Scientific Forecaster Discussion
fxak69 pafg 182233 cca
Northern Alaska forecast discussion...corrected
National Weather Service Fairbanks Alaska
233 PM akdt Mon Jun 18 2018
weather focus centers on additional rainfall over the central
interior, the western interior, the West Coast and most of the
Brooks range as well as very strong winds in and near the eastern
Aloft at 500 mb a deep longwave trough with an anchoring low over
Bristol Bay remains in place over the eastern Bering Sea and
western Alaska while ridging builds north and west over eastern
Alaska and the Yukon. The Patten remains essentially the same
through the rest of the week but will drift slowly to the west
with the trough axis sliding into the central Bering and the ridge
building west over the eastern and central interior. This will in
effect produce additional rounds of rain and showers over the
western interior and West Coast and will produce scattered
showers and isolated thunderstorms over the eastern and central
interior and periods of strong winds through the Alaska Range
passes as multiple shortwaves move north and west over the
northern Alaska through the week.
On the surface a 995 mb low currently located near Bethel will
continue to produce periods of rain over the western Alaska Range,
the central and western interior as well as the West Coast and
most to the Brooks range. Rainfall totals from this evening
through Tuesday evening are expected to be between a trace and a
half inch over the central interior and between one half inch and
one and a half inches over the western interior, the West Coast
and the Brooks range through Tuesday evening. The heaviest
rainfall is expected in the favored upslope areas of the western
Brooks range. Will need to monitor rivers draining the Brooks
range where recent rainfall, high snow levels and warm
temperatures combined with expected rainfall through Tuesday
evening will likely produce significant rises on rivers draining
the Brooks range. In particular The Sag river on the North Slope
is expected to rise significantly but remain under action stage
into Tuesday and Wednesday. Continue to monitor.
Strong southerly winds aloft and a strong trough on the surface
combined with a Strong Mountain wave have produced warning level
winds along and near the northern foothills of the eastern Alaska
Range with 80 mph wind gusts recorded just south of Delta
Junction. Expect the strong winds to continue into this evening
and then decrease slowly overnight.
The 12z model suite initialized well against the 12z surface
analysis and verified well against the 18z surface analysis. Model
spread remains limited through the short range as well as the
Middle Range. Model spread increases significantly by the end of
the week and into next weekend.
Coastal hazard potential days 3 and 4...none.
the surge of moisture associated with a powerful shortwave moving
northward across the state today with significant wetting rains
expected over the central and western portions of the state. The
exception to this will be the eastern interior from the Tanana
Valley to the Yukon Flats where rainfall chances will be minimal
tonight as a result of strong downsloping and weak high pressure.
Strong winds will persist through the Alaska Range through
Tuesday morning, though the lowest relative humidity values will
be displaced well to the east. A breakdown in the ridge by midweek
may help increase chances for rain across the region as weaker
shortwaves continue to propagate northward.
24 hour rainfall totals from Monday evening to Tuesday evening
will total between a trace and a half of an inch in the central
interior. Over the western interior, the West Coast and the Brooks
range expect 24 hour rainfall totals from one half of an inch to
one and a half inches with the heaviest rain falling in the
western Brooks range in favored upslope areas. Warm temperatures
aloft over the Brooks range combined with heavy rainfall over the
last several days and additional rainfall expected tonight and
tomorrow will produce significant rises on rivers draining the
Brooks range and in particular The Sag river. Current forecasts
keep The Sag river below action stage but will need to monitor
closely as additional rain falls over the Brooks range.
High Wind Warning for akz223-akz226.
Small Craft Advisory for pkz210-pkz220-pkz225.