233 
 WTPZ42 KNHC 240832
 TCDEP2
 TROPICAL DEPRESSION SEVENTEEN-E DISCUSSION NUMBER   4
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP172008
 200 AM PDT FRI OCT 24 2008
  
 THE LOW-LEVEL CENTER REMAINS DIFFICULT TO LOCATE...AND THERE MAY
 EVEN BE MULTIPLE SWIRLS WITHIN THE LARGER CYCLONIC GYRE. THERE IS
 CONSIDERABLE SCATTER AMONG THE VARIOUS SATELLITE FIX POSITIONS...SO
 I HAVE OPTED TO USE AN APPROXIMATE LOCATION OF THE GEOMETRIC CENTER
 OF THE LARGER CYCLONIC ENVELOPE DUE TO THE UNCERTAINTY IN NIGHTTIME
 FIXES. THE INITIAL INTENSITY IS BEING MAINTAINED AT 30 KT...MAINLY
 DUE TO THE SCATTER IN THE FIX POSITIONS WHICH ALSO AFFECTS THE
 INTENSITY ESTIMATES WHEN USING THE DVORAK SHEAR PATTERN TECHNIQUE.
 IT IS ENTIRELY POSSIBLE THAT TD-17E IS ALREADY A MINIMAL TROPICAL
 STORM. IN ORDER TO ALLOW FOR THIS POSSIBILITY...I HAVE INCREASED
 THE GUST DIFFERENTIAL IN THE FORECAST/ADVISORY PRODUCT AND ALSO
 ADDED 12-FT SEA HEIGHTS IN THE NORTHEAST QUADRANT.
  
 THE INITIAL MOTION IS AN UNCERTAIN 325/07. IT IS POSSIBLE THAT A NEW
 CIRCULATION CENTER COULD DEVELOP NEAR THE SMALL BURST OF INTENSE
 CONVECTION LOCATED IN THE NORTHEAST QUADRANT...WHICH WOULD MAINTAIN
 THE PREVIOUS ADVISORY MOTION OF 360/10. HOWEVER...NONE OF THE
 RELIABLE NHC MODELS SUPPORT THAT MOTION FOR MORE THAN 6-12 HOURS
 BEFORE TURNING THE CYCLONE SHARPLY NORTHWESTWARD. SOME MODELS SUCH
 AS THE GFDL AND HWRF EVEN TURN THE DEPRESSION WEST-NORTHWESTWARD
 ALMOST IMMEDIATELY FROM ITS CURRENT POSITION. THE OFFICIAL FORECAST
 TRACK IS SIMILAR TO THE PREVIOUS ADVISORY...BUT TO THE LEFT OF THE
 MODEL OF CONSENSUS...AND GRADUALLY BENDS THE TRACK OF A WEAKENING
 DEPRESSION TOWARD THE WEST-NORTHWEST BY 24 HOURS AND THEN WESTWARD
 AFTER 36 HOURS AS A SURFACE-TO-700 MB RIDGE BUILDS ACROSS MOST OF
 MEXICO IN THE WAKE OF A STRONG COLD FRONT CURRENTLY PUSHING
 SOUTHWARD ACROSS THE WESTERN GULF OF MEXICO AND EASTERN MEXICO.
  
 AS MENTIONED PREVIOUSLY...THE DEPRESSION MAY ALREADY BE VERY NEAR
 TROPICAL STORM STRENGTH DEPENDING ON JUST HOW CLOSE THE CENTER
 ACTUALLY IS TO THE COLD-TOPPED CONVECTION IN THE NORTHEAST QUADRANT
 OF THE CIRCULATION. HOWEVER...THE BUILDING LOW- TO MID-LEVEL RIDGE
 ACROSS MEXICO WILL ACT TO BLOCK ANY SIGNIFICANT POLEWARD MOTION...
 WHICH WILL SERVE TO INCREASE THE CURRENT 30-KT SOUTHWESTERLY
 VERTICAL WIND SHEAR ACROSS THE CYCLONE. THEREFORE...UNLESS TD-17E
 REACHES TROPICAL STORM INTENSITY WITHIN THE NEXT 6 HOURS OR SO...IT
 IS HIGHLY UNLIKELY THAT THIS SYSTEM WILL GET NAMED SINCE THE SHEAR
 IS FORECAST BY THE SHIPS MODEL TO INCREASE TO 40-45 KT BY THE
 12-HOUR FORECAST PERIOD.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      24/0900Z 15.7N 106.1W    30 KT
  12HR VT     24/1800Z 16.5N 106.7W    30 KT
  24HR VT     25/0600Z 17.5N 107.6W    30 KT
  36HR VT     25/1800Z 18.0N 108.6W    30 KT
  48HR VT     26/0600Z 18.1N 110.1W    25 KT
  72HR VT     27/0600Z 18.1N 112.2W    20 KT...REMNANT LOW
  96HR VT     28/0600Z 18.1N 115.3W    20 KT...REMNANT LOW
 120HR VT     29/0600Z...DISSIPATED
  
 $$
 FORECASTER STEWART