May 31, 2018

  GFS Forecast: analysis time: 12Z 2018-05-29 :: valid time: 20Z 2018-05-31 ( Alaska LT: Wed. 2018-05-31 12:00PM)

Links to plots Below

Sea ice contours: 15% (blue), 50% (black), 90% (red)

2-m temperature contour: -1.8 °C

U/V transect contour: 0 m/s 

Update [16:00PM, Tue. May. 30, 2018 PST]:  

Conditions are very similar to the forecast 24 hours ago. The main difference is that the off shore low level cloud will still be present at 3PM, on May 31, Alaskan local time (Wednesday). The new GFS forecast and the WRF runs suggests low level cloud (a thin layer around 1000 ft, capped by the temperature inversion above) extending to 72°N. It is clear other wise. 

Update [16:30PM, Mon. May. 29, 2018 PST]:  

Clear conditions with some low cloud/fog near coast in early morning , but clear out later shore (Note, this low level cloud is not seen in GFS forecast). The surface visibility is over 5 miles and ceiling height is above 3000 ft along 150 °W line.  The relative humidity of near surface air is still high around 90%. 

Near surface the temperature is below -1.8 °C at 6AM but warms up to around -1 °C at 9AM, and around 0 °C at 15PM. There is some warm air (around 5 °C) that is advected over the ice at 1 km level. A little to the north of this temperature inversion and at a lower altitude, a weak low-level wind jet is present, with the maximum wind at the jet core over 10 m/s. 

With a closer look at the 700 hPa RH map along the coast, a wave-breaking-like feature is evident and transport of heat and moisture into the ice covered area by these moisture intrusion events. It is also shown in the 2PVU map, but not as clear. 

    • Flight information

2018-05-31 12PM Alaska LT

2018-05-31 3PM Alaska LT

2018-05-31 12PM Alaska LT

2018-05-31 3PM Alaska LT

  • 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 150 °W)

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 150 °W

  • Flight conditions at different altitudes along 150 °W