textproduct: Fairbanks

KEY MESSAGES

Central and Eastern Interior...

- Scattered rain showers will continue across the Interior as a cold front begins to build in out of the west. Isolated thunderstorms will be also be possible in the Eastern Alaska Range northeast across the Middle/Upper Tanana Valley and Fortymile Country through this evening.

- Behind and along the cold front, winds will ramp up out of the west as drier conditions build in. Wind gusts for most will peak Wednesday with gusts up to around 30 to 40 mph. Wind Advisories remain in effect tonight into Wednesday.

- Temperatures will trend cooler today into Wednesday associated with the front, with highs in the 50s/60s and lows mostly in the 50s, with a warming trend expected Thursday into Friday with southerly flow increasing.

- A strong low will track northeast from the Western Bering Sea through Siberia towards the Chukchi Sea Wednesday into Thursday and Friday, ejecting a warm front into the Interior Thursday followed by atmospheric river moisture Friday into Saturday.

- This system will support widespread rain and breezy winds regionwide, with rainfall amounts through Saturday west of and including FNSB around 0.50 to 1.50 inches and along the Central Alcan Border near Eagle. Lighter totals are expected across the Yukon Flats and Upper Tanana Valley given downsloping flow.

West Coast and Western Interior...

- Rain showers will continue across Western Alaska today, culminating with a cold frontal passage tonight into Wednesday with wind gusts around 25 to 35 mph.

- A strong low will track northeast from the Western Bering Sea through Siberia towards the Chukchi Sea Wednesday into Thursday and Friday, ejecting a warm front into Western Alaska late Wednesday into Thursday followed by atmospheric river moisture Friday into Saturday.

- This system will bring widespread rain, gusty winds, and onshore flow, with high surf and minor coastal erosion expected.

- High Surf Advisories have been expanded to include all of the coastline from the Yukon Delta to Kivalina for water level rises around 2 to 4 feet above the normal highest high tide line. High Wind Warnings have also been issued for St. Lawrence Island and the Bering Strait for wind gusts up to 65 mph.

- Coastal impacts will continue to be monitored, with the potential for upgrades for some zones from High Surf Advisories to Coastal Flood Advisories dependent on the latest forecast trends.

- Storm total rainfall amounts will be around 0.50 to 1.50 inches regionwide, locally higher in the Southern Seward Peninsula, NW Arctic Coast, Western Brooks Range, and Kobuk/Noatak/Wulik River Valleys around 1.50 to 2.50 inches.

- Temperatures will hold steady this week with southwest flow, with highs in the 40s/50s to low 60s and lows mostly in the 40s.

North Slope and Brooks Range...

- A front lifting northeast will bring isolated to scattered rain showers to the Brooks Range and NW Arctic Coast, with that front then tracking east Tuesday into Wednesday with more scattered to widespread rain chances with a rain/snow mix across higher elevations of the Brooks Range.

- A strong low will track northeast from the Western Bering Sea through Siberia towards the Chukchi Sea Wednesday into Thursday and Friday, ejecting a warm front into Western Alaska late Wednesday into Thursday followed by atmospheric river moisture Friday into Saturday.

- This system will bring widespread rain, gusty winds, and onshore flow to Western/NW Arctic Coast, where high surf and minor coastal erosion is expected.

- Storm total rainfall amounts are expected to be around 0.50 to 1.50 inches regionwide, with higher totals in the Western Brooks Range around 1.50 to 2.50 inches.

- High Surf Advisories have been issued for the Western/NW Arctic Coasts from Point Hope to Wainwright for water level rises around 3 to 5 feet above the normal highest high tide line. High Wind Warnings have also been issued for Point Hope to Point Lay for wind gusts up to 65 mph.

- Temperatures will see warming trend through Friday, with highs climbing to the 40s/50s to low 60s and lows in the 30s/40s, colder across higher elevations of the Brooks Range.

SYNOPSIS

This is the work PIL for AFD Synopsis.

SHORT TERM

Today through Friday. Not much change has been made to the overall forecast. A quick look at satellite imagery shows much of the state covered with mid to low level clouds and scattered showers. This is associated with a 544 decameter upper level low that has set up over Bristol Bay. This continues to provide much of Northern Alaska with southerly flow aloft, allowing for the continuous influx of moisture and shortwaves. The southerly flow continues to provide the Alaska Range passes with gusty southerly winds and is expected to continue throughout Tuesday morning. The rest of the day will consist of this upper level low progressing eastward across the Alaska Peninsula, and into the northern portion of the Gulf of Alaska. This will continue to provide isolated showers across portions of Northern Alaska. As the shortwave moves into the northern Gulf, 850mb and 925mb temperatures are showing a slight cooling trend as cooler air moves in from the NW. This will help to slightly amplify the trough, setting up west to northwesterly flow across Northern Alaska as the trough axis moves across the Alaska Panhandle.

Starting early Wednesday morning, this northwesterly setup will allow for a shortwave to move E-SE from the Chukchi to the southern portions of the Yukon Flats. Previous model runs were showing a good amount of disagreement with the trajectory of how far south the trough will be able to push as it shifts east. The latest runs show that models are trending toward the ECMWF, which was expected based on the discussion from the previous morning. A weak cold front is expected to progress W to E across as part of this trough. This will allow for isolated showers to continue across the North Slope and most of the Central/Eastern Interior. As the front moves across the state Tuesday night into Wednesday, a 30-40kt westerly, low-level jet is expected to form across much of the Interior. This will provide much of this area with increased wind gusts through Thursday morning. The strongest winds across the Interior are expected to be at the higher elevations, along with any valleys that are not sheltered by terrain to their west. A series of wind advisories are in effect across the Interior through Wednesday night.

Meanwhile, a 980mb low will be moving NE from the Western Bering into Siberia Wednesday night with an upper-level ridge building up over the Bering Sea. This building ridge will set up the potential for a 1040mb high to set up in the north Pacific and play a major role for the remainder of the forecast period. An associated warm front will extend to the SE from the low over Siberia, moving NE across the West Coast Wednesday night into Thursday. The low over Siberia and the high in the north Pacific will set up a period for prolonged south to southwesterly flow across the Bering Sea and West Coast. Integrated Vapor Transport outputs from several models are showing the potential for this system to tap into an atmospheric river stretching as far southwest as Japan. This will provide much of the West Coast a chance to see heavy rainfall through the end of the week, with storm totals as high as 1.5" to 2" in some locations. With the southwesterly flow, the most favorable positions for the heaviest precipitation will be on the south side of higher terrain. These areas include the southern Seward Peninsula and areas south of the Western Brooks Range. The prolonged period of strong, southwesterly winds will also provide a chance for coastal concerns across the West Coast. More on this will be discussed in the Coastal Hazard section.

By Thursday, the ridge from the Bering will continue to shift east across the state as the low from Siberia shifts NE out of Siberia and into the Chukchi. By this point, the strongest gusts across the West Coast will shift through the Bering Strait and the NW Arctic Coast. The strength of this ridge will play a role as too how much precipitation will fall across the southern portions of the Interior. The latest guidance is showing the potential for a decent amount through the start of the weekend.

Main updates today on the day shift centered around upgrading the High Wind Watches to High Wind Warnings for St. Lawrence Island northeast through the Bering Strait to the NW Arctic Coast, and including the Yukon Delta and Interior Norton Sound to High Surf Advisories. Impacts remain on track, with the continual monitoring of latest coastal conditions expected. Here is where we could see the potential upgrades for some coastal zones to Coastal Flood Advisories dependent on latest forecast guidance. The wind forecast and storm track remains in good agreement.

LONG TERM

Saturday through next Tuesday. The extended period begins on Saturday with an arctic low oriented over the Chukchi Sea, and a powerful sustained ridge over Alaska. This arctic low is accompanied with an atmospheric river, and will continue developing as it progresses east through North Alaska throughout Saturday. As this system moves, it will force the sustained ridge east out of Alaska. As this pattern continuously shifts throughout Saturday, the pressure gradient that was initially set up between these systems will weaken, but remain elevated through Sunday.

Total rainfall amounts from this system vary depending on location. The heaviest rainfall amounts are localized to areas of higher terrain, specifically the western portion of the Brooks Range, western Alaska Range, and the Kigluaik Mountains, with possibilities of totals between 1.5" to 2.5". Along the West Coast rainfall amounts will likely be more mild, ranging between 0.5" to 1.2" in most areas. Within the Interior rainfall totals will likely range between 0.5" to an 1" with locally higher amounts possible throughout this upcoming weekend.

The arctic low will fully move out of Northern Alaska by Sunday morning which allows a ridge to begin to situate itself over the Bering Sea by Sunday afternoon. This ridge will then track east over Alaska as a new low pressure system moves north into the Bering Sea Monday morning. There is reasonable disagreement between models on how these systems will orient themselves coming to the beginning of the next week, and impacts will be dependent on this orientation.

If the ECMWF ensemble is correct, there is a strong likelihood for the low pressure system to move north through the Bering Strait and possibly approach Alaska through the Norton Sound on Tuesday. This pattern could bring moderate to heavy precipitation and gusty winds for the West Coast, as well as some potential hydrologic impacts. However, if the GFS ensemble holds true, then the low will likely get wrapped up into another systems flow and be directed away from Alaska. In this solution impacts would remain minimal as the system trends away from our area. This pattern will continue to be monitored, until the track has more confidence between model solutions.

COASTAL HAZARD POTENTIAL

A developing Siberian low will move northeast towards the Chukchi Sea setting up southwesterly flow across the West Coast. This low will bring gale force winds into Norton Sound and Kotzebue Sound. With these strong winds and long fetch of the winds we will see water rises across the West Coast. For much of the coastline we could see rises of 2 to 5 feet with the highest rises from Elim to Unalakleet. These 2 to 5 feet rises across the West Coast has led us to issue High Surf Advisories across the Coastline from Hooper Bay to Point Lay. While no flooding is expected, localized beach erosion may occur.

With the strong southwesterly winds continuing for roughly 48 hours, there will be multiple high tide cycles that will be elevated. Waters will begin to rise Wednesday and will peak Thursday night for the communities along the Norton Sound and the Y-K Delta Coastline. The higher waters are expected to continue through Friday. For communities along Kotzebue Sound and then the NW Arctic Coastline waters will rise early Thursday morning and peak Friday morning. The higher waters for this region will continue into Saturday.

FIRE WEATHER

Relatively cool and wet weather continues today across most of the Interior as a low over the Gulf shifts eastward, with rain spreading across most of the area. Fire weather concerns remain low in Western Alaska and the North Slope, with the Central/Eastern Interior and especially the southeastern Interior being the primary area of concern. With areas of clearing and relatively dry weather still in place, portions of the Upper Tanana Valley are in the low to mid 60s with RH values in the 30s. Isolated thunderstorms will also be possible in the vicinity of these areas ahead of rain chances tonight into Wednesday. Highs in the Central and Eastern Interior today will drop into the low to mid 50s most areas Wednesday as further rain and clouds move in, with min RH values remaining well above critical thresholds. Even the Upper Tanana Valley will see chances for wetting rains during this time frame. By Thursday, rain will diminish across the southeastern Interior, with some brief warming and drying possible by Friday ahead of additional rain this weekend.

HYDROLOGY

A strong low will move into the Chukchi Sea late Wednesday night and will be accompanied with an atmospheric river extending to the tropics. This atmospheric river will help to produce 72 hour rainfall totals of 0.5" to 2.5" for most of Northern Alaska. The Upper Tanana Valley and Upper Yukon will be the driest spots with only up to 0.15" of rainfall expected. On the flip side the wettest areas will be the Southern Seward Peninsula and the south slopes of the Western Brooks Range will be the wettest.

In the Western Brooks Range and Northwestern Interior particularly the Kobuk, Noatak, and Wulik a hydrologic outlook has been issued. With the continued periods of heavy rainfall in the region the smaller streams will be more vulnerable to see bankfull conditions and rapid rises. No flooding in this region is expected.

Across most of Northern Alaska the mainstem rivers are low and this next round of moderate rainfall is not expected to create any flooding hazards. However, on the smaller creeks and streams could see rapid rises and/or bankfull conditions. Recreators should be prepared for rapidly changing water conditions in the smaller tributaries.

AFG WATCHES/WARNINGS/ADVISORIES

AK...High Surf Advisory from 10 PM Wednesday to 4 AM AKDT Saturday for AKZ801-802. High Wind Warning from 4 AM Thursday to 4 PM AKDT Friday for AKZ801. High Surf Advisory from 4 AM Wednesday to 4 AM AKDT Saturday for AKZ815>818. High Surf Advisory from 4 AM Wednesday to 10 PM AKDT Friday for AKZ820>822. High Wind Warning from 10 PM Wednesday to 4 PM AKDT Friday for AKZ820-821-827. High Surf Advisory from 10 PM this evening to 10 PM AKDT Friday for AKZ824-825. Wind Advisory from 10 PM this evening to 10 PM AKDT Wednesday for AKZ831>846. MARINE...Small Craft Advisory from 4 AM to 4 PM AKDT Wednesday for PKZ801-810-850-853-855. Small Craft Advisory from 4 AM to 6 PM AKDT Wednesday for PKZ802-803. Small Craft Advisory until 10 PM AKDT this evening for PKZ803. Small Craft Advisory until 6 PM AKDT Wednesday for PKZ804. Small Craft Advisory from 10 PM this evening to 4 PM AKDT Wednesday for PKZ805>807. Small Craft Advisory until 7 PM AKDT this evening for PKZ808. Small Craft Advisory from 4 AM to 1 PM AKDT Wednesday for PKZ808. Small Craft Advisory until 4 PM AKDT Wednesday for PKZ809. Small Craft Advisory from 7 AM to 10 AM AKDT Wednesday for PKZ811. Small Craft Advisory from 10 AM to 4 PM AKDT Wednesday for PKZ812. Small Craft Advisory from 4 AM to 7 AM AKDT Wednesday for PKZ816. Small Craft Advisory from 1 PM to 4 PM AKDT Wednesday for PKZ816. Small Craft Advisory from 1 AM to 7 AM AKDT Wednesday for PKZ817. Small Craft Advisory from 1 PM to 6 PM AKDT Wednesday for PKZ817-851. Small Craft Advisory until 4 PM AKDT Wednesday for PKZ852. Small Craft Advisory from 10 PM this evening to 10 AM AKDT Wednesday for PKZ854. Small Craft Advisory until 10 PM AKDT this evening for PKZ855. Small Craft Advisory from 1 AM to 4 PM AKDT Wednesday for PKZ856.