July 11, 2017

GFS Forecast: analysis time: 00Z 2017-07-11 :: valid time: 22Z 2017-07-11 

Update [21:35PM, Mon. Jul 9, 2017 PST] : 22-hour forecast. Largely consistent with forecast 30 hours ago. 

Update [18:07PM, Sun. Jul 9, 2017 PST] : 52-hour forecast. Some clouds show up just south of 73N around 300 m. 

Update [15:30PM, Sat. Jul 8, 2017 PST] : 76-hour forecast. Now sea ice finally open up near the coast, with the ice edge (15%) at slightly north of 72N now. From there all the way to 80N, the sea ice concentration stays lower than 80% most of the time. High pressure still dominates but the warm advection is not particularly stronge, with temperature of 3C at the level of inversion (750 m).  Still dry and no low level (<3km) or mid-level (<6km) clouds along 150W. The RH below 300 m is around 85% or higher at most places. Again, the 73N is relatively compared to immediate north and south, so good for ocean drops. 

Update [11:12AM, Fri. Jul 7, 2017 PST] : 108-hour forecast. The high pressure over BCSIZ is moving to the southeast. Stronger temperature inversion. Some clouds are moving in, but low levels (below 300 m) are still dry, so not likely a problem for buoy and CTD drops. Sea ice is melting away fast close to the coast.  May see a clear ice edge on next Tuesday. 

Update [15:25PM, Wed. Jul 5, 2017 PST] : 147-hour forecast. Another low forming to the north of Chukchi (shown in 700 hPa geopotential height and 2PVU pressure plots), which generates some clouds and moist stripes along 150W. The high pressure still dominates in Beaufort and temperature inversion gets stronger. 

Update [11:35PM, Tue. Jul 4, 2017 PST] : 171-hour forecast. Forecast changes quite a bit from 24 hours ago. The high pressure still dominate the BCSIZ region but the low to the northeast moves further away. The winds shifted consequently. The warm advection is still there, but the inversion is weaker. The stripe of moist air is gone. Now, it is dry along the 150W, except for the lowest 200 m. No sign of clouds along this line either. Near surface air is warm and moist. So shouldn’t be a problem at all to find open water for ocean probes. 

Update [5:11PM, Mon. Jul 3, 2017 PST] : 195-hour forecast. Now a high pressure over Beaufort and a strong low to the north.  Westerly winds from the south. Warm and dry air advected advection into this region with strong temperature inversion south of 73N. The stripe of moist air is advected from the west by the strong westerly winds. The surface is warm, above freezing, and moist (RH>85%) along 150W. Some low level clouds around 73N. 

Update [4:35PM, Jun 30, 2017 PST] : Cold, moist, cloudy, and Westerly wind along 150W. At the southern edge of a low pressure system to the northeast. No inversion, or inversion height below 1000 hPa. Typical state 2 conditions. Forecast from 24 hours ago was very different from the forecast shown here. Expect conditions to change over the weekend. 

  • Pan-Arctic maps

Sea ice concentration at analysis time

Mean sea leve pressure at valid time

700 hPa Geopotential Height

700 hPa temperature

700 hPa relative humidity

700 hPa wind speed

Pressure on 2PVU surface

Pressure on 2PVU surface

Low-level cloud cover

Mid-level cloud cover


  • Beaufort and Chukchi seasonal ice zone (the map is centered at 150W)

Sea ice concentration at analysis time

Mean sea leve pressure at valid time

2-m air temperature

2-m relative humidty

low cloud fraction

middle cloud fraction


  • Transects along 150W