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Northern Alaska forecast discussion 
National Weather Service Fairbanks Alaska
610 am akdt Tuesday Apr 21 2015

Discussion...
models initialized well and exhibit consistent run to run
solutions with minimal spread between model families through the
short term...however they begin to diverge on details in the middle
term and exhibit considerable spread in the long term.

Aloft at 500 hpa...a 504 dam low currently just east of St
Lawrence Island will move to the northwest to be located over the
Bering Strait Wednesday morning and over northern portions of the
chukotsk peninsula Wednesday evening. This low is the Focal Point
for several bands of snow showers that have been rotating northwest
over the West Coast...Norton Sound...southern Seward Peninsula and
St Lawrence Island. Snow shower activity is mixing stronger winds
aloft down and creating periods of low visibility in snow and
blowing snow as the bands pass. A high amplitude ridge currently
centered over northern British Columbia and the western half of
the northwest territories will shift to the east Wednesday as a
515 dam low moves into the northern Gulf of Alaska. A 525 dam low
currently over the eastern Brooks range will deepen to 520 dam as
it moves to the northwest to be located 150 nm north of Point
Barrow Wednesday morning. This upper level low combined with left
front portion of a jet streak moving to the northwest will provide
upper level support for a winter storm moving over the eastern
Brooks range and eastern North Slope today and tonight.

On the surface a 1000 mb low over the eastern Brooks range will
continue to move to the northwest and will be located near Barter
Island this evening. 6 to 8 inches of snow forecast for the crest
of eastern Brooks range northward centered along the Dalton
Highway. Snow amounts will taper along the coast with 3 to 6
inches expected in and near Prudhoe Bay...however winds are
expected to create some blowing and drifting snow in these areas.
Issued a Winter Storm Warning for heavy snow for zone 206 and
Winter Weather Advisory for blowing snow for zone 203.

A 998 mb low centered near St Lawrence Island continues to be the
Focal Point for vigorous bands of snow showers and squalls that
continue to rotate through the lower yk Delta...Norton Sound...southern
portions of the Seward Peninsula...St Lawrence Island and the
Bering Strait today. Winter weather advisories issued for blowing
snow and low visibilities as snow and winds mixing down from aloft
for zones 211...212...213...214 and 215 as poison tail wraps
around the low.

A weak trough extending south of the low over the eastern Brooks
range is the Focal Point for scattered snow showers and light snow
east of Fairbanks with Salcha picking up a couple inches of snow
overnight. The trough will weaken as it drifts slowly to the north
and east and high pressure builds in from the south.

&&

Fire weather...
winds through the Alaska Range passes will increase tonight to 15
to 25 miles per hour as high pressure builds in from the south. Increased
cloud cover as well as scattered snow showers this morning over
the southern interior will prevent min relative humidity values from dropping
below 30 percent this afternoon. Drying trend begins Wednesday
with min relative humidity values dropping below 30 percent in the afternoons
and evenings through the end of the week across snow free areas of
the southern interior.

&&

Afg watches/warnings/advisories...
Winter Storm Warning for akz206.

Winter Weather Advisory for akz203-akz211-akz212-akz213-akz214-
akz215-akz218.

Brisk Wind Advisory for pkz200-pkz210-pkz215-pkz220-pkz245.
&&

$$

Ccc Apr 15

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