000 WTPZ42 KNHC 082032 TCDEP2 TROPICAL STORM GILMA DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP072012 200 PM PDT WED AUG 08 2012 GILMA HAS BEEN ON THE VERGE OF BECOMING A HURRICANE THROUGHOUT THE DAY...SHOWING MIXED SIGNALS ABOUT ITS INTENSITY. SATELLITE INTENSITY ESTIMATES HAVE BEEN 65 KT FROM TAFB AND 55 KT FROM SAB. AMSU INTENSITY ESTIMATES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN AND CIRA AT COLORADO STATE UNIVERSITY HAVE BEEN 57-63 KT. ALSO...EARLIER MICROWAVE DATA SHOWED AT BEST A PARTIAL EYEWALL UNDER THE CENTRAL DENSE OVERCAST...WHILE LATER VISIBLE IMAGES HAVE HINTED AT EYE FORMATION. GIVEN THE AMBIGUITIES...THE INITIAL INTENSITY WILL REMAIN AT 60 KT...JUST BELOW HURRICANE STRENGTH. WHILE THE OUTFLOW REMAINS GOOD IN THE SOUTHWESTERN SEMICIRCLE...A BAND OF CIRRUS CLOUDS APPROACHING THE STORM FROM THE NORTHEAST SUGGESTS SOME LIGHT VERTICAL WIND SHEAR IS OCCURRING. THE INITIAL MOTION IS NOW 285/9 KT. THE CYCLONE IS BEING STEERED BY A MID- TO UPPER-LEVEL RIDGE EXTENDING WESTWARD OVER THE NORTHEASTERN PACIFIC FROM THE SOUTHWESTERN UNITED STATES. THIS SHOULD KEEP GILMA ON A WEST-NORTHWESTWARD TRACK AT A DECREASING FORWARD SPEED DURING THE NEXT 24 HR OR SO. AFTER THAT...THE GLOBAL MODELS CONTINUE TO SHOW A LARGE AREA OF BROAD LOW- TO MID-LEVEL CYCLONIC FLOW...POSSIBLY INCLUDING THE REMNANTS OF ATLANTIC HURRICANE ERNESTO...FORMING TO THE EAST OF GILMA. THE LATEST DYNAMICAL MODEL RUNS SHOW THIS FEATURE HAVING LESS OF AN IMPACT ON GILMA THAN PREVIOUSLY FORECAST...AND AS A RESULT THE GUIDANCE ENVELOPE HAS SHIFTED WESTWARD AFTER 48 HR. THE NEW FORECAST TRACK IS NUDGED A LITTLE TO THE WEST OF THE PREVIOUS FORECAST AND IS IN BEST OVERALL AGREEMENT WITH THE GFS MODEL. GILMA IS NOW OVER SEA SURFACE TEMPERATURES OF NEAR 27C...AND THE FORECAST TRACK TAKES THE CYCLONE OVER PROGRESSIVELY COOLER WATERS. A LITTLE STRENGTHENING IS POSSIBLE TONIGHT...AND THE INTENSITY FORECAST STILL CALLS FOR GILMA TO BECOME A HURRICANE. STEADY WEAKENING SHOULD OCCUR AFTER 24 HR...WITH THE CYCLONE FORECAST TO WEAKEN TO A DEPRESSION BY 96 HR AND TO DEGENERATE TO A REMNANT LOW BY 120 HR. THE NEW INTENSITY FORECAST IS SIMILAR TO... BUT A LITTLE ABOVE...THE SHIPS AND LGEM MODELS. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 16.1N 117.8W 60 KT 70 MPH 12H 09/0600Z 16.5N 118.8W 65 KT 75 MPH 24H 09/1800Z 17.2N 119.9W 65 KT 75 MPH 36H 10/0600Z 17.8N 120.8W 60 KT 70 MPH 48H 10/1800Z 18.4N 121.4W 50 KT 60 MPH 72H 11/1800Z 19.5N 122.0W 40 KT 45 MPH 96H 12/1800Z 20.0N 122.5W 30 KT 35 MPH 120H 13/1800Z 20.5N 123.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ FORECASTER BEVEN