The first tropical depression of 2015 over the Western North Pacific Ocean formed east of Yap on Tuesday.  At 7:00 p.m. EST on Tuesday the center of Tropical Depression 01W (TD01W) was located at latitude 10.1°N and longitude 139.9°E which put it about 130 miles east-northeast of Yap and about 1250 miles east-southeast of Manila, Philippines.  TD01W was moving toward the northwest at 13 m.p.h.  The maximum sustained wind speed was 35 m.p.h. and there were gusts to 45 m.p.h.  The minimum surface pressure was estimated to be 1000 mb.

A subtropical ridge is generating southeasterly winds over the top of TD01W and producing moderate wind shear.  The wind shear is causing much of the thunderstorm activity to be located in the northwestern part of the circulation around TD01W.  The lack of thunderstorms in the southern portion of the circulation is limiting the intensification of the tropical depression.  TD01W is over Sea Surface Temperatures that are around 30°C and so the potential for intensification exists if the speed of the upper level winds diminish.

The subtropical ridge is expected to continue to steer the tropical depression in a general west or west-northwesterly direction during the next few days.  This projected path could bring the tropical cyclone near the Philippines later this week.

Tropical Depression 22W organized rapidly on Monday and intensified into Tropical Storm Hagupit.  At 10:00 p.m. EST on Monday the center of Tropical Storm Hagupit was located at latitude 6.1°N and longitude 146.0°E which put it about 490 miles south-southeast of Guam and about 570 miles east-southeast of Yap.  Hagupit was moving toward the west at 24 m.p.h.  The maximum sustained wind speed was 65 m.p.h. and there were gusts to 80 m.p.h.

Hagupit has developed multiple spiral bands of thunderstorms and there are some indications that an eye may be forming at the center of the circulation.  There is a large and well developed circulation around the tropical storm.  The winds in the upper levels are relatively light and upper level divergence continues to pump out mass from the center of circulation.  Hagupit will continue to move over warm Sea Surface Temperatures and the environment is favorable for continued intensification.  Hagupit could become a typhoon on Tuesday and it could be a strong typhoon in several days.

A subtropical ridge north of Hagupit is steering the storm toward the west and it is likely to steer the tropical storm in a general west-northwesterly direction during the next 48-72 hours.  The projected path would bring Hagupit very close to Yap in about 36 hours.   There is more uncertainty about the possible track of Hagupit after it passes Yap because an upper level trough moving north of the storm could weaken the subtropical ridge.  If the ridge weakens, the winds at the steering level could become weaken and the motion of Hagupit could slow.