Area Forecast Discussion
Issued by NWS Juneau, AK
Issued by NWS Juneau, AK
621 FXAK67 PAJK 112320 AFDAJK Southeast Alaska Forecast Discussion National Weather Service Juneau AK 320 PM AKDT Thu Jul 11 2024 .SHORT TERM...Satellite imagery this afternoon showing the remnants of the previous days front over British Columbia with the next low that will reach SE AK tracking towards the NE Gulf. Heavy rain from yesterday brought up levels on local rivers and streams but most have already crested. For tonight rain will increase over the northern half of the panhandle as the front associated with the approaching low moves inland. By the early morning the low will have weakened to an open wave trough and the front will begin to shear apart. Rainfall rates and spread will diminish into Friday afternoon and evening with the south seeing the least amount of precipitation. Southerly winds drop over as the evening progresses and pressure gradient eases. An increase in speeds again tomorrow as the front moves inland but overall the range will be 10 to 15 kt with Lynn Canal closer to 15 to 20 kt. .LONG TERM.../Saturday through Wednesday/ Continuing from the short range, the break over the panhandle will be relatively brief as our next system moves into the northern gulf by late Saturday morning. As mentioned in the special weather statement sent out Wednesday evening, this system is expected to bring a strong frontal band into the panhandle through the day Sunday and bring widespread moderate to heavy rainfall through late Sunday night into Monday morning, with heaviest rainfall expected along the NE gulf coast and along the Icy Strait Corridor. The orientation and progression of this front could strongly influence rainfall totals during this time depending on where the plume of moisture sets up and how much it wobbles. Ensemble model guidance continues to support high probabilities of 24 hour precipitation totals greater than 1 inch for the above mentioned areas. As of this forecast, the highest rainfall totals are expected along the NE gulf coast and Yakutat, with a 60% or greater chance of 2.5 inches or more in a 24 hour period. The expected timing of the heaviest rain remains Sunday morning through early Monday morning, progressing from west to east, with peak timing sometime Sunday afternoon or evening. Through the day Monday the front is expected to begin shearing apart with moisture transport on a downward trend and as such should see precipitation begin to lighten up and a potential transition to showers as opposed to persistent rain. However cloud cover overall is expected to persist with Wednesday still giving the best chance for more breaks. With this expected heavy rain, many area streams and rivers are likely to see significant rises during this timeframe. Close coordination with the Alaska River Forecast Center continues as flood potential is assessed as the event approaches. In term of winds, this strong frontal band is likely to produce low end gales west of Yakutat due to development of a barrier jet. For the NE gulf coast expectations are for high end small craft winds of around 30 kt by late Saturday night into Sunday morning. The front will then gradually push inland through Sunday afternoon and into the evening. This will lead to increasing winds of 15 kt or more along the front, especially for the northern and central inner channels. For land areas along the Icy Strait corridor as well as outer coastal communities, can expect gusts up to 30 mph with the frontal passage, with winds across the panhandle trending downwards Monday night into Tuesday. Looking towards the middle of next week we are likely to have a brief lull between systems, though the pattern overall looks to remain active. && .AVIATION...Today has been mostly MVFR to VFR conditions. This is all ahead of the next front that is expected to move in later this afternoon with aviation impacts lasting through the overnight. As the next front and round of weather tracks through, conditions will deteriorate as rainfall increases. Aviation conditions will drop, mainly due to CIG, to IFR to low-end MVFR. There is evidence of LIFR conditions possible overnight with CIGs getting close to 500 feet. && .AJK WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...Small Craft Advisory for PKZ643-644-651-652-664-671-672. && $$ SHORT TERM...PRB LONG TERM....STJ AVIATION...GJS Visit us at http://www.weather.gov/Juneau