Area Forecast Discussion - Northern


FXAK69 PAFG 012303
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
303 PM AKDT FRI JUL 1 2016
.SYNOPSIS...
Aloft...
A ridge stretching east to west across northern Alaska will
persist through the weekend then retreat east in NW Canada next
week as a trough develops over the Bering Sea. A low aloft in the
Gulf of Alaska will move over SE Alaska Sat and then move slowly
east. A series of short wave troughs rotating around this low will
move west across Interior Alaska bringing bands of showers and
isolated to scattered thunderstorms to the eastern and southern
Interior through the weekend.

A strong short wave that now lies from Denali to Livengood to Old
Crow will move to McGrath to Tanana to Arctic Village by 4am
Sat...and then weaken in place through Sun. There is a wide band
of showers NW of this trough that becomes scattered north of the
Yukon River. This dropped .10 to .25 inch of rain over the eastern
Interior south of Circle with up to .50 inch in the hills north of
Fox and east of Delta Junction. Expect this to drop another .50 to
1 inch over zones 221 225 and 227 through Sat with the heaviest
amounts in Denali Park. From .50-1.5 inch of rain has already
fallen in Denali Park so this will keep small stream and rivers
there high through the weekend and could still cause mud and rock
slides.

A second and weaker short wave trough near Old Crow will move to
Fort Yukon by 4am Sat...to Denali to Livengood by 4pm Sat...and
then slowly dissipate through Sun. This will cause scattered
showers and scattered PM thunderstorms in eastern zone 216
western 221 and 227 Sat and into Sun. The thunderstorms could
have small hail Sat.

A third short wave trough over the southern Yukon Territory will
move to the ALCAN Border by 4pm Sat and then weaken over the
eastern Interior through Sun. This will bring more widespread
showers to zones 224 226 Sat into Sun and keep scattered showers
and at least isolated thunderstorms going in the remainder of the
eastern Interior. There is the potential for hail again Sun and
this will need to be watched.

A fourth short wave is expected to move to the extreme SE interior
Sun night and Mon and could bring heavy rain...but this still has
a lot of uncertainty.

Surface...
An Arctic warm front from Barter Island to Deadhorse will move to
Barter Island north by 4am Sat then move north of the coast.
Expect fog to reform along this front tonight and then move
offshore Sat.

A 1022 mb high over the central Bering Sea will weaken slowly
through Sun.

An Arctic cold front in the western Chukchi Sea will move east to
Barrow to Cape Lisburne then west by 4pm Sat...to Deadhorse to a
1007 mb low near Point Hope by 4am Sun...and then quasi-
stationary. Fog and a chance of rain will accompany the front.
Westerly flow will increase south of the low center and should
return widespread fog to the southern Chukchi and north Bering
Seas and most of the West Coast of AK by Sat night.

&&
.DISCUSSION...
Models are similar on the large scale flow pattern and features
but differ some on timing and location of weak short wave troughs
moving west across the Interior. Since these weak short wave
troughs are the main force driving convection over the interior
the location is important. We favor the GFS locations of the short
waves and heavy rain through Sat night Sun and then the flow
becomes so weak that we can really only deal with short wave
location and accompanying rainfall in a probabilistic sense.

Coastal Hazard Potential Days 3 and 4...None.

&&
.FIRE WEATHER...
Continued wet across southern and eastern Interior with drier and
warmer conditions in the northwest Interior. Expect isolated
thunderstorms a a few lightning strikes today and Sat...except LAL
3 Sat in eastern Zone 216...western 221 and 227. Sun could see LAL
3 over the eastern Interior but uncertain at this point so left it
as LAL 2 for Sun.

&&
.HYDROLOGY...
The past 36 hrs saw .10 to .25 inch of rain fall over the eastern
Interior south of Circle with up to .50 inch in the hills north of
Fox and hills east of Delta Junction...while Denali Park had
between .50-1.5 inch. Expect another .50 to 1 inch over zones 221
225 and 227 through Sat with the heaviest amounts in Denali Park.
This will keep small stream and rivers in Denali high through the
weekend and could cause mud and rock slides through the weekend.

There is a potential for heavy rain in zones 224 and 226 SE of
Tok Sun night and Mon but still much uncertainty on this.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ245.
&&

$$

JB JUL 16