Severe Thunderstorm Warning 4, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
250 PM AKDT Thu Jun 19 2025

.SYNOPSIS...High pressure as part of an omega block pattern
remains over Interior Alaska with numerous shortwave troughs
rotating through the flow bringing thunderstorms mainly in the
afternoon and evening hours across northern Alaska. Warm
temperatures also persist. The pattern will be slow to change with
just slight cooling expected over the weekend before an influx of
moisture brings heavier showers and more thunderstorms early next
week.

&&

.KEY WEATHER MESSAGES...
Central and Eastern Interior...
- Highs mainly in the 80s are expected to continue through Sunday

- Widely scattered thunderstorms are occurring Thursday afternoon
  and will continue through Thursday evening mainly between the
  Tanana and Yukon Rivers with more isolated storms near the
  Alaska Range

- These storms will be extremely slow to move with wetting rains
  expected beneath them. A shortwave moving through the flow
  Thursday night will likely re-enhance shower and thunderstorm
  activity around 10pm that will persist through the early morning
  hours of Friday.

- On Friday, thunderstorms will become scattered in the White
  Mountains and high terrain north of Fairbanks. Red Flag Warnings
  for lightning and dry fuels have been issued from 4pm until
  midnight.

- Thunderstorms move to mostly the Eastern Interior this weekend
  and become more isolated as temperatures cool slightly.

West Coast and Western Interior...
- Widely scattered thunderstorms across the Nulato Hills and east
  along the Yukon River and south to McGrath Thursday evening and
  overnight into the early hours of Friday morning.

- Thunderstorms become more isolated on Friday and Saturday and
  are not expected Sunday as southerly flow increases over the
  area.

- A weak front moving through the area on Friday night may cause
  thunderstorms to persist through the night across the Nulato
  Hills and Seward Peninsula.

- Friday will be the warmest day with highs in the 70s and 80s
  before cooling over the weekend.

North Slope and Brooks Range..
- Isolated storms are expected every afternoon through the end of
  the week, then the risk moves east to the Eastern Arctic Coast
  and Brooks Range this weekend, with widely scattered
  thunderstorms expected Saturday over the Brooks Range
	- Any storm can come with frequent lightning, briefly heavy rain
   and gusty winds.

- Temperatures remain warm through the weekend and into next week.

&&

.FORECAST ANALYSIS AND DISCUSSION...A slow moving omega block
pattern remains in place with the high centered over the central
interior and lows aloft near Haida Gwaii and the Western Aleutians
respectively. Numerous shortwaves wrapping around the high will
continue to spark thunderstorms over the next few days. The most
defined shortwave today will move from southeast to northwest over
the area from Minchumina to Delta Junction to the Yukon River and
this will be where the focus of thunderstorm activity will be
today, though the late timing of the shortwaves may causes the
thunderstorms to become showers. With PWATs near record values for
the date and steering flow/storm motion vectors indicating slow or
stationary storms, expect these thunderstorms to produce very
heavy rain where they do form.

On Friday, the omega block shifts slightly east, bringing
southerly flow over the central Interior and southeast flow over
the west. A shortwave on Friday night may cause storms to persist
all night across the Nulato Hills and Seward Peninsula. On
Saturday, south flow pushing north to the Brooks Range will make
that area the focal point for thunderstorms before the low in the
Aleutians shifts east to Bristol Bay Sunday, bringing cooler
temperatures and more stability.

&&

.FIRE WEATHER...A Red Flag Warning for abundant lightning and dry
fuels is in effect from 4pm Friday until midnight on Friday night for
the Chatanika River Valley and the White Mountains. Thunderstorm
activity is expected to continue overnight Thursday into Friday
across much of the Interior before becoming showers overnight into
Friday. Thunderstorms Thursday into early Friday will be
extremely slow moving and wetting rain is expected beneath any
thunderstorm. Upper levels of the atmosphere begin to slowly dry
out on Friday, and along with faster storm motion, CWRs will be
lower beneath thunderstorms. However, thunderstorms will
definitely not be dry. There will still be very little wind to
speak of beneath the high aside from thunderstorm outflow winds,
and min RHs will slowly moderate except across the Tanana Valley
on Saturday due to Chinook flow. High temperatures will be mostly
in the 80s through Sunday before cooling next week.

&&

.HYDROLOGY...Flooding continues on the North Slope for the Colville, Kuparuk
and Sag Rivers. We are observing water levels dropping for all the
rivers as snowmelt ceases. We expect most of the significant
flooding to be ending later this week or over the weekend. The
active warnings and advisories can be found on our website for the
latest details.

&&

.EXTENDED FORECAST DAYS 4-7...Confidence is increasing that a low
will move east from the Aleutians to undercut the ridge of high
pressure over the Yukon early next week. This will bring
increasing showers and moisture across the area and likely
thunderstorms as well. Temperatures will cool to closer to
seasonable, though will likely remain above normal through early
next week especially in the Interior and North Slope.

Coastal Hazard Potential Days 3 and 4...None

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Red Flag Warning for AKZ934-942.
PK...Brisk Wind Advisory for PKZ814-860.
     Brisk Wind Advisory for PKZ815-861.
&&

Chriest

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