Scientific Forecaster Discussion
Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
1259 PM akdt Tuesday Jul 28 2015
Models initialized well and verified well against the 12z
analysis. Model spread is minimal both in the short range as well
as the medium range. Even the long range models are in reasonable
agreement in building a long wave ridge over the eastern Bering
Sea and western Alaska by and a long wave trough over eastern
Alaska next week.
One the North Slope a 1024 mb high pressure system north of
Siberia continue to produce extensive low ceilings and areas of
fog with onshore flow. Chilly airmass pushing onshore but expected
to remain north of the Brooks range with a rain snow mix noted
last several hours in Barrow.
Areas of low ceilings and fog continue over the immediate West
Coast areas where northwest flow is onshore. Middle level ceilings
noted in inland areas and where northwest flow is offshore . Only
precipitation expected along the West Coast is in the northern
Nulato Hills as the western end of the thermal trough extends into
the eastern Seward Peninsula. Scattered showers and isolated
thunderstorms are expected in these areas.
The thermal trough mentioned above stretches from the eastern
Seward Peninsula east to near Bettles and then northeast to near
Old Crow in the Yukon. A moist and unstable airmass sits over the
interior to the south of the trough with McGrath 12z sounding
again showing over three quarters of an inch in precipitable water
and the Fairbanks sounding showing over nine tenths of an inch. A
broad area of minus lifted indices as well as cape levels in the
300 to 500 joules range combined with weak winds aloft will
trigger slow moving thunderstorms with the potential to drop heavy
rain and produce gusty winds and small hail. Locally heavy precipitation
will again be possible this afternoon and tonight. Little Chena
Ridge to the northeast of Fairbanks picked up nearly 2 and one
half inches of rain overnight with stalled out thunderstorms.
Continue to monitor local drainages for rapid rises on small
streams and rivers as more and more local areas become saturated.
Coastal hazard potential days 3 and 4...none
Fire weather...cooler...fairly wet regime will persist over the
southeast interior through Wednesday...then a drying trend with
warmer conditions for the weekend. Afternoon thunderstorms and
showers east of Tanana in the interior...with some scattered
showers and thunderstorms in the middle Yukon and upper Kuskokwim
valleys tonight and tomorrow. The driest area will be the
northwest inland areas over the Kobuk and Noatak valleys. Most
areas will remain above 30 percent today and tomorrow with
generally light winds and excellent overnight recovery.
slow moving thunderstorms and showers will continue to drop
locally heavy rainfall this afternoon and tonight as well as
Wednesday afternoon and evening. Continue to monitor potential
for heavy precipitation falling on recent burn scars and steeper terrain.
Small Craft Advisory for pkz220.
Ccc Jul 15