000
FXAK69 PAFG 112258
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
258 PM AKDT Tue Aug 11 2020

.SYNOPSIS...
A low aloft near Eagle Summit will weaken slowly through Thu. This
is causing showers over much of the Interior N and E of Fairbanks
that will become fewer in areal coverage Wed and Thu. The heavy
rain associated with this feature has tapered off, though there
will be localized brief heavy showers in thunderstorms through
Wed. This feature dropped over 1 inch of rain Sun and Mon from
Circle south to Gold King and east to Tanacross, with over 2
inches of rain along the north side of the Alaska Range Between
the Delta River and Robertson River. Mountainous areas could have
had as much as 4 or 5 inches. We will continue flood watches
through Wed morning for Delta Junction to Black Rapids and Delta
Junction to Tanacross to account for longer run creeks and rivers
which have not drained down to their mouths yet.

A second low aloft over the southwest Interior will move over the
Western Alaska range tonight, and just south of the Eastern Alaska
Range on Wed. Scattered showers and Isolated PM thunderstorms
associated with this low aloft now over the SW Interior will move
over the Wrn AK range tonight and over the Ern AK range on Wed.

High pressure aloft build over Wrn Alaska on Wed will build over
all but the SE Interior on Thu and over all of the Interior on
Fri, then persist through Sun. This will result in a warming and
drying trend over Nrn AK Wed through Tu, with temp well above
normal Thu into the weekend.


Surface...
An occluded front that lies from Cordova to Old Crow will
weaken in place through Wed. Showers occuring along this feature
will become scattered on Wed. Isolated thunderstorms will occur
near this feature today and Wed.

A thermal low pressure trough that lies from Old Crow to
Anaktuvuk Pass will persist through Wed, then move to Chicken to
Atigun Pass on Thu then diminish. Scattered showers and isolated
thunderstorms will occur along this feature each PM, then become
isolated showers each AM.

An occluded front in the Chukchi Sea will move to just east of
Utqiagvik to Point Hope then west by 4am Wed, then to Nuiqsut to
POint Lay west by 4pm Wed, then to Barter Island to Utqiagvik and
west as a warm front by 4am Thu, then to Barter Island northwest
by 4pm Thu, to Demarcation Point NW by 4am Fri, then move east of
the Alcan Border and weaken by 4pm Fri. Rain and SW winds 10-20 kt
will spread east along the Arctic Coast with the front tonight and
Wed. The exception  will be SW winds g40 mph near Cape Lisburne
now that will decrease tonight. A chance of rain will spread back
across the Arctic Coast with the warm front on Wed night and Thu.
Could see highs in the 60s along the Arctic Coast on Thu and Fri.
This front will cause stratus and fog through Wed along the
Arctic Coast.

High pressure over the Nrn Bering Sea will persist into Fri, and
possibly into the weekend. This will cause onshore flow most of
the West Coast through Fri, with the onshore flow causing periods
of stratus and fog along the West Coast through Fri.

&&

.DISCUSSION...
At 12Z models initialize about 100M too low on h500 heights over
the Interior, otherwise look good. This indicates that conditions
will be slightly more stable with slightly less rain today and
tonight. Models show similar solutions aloft through 4pm Wed.
After that time the GFS and NAM move a low north of Wrangel Is
east or keep it in place, while the ECMF and Canadian both
retrograde this low. The ECMF and Canadian also build the ridge
aloft over Nrn AK more quickly than the GFS and NAM as a result.
At this time favor the ECMF and Canadian solution of the ridge
building over Nrn Ak Thu and Fri while keeping the low aloft west
of Wrangel Is, and persisting into the weekend.

At the surface at 15Z models all verify well. Models show similar
solutions through 4pm Wed, then the ECMF keeps the surface low
near Wrangel Is much further west than the NAM, and further west
than the GFS. Keeping with the solutions aloft, we will use the
ECMF for the surface pattern after 4pm Wed. So we will use a blend
of the NAM. GFS and ECMF through 4pm Wed for surface winds and
temps, then use the ECMF for Wed night into Fri. This will have
lower wind speed along the Arctic Coast of AK Wed night into Fri.

For precip. models show similar areal coverage through 4pm Wed,
but differ on amounts. Nam amounts seem a bit high. Prefer to use
a blend of the NAM/GFS and ECMF for areal coverage and amounts,
which will lessen the higher amounts shown by the NAM alone. After
4am Wed, prefer the ECMF precip due to its preference aloft and at
the surface reflecting the ridge aloft building in more quickly.

Bottom line is we will use a blend of the NAM/GFS and ECMF
through 4pm Wed for all fields, then use the ECMF for temps,
winds, precip and clouds for Wed night into Fri.


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

&&

.FIRE WEATHER...
A low aloft over the southwest Interior will move over the
Western Alaska Range tonight, and just south of the Eastern
Alaska Range on Wed. Scattered showers and Isolated PM
thunderstorms associated with this low aloft now over the SW
Interior will move over the Wrn AK range tonight and over the Ern
AK range on Wed.

A low aloft near Circle will weaken slowly through Thu. This is
causing showers and Isolated thunderstorms over much of the
Interior N and E of Fairbanks that will become fewer in areal
coverage Wed and Thu.

High pressure aloft build over Wrn Alaska on Wed will build over
all but the SE Interior on Thu, and over all of the Interior on
Fri, then persist through Sun. This will result in a warming and
drying trend over Nrn AK Wed through Thu, with temp well above
normal and RH below normal Thu into the weekend.

&&

.HYDROLOGY...
The heavy rain over the SE INterior has tapered off, though there
will be localized brief heavy showers in thunderstorms through
Wed. Over 1 inch of rain fell Sun and Mon from Circle south to
Gold King and east to Tanacross, with over 2 inches of rain along
the north side of the Alaska Range between the Delta River and
Robertson River. North Facing slope of the Alaska Range could
have had as much as 4 or 5 inches. We will continue flood watches
for potential flooding through Wed morning for rivers and creeks
draining the Alaska Range from Delta Junction to Black Rapids and
Delta Junction to Tanacross to account for longer run creeks and
rivers which have not drained down to their mouths yet. High water
is expected on the Charley River, the Goodpaster River, the
Salcha River, the Fortymile River the Tanana River and Birch
Creek, but flooding is not expected on these rivers.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Flood Watch for AKZ223-AKZ224-AKZ226.

Small Craft Advisory for PKZ225-PKZ230.

&&

$$

JB AUG 20