textproduct: Fairbanks

SYNOPSIS

A summer-like pattern will continue over most of Northern Alaska as a ridge builds in from the south and stations itself over the area through the weekend. On the west side of the ridge, scattered showers and isolated storms will be prevalent through this evening from McGrath northward to the Western North Slope. A weak piece of energy from a low in the Pacific will race northward and be the main driver of precipitation chances today. The Eastern North Slope will remain dry due to a surface high north of Kaktovik. Easterly winds along the Eastern Arctic Coast should keep it cooler than the Plains and Chukchi Sea Coast. Otherwise, the Central and Eastern Interior will be baking as highs remain in the 70s/80s through the end of the week. There will be a chance for isolated showers/thunderstorms, especially in the higher terrain Thursday afternoon, but the most prominent time period for some wet weather will be Friday as a weak upper level disturbance provides moisture and enough lift to support showers and thunderstorms across the Interior.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Warm and dry with highs in the 70s/80s today, tomorrow and Saturday. Friday will be a few degrees cooler, especially north of Fairbanks with an increase of clouds and scattered showers.

- From Fairbanks south/east it should remain mostly dry, but there will be a slight chance for a shower Friday morning into the afternoon as a weak disturbance moves overhead.

West Coast and Western Interior... - Warm today with scattered showers and isolated storms, mainly in the Interior today as a weak disturbance moves from south to north.

- Temperatures are warm today with highs in the 60s to near 70 along the coast, and in the mid to upper 70s inland. Tomorrow is a few degrees cooler due to an increase of clouds and showers but highs warm once again Friday through the weekend.

- After the showers/storms today and tomorrow, Friday through the weekend will be much drier with increased sunshine.

North Slope and Brooks Range.. - Warm weather is expected across the Central and Western North Slope with highs in the 60s along the coast, and mid 70s in the Plains. Cooler temperatures from Deadhorse east with highs in the 50s/60s. The Brooks Range will be in the 60s and 70s.

- Scattered showers and thunderstorms expected, particularly in the Western Brooks Range/North Slope today and tomorrow.

- Shower coverage shifts over the eastern North Slope on Friday with a chance for a thunderstorm in the Plains and Brooks Range with drier and warmer weather expected on Saturday.

SHORT TERM

Although we are seeing an increase in ridging, there are quite a bit of moving pieces to this forecast and each one will contribute to different types of weather across Northern Alaska. Getting into the details, we'll look at the general overview of the upper levels. We are beginning to see our overarching pattern take shape over the Interior as a 594 decameter ridge near 30N extended northward through the Arctic Coast. A relatively weak 560 decameter low south of the Alaska Peninsula near 45N is being sheared apart allowing for a shortwave to extend northward in the Western Interior today, then towards the Brooks Range/North Slope tomorrow. Accompanied by this shortwave is a 300mb jet streak, around 50-80kt which will help support some wet weather in Western Alaska today and tomorrow, the Eastern Alaska on Friday as it shifts east.

Otherwise, the main ridge of high pressure will be getting choked in the middle by two areas of lower pressure on each end. This allows for an anomalous +2 sigma high to set up over Northern Alaska by Friday. The high will gradually meander northwest this weekend, then potentially east by next week. But that will be spoken about more in the long range forecast.

Getting into more of the specifics, there was a shortwave mentioned before from a low in the Pacific. This wave of energy will be coming with jet support and 700mb moisture. This energy will be running into an atmosphere capable of producing thunderstorms and will be the forcing mechanism. Isolated to scattered showers and thunderstorms are likely to develop this afternoon in the Western Interior, then gradually shift northward to the Brooks Range this evening. The shortwave will lose some of its punch as it slows and weakens over the Brooks Range tonight. However, it will be over an unstable airmass, so thunderstorms are still likely to occur north of the Yukon River with a bullseye over the Northwestern Brooks Range and Western Arctic Plains Thursday afternoon/evening. Moving into Friday, this energy will be forced southeast by a weak cold front moving into the North Slope, allowing for slightly cooler temperatures across the area. With a degrading moisture source and less instability, a few thunderstorms are possible in the Brooks Range, Central and Eastern Interior Friday afternoon, but most of the area would only see rain showers. This weekend, the ridge builds overhead with very warm temperatures likely.

Getting into temperatures, something being monitored are the 850 mb temperatures which will be well above our normal values across the area. For reference, the median 850 mb temperature for this time of the year is around 5C. As this ridge builds in, we will be seeing temperatures approximately between 10-12C across most of Northern Alaska by Saturday. 850 mb temperatures this warm tend to support surface temperatures in the 70s to low 80s for most valley locations, disregarding cloud cover or any other atmospheric features. Regarding cloud cover however, the ridge will be pretty dry aloft, so there shouldn't be too many clouds except by any pop up shower or storm. So, there will be widespread valley temperatures in the 70s and 80s, even on the North Slope this weekend.

FIRE WEATHER

Conditions will continue to warm today and tomorrow with many valley locations expected to be in the 70s and low 80s, even in the Arctic Plains. A shortwave will drift northward into an unstable atmosphere over Western Alaska today through tomorrow allowing for isolated to scattered thunderstorms from McGrath to the Western Arctic Plain. the bulk of the activity will be north of the Yukon River today, then in the Western Arctic Plain and Brooks Range tomorrow. Isolated thunderstorms are then possible in the Central/Eastern Interior on Friday. Temperatures will cool on Friday, particularly on the North Slope with highs expected to be 5 to 10 degrees cooler, in the 60s and low 70s. Most of Interior will also be approximately 3 to 5 degrees cooler due to an increase in clouds and potential for showers and storms, but only by a couple of degrees. The one exception will be in the Kuskokwim Valley which remains in the upper 70s and low 80s while the remainder of the Interior will be near the mid to upper 70s. This weekend, the ridge builds in overhead allowing for a warming trend over most of Northern Alaska.

Winds will remain fairly weak, but each afternoon there will be variable diurnal wind gusts which may peak around 15 to 20 mph, though they will be occasional and not widespread enough to pinpoint exact locations. Min RHs will be low but mainly remain above critical values with valley locations bottoming out near 30% through the weekend. Isolated 25-30% values are possible in the Tanana/Kuskokwim valleys, particularly this weekend. We will gain more confidence in any critical values over the next couple of days.

HYDROLOGY

No concerns at this time.

LONG RANGE

Throughout the extended period the stagnant high that has remained persistent over Alaska will begin to progressively weaken and be forced north and east by a closed low originating from the Bering Sea that will travel towards the southwest coast of Alaska on Sunday morning. Though there is low confidence, model guidance suggests that by the end of the extended period, Alaska will be divided by ridging along the Brooks Range and Interior and general troughing towards southern portions of Alaska. Cooler temperatures will likely be felt throughout the southwestern portions of Alaska as soon as Monday when the state begins to be divided between Northern ridging and southern troughing, with the cooler conditions lasting through Tuesday. Generally drier conditions will persist at the beginning of the extended period as the ridge lingers through Saturday. As the Bering Sea low approaches the southwest coast on Saturday wetter weather and thunderstorm potential increases throughout the YK-Delta with chances for scattered thunderstorms Saturday evening and isolated storms in the Interior through Tuesday. Relatively calm winds are expected throughout the extended time frame with the exception of the Alaska Range Sunday to Tuesday, as the Bering Sea Low increases the likelihood of both Isabel and Windy Pass experiencing higher wind gusts throughout the end of this period, although the peak strength and timing of these wind speeds are still not certain.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Heat Advisory for AKZ816. Heat Advisory for AKZ806-808. PK...None.