Scientific Forecaster Discussion
fxak69 pafg 261308
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
508 am akdt Mon Jun 26 2017
the 26/00z 500 mb analysis shows large 500 dm low located in the
high Arctic centered near 83n 158.5w. A short wave trough was
dropping south around this low, with the axis at 00z positioned
over eastern Siberia. A second upper low at 535 dm was located
over the western Bering around 275 miles northwest of Adak. Lastly
a 552 dm low was located in the far eastern Gulf around 110 miles
southeast of Sitka. Ridging was seen between the latter two upper
lows with the axis centered over the central Gulf through central
Alaska. A short wave continues to round the crest of this ridge
with the axis stretching from Nenana to Nuiqsut.
At the surface, a 981 mb low was centered just off the North Pole
near 86.5n 167e. The weak Arctic front stretches from the
chukotsk peninsula eastward toward Barrow, then bends
northeastward toward the Canadian archipelago. Weak high pressure
was seen over Mainland AK, with a weak 1014 mb center located
around 45 miles north of Kaktovik. A 994 mb low was seen over the
Bering around 335 miles west southwest of St Matthew island. An
expansive area of high pressure at 1032 mb was observed over the
North Pacific, located around 43.8n 147.8w.
Models for the 26/00z run remain in fair to good agreement
through the upcoming week. The upper low in the high Arctic will
continue to drift northward to pass just south of the pole on the
Canadian side by Tuesday morning. The short wave rounding this
low, presently over eastern Siberia, will merge with the upper low
in the western Bering to form elongated troughing from the Bering
Sea to the siberian Arctic, which looks to persist through the
upcoming week. This will, in turn, amplify the downstream ridge
over western Canada, promoting deep southerly flow over the entire
state by late Tuesday night. The short wave over northeast
Alaska/eastern Brooks range is expected to cut itself off from the
larger low over the high Arctic and drift southeast toward the
eastern interior today, before drifting into the northern Yukon
At the surface, 984 mb low over the high Arctic will drift off to
the east over the Canadian high Arctic today, as high pressure
expands over the central and eastern Beaufort Sea and lingers for
the remainder of the week. The 994 mb low 335 miles west
southwest of St Matthew island looks to remain nearly stationary
through Tuesday night, before subtly wobbling north to merge with
low pressure over east Siberia late Wednesday to form broad
surface troughing over the chukchi and Bering seas westward into
eastern Siberia. Thermal troughing will develop over the interior
again on Tuesday, and will shift over the Brooks range and North
Slope for Wednesday.
North slope: the residual Arctic front will bring showers to the
western Beaufort and Chukchi Sea, including Point Hope today
before the front shifts to the north. Easterly surface flow will
resume today and persist for the remainder of the week as high
pressure builds to the north of the Arctic coast. Periods of fog
is expected with this east flow. A return to a showery regime is
expected by Wednesday/Thursday as pieces of upper level energy
eject northward from cyclonic flow over the Bering Sea.
West coast: a short wave and associated surface front will
continue to lift northward from the low in the western Bering
today, bringing periods rain to St Lawrence Island today with
mainly showers for Norton Sound and yk Delta through this evening.
Chances of rain will persist through this week as disturbances
rotate around the Bering Sea trough. Southeast winds will
remain at Small Craft Advisory levels from Dall Point to whales
with the passage of the weather front, subsiding this evening.
Temperatures will range from the the 50s and lower 60s over the
next several days for most coastal locations.
Interior: upper ridge of high pressure will bring fair weather to
most of the interior today. Short wave trough in the eastern
Brooks range will drop into the east interior today, focusing
afternoon/evening convection along and southeast of a line from
Chalkyitsik to North Pole. Thermal troughing looks to resume for
the interior Tuesday with a chance of showers for most of the
interior along with isolated thunderstorms for zones 217, 218
219, 220 and 224. The focus for convection will shift further
north into the Brooks range for Wednesday afternoon and evening.
Chances of rain will persist through the week for the west
interior mid to late week as weak disturbances rotate northward
from the broad upper low in the Bering Sea. The deep southerly
flow regime developing will promote periods of gap winds through
Alaska Range passes from today through this week.
Coastal hazard potential days 3 and 4...none.
Fire weather...overall slightly warmer and drier conditons are
expected today for the interior as upper level ridge aloft moves
into the area. Convection looks to remain limited to the east
interior and eastern Alaska Range. Thermal troughing looks to
redevelop for the interior Tuesday with isolated afternoon/evening
thunderstorms for zones 217, 218 219, 220 and 224, with the threat
of convection shifting north into the Brooks range for Wednesday.
Chances of rain and higher humidity is expected from Tuesday
through the rest of this week for the west interior as weak
disturbances rotate northward from the broad upper low in the
Bering Sea. Dry weather looks to persist for the Yukon Flats and
southeastern Brooks range with min relative humidity values between 25 to 35
percent through this week.
Hydrology...local streams and rivers that drain from the eastern
Alaska Range will continue to fall today, although the Tanana and
fortymile rivers are now seeing rises from recent heavy rains last
weekend. These rivers in the east interior are expected to crest
today and tonight, and the fortymile will have to be watched today
and tonight as there is the potential for the river to reach
Small Craft Advisory for pkz210.