Northern Alaska forecast discussion 
National Weather Service Fairbanks Alaska 
300 PM akdt Sat may 18 2013 


Discussion... 
in the upper levels...a deep long wave trough of low pressure 
extends from north of wrangle island to the low pressure located 
just north of Kodiak Island. This long wave trough and slowly get 
pushed eastward as high pressure over the Bering Sea builds over 
the area. This will push the precipitation towards Yukon 
territory by Sunday afternoon into evening. A surface low 
pressure system in the chukotsk peninsula will move towards the 
Seward Peninsula and be located north of Cape Lisburne on Sunday 
afternoon allowing for tightening of the surface pressure gradient 
and increasing winds as well as allowing for upslope flow for 
orographic precipitation. Aloft and at the surface...high 
pressure will move towards the central and interior Alaska as the 
next strong low pressure system begins to move eastward across the 
Bering Sea. Except for some minor differences...the models are in 
generally good agreement and give way to higher confidence of 
precipitation and and cooler temperatures across the West Coast of 
Alaska. 


North Slope...fairly quiet in the North Slope area at this time. 
Early in the morning fog and low stratus caused some low 
visibilities of 1 to 2 miles. Expect areas of fog to redevelop 
overnight into tomorrow morning once again. Gusty winds along and 
north of Barter Island will continue through tomorrow morning as 
the surface pressure gradient tightens associated with the low 
pressure. However...winds will diminish tomorrow as the surface 
pressure sue weakens. 


Western Alaska...high pressure currently over the West Coast as 
the approaching front associated with surface and upper level low 
pressure systems over the Bering Sea approaches on Sunday through 
Monday. This system will continue to effect the West Coast 
through the remainder of the work week. The southerly to 
southwesterly flow will strengthen over the Bering Strait and West 
Coast and allow for upslope precipitation over the typical 
locations on the Seward Peninsula and northward. Will also see 
areas of fog developing along the West Coast. Increasing winds 
over the Bering and chukchi seas will allow for brisk wind 
advisories to be hosted through Sunday afternoon...but will need 
to be extended. 


Central and interior...winter weather that returned to the area 
and will slowly diminish through tonight for many locations. 
Winter weather warnings and advisories over Alaska Range will be 
allowed to expire as little additional snow accumulation is 
expected. Only exception will be for public zone 220 for the Yukon 
uplands areas east of Fort Yukon and public zone 224 that has been 
extended through tomorrow morning for areas northwest of Tok. 
Additional snow accumulations is anticipated for up to 3 to 4 
inches at higher elevations in these two areas. Thus the winter 
weather warning and advisory will remain in effect for these two 
locations. Otherwise much colder than normal air mass over the 
central and interior Alaska today will gradually warm over the 
next couple of days. By Wednesday temperatures will be near normal 
if not slightly above as high pressure builds into the area. This 
will have subsequent effect on the river break up. 


&& 


Fire weather... 
none. 


&& 


Hydrology... 
breakup is in progress on the upper Yukon river and ice will 
proceed to move slowly over the next couple of days. A Flood 
Watch for ice jam flooding is still in effect along the Yukon 
river for Circle City. Also still in effect is the Flood Advisory 
for ice jam flooding along the Tanana river in Salcha as an ice 
jam continues cause minor flooding that is impacting several 
residential yards. More snow melt is expected into early next 
week as temperatures warm across the central and eastern Alaska. 


A Flood Advisory has been issued through tomorrow afternoon for 
areas along the chena river near nordale. There is some minor 
flooding that is occurring. 


&& 


Afg watches/warnings/advisories... 
Winter Storm Warning for akz218. 


Flood Watch for akz220. 


Winter Weather Advisory for akz224. 


Brisk Wind Advisory for pkz200-pkz210-pkz220-pkz225-pkz230- 
pkz240-pkz245. 
&& 


$$ 


Mak may 13