textproduct: Fairbanks

KEY WEATHER MESSAGES

Central and Eastern Interior... - Temperatures remain warm throughout today, then take a tumble on Sunday as a front brings rain and cooler temperatures.

- What was once heavy rain, looks to be more of a light to moderate rain from Saturday afternoon through Sunday with 0.25 to 0.50" around the Interior, heaviest in the Northern Interior due to upslope flow. - Additional showers expected on Sunday, exact totals are uncertain at this time given the large spread seen between models.

- SW winds increase behind the cold front with gusts between 25 and 25 mph. The strongest gusts will be at the higher elevations. Winds will remain elevated through the middle parts of next week.

West Coast and Western Interior... - A cold front will move across the western Interior, today, bringing another round of widespread showers. Some may be heavy at times. Total rainfall accumulation across the West Coast and Western Interior expected to be between 0.25" and 1.0". Heaviest precipitation expected over the middle Yukon. - Thunderstorm activity will be limited over the West Coast through the end of the weekend with the cold frontal passage.

- A cooling trend arrives this weekend with continued chances for showers.

- SW winds increase behind the cold front with gusts between 25 and 25 mph. The strongest gusts will be at the higher elevations. Winds will remain elevated through the middle parts of next week.

North Slope and Brooks Range.. - Much colder in the Plains and along the coast today with highs in the 30s to low 40s and areas of stratus.

- A gradual warm up is expected into the weekend and next week as a front brings more southerly flow.

- The Brooks Range will get some rainfall on Sunday and into Monday with localized areas approaching 0.5" to 1.0", especially on the south facing slopes. Lighter showers expected north of Range.

FORECAST ANALYSIS AND DISCUSSION

Overall pattern remains on track, however a few smaller details have shifted the forecast around a bit. Specifically, the QPF forecast.

A 540 decameter, Bering low continues to spin west of St. Paul Island while an upper-level ridge continues to strengthen over northwest Canada. Models are no longer showing the potential for the bulk of a shortwave, currently in the northern gulf of Alaska, to get wrapped in the flow and work its way up the Eastern Interior. Satellite imagery this morning shows the position of this shortwave approximately 100 miles SE of where models had it positioned in model runs, yesterday. This is resulting in this shortwave to get wrapped into a low moving into the NW portion of the lower 48. Models are also showing the shortwave in the gulf to become a close, upper-level low. This will steal a abundant amount of moisture that was previously expected to move across the Interior throughout the day, today. Nevertheless, scattered showers are still expected across the Interior as the broad W-E oriented trough axis, extending from the low in the Bering, shift north. Precipitation totals are expected to be between 0.5" and 1.0" across much of the Interior throughout Sunday.

Meanwhile, a cold front associated with the Bering low will move NE throughout the day today. This will help to enhance the precipitation chances across the southern half of the CWA. Ahead of the front, chances for afternoon thunderstorms will continue this afternoon. This will be focused from the northern portions of the Central Interior, east, across the Yukon Flats. Some southern portions of the Eastern Interior will also see a chance for storms as the front is not expected to move across the SE Interior until later tonight. The NE tracking front will start off with a negative tilt before becoming more E-W oriented. This is largely due to ridging that is expected to remain in place over the NW portion of the state, causing the western side of the front to slow by Sunday morning.

Behind the cold front, an increase in southwesterly surface winds can be expected with gusts between 25 and 35 mph, with the strongest winds at higher elevations. With the previously mentioned shortwave moving SE, this has lightened the low-level jet that is expected to form behind the front. More uncertainty begins to settle in by Sunday as models are in disagreement with the amount of rain that is expected with the showery conditions behind the front. Latest model runs show the GFS the most aggressive with much of the Interior getting an additional 0.5" to 1.0" of rain throughout the day on Sunday. There has not been very good run-to-run consistency with this. Generally behind a cold front, conditions typically dry out. Models are showing this, including the GFS, on PWAT anomaly outputs. With this in mind, this will be something that will continued to be monitored closely over the next several model runs.

As the start of the next week approaches, a broad troughing pattern is looking to settle in across the state. This will continue to bring cooler temperature and isolated showers throughout the middle portions of the week. Eventually, the cold front will stall somewhere over the central Brooks Range as a strong Arctic trough swings energy westerly across the Arctic Sea. There is a fair bit of disagreement amongst models with the positioning of where this front stalls. In addition, the low from the Bering will be moving across the YK-Delta, into the Upper Kuskokwim through the start of the week (hence the broad troughing mentioned previously). Models are showing this low to move into the northern portion of the gulf of Alaska sometime Tuesday. This could potentially setup another round of upper-level easterly flow across the Interior for the later half of the week.

FIRE WEATHER

Today the pattern begins to shift as we have a low pressure system in the Bering Sea bringing a cold front through the Interior today. Ahead of this cold front however we could see isolated thunderstorms develop around midday. These thunderstorm chances will be in the Eastern Interior, and the Central Interior along the Tanana/Yukon River. Scattered thunderstorms are possible today in the Fortymile Country and north along the AlCan Border to the Brooks Range. There will be a short window for these scattered storms because the cold front should begin to move through the area around 3 pm. The cold front will bring widespread wetting rains, gusty winds, and cooler temperatures. Most of the wetting rains will be associated with the frontal passage itself with up to 0.8" of rain in the Western Interior, Brooks Range, and Alaska Range. In the Upper Tanana Valley, Tanana Valley, and White Mountains precipitation amounts continue to trend downwards with up to 0.25" expected. Across the Interior higher amounts are possible due to the convective nature of the rain showers on Sunday. The showers on Sunday will be slow moving and could produce heavy rains in that area. After this front expect temperatures to remain cool through the middle of next week, with isolated to scattered rain showers remaining possible.

HYDROLOGY

No update from previous discussion Rain is still expected in the Interior and Denali National Park area this weekend, but with much lower rainfall totals than models initially suggested. River rises are expected in conjunction with this precipitation but because water levels are normal (low) these rises will not result high or impactful water levels.

The heaviest rain will likely be along the southern Brooks Range and northern Interior, but it does not seem too impactful as of now.

See water.noaa.gov for current and forecast water levels.

EXTENDED FORECAST DAYS 4-7

A Bering Sea low continues to move Eastward into the YK-Delta this upcoming Monday. On Tuesday a ridge will divide the South West Interior from the South East Interior blocking a significant amount of vorticity maxima in the two localized areas. This allows more precipitation and wetting rains to these select locations on Tuesday afternoon. On Wednesday morning the trough will begin to move Eastward pushing the ridge towards Canada, which will allow for isolated to scattered showers in the Central/Eastern Interior. A trough will begin to deepen Wednesday afternoon along the West Coast. This trough has a possibility of bringing widespread rain showers along the West Coast Tuesday through Thursday morning. Winds are expected to remain light during this time period, while temperatures trend slightly below normal, as a combination of the cloud cover, precipitation and arctic air.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ804-805. Small Craft Advisory for PKZ806. Small Craft Advisory for PKZ810-856. Small Craft Advisory for PKZ811. Small Craft Advisory for PKZ812. Small Craft Advisory for PKZ852-858. Small Craft Advisory for PKZ857.