textproduct: Fairbanks

SYNOPSIS

Persistent ridging is the primary weather maker for the upcoming workweek. For most parts of northern Alaska, this means above normal temperatures mainly in the 70s and dry weather. A series of weak upper level low pressure systems spin around the Bering Sea, but impacts to Alaska will be limited. However, subtle disturbances embedded within the southerly flow to the east of these lows bring afternoon shower and thunderstorm chances as early as Tuesday, but more likely by Wednesday. Another weak low pressure shifts west toward the eastern Arctic coastline early this week before lifting northeast across the Beaufort Sea on Wednesday/Thursday. This system brings rain shower chances, mainly to the Eastern Brooks Range on Monday/Tuesday in addition to periods of low stratus and fog during onshore flow.

KEY MESSAGES

Central and Eastern Interior...

- A few rain showers are possible Monday & Tuesday as a quick moving disturbance drops south across the area. Any rainfall will be light and most places will be dry most of the time.

- Temperatures warm steadily through the week with highs climbing through the 70s to the low 80s by Thursday through the weekend. Mostly clear skies allow low temps falling into the 50s each night.

West Coast and Western Interior...

- Rain showers diminish along the West Coast this afternoon and evening with skies clearing tonight into Monday for most places.

- High pressure results in mostly sunny skies and drier weather with high temperatures approaching 70 along the coast and mid 70s to around 80 across the Western Interior.

- After a mostly dry Monday, diurnal shower chances return on Tuesday and become scattered on Wednesday before diminishing on Thursday. Isolated afternoon and evening thunderstorms chances generally shift from south to north Tue-Thu too.

North Slope and Brooks Range..

- Low stratus and areas of fog continue along the eastern Arctic Coast through the weekend with temperatures mainly in the upper 30s to lower 40s where onshore winds prevail.

- Elsewhere across the North Slope, highs stay mainly in the 60s with 70s likely near Umiat by Wednesday when southerly downslope flow develops north of the Brooks Range returns. This includes the western Arctic Coast where east-southerly offshore flow prevails.

- Rain chances increase across the eastern Brooks Range and Arctic Coast on Monday then diminish on Tuesday. Farther west, scattered showers and isolated thunderstorms Wednesday evening through Friday.

SHORT TERM.../Sunday night through Wednesday/

The most persistent feature for this forecast period is a 576 dm ridge centered near Denali this afternoon. This ridge gradually weakens without moving much through Tuesday before building and lifting north across the interior on Wednesday. Farther west, an energetic but weakening closed low (558 dm) tracks south across the Aleutians tonight. This system phases with a trough further south into a seasonably strong low over the North Pacific Ocean on Monday and Tuesday before lifting north toward Alaska during the extended forecast period. The final synoptic scale feature of note is a closed low over the eastern Beaufort Sea that retrogrades westward toward the eastern Arctic Coast by Tuesday before lifting north across the Beaufort (again) on Wednesday.

The Beaufort low is the same system that sent a cold front across the interior Thursday night into Friday that shifted most of the moisture eastward into Canada. As a result, there's not much moisture left for this system to work with. However, a shortwave tracking southeast across the interior on Monday may have enough lift to squeeze out a few showers near the Canadian border Monday afternoon and evening. Rain showers are more likely closer to the main low pressure Monday night into Tuesday across the eastern Arctic Coast and Brooks Range, but amounts stay light.

An arguably more important pair of disturbances track north along the West Coast Tuesday through Thursday. These disturbances are embedded within moist southerly flow near the apex of the persistent ridge feature. Precipitable water values around 1 inch and 850 mb temps around +10C support embedded thunderstorm chances that shift from near the YK Delta to the western North Slope between Tuesday and Thursday. Model guidance has consistently identified Wednesday as having the most thunderstorm activity, which appears to be focused across the Western Interior.

FIRE WEATHER

Generally warm weather with little in the way of strong winds is expected across the area to start the week, with a ridge aloft over southern Alaska extending northward across the southern Interior. This will yield widespread highs in the 60s and low 70s this afternoon, with a few areas potentially reaching into the low 80s by Monday and Tuesday. In spite of these warm temperatures, minimum RH values are likely to remain in the 30s or higher in most areas. By Wednesday, much of the Eastern Interior could see highs rise into the low to mid 80s, with min RHs in the 20s possible. The driest areas are likely to be in the Upper Tanana Valley, especially by Friday when the warmest temperatures will also be possible. On the western end of the ridge, thunderstorms will be possible Wednesday afternoon with sufficient instability in place, with thunderstorm chances moving into the Northern Interior by Thursday, then the Eastern Interior Friday.

EXTENDED FORECAST DAYS 4-7

To start the extended time frame, troughing will occupy the Western Bering Sea with some associated offshore showers occurring. On the opposite of the state, a ridge aloft with very warm air will extend across much of mainland Alaska from the southeast. This latter feature will support surface temperatures late this week broadly rising into the 70s and 80s in the Interior from Wednesday onward and especially moving into the weekend, with the southern North Slope potentially seeing highs rise into the low to mid 70s. There will be chances for thunderstorms each day rotating around the periphery of the ridge; these thunderstorm chances will align with a combination of surface instability and dynamic support aloft, with chances in the Western Interior on Wednesday, the Northern Interior and Brooks Range Thursday, and the Eastern Interior Friday. By Saturday, with a southeastern Bering Sea low driving flow across the Alaska Range, thunderstorms will be possible across much of the Interior and West Coast. The magnitude of this thunderstorm activity remains uncertain due to placement of the low and the ridge. Moving into next week, while warm temperatures remain a possibility, there is substantial uncertainty on any finer forecast details, with little agreement of the position of the ridge and the low.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...None.