES.  THE
TRACK GUIDANCE IS IN EXCELLENT AGREEMENT ON THIS SCENARIO...BUT
DIFFERENCES ARISE AS A RESULT OF THE FORECAST DEPTH OF THE CYCLONE.
THE OFFICIAL TRACK GUIDANCE CONTINUES TO RELY ON A BLEND OF THE
ECWMF AND GFS SOLUTIONS...WHICH FAVOR A STRONGER REPRESENTATION OF
JOYCE THAN THE GFDL/HWRF SOLUTIONS WHICH HAVE BEEN FORECASTING A
MUCH WEAKER SYSTEM.
 
THE INTENSITY FORECAST COULD BE CHALLENGING.  THE PROXIMITY OF JOYCE
TO A MID- TO UPPER-LEVEL LOW AND ASSOCIATED TROUGH TO THE WEST IS
IMPARTING SOUTHERLY SHEAR OVER THE CYCLONE.  A DRY SAHARAN AIR
LAYER WITHIN THE TROUGH IS ALSO WRAPPING AROUND THE SOUTHWESTERN
PART OF THE CIRCULATION.  WITH THE CYCLONE FORECAST TO GET CLOSER
TO THE TROUGH IN THE NEXT COUPLE OF DAYS...LITTLE ADDITIONAL
INTENSIFICATION IS EXPECTED IN THE SHORT TERM.  IN ABOUT 4
DAYS...GLOBAL MODELS SHOW THE POSSIBILITY OF A DECREASE IN SHEAR
OVER JOYCE IF IT IS FAR ENOUGH AWAY FROM THE UPPER-LEVEL OUTFLOW OF
ISAAC.  THE OFFICIAL NHC FORECAST IS SIMILAR TO BUT A LITTLE BELOW
THE LGEM/SHIPS OUTPUT...SHOWING LITTLE CHANGE IN STRENGTH IN
THE SHORT-TERM WITH SOME INTENSIFICATION LATER ON.
 
THIS TIES THE SECOND-EARLIEST FORMATION OF THE TENTH NAMED TROPICAL
STORM OF A SEASON.  IN 2005...TROPICAL STORM JOSE FORMED ON 22
AUGUST AND IN 1995 TROPICAL STORM JERRY FORMED ON THIS DATE.
 

FORECAST POSITIONS AND MAX WINDS
 
INIT  23/1500Z 15.2N  42.2W   35 KT  40 MPH
 12H  24/0000Z 16.0N  44.2W   40 KT  45 MPH
 24H  24/1200Z 17.1N  46.9W   40 KT  45 MPH
 36H  25/0000Z 18.4N  49.6W   40 KT  45 MPH
 48H  25/1200Z 19.9N  52.7W   40 KT  45 MPH
 72H  26/1200Z 23.9N  59.1W   40 KT  45 MPH
 96H  27/1200Z 28.5N  63.7W   45 KT  50 MPH
120H  28/1200Z 33.5N  62.4W   50 KT  60 MPH
 
$$
FORECASTER KIMBERLAIN
 

WTNT45 KNHC 232043
TCDAT5
 
TROPICAL STORM JOYCE DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL102012
500 PM AST THU AUG 23 2012
 
SATELLITE DATA INDICATE THAT THE CENTER OF JOYCE HAS UNEXPECTEDLY
BECOME EXPOSED. THE DEEP CONVECTION...WHICH WAS EARLIER THOUGHT TO
BE PARTIALLY COVERING THE CENTER...HAS BEEN CARRIED FAR TO THE
NORTHWEST ALONG WITH A STRONG MID-LEVEL CYCLONIC CIRCULATION...
LEAVING THE LOW-LEVEL CENTER BEHIND. AN 1816 UTC SSMI OVERPASS
CONFIRMED THIS STARK DECOUPLING...WHICH APPEARS TO HAVE RESULTED
FROM A COMBINATION OF SOUTH-SOUTHEASTERLY SHEAR AND DRY AIR. 
ALTHOUGH DVORAK T-NUMBERS HAVE DECREASED AS A RESULT OF THE
DECREASE IN ORGANIZATION...IT IS ASSUMED THAT TROPICAL-STORM-FORCE
WINDS ARE STILL OCCURRING IN THE CONVECTION WELL TO THE NORTH IN
ASSOCIATION WITH THE MID-LEVEL CYCLONIC CIRCULATION.  THE WIND RADII
HAVE TEMPORARILY BEEN ADJUSTED TO REFLECT THIS DISPLACEMENT.
 
THE INITIAL MOTION ESTIMATE IS A HIGHLY UNCERTAIN 300/12 SINCE THE
CENTER POSITION WAS NOT WELL KNOWN EARLIER.  JOYCE IS EXPECTED TO
BE STEERED WEST-NORTHWESTWARD TO NORTHWESTWARD FOR THE NEXT FEW DAYS
AROUND THE SOUTH SIDE OF A SUBTROPICAL RIDGE OVER THE CENTRAL
ATLANTIC.  A TURN TOWARD THE NORTH AND THEN NORTHEAST SHOULD OCCUR
IN ABOUT 4-5 DAYS AS JOYCE ENCOUNTERS A BREAK IN THE RIDGE OVER THE
WESTERN ATLANTIC AND RECURVES INTO A STRONG BAND OF WESTERLIES TO
THE NORTH. THE NHC TRACK FORECAST HAS BEEN SHIFTED TO THE
RIGHT IN THE FIRST 48-72 HOURS TO ACCOUNT FOR THE POSSIBLE
REFORMATION OF JOYCE TO THE NORTH.  THE REMAINDER OF THE FORECAST
IS SIMILAR TO THE PREVIOUS ONE AND IS CLOSE TO A BLEND OF THE
ECMWF/GFS...WHICH SHOWED A DEEPER REPRESENTATION OF THE CYCLONE.
 
ONE OF TWO OPTIONS SEEMS PLAUSIBLE IN THE SHORT TERM WITH REGARD TO
THE INTENSITY FORECAST. A NEW LOW-LEVEL CENTER COULD FORM IN
ASSOCIATION WITH THE MID-LEVEL CYCLONIC CENTER AND BECOME DOMINANT.
THE OTHER POSSIBILITY IS THAT NO NEW CENTER WILL FORM AND JOYCE
WILL DISSIPATE. ASSUMING THAT JOYCE SURVIVES DURING THE NEXT DAY OR
TWO...THE PROSPECT FOR INTENSIFICATION SEEMS UNLIKELY FOR THE NEXT
2-3 DAYS. THE CONTINUED PROXIMITY OF A MID- TO UPPER-LEVEL
TROUGH...COUPLED WITH THE EFFECTS OF DRY AIR...SHOULD INHIBIT ANY
SIGNIFICANT STRENGTHENING. LATER IN THE FORECAST PERIOD...GLOBAL
MODELS CONTINUE TO ADVERTISE SOME CHANCE OF JOYCE INTENSIFYING
AROUND THE TIME IT RECURVES. THE NEW NHC INTENSITY FORECAST HAS
BEEN REDUCED DURING THE FIRST COUPLE OF DAYS AND MODIFIED UPWARD ON
DAYS 4-5.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/2100Z 15.9N  42.5W   35 KT  40 MPH
 12H  24/0600Z 17.1N  45.1W   35 KT  40 MPH
 24H  24/1800Z 18.5N  47.9W   35 KT  40 MPH
 36H  25/0600Z 20.0N  50.8W   35 KT  40 MPH
 48H  25/1800Z 22.1N  54.4W   35 KT  40 MPH
 72H  26/1800Z 26.3N  60.4W   45 KT  50 MPH
 96H  27/1800Z 30.8N  63.0W   50 KT  60 MPH
120H  28/1800Z 34.5N  60.4W   55 KT  65 MPH
 
$$
FORECASTER KIMBERLAIN
 

WTNT45 KNHC 240236
TCDAT5
 
TROPICAL DEPRESSION JOYCE DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL102012
1100 PM AST THU AUG 23 2012

CONVECTION HAS NOT REFORMED NEAR THE LOW-LEVEL CENTER OF JOYCE...AND
SATELLITE DATA SHOW THAT IT REMAINS EXPOSED WELL TO THE SOUTH OF ITS
DYING MID-LEVEL CIRCULATION.  AN ASCAT PASS AROUND 0000 UTC
SUGGESTED MAXIMUM WINDS OF 25-30 KT...SO 30 KT WILL BE USED AS THE
INITIAL INTENSITY. ALTHOUGH THE CYCLONE WILL BE MOVING OVER
PROGRESSIVELY WARMER WATERS...MODERATE OR STRONG SOUTHERLY SHEAR
IS LIKELY FOR THE NEXT COUPLE OF DAYS. THESE CONDITIONS SHOULD NOT
ALLOW FOR MUCH STRENGTHENING...SO LITTLE CHANGE IS SHOWN DURING
THAT TIME.  IN A FEW DAYS...JOYCE COULD BE POSITIONED IN A LIGHTER
SHEAR ENVIRONMENT TO THE NORTH OF AN UPPER-LEVEL LOW.  THUS...SOME
INTENSIFICATION WILL BE SHOWN AT LONG RANGE...WHICH IS CONSISTENT
WITH THE SHIPS MODEL AND THE PREVIOUS FORECAST.   IT IS WORTH
MENTIONING THAT...CONSIDERING THE MARGINAL ENVIRONMENT...IT WOULD
NOT BE SURPRISING IF JOYCE DEGENERATED INTO A REMNANT LOW SOMETIME
DURING THE NEXT DAY OR TWO.  

THE DEPRESSION APPEARS TO BE MOVING ABOUT THE SAME AS BEFORE...
300/12.  JOYCE SHOULD ACCELERATE TO THE NORTHWEST OVER THE NEXT DAY
OR SO AS IT MOVES INTO FASTER FLOW BETWEEN A RIDGE OVER THE CENTRAL
ATLANTIC AND A TROUGH EAST OF THE LEEWARD ISLANDS.  A TURN TO THE
NORTH AND NORTHEAST SHOULD OCCUR AFTER DAY 3 AS THE CYCLONE ROUNDS
THE WESTERN PERIPHERY OF THE RIDGE. THE MODEL GUIDANCE IS IN
RELATIVELY GOOD AGREEMENT ON THIS SCENARIO WITH ONLY SOME MINOR
DIFFERENCES. THE OFFICIAL FORECAST IS BASICALLY AN UPDATE OF THE
PREVIOUS ONE FOR THE FIRST COUPLE OF DAYS...THEN IS ADJUSTED TO THE
LEFT DURING RECURVATURE IN THE LONG RANGE.  
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0300Z 16.3N  43.7W   30 KT  35 MPH
 12H  24/1200Z 17.4N  46.0W   30 KT  35 MPH
 24H  25/0000Z 18.9N  48.9W   30 KT  35 MPH
 36H  25/1200Z 20.7N  52.2W   30 KT  35 MPH
 48H  26/0000Z 22.8N  55.5W   30 KT  35 MPH
 72H  27/0000Z 27.0N  62.0W   35 KT  40 MPH
 96H  28/0000Z 31.5N  64.5W   45 KT  50 MPH
120H  29/0000Z 36.0N  58.0W   50 KT  60 MPH
 
$$
FORECASTER BLAKE
 

WTNT45 KNHC 240848
TCDAT5
 
TROPICAL DEPRESSION JOYCE DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL102012
500 AM AST FRI AUG 24 2012
 
DEEP CONVECTION NEAR TROPICAL DEPRESSION JOYCE HAS BEEN VIRTUALLY
NON-EXISTANT FOR ABOUT 10 HOURS DUE TO THE COMBINED INHIBITING
INFLUENCES OF MODERATE VERTICAL SHEAR AND DRY AIR. BOTH TAFB AND
SAB DVORAK INTENSITY ESTIMATES ARE 30 KT...WHICH IS THE INITIAL
INTENSITY. REDEVELOPMENT APPEARS UNLIKELY DUE TO THE CONTINUED
HOSTILE ENVIRONMENT THAT THE CYCLONE IS EMBEDDED IN. INDEED...ALL
OF THE GLOBAL AND REGIONAL HURRICANE MODELS...WITH THE NOTABLE
EXCEPTION OF THE GLOBAL FORECAST SYSTEM...INDICATE THAT JOYCE
SHOULD DISSIPATE WITHIN THE NEXT COUPLE OF DAYS. THE INTENSITY
PREDICTION KEEPS THE CYCLONE AS A TROPICAL DEPRESSION THROUGHOUT
THE FORECAST PERIOD...MOST SIMILAR TO THE LGEM STATISTICAL MODEL.
HOWEVER...IF CONVECTION DOES NOT REDEVELOP SOON...JOYCE COULD
BECOME A POST-TROPICAL REMNANT LOW AND ADVISORIES WOULD BE
DISCONTINUED. 

THE EXPOSED LOW-LEVEL CENTER IS CLEARLY EVIDENT FROM THE GOES-EAST
SHORTWAVE INFRARED IMAGERY.  THIS ALLOWS FOR A CONFIDENT ASSESSMENT
OF THE MOTION OF JOYCE TOWARD THE WEST-NORTHWEST AT 12 KT.  JOYCE
SHOULD CONTINUE MOVING IN THIS DIRECTION AT A FASTER RATE OF SPEED
FOR THE NEXT THREE DAYS AS IT IS STEERED PRIMARILY BY THE LOW-LEVEL
FLOW OF THE BERMUDA-AZORES HIGH.  AT DAYS FOUR AND FIVE...THE
CYCLONE SHOULD RECURVE NORTHEASTWARD AND ACCELERATE ON THE NORTH
SIDE OF THE HIGH. THE TRACK FORECAST IS CLOSEST TO THE TVCA
CONSENSUS TECHNIQUE AND IS SLIGHTLY TO THE WEST OF THE PREVIOUS
ADVISORY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0900Z 16.9N  45.0W   30 KT  35 MPH
 12H  24/1800Z 17.8N  47.0W   30 KT  35 MPH
 24H  25/0600Z 19.2N  50.6W   30 KT  35 MPH
 36H  25/1800Z 21.0N  54.0W   30 KT  35 MPH
 48H  26/0600Z 22.8N  57.5W   30 KT  35 MPH
 72H  27/0600Z 27.0N  63.0W   30 KT  35 MPH
 96H  28/0600Z 31.5N  64.0W   30 KT  35 MPH
120H  29/0600Z 36.5N  56.0W   30 KT  35 MPH
 
$$
FORECASTER LANDSEA
 

