Area Forecast Discussion
Issued by NWS Fairbanks, AK

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

000
FXAK69 PAFG 222154
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
154 PM AKDT Sun Jul 22 2018

.DISCUSSION...

Synopsis...
A slow synoptic pattern is expected for the next several days with
persistent ridging over eastern AK facilitating warm temperatures
for much of the central and eastern Interior through mid week.
Record or near-record highs will be possible this afternoon and
tomorrow. Isolated showers and thunderstorms are expected across
much of the western interior as well as the Brooks Range and
eastern North Slope thanks to the presence of low pressure over
the southern Bering and Northern Arctic.

Aloft 500 mb...
Strong ridging exists over the eastern half of the state with the
axis extending northwestward from Haines across the ALCAN border
near Eagle to Barter Island and well into the northern Arctic. A
secondary branch of the main axis will extend westward across the
Tanana Valley to the Koyukuk Valley and Seward Peninsula as the
high exploits a weakness in the longwave trough over the Bering
Sea. 500 mb heights up to 584 dam will be observed over the far
southeastern interior with heights up to 580 dam extending north
of Fort Yukon and west of Fairbanks. Heights up to 576 dam will
reach well north of Barter Island, resulting the potential for
widespread record or near-record high temperatures for much of
eastern AK. The ridge axis continues to track slowly eastward in
advance of a 558 dam low over the southern Bering which is
expected to cross the Aleutians near Cold Bay into the Gulf of
Alaska by late Monday. However, warm temperatures will persist
across the eastern Interior into the mid week due to the
persistence of the western branch of the ridge axis as the low
tracks eastward across the Gulf. Additionally, a 518 dam Arctic
low north of Wrangel Island will track northeastward, crossing
80N this evening and reaching the far northern Canadian Arctic by
Tuesday.

North Slope...
A strong cold front extending southwestward from a 984 mb low in
the northern Arctic will graze the North Slope as it tracks slowly
east. The front will impact the Chukchi coast from Point Lay to
Barrow early Monday and sweep quickly eastward through Tuesday.
Warm temperatures today ahead of the front will be supported by
strong ridging and mainly offshore flow, resulting in modest
instability across much of the North Slope. Isolated thunderstorms
will be possible through this evening for areas south and east of
Nuiqsut, becoming more likely tomorrow across the central and
eastern Brooks Range as frontal forcing, terrain uplift, and warm
temperatures combine to enhance convection. Rainfall amounts could
be locally heavy Monday, specifically across the central Brooks
Range where widespread amounts of 0.25 to 0.5 inches are likely
along with the potential for higher amounts in locally heavy
downpours. Weak surface high pressure trailing in the wake of the
front will bring onshore winds and cooler temperatures tomorrow
along the immediate coastline. A second Arctic low will follow a
similar path, with a cold front expected to reach the Chukchi
coast late Tuesday.

West Coast and Western Interior...
Low pressure tracking southeast across the southern Bering will
send moisture northward, bringing cloudy, showery conditions along
the coastline from the Y-K Delta to the Bering Strait. Sufficient
moisture will reach the western Interior to support isolated
shower and thunderstorm activity from the Yukon Valley to the
western Brooks Range. Conditions will remain fairly similar
Monday, though temperatures will assume a slow downward trend
through mid week as the pattern progresses eastward.

Central and Eastern interior...
Near-record to record high temperatures are expected this afternoon
as well as Monday afternoon thanks to strong, persistent high
pressure. Clear skies can be expected east of Tanana with a small
chance of showers for areas farther west. Thermal troughing over
the Tanana Valley will enhance southerly gap flow through the
Alaska Range, resulting in windy, drying conditions around the
Delta Junction area southward to Isabel Pass. Therefore, Red Flag
warnings have been issued for the eastern Alaska Range and Tanana
Valley near Delta Junction beginning Monday afternoon through
Tuesday. The thermal trough will progress northward to the Yukon
Flats Monday, with the potential for even warmer temperatures for
this area tomorrow afternoon. Slow progression of the synoptic
pattern will bring gradually cooler temperatures and chances for
showers and thunderstorms eastward by the mid week, but persistent
ridging over the eastern interior will make this a slow process.


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

&&

.FIRE WEATHER...
Thermal troughing across the Tanana Valley will amplify gap flow
through the Alaska Range, resulting in warm, dry, windy
conditions near the Delta Junction area. Relative humidity will
remain marginal today, though continued drying with poor overnight
recovery will result in red flag conditions tomorrow afternoon
and Tuesday along the eastern Alaska Range. We will continue to
evaluate conditions as necessary considering the slow moving
nature of the overall pattern. Similar conditions will persist
largely unchanged through the mid week with relative humidity
dipping to the mid 20 percent range across much of the eastern
interior from the Alaska Highway northward into the Yukon Flats.
The limiting factor will be winds, as strong ridging will keep
winds light for most areas.

&&

.HYDROLOGY...
Most rivers slowly falling or steady, but with very
warm temperatures and high freezing levels across the area,
glacially feed rivers, Nabesna River near Northway and Tanana
River near Tetlin, and streams have already started to rise.
Additionally, locally heavy rainfall across the central Brooks
Range is possible Monday. No significant impacts are expected,
elevated water levels in streams are possible. For the latest
information go to www.weather.gov/aprfc.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning for AKZ223-AKZ226.

Small Craft Advisory for PKZ225-PKZ230-PKZ235.
&&

$$

COWMAN JUL 18


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.