Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
251 am akdt Tuesday may 21 2013
Discussion...
aloft...502 dam low located 300 nm northwest of Barrow continues
to slowly retreat to the northeast while a strong ridge continues
to build into central and eastern Alaska Mainland. A low over the
southern Bering Sea continues to move north and east to be near St
Paul island Tuesday afternoon and near Nunivak Island Wednesday
morning. Upper level low currently located over northern British
Columbia continues to dig south and east through Wednesday. As the
upper level ridge over the central and eastern Alaska splits with
parent ridge remaining in the Gulf of Alaska and the northern
portion pushing into the northwest territories an upper level low
races north along the alcan border Thursday and Friday. Upper level
ridge in the Gulf of Alaska surges north again to cover central
and eastern Alaska into the weekend. A series of short waves
continue to push north and northeast over the West Coast and
western interior through the week.
On the surface weak ridging covers the central and eastern
interior while a 998 mb low in the southern Bering Sea continues
to move north and east to be just east of St Paul island Tuesday
afternoon and near St Matthew island Wednesday morning. Moisture
primarily in the form of rain will continue to move north along the
West Coast and western interior through the week. Snow north of
the Seward Peninsula gradually transitioning to rain or rain snow
mix this morning and is expected to remain rain today as warm air
mass continues to move to the north. A rain and snow mix is found
along the western North Slope and will continue through the week
as series of short waves move north in the long wave.
Models are in good agreement through the weekend on placement of
synoptic scale features. Both the GFS and the European model (ecmwf) remain quite
bullish on warm temperatures building into the eastern interior
with the GFS advertising 850 mb temperatures around 12 degrees c
and the European model (ecmwf) advertising around 10 degrees c. Will need to
monitor the eastern interior for potential for rapid snow pack
melt. Snow pack melt especially at altitude in the eastern Alaska
Range and higher terrain in the eastern interior has been hampered
by recent record cold and in many locations the addition of
significant snow.
&&
Fire weather...
expect warming temperatures and day time relative humidity values dropping into
30 to 40 percent across the central and eastern interior as upper
level high pressure ridge builds over the area. Development of a
thermal trough over the eastern interior will increase the
potential for gusty afternoon winds in these areas.
&&
Hydrology...
Flood Warning continues for Fort Yukon and a Flood Watch remains
in place downstream to Tanana as breakup activity on the Yukon progresses.
&&
Afg watches/warnings/advisories...
Flood Watch for akz220-akz221.
Brisk Wind Advisory for pkz200-pkz210-pkz215-pkz220-pkz225.
&&
$$
Ccc may 13
