000 WTPZ41 KNHC 310836 TCDEP1 TROPICAL STORM VANCE DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212014 200 AM PDT FRI OCT 31 2014 Several overnight microwave images and ASCAT data indicate that the center of Vance is located farther south and east than previously estimated. The center is near the southern edge of the large mass of deep convection due to moderate south-southwesterly shear. The ASCAT data and Dvorak satellite intensity estimates support maintaining an initial wind speed of 40 kt. The shear and some dry low- to mid-level air are expected to continue to affect the tropical cyclone during the next 12 to 24 hours, and only gradual strengthening is expected during that time. Environmental conditions are forecast to become more conducive for strengthening over the weekend, and most of the intensity guidance shows Vance becoming a hurricane in 2 to 3 days. By day 4, increasing southwesterly upper-level flow ahead of a large mid-latitude trough is expected to cause a significant increase in shear. This should cause weakening late in the period. The NHC intensity forecast is similar to the previous advisory and is near the model consensus. Due to the center relocation, the initial motion is a highly uncertain 245/3 kt. Vance is expected to move west-southwestward today around the southeastern portion of a mid-level ridge near the southern Baja California peninsula. The ridge is forecast to shift eastward during the next several days while the aforementioned trough approaches the west coast of California. This should cause Vance to turn west-northwestward, then northwestward over the weekend. After 72 hours, Vance is forecast to turn northward, then northeastward ahead of the trough. The track guidance remains in agreement on this scenario but there remains some spread in the timing of the northward turn, and the forward speed of Vance later in the period. The updated NHC forecast is similar to the previous track through 72 hours, but is a little faster than the previous advisory at days 4 and 5. FORECAST POSITIONS AND MAX WINDS INIT 31/0900Z 10.5N 101.0W 40 KT 45 MPH 12H 31/1800Z 10.1N 101.6W 45 KT 50 MPH 24H 01/0600Z 9.8N 103.1W 50 KT 60 MPH 36H 01/1800Z 10.0N 104.8W 55 KT 65 MPH 48H 02/0600Z 10.9N 106.8W 60 KT 70 MPH 72H 03/0600Z 14.0N 110.0W 70 KT 80 MPH 96H 04/0600Z 18.5N 109.0W 60 KT 70 MPH 120H 05/0600Z 22.5N 106.0W 40 KT 45 MPH $$ Forecaster Brown