Flood Watch 2, NWS Juneau, AK

766 
WGAK67 PAJK 130649
FFAAJK

FLOOD WATCH
NATIONAL WEATHER SERVICE JUNEAU AK
1049 PM AKDT FRI AUG 12 2016


AKZ018-132030-
/O.CON.PAJK.FA.A.0002.160813T2100Z-160815T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
TAIYA INLET AND KLONDIKE HIGHWAY-
INCLUDING THE CITY OF...SKAGWAY
1049 PM AKDT FRI AUG 12 2016

...FLOOD WATCH REMAINS IN EFFECT FROM SATURDAY AFTERNOON THROUGH
LATE SUNDAY NIGHT...

THE FLOOD WATCH CONTINUES FOR

* NORTHERN INNER CHANNELS...INCLUDING THE FOLLOWING AREA...SKAGWAY
  AND THE TAIYA RIVER.

* FROM SATURDAY AFTERNOON THROUGH LATE SUNDAY NIGHT

* BETWEEN 1 AND 2 INCHES OF RAIN IS EXPECTED OVER THE NORTHERN
  INNER CHANNELS FROM SATURDAY AFTERNOON THROUGH SUNDAY NIGHT. THE
  FORECAST RAINFALL AMOUNTS MAY CAUSE THE TAIYA RIVER NEAR SKAGWAY
  TO RISE FROM 16 FEET SATURDAY MORNING TO 17 FEET SATURDAY
  EVENING AND PEAK AROUND 17.7 FEET SUNDAY EVENING.

* AT 17.7 FEET...THE NATIONAL PARK SERVICE MAY CLOSE THE CHILKOOT
  TRAIL DUE TO FLOODING IMPACTS ON THE LOWER PORTIONS OF THE
  TRAIL. WATER CAN BE KNEE DEEP OR HIGHER WHEN THE RIVER GAUGE
  REPORTS 17.7 FEET.

* THE SKAGWAY RIVER IN SKAGWAY MAY ALSO RISE ONE AND A HALF FEET BY
  SUNDAY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WATCH MEANS CONDITIONS ARE FAVORABLE FOR THE DEVELOPMENT OF
FLOODING IN AND CLOSE TO THE WATCH AREA.

PERSONS NEAR STREAMS SHOULD STAY ALERT AND BE PREPARED TO TAKE
ACTION IF A WARNING OR ADVISORY IS ISSUED... OR FLOODING IS
OBSERVED.

THIS STATEMENT WILL BE UPDATED BY NOON AKDT SATURDAY OR SOONER IF
CONDITIONS WARRANT.

&&

$$

381 
WGAK67 PAJK 131951
FFAAJK

FLOOD WATCH
NATIONAL WEATHER SERVICE JUNEAU AK
1151 AM AKDT SAT AUG 13 2016

AKZ018-132100-
/O.CAN.PAJK.FA.A.0002.160813T2100Z-160815T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
TAIYA INLET AND KLONDIKE HIGHWAY-
INCLUDING THE CITY OF...SKAGWAY
1151 AM AKDT SAT AUG 13 2016

...FLOOD WATCH IS CANCELLED...

THE FLOOD WATCH FOR THE NORTHERN INNER CHANNELS HAS BEEN REPLACED
BY A FLOOD WARNING. SEE FLOOD WARNING STATEMENT FOR FURTHER
DETAILS.

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
539 AM AKDT FRI AUG 12 2016

.SHORT TERM...As a largescale low barrels eastward into the gulf
from the Bering Sea, a longwave trough over the central Bering Sea
will respond by pivoting to the northeast tonight. Fetch from the
south and southwest is impressive on water vapor imagery with
precipitable water values approaching 200 percent above normal. A
band of moderate to heavy rain lifted across the northern
Panhandle overnight ahead of a warm front with Yakutat and Glacier
Bay the beneficiaries of 1.5 to 2 inches of rainfall. Given rising
water on the Taiya River and cooling cloud tops over our northern
reaches all night, we think the basin has also seen robust
amounts. As the trough pivots northeast, ridging aloft has begun
to suppress additional rain amounts, and the concentration of
heavy rain will move west of Yakutat. Thus we lowered pops today
across the north, but raised them across the south this morning as
a weaker wave crosses the central panhandle ahead of the main
system to the west. Moving ahead for tonight, the Bering Sea sea
system races east lifting the longwave trough onshore, and with it
the rain moves back into the main Panhandle. The heaviest rain
once again moving into Yakutat and Pelican by early morning
Saturday.

The longwave trough supports a surface front graced by 30 kt
southeasterlies that near the coast through tonight. NAM and GFS
both extended the winds farther south into zone 41 tonight as the
front approaches shore so we followed suit. We also increased
winds through much of the central Panhandle as a 30 kt low level
jet supplies momentum of southerlies from aloft. A ridge lying
across the Panhandle ahead of the front has induced small craft
southerlies through northern Lynn Canal tonight. Seven hundred
millibar southwesterlies across the Chilkat Range will help keep
the southerly gradient tight through the afternoon, but a backing
to the south tonight will reduce the lee-side troughing effect, so
winds should weaken.

Edits tonight were confined to elements of most impact, pop/qpf
and winds, but only small changes were needed. We used mainly the
NAM for updates.

.LONG TERM...Significant rainfall still on track for this weekend
across the northern half of the panhandle. Rainfall amounts
through Monday morning will range from 4 to 5 inches over the
northeast gulf coast, 2 to 3 inches across the northern half of
the panhandle, and around an inch across the southern panhandle.
There is the potential for flooding and more information on that
can be found in the hydrology section below. Expect periods of
gusty winds over the weekend as a couple frontal features cross
the area. Main front will push into the region Saturday night and
Sunday with 25-30 kt over the gulf. Expect 20-25 kt over the
inside waters as the front pushes inland. Upper level trough lifts
northeast through the area early next week with a building ridge
of high pressure becoming the dominant weather feature for
Southeast Alaska. This feature will help to greatly diminish
precipitation chances with the potential for a couple dry days mid
week.

Little change to previous forecast as models remain in generally
good agreement. For what few changes were made used the 06z NAM.

&&

.AVIATION...Very moist conditions with relatively high dewpoints
over our region have resulted in low ceilings across Southeast
with additional IMC visibilities from Petersburg south in fog,
potential drizzle, and rain. We are expecting weak improvement
across the south this afternoon to MVMC as low level winds
increase. Some weak wind shear may afflict Yakutat late tonight
as the front nears shore.

&&

.HYDROLOGY...Rainfall sent the Taiya River near Skagway to
bankfull conditions this morning. The river should begin to fall
today as rainfall rates will come down this morning. Since we were
not expecting such a sharp rise overnight, confidence is
increasing in potential flooding this weekend. Our hydrologic
outlook statement remains for zones 17, 19-20, 22, and 25, but a
special weather statement has replaced this for the
Skagway/Klondike zone. We will consult AKRFC today for a possible
flood watch this weekend.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-041>043-051>053.
     Small Craft Advisory due to Seas for PKZ022.
&&

JWA/TPS

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