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| #201979 (Received by flhurricane at: 5:08 AM 20.Jul.2008) TCDAT3 TROPICAL STORM CRISTOBAL DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032008 500 AM EDT SUN JUL 20 2008 THE SATELLITE PRESENTATION OF CRISTOBAL REMAINED UNIMPRESSIVE- LOOKING OVERNIGHT. THERE HAS BEEN VERY LITTLE DEEP CONVECTION NEAR THE CENTER WITH THE PRIMARY BANDS OF THUNDERSTORMS WELL DISPLACED TO THE SOUTH AND SOUTHEAST. FLIGHT-LEVEL WINDS FROM AIR FORCE HURRICANE HUNTER DATA INDICATE THAT THE MAXIMUM WINDS REMAIN NEAR 40 KT. SOME SFMR READINGS FROM THE AIRCRAFT GAVE HIGHER SURFACE WINDS BUT THESE APPEAR TO BE ERRONEOUS DUE TO INTERFERENCE. ALTHOUGH SURFACE OBSERVATIONS SHOW LITTLE EVIDENCE OF DRY AIR...WATER VAPOR IMAGERY SHOWS SOME EVIDENCE OF MID-LEVEL SUBSIDENCE OVER THE NORTHEASTERN PORTION OF THE CIRCULATION AND UPPER-LEVEL OUTFLOW IS BEING SHUNTED OVER THE NORTHERN SEMICIRCLE. 200 MB WIND FORECASTS FROM THE GFS SUGGEST A MORE FAVORABLE UPPER-LEVEL ENVIRONMENT WITHIN THE NEXT DAY OR SO...AND SOME INTENSIFICATION IS FORECAST AS IN THE PREVIOUS ADVISORIES. THE OFFICIAL WIND SPEED FORECAST IS A LITTLE HIGHER THAN THE INTENSITY FORECAST MODEL CONSENSUS. WITHIN 2-3 DAYS THE SYSTEM IS EXPECTED TO LOSE STRENGTH DUE TO RAPIDLY INCREASING SOUTHWESTERLY SHEAR...AND LOSE TROPICAL CHARACTERISTICS. THE INITIAL MOTION IS SLOWLY NORTHEASTWARD...040/5. CRISTOBAL IS EXPECTED TO GRADUALLY INCREASE ITS FORWARD SPEED AS IT BECOMES PICKED UP IN THE FLOW AHEAD OF A BROAD MID-TROPOSPHERIC TROUGH. BY 72-96 HOURS OR SOONER THE SYSTEM IS EXPECTED TO MERGE WITH A LARGER EXTRATROPICAL CYCLONE NEAR THE CANADIAN MARITIMES. THE OFFICIAL TRACK FORECAST IS ABOUT IN THE MIDDLE OF THE MODEL GUIDANCE AND SIMILAR TO THE PREVIOUS NHC TRACK. FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 33.9N 77.2W 40 KT 12HR VT 20/1800Z 34.7N 76.0W 45 KT 24HR VT 21/0600Z 35.8N 74.4W 50 KT 36HR VT 21/1800Z 37.5N 72.0W 55 KT 48HR VT 22/0600Z 40.2N 69.0W 45 KT 72HR VT 23/0600Z 47.0N 61.0W 35 KT...EXTRATROPICAL 96HR VT 24/0600Z...ABSORBED $$ FORECASTER PASCH |
