Weather Service Report


616 
FXAK69 PAFG 252126
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
126 PM AKDT Tue Jul 25 2017

.DISCUSSION...

Models...Surface initialized well against the 25/18Z analysis.
They are in good agreement out to around 84 hours before
differences start showing up in the major features. The big
difference being how they handle the upper level low that will
move moving south over the west coast. Over the Arctic persistent
westerly flow will continue, but by Friday afternoon models
diverge on how the ridge builds north over the Beaufort Sea.

Aloft...At 500 hpa...A 521 dam low high in the Siberian Arctic 
will persist with ridging building over the Beaufort Sea Friday 
and Saturday, so westerly to southwesterly flow will persist over 
the Arctic through the weekend. A 554 dam low over the Bering 
Strait will continue to dive to the southeast to be over King 
Salmon by Wednesday afternoon, and continues south into the 
Pacific. A 562 dam low over the northeast Pacific will move 
northeast into British Columbia by Wednesday evening. Ridging from
a 597 dam high over the north Pacific will build north over the 
Chukchi Sea tonight, then rotate southeast Wednesday night with 
the axis extending from Amchitka Island to Nuiqsut by Thursday 
morning, then extending north along 150W. By Friday morning the 
ridge will rotate to lie over the Alaska Peninsula to Lake Iliamna
to Anchorage to Demarcation Point and north over the Beaufort 
Sea. A 553 dam low over the Sea of Ohkotsk will move northeast 
into Siberia, then east of the Chukotsk peninsula by Thursday 
evening, then over St Lawrence Island by Friday evening at 558 dam
with troughing extending from Unimak Island north to St Lawrence 
Island then over 170W. At 850 hpa...No significant change in 
temperatures into Wednesday, then a warming trend over the 
interior that will continue into the weekend. 

Surface...A broad area of low pressure with a 1010 mb low over 
the Upper Yukon Flats, 1010 mb low over Kotzebue Sound, and a 1012
mb low over the southwest mainland this afternoon. A cold front 
lies from Kotzebue to Russian Mission to Togiak this afternoon and
will move southeast to lie from Sleetmute southeast over Kodiak 
island by Wednesday morning. The thermal trough which lies over 
the upper Yukon Flats will slide south to the Upper Tanana Valley 
and north slopes of the Alaska Range by Wednesday morning. A ridge
is continuing to build over the eastern Bering Sea, Chukchi Sea, 
and Arctic Coast with a 1020 mb high over the Gulf of Anadyr, a 
1020 mb high over the Chukchi Sea, and a 1018 mb high over 
MacKenzie Bay. By Thursday morning the ridging will lie from the 
eastern Bering Sea to the Bering Strait to Barrow and east with a 
1021 mb high near St Matthew Island, a 1021 mb high over Barrow, 
and a 1020 mb high north of MacKenzie Bay. Wednesday night a cold 
front will move to the Bering Strait then stall over the area 
Thursday as it decays. The high over Barrow will move east to be 
just north of MacKenzie Bay Thursday morning at 1022 mb. As the 
high moves east the Thermal trough will slide a bit north to lie 
from Northway to Livengood, then southwest to McGrath. 

Arctic Coast and Brooks Range...A weather front moving through 
the area will be east of the area by Wednesday morning. Expect
some clearing skies Wednesday from west to east across the area as
mainly offshore flow develops with the high moving east.
Temperatures will generally be in the mid 40s to mid 50s on the 
coast and 50s to lower 60s inland Wednesday, then rising Thursday
with coastal areas rising into the 50s to lower 60s, and inland 
areas reaching into the 70s. The warmer temperatures will last
into the weekend. Winds turning east to southeast at 5 to 20 mph
for most areas the remainder of the week.

West Coast and Western Interior...cloud to mostly cloudy
conditions will continue over the coastal areas this week with
periods of showers. There will be a little break Wednesday with
some clearing before the next system moves to the eastern Bering 
Sea bringing another round of showers to the area. For the inland 
areas clearing early Thursday will last into Friday, then 
increased clouds and a chance of showers. Temperatures quite a 
bit warmer on Thursday after it clears out, then cooling back down
a bit with the increased cloudiness. Winds northwest at 5 to 15 
mph for most areas, with 20 to 30 mph winds on some of the outer 
Capes. As the next system moves to the Bering Strait Thursday, 
winds will snap around to southeast to south with 10 to 20 mph 
winds over the coast, and 15 to 30 mph winds on the Capes. Winds 
inland will generally be less than 10 mph. Heaviest rainfall has 
ended over the Upper Noatak and Upper Kobuk Basins and streams 
remain high so Advisory will continue into the evening then be 
reevaluated.

Central and Eastern Interior...Isolated to scattered showers
continue across the area through Wednesday afternoon then
clearing. Rainfall amounts generally less than one tenth inch,
some locations in the Alaska Range could see up to one quarter
inch. Isolated thunderstorms south of Chicken this evening, then
over most of the area on Wednesday. Clearing across the Central 
and Eastern Interior Thursday with warming temperatures that will 
last through the weekend. Central interior will see some increased
clouds on Friday with a chance of showers as front pushes over 
the West Coast. Winds will generally be light, but they pick up to
10 to 20 mph along the AlCan Border north of Eagle and over the 
Upper Yukon Flats Wednesday night and Thursday.

&&

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

&&

.Fire Weather...Pretty quiet with isolated to scattered showers 
through Wednesday evening, then a drying trend for all the
interior areas. Isolated Thunderstorms over the eastern and
southeastern interior Wednesday with the thermal trough over the
area, then over the Upper Tanana valley along the north slopes of
the Alaska Range to the Upper Kuskokwim and Middle Yukon south of
Galena Thursday. High pressure building in will bring drier and
warmer conditions to the Central and Eastern Interior, but no Red
Flag conditions expected.

&&

.Hydrology...Heaviest rainfall has ended over the Upper Noatak 
and Upper Kobuk Basins and streams remain high so Advisory will 
continue into the evening then be reevaluated. Significant rises
in the middle Koyukuk River near Bettles with this last rain
event, but everything remains well within banks, so no issues.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Small Craft Advisory for PKZ210-PKZ220-PKZ225.

&&

$$

SDB JUL 17

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