Tropical Depression 9W Forms
After a brief few days which saw the Earth void of any tropical cyclones, a new tropical depression has formed in the West Pacific. The disturbance that became this depression has been tracked for days and overall the Joint Typhoon Warning Center (JTWC) has done a good job in predicting the system's development. Advisories were initiated on the system, dubbed TD 9W, this afternoon. As of the first advisory on the system, 9W is located about 220 nautical miles north of Manila, Philippines. It is moving west at about 14 knots. 9W currently has maximum sustained winds of just 25 knots (30mph), so it is barely a tropical cyclone right now.
Forecast for 9W
9W is currently very disorganized. The center has struggled to consolidate and has been difficult to locate on satellite imagery. In addition, 9W is very tangled up in the Philippines, making it difficult for it to strengthen. It is also under moderate wind shear from the east, so much of its convection is on its west side. Because of this shear and the land interaction, major strengthening is not anticipated during the next 24 hours. Beyond that time, however, 9W will enter into the warm waters of the South China Sea, where shear is lower and the air is very moist. This will allow 9W to strengthen, and the JTWC forecasts a peak intensity of 55kts (65mph), making 9W a moderate to strong tropical storm. I am a little more aggressive in my intensity forecast as I think 9W will take advantage of these favorable conditions and peak as a minimal typhoon with winds of 65kts (75mph) in about 4 days. The track forecast is fairly simple, but is complicated some by low confidence in the center location and the very real possibility that the center could reform over the next 24 hours. However, 9W should track generally to the west or WNW for most of the forecast period under the influence of a building subtropical ridge. This track will have 9W skirt the southwest portion of China before eventually making landfall in Vietnam in about 5 days, after which it will quickly weaken and dissipate. The main threat will be heavy, flooding rainfall and dangerous mudslides, with damaging winds and storm surge lesser threats.
Figure 1: Official JTWC forecast track of 9W.
Figure 2: The disorganized Tropical Depression 9W.
The Atlantic and East Pacific are very quiet right now, with no areas being watched for development in either basin. Conditions in the Atlantic, Caribbean, and Gulf are mostly unfavorable except for warm waters, so any development through early August is unlikely. It's difficult and usually quite foolish to speculate beyond then, but right now I still feel pretty confident in about 12 named storms, though that may need to be adjusted downwards a bit if conditions remain unfavorable. El Nino appears to be progressing on or slightly behind schedule, but it still appears it will be here for the peak of the season, though a strong El Nino is very unlikely.
Lastly, as I wrote about a week or so ago, I will be going on vacation to Vermont starting tomorrow. I'll still be around but not as much and I probably won't have time for any full blogs. Luckily, unlike when Dr. Masters goes on vacation, the tropics should be very quiet while I'm gone. Thank you for reading and have a great weekend!
Figure 3: The Von Trapp Family Lodge in Stowe, VT, where I will be staying this week. You're jealous :)