Scientific Forecaster Discussion
000 FXAK69 PAFG 241251 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 451 AM AKDT Mon Apr 24 2017 .SYNOPSIS... Aloft... A ridge over Northern Alaska will weaken slowly through Wed then strengthen slowly in the second half of the week. Temperatures will remain above normal over the area south of the Brooks Range, while the North Slope will remain below normal through at least mid-week. Interior Alaska will see a general increase in clouds through mid-week but remain generally dry while the West Coast has increasing chances of precipitation through mid-week. A short wave trough in the Gulf of Alaska will move north over the Alaska Range Mon night, to Bethel to Eagle by 4pm Tue, and to the Bering Strait to Circle by 4pm Wed. Will see moisture increase ahead of this trough with a chance of precipitation along with the trough. Will see weak downslope winds along the Alaska Range following the trough Tue. A second short wave trough in the high Arctic will move south along the Arctic Coast of Alaska Tue night and along the Brooks Range Wed. Expect this to continue feed of low level clouds, flurries and fog into the North Slope with clearing behind this trough. Surface... A cold front stretching from 300 nm north of Barter Island to Barrow to Cape Lisburne will move to Demarcation Point to Cape Lisburne by 4pm Mon...then along the Brooks Range by 4am Tue and then persist into Wed. A large area of stratus along with fog and flurries is visible on Satellite extending north to 80N. Expect the stratus along with fog and flurries to push south over the North Slope with the front and persist into Wed. Will see some clearing Wed from the north with the trough aloft mentioned above. Patchy low fog currently along the Arctic Coast will thin by afternoon as the stratus lay mentioned above moves over the surface fog. A 1028 mb high over the Chukchi Sea north of the front will build southeast over the Chukchi Sea today and persist into Wed. This will cause north winds along the capes of the West Coast and through Brooks Range passes to persist through Wed. An Arctic front stretching from Savoonga to Nome to Indian Mountain to Circle will persist through Wed. Expect any precipitation to fall as snow north of this front and mixed along and south of the front...with mainly liquid further south of the front. A weak lee side trough over the Tanana Valley will persist through Tue. This will cause gap flow winds through Alaska Range passes through Tue...with some increase Tue as the trough aloft passes north and enhances the lee side trough. && .DISCUSSION... Models initialize 10 to 20 dm too weak with heights in the high aloft over Northern Alaska. Expect this to cause high aloft to weaken slower than models indicate. Models agree on large scale pattern of ridge weakening slowly through Wed then rebuilding slowly through next weekend. The GFS again over does precipitation in the eastern Interior for the first several days. With weak downslope flow through Tue the precipitation in the eastern Interior will remain nil today with just isolated showers from Tue into Wed along the arctic frontal boundary. GFS and ECMF precipitation more similar over the West Coast and a mix of them seems reasonable. && .FIRE WEATHER... Today will be slightly higher rh than Sun...then increasing gradually through Wed as clouds increase. Highs will be in the 50s south of the arctic front with lows in the 20s and 30s. Alaska Range passes will see gusts to 30 mph through Tue. Could see gusts spread north to Delta Junction on Tue with near red flag conditions, but expect rh higher than 25% on Tue in the gusty areas. && .AFG WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory for PKZ210. Brisk Wind Advisory for PKZ220-PKZ225.