000 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