Area Forecast Discussion
Issued by NWS
FXAK67 PAJK 241334
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
534 AM AKDT Mon Apr 24 2017
.SYNOPSIS...Broad area of low pressure centered along the central
Aleutians impacts the Gulf of Alaska with a trough extending over
gulf to the British Columbia coast. Higher pressure over northern
Canada will weaken as the center moves east towards Hudson Bay.
.SHORT TERM.../Monday through Tuesday night/ Short term forecast
features scattered shower activity Monday through Monday night
across most of southeast Alaska. Shower activity will dry up from
south to north as a low approaches from the south and induces
offshore flow. The front associated with this low is being
depicted stronger by models overnight and this represent the
biggest change to the forecast since yesterday. Preferred the
placement of the low as depicted by GFS, but felt the winds with
this model were a little too strong. Thus winds speeds were
trimmed down a bit. Still, strong wind gusts in excess of 40 mph
are likely for the southern outer coast on Tuesday afternoon with
gales over coastal marine zone 41 and the Dixon Entrance. Small
craft conditions will spread north over the inner channels Tuesday
evening before diminishing to 15 kts or so by Wednesday morning.
Think marginal gales are also possible for Cross Sound Tuesday
Daytime highs today not as warm as yesterday under mostly cloudy
to overcast skies. Look for low to mid 50s for today and Tuesday.
Overnight lows, however, should be warmer, ranging from the upper
30s to lower 40s as opposed to freezing or near freezing
conditions observed in northerly locations Sunday night under
mostly clear skies.
.LONG TERM.../Wednesday morning through Sunday/ The models are
in much better agreement with the low discussed above that will
lift out of the north Pacific at the start of the long term
period. A 986mb surface low is forecasted to be just west of Dixon
Entrance by Wednesday morning as a upper trof lifts north from
the polar jet that has been over the Central Pacific the past 2
weeks. This low will increase precip over the southern half of the
area as the track is a bit further north than previous forecast.
The northern areas will see just a chance of precip with more
offshore flow along with north winds less than 15 kt.
The low will slowly lift north but will remain south of Sitka
through Wednesday night before weakening and lifting east into
the inner channels. Rain will remain a high threat south of the
low but north it will be on the drier side. After the low moves
into Canada there will be a period of onshore flow but towards the
weekend it looks like the northern half of the forecast area
could be dry with a low moving over Dixon Entrance. The southern
areas will see a higher threat for precip over the weekend being
closer to the low and near an area of deformation.
There is average forecaster confidence through the long term
period. The overall trend in the models is to have bits of energy
from the jet lift north into the gulf but overall most of the
weather systems will be south of the area. For any changes done to
the forecast the 00z nam, and 00z gfs was used through Thursday
and then WPC after that.
MARINE...Small Craft Advisory for PKZ052.
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