Synopsis
Key Messages:
- A low in the Gulf will keep rain showers across the panhandle through tonight. Drier trend expected for Friday going into the weekends.
- Clearing skies and cooling trend to start out the weekend, with overnight temperatures dipping down into the low to mid 30s, and the northern panhandle possibly getting down into the upper 20s.
Short Term
Showers continue to move into the panhandle this evening, with on and off heavier showers across the northern half of the panhandle. Currently, a round of more organized showers is pushing through from Juneau northward, bringing up to 0.1 in/hr rates at times as they move northward through the evening, however any heavier showers will be brief and not persist. Heavier showers are expected to occur on and off through the evening, before transitioning to predominantly lighter showers tonight with more breaks between them. Chances for snow mixing in will be possible along the northern highways later tonight, however rain is still expected at sea level for Haines and Skagway as the cooling temperatures and lowered snow levels are expected only after the precipitation moves out of the area and clearing begins overnight.
Shower chances diminish tonight as the low in the northern Gulf weakens further and pulls southwestward to join with a low further out in the Gulf, dragging away much of the precipitation out of the northern and inland parts of the panhandle by Friday and bringing a start to a drying trend. Chances remain mainly for the central and southern outer coastline before also diminishing by the evening. Strengthening high pressure over the Interior and Yukon extending down into B.C. to the east of us Friday will bring offshore flow, keeping drier weather into the weekend. Skies will begin clearing into the day Friday and stay mostly clear into Saturday, bringing colder nighttime temperatures to the area, starting with the northern panhandle and more inland areas before extending further southward as the Gulf low stays to the south.
Nighttime temperatures tonight will be cooler than last night for areas that see more clearing, with fog chances in these areas increasing overnight with the clear skies and remnant moisture. Friday into Saturday will have more widespread cooler nighttime temperatures due to the dry conditions and clear skies, allowing for the northern panhandle to see minimum temperatures into the low 30s to high 20s, and the southern panhandle temperatures into the mid 30s by early Saturday morning.
Long Term
/Saturday through Monday/... Drier weather is expected into the weekend as offshore flow will become predominate Saturday into Sunday with high pressure beginning to build over the gulf. Late Friday into Saturday, a low pressure system will quickly move south of the panhandle. This, along with high pressure over the Yukon, will increase the pressure gradient which in turn will increase wind speeds. Strongest wind speeds will most likely be across the northern inner channels, including Taku Inlet, with northerly winds around 20 kts possible. The low pressure system to the south still looks to be on the weaker side which could prevent winds getting any stronger. Because of this weak outflow, low overnight temperatures will continue to drop. This will bring low temperatures into the 30s with the northern panhandle, becoming more likely to see lows in the mid to high 20s overnight. At the end of the weekend, a weak short wave will slightly increase precipitation chances over the northern gulf coast. Any precipitation amounts will remain on the lighter side with little to no forecasted accumulation amounts.
Aviation
/Through Friday afternoon/...Slight variation to the conditions seen earlier in the day as a shortwave feature enhanced shower activity over the panhandle from Icy Strait northward. This is leading to gusty surface winds occasionally to around 15 to 20 kt, primarily out of the SE, as well as MVFR conditions due to heavier rain dropping VIS to around 5sm at times. These conditions are expected to begin to wane by the evening as support diminishes. Some slight clearing behind this band of showers has the potential to allow for some patchy fog development along the Icy Strait corridor, though confidence remains low as of this discussion. There is slightly higher confidence that southern TAF sites including Klawock and Ketchikan could see patchy fog late tonight into Friday morning as shower activity and cloud cover thins out a bit more down there. Winds for the northern inner channels are expected to weakly switch out of the north before gradually strengthening later Friday. However, aside from previously mentioned gusty winds in the vicinity of showers, no significant wind or LLWS is expected through the TAF period.
Marine
Outer waters: Widespread showers and elevated seas will gradually taper off Thursday night as the low in the northwestern gulf falls apart. Small craft advisories along the central and southern coastal waters will fall off through Thursday night as significant wave heights subside from 7-9ft to 4-5ft. A synoptic shift takes over on Friday and Saturday as high pressure builds across the gulf, and a separate ridge strengthens inland over Canada. At the same time, a compact low pressure system will move northward toward British Columbia. This set up will cause outer coast winds to transition into a sustained west to northwesterly flow through Sunday, while keeping the bulk of the southern system's active precipitation just east and south of the outer coastal waters. Winds in the southern gulf are expected to reach 25-30kts and only 10-15kts in the northern gulf.
Inner waters: Across the inner channels, the primary forecast concern shifts to a developing offshore gradient late Thursday night. While onshore flow maintains light rain showers through the evening, the ridge building over western Canada will quickly bring in a drier and cooler airmass by Friday. The pressure gradient will tighten quickly between the ridge to the east, the high in the gulf, and the low pressure center moving towards British Columbia form the south. This setup brings a sharp increase in northerly winds by Friday night. Breezy northern winds up to 20kt are expected to persist through Saturday before the surrounding systems fall apart.
Ajk Watches/Warnings/Advisories
PUBLIC...None. MARINE...Small Craft Advisory for PKZ641>644-661>664.
SHORT TERM...Contino LONG TERM...EAB AVIATION...STJ MARINE...AGP
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