Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
138 PM akdt Friday may 22 2015
Main forecast highlights include an unsettled wet pattern for most
of western Alaska...record breaking warmth and red flag conditions
for the interior...and above normal temperatures for the North
Very good model agreement among the 22/12z deterministic model
suite regarding the main synoptic features through 24/00z Monday.
Increasing spread in model solutions thereafter...mainly with the
progression of lows over the Bering Sea during the extended. There
is some consensus between the ecwmf and GFS with the ridge
rebuilding over the interior middle to late next week.
Additionally...the Gem...GFS...NAM and ecwmf continue to
advertise extreme warmth at h850 Saturday afternoon and evening
over the interior...warming to between 13c to 15c 00z Saturday.
North Slope...the main forecast concern will be the continued
above normal warmth and how this impact ongoing Hydro issues.
Surface temperatures are expected to warm 10 to 20 degrees warmer
than forecast highs today as very warm h850 temperatures spread
northward from the interior. This will bring temperatures along
the Arctic coast to the middle 40s to middle 50s and the coastal plain
just north of the Brooks range into the middle to upper 60s to near
70 degrees late tomorrow afternoon and evening...and again on
Sunday. These above normal temperatures will help to continue snow
melt over the North Slope and may add to ongoing issues with snow
melt related flooding for the kuparuk...Colville and sag rivers.
Areas of fog may develop along the immediate coast and coastal
waters from Barrow east through Sunday.
Western Alaska...an upper level shortwave south of the Alaska
Peninsula will move north over the southern Kuskokwim Mountains
and the Kilbuck Mountains tonight and approach the Seward
Peninsula Saturday. Ahead and near this shortwave...an initial
shot of moisture will spread north bringing isolated to scattered
rain showers tonight over the southwest to the Seward Peninsula.
An occlusion associated with a 967 mb low 300 miles north of
Shemya...formerly typhoon Dolphin...will move northeast and move
onshore over the southwest coast late tonight and north stretching
from Saint Lawrence Island to Kotzebue Saturday afternoon. Periods
of rain will accompany this front for the lower Yukon
valley...Saint Lawrence Island and Norton Sound. Elsewhere along
the West Coast and western interior...isolated to scattered
showers at best through Sunday.
Eastern and central interior...record breaking warmth is expected
Saturday across much of the interior...where temperatures are
expected to climb into the 80s. The upper level ridge overhead
will remain in place through late Saturday...keeping the interior
very dry while ramping up h850 temperatures to between 13c to 15c
by 24/00z Saturday. For Fairbanks...the current record maximum
temperature for the 23rd of 80 degrees is definitely in
jeopardy...especially where the forecast high is 85 degrees. This
heat will be short lived as the ridge axis is prognosticated to shift
east into Canada Sunday...allowing h850 and surface temperatures
to cool down into the 60s and 70s Sunday and Monday.
The thermal trough will redevelop and strengthen over the
southern interior Saturday...which in turn will allow gap flow
through the Alaska Range passes and in Delta Junction and Fort
Greely to develop and strengthen Saturday. Gap flow winds will
peak in Saturday afternoon and evening...with sustained winds
warily around 30 miles per hour and gusts maxing out around 45 miles per hour through
Isabel Pass and Tok cutoff...and up to 55 miles per hour along the Parks
Highway. All winds are expected to be sub criteria for wind
advisories. Winds will decrease Sunday as the thermal through
shifts north towards the Brooks range but will still have winds
gusting to at least 30 miles per hour through the passes.
Convective parameters are indicating the slight chance of some
isolated thunderstorms near Eagle in the fortymile country
Saturday afternoon and evening...but due to the lack of
moisture...these will most likely be dry thunderstorms. There is
convective potential again Sunday and Monday from Chicken north
to Arctic Village and east into Canada. Isolated dry
thunderstorms expected Sunday...then will accompany scattered rain
showers Monday as moisture is advected over the Bone dry interior.
The possibility of dry thunderstorms will add fuel to the
fire...especially over the eastern interior where elevated fire
threat with several ongoing fires exist...especially on Saturday.
Very dry and hot conditions will persist into the weekend.
Ongoing red flag warnings for low relative humidity through Saturday evening are
on track for zones 220...222 and 224 as are the ongoing red flag
warnings for strong winds and low relative humidity through Saturday evening for
zones 223...225 and 226. The thermal trough will strengthen
Saturday as a surface high pressure system moves southeast in to
the Yukon. Gusty winds are expected to develop in and near the
Alaska Range passes tonight which will limit relative humidity
recovery in these areas. Compounding the threat of low relative humidity value
and high temperatures will be the threat of isolated dry
thunderstorms along the Canadian border in fortymile country
Saturday and along and east of a line from Chicken to Arctic
Village Sunday afternoon and evening.
warnings...advisories...and watches will continue through at least
Saturday. Extreme warmth over the North Slope may add to snow melt
related flooding issues.
red flag warning for akz220-akz222-akz223-akz224-akz225-akz226.
Flood Watch for akz203-akz220.
Small Craft Advisory for pkz210-pkz230.
Brisk Wind Advisory for pkz220-pkz225-pkz235.
lth may 15