Marine Weather and Tide Forecast for Prudhoe Bay, AK

KEY WEATHER MESSAGES
Central and Eastern Interior...
- Isolated to scattered thunderstorms in the valleys with widespread thunderstorms over the White Mountains and Fortymile.
Chances for erratic outflow wind gusts up to 50 mph, frequent lightning and hail up to 3/4" in diameter.

- Red Flag Warning for Delta Junction and Isabel Pass as winds increase and minimum RHs decrease to critical values Saturday afternoon, 20 to 30 mph sustained wind, gusts to 45 mph and RHs near as low as 20%. Sunday consists of stronger winds, 30 to 40 mph with gusts to 55 mph and RHs near 30%.

- Warm and dry conditions persist this weekend with the warmest temperatures of the year so far likely for the Interior.

West Coast and Western Interior...
- A few thunderstorms today in the Upper Kuskokwim, otherwise areas of stratus on the West Coast with partly to mostly sunny skies elsewhere.

- Temperatures remain warm through the weekend with the warmest weather of the year so far expected in the Western Interior.
Highs in the low to mid 70s. Seasonably warm along the West Coast. Highs in the 50s to near 60 from Wales northward, with 60s to near 70 south. 40s to near 50 in St. Lawrence Island.

- Widespread rain moves into the Western Interior Sunday night and continues through Tuesday with around 0.25 to 0.75" of rain possible.

North Slope and Brooks Range...
- Seasonably mild on the Arctic Coast with highs in the 30s and 40s through the weekend. Warmer in the Plains and Brooks Range with highs in the 60s and even 70s.

- Isolated thunderstorms expected in the Central and Eastern Brooks Range, potentially as far north as the Shublik Mountains.

- Moderate to heavy rainfall looks to aim at the Brooks Range from Monday to Wednesday. Exact placement of the heaviest rain is uncertain but a widespread 1/2" to 3/4" of rain is expected with some of the localized highest amounts up to 1" or more possible.

FORECAST ANALYSIS AND DISCUSSION
The upper levels aren't much different than the previous days.
Looking at satellite and radar, current conditions show the shortwave trough moving over the Brooks Range with branches of energy extending into the Interior. Thunderstorms begun developing at 10AM and they will continue to develop through about 10PM before diminishing in coverage tonight. A 19z special sounding showed over 600 J/kg of SBCAPE, ~350 J/kg of DCAPE with minimal shear. These parameters can support frequent lightning, gusty winds and small hail. The main coverage area will be in the Eastern Interior with isolated to scattered thunderstorms over the Central Interior and Brooks Range.

Otherwise, moving into the weekend, ridging will keep things warm and dry weather across most of Northern Alaska. There is a Red Flag Warning for Delta Junction as chinook flow increases this weekend. Wind speeds peak around 30 mph Saturday afternoon, then 40 mph Sunday afternoon. Higher gusts are likely. RHs will be driest on Saturday, as low as 20%, then 30% on Sunday.

By Sunday a front from the Gulf of Alaska will bring showers to the Western Interior which will continue into early next week.
These showers may be heavy at times with rainfall amounts around 1/4" to 3/4" possible, heaviest in the higher terrain. The Brooks Range will see the heaviest rainfall in Northern Alaska with some locations possibly approaching 1" or more early next week. The same front will also provide moisture to the Central/Eastern Interior but with southerly chinook flow, these will be sporadic showers rather than widespread rain.

FIRE WEATHER
The main concern is the Red Flag Warning currently issued for Delta Junction and Isabel Pass this weekend. Sustained wind speeds peak around 30 mph Saturday afternoon, then 40 mph Sunday afternoon. Higher gusts are likely, especially on Sunday. RHs will be driest on Saturday, as low as 20%, then 30% on Sunday.
Temperatures across the Interior valleys will be in the 70s with min RHs around 20% to 30% through Sunday. Winds will be strong in the AK Range Passes but fairly weak elsewhere through Saturday.
Gusty southeast winds develop Sunday afternoon in the Eastern Interior and Brooks Range with sustained winds around 15 to 30 mph. The winds shift southwest on Monday with many locations in the Interior sitting around 15 to 30 mph for sustained winds, highest at the higher terrain. Otherwise by Monday the pattern becomes a bit wetter and cooler as a Gulf of Alaska low brings a high chance for wetting rain in the Brooks Range and Western Interior. Chances are lower in the Central/Eastern Interior as the showers will be a bit more sporadic early next week. Thunderstorm chances remain low after today with a couple of storms possible in the Southern Interior and Lower Yukon/Upper Kuskokwim on Saturday, then a narrow swatch of the Western Interior and Brooks Range on Sunday.

HYDROLOGY
Most of the North Slope Rivers have broken up with little to no impacts. Moving forward as summer arrives and temperatures rise, there is a potential for snowmelt rises. Near normal temperatures, which include above freezing overnight temperatures, are predicted as we enter next week.

Most of the remaining snowpack is in the foothills and mountains where temperatures will be highest. This could lead to rapid melt and river rises. We are also anticipating a widespread 1/2" to 3/4" of rain early next week which may exacerbate river rises since there will be a combination of snowmelt and rain runoff.

Most of the ice on the larger rivers has already moved out which leaves more room to accommodate the increasing snowmelt and rain.
This contrasts with last year's late breakup when the snowmelt all entered the river systems while ice was mainly still in place.

Rising of water levels in rivers can be expected late this weekend or early next week.

.EXTENDED FORECAST DAYS 4-7...
A broad trough extending from Eastern Siberia will continue to support cooler temperatures and a wetter weather pattern on Tuesday. Deep moisture associated with this system is expected to remain focused across the Brooks Range where periods of moderate to locally heavy rainfall are expected Tuesday into early Wednesday. Ensemble guidance continues to indicate anomalously high PWAT values supporting efficient rainfall production and the potential for several hours of steady precipitation. Farther south, scattered showers are possible across portions of the Western Interior, yet model confidence remains low on exact timing and location of heavier rainfall.

High confidence that Wednesday starts to see upper level ridging spread across the state as the broad upper level troughing begins to weaken. This pattern will result in a drying trend for much of the Interior with precipitation becoming increasingly isolated throughout the week. Models generally remain in good agreement that this widespread ridging pattern will remain the dominant pattern throughout the rest of the week with temperatures gradually expected to increase through Friday.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES
AK...Fire Weather Watch for AKZ937.
PK...Small Craft Advisory for PKZ801.
Small Craft Advisory for PKZ806-811.
Small Craft Advisory for PKZ812-858.
Small Craft Advisory for PKZ850.