Alert archive / Alaska / Flash Flood Warnings in 2020
Flash Flood Warning 1, NWS Juneau, AK
NWS Juneau, AK issued this flash flood warning at Dec 2, 2020, 4:04 PM AKST. It took effect at Dec 2, 2020, 4:12 PM AKST. It was in force for 6 hr. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Dec 2, 2020, 4:04 PM AKST (01:04 UTC)
- In effect from
- Dec 2, 2020, 4:12 PM AKST
- Expired
- Dec 2, 2020, 10:00 PM AKST
- In force
- 6 hr
- Issued by
- NWS Juneau, AK
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Did it verify
Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this flash flood warning while it was in force. That is not proof nothing happened: reports are thin where few people live.
Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.
The nearest sounding before it
Yakutat, (PYAK), launched 00:00Z, 1.1 hours before the alert went out and 230 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 8 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 479 m above ground
- 0-6 km bulk shear
- 80 kt
- 0-1 km storm-relative helicity
- 596 m²/s²
- 0-3 km storm-relative helicity
- 822 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
539
WGAK57 PAJK 030112
FFWAJK
AKZ019-030700-
/O.NEW.PAJK.FF.W.0001.201203T0112Z-201203T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Juneau AK
404 PM AKST Wed Dec 2 2020
The National Weather Service in Juneau has issued a
* Flash Flood Warning for...
Haines area.
* Until 1000 PM AKST.
* At 404 PM AKST, law enforcement reported landslides ongoing across
the warned area. 4 to 8 inches of rain has fallen across the warned
area with an additional 1 to 2 inches expected over the next 12 hours.
HAZARD...Additional landslides caused by heavy rain.
SOURCE...Law enforcement.
IMPACT...Additional landslides probable. Those living near steep terrain
should be aware of the increased danger.
Excessive rainfall over the warned area will cause landslide near
steep terrain. The mud slide can consist of rock, mud, vegetation and
other loose materials.
Additional rainfall amounts of 1 to 2 inches are possible in the warned area.
Although less than what has previously been observed is expected to fall, already
saturated grounds could give way easily.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Stay away from steep terrain. Act quickly to protect your life.
Please report flooding or landslides to your local law enforcement agency
when you can do so safely.
&&
LAT...LON 5933 13542 5909 13530 5917 13560 5920 13570
5943 13595
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1 to 2 inches of rain in the next 12 hours.
$$1 follow-up statement
069
WGAK77 PAJK 030659
FFSAJK
Flash Flood Statement
National Weather Service Juneau AK
957 PM AKST Wed Dec 2 2020
AKZ019-030707-
/O.EXP.PAJK.FF.W.0001.000000T0000Z-201203T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Haines Borough and Lynn Canal-
957 PM AKST Wed Dec 2 2020
...THE FLASH FLOOD WARNING FOR HAINES WILL EXPIRE AT 1000 PM AKST...
The heavy rain is diminishing. A Flash Flood Watch remains in effect
until 9AM Thursday. Please continue to heed any remaining road
closures.
LAT...LON 5933 13542 5909 13530 5917 13560 5920 13570
5943 13595
$$What forecasters said that day
The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Juneau, AK wrote its last area forecast discussion before this flash flood warning went out at Dec 2, 3:32 PM AKST, 32 minutes earlier.
Area forecast discussion, Dec 2, 3:32 PM AKST, 32 minutes before
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
332 PM AKST Wed Dec 2 2020
.SHORT TERM.../Wednesday through Thursday/
...IMPACTFUL STORM SYSTEM CONTINUES TO BATTER SOUTHEAST ALASKA...
The atmospheric river responsible for record rainfall totals
continues to dump heavy rain across portions of Southeast Alaska.
Juneau, Gustavus, Sitka, Craig, Haines, and many other towns
received between 4 and 10 inches of rain in the past 24 hours
smashing daily rainfall records. Rivers and streams have risen and
are cresting this afternoon across the Icy Strait corridor. A
Flood Advisory remains in effect for Gustavus as the Salmon River
reached record levels this afternoon. Flooding along Auke Lake and
Jordan creek prompted a Flood Warning for the Juneau area earlier
today which has since been allowed to expire. Heavy rains plus
rising snow levels have caused multiple mudslides in Juneau and
Upper Lynn Canal prompting the issuance of a Flash Flood Watch for
Haines and Skagway. Extreme caution should be taken near steep
terrain, especially in Upper Lynn Canal. A serious situation has
been developing in Haines as debris flows have destroyed homes
and have prompted evacuations. An Additional 1 to 3 inches is
expected in Upper Lynn Canal through tomorrow morning on top of
already saturated grounds. Despite rainfall rates diminishing,
the additional rainfall tonight will cause minor flooding and
other impacts through the north and central Panhandle.
A wave moving northward in the gulf tonight will re-orient the
atmospheric river in a more east to west fashion as it pushes a
front north and eastward through the Panhandle. Gales just ahead
of this front in the coastal waters will diminish later this
evening. Small crafts through the Inner Channels will begin to
diminish towards the morning hours on Thursday. A strong 70 kt
low level jet just above the surface and ahead of the front will
push into the Panhandle this evening keeping surface winds
elevated. Gusts to 60 mph are expected along the NE Gulf Coast
including Yakutat, where the High Wind Warning is in effect till 9
PM. Think the winds will calm down in that area before 9 PM
though. Strong winds with gusts of 40 to 50 mph expected this
evening along the Outer Coast from Hydaburg to Sitka and further
inland towards Juneau and Upper Lynn Canal. Winds should diminish
everywhere by the morning hours on Thursday.
Winter weather continues to impact the highest elevations of the
highways this afternoon. Decided to extend the Winter Storm
Warning for White Pass though tomorrow morning for an additional
10 inches of snow. Despite rising snow levels across much of the
Panhandle, cold air advection tonight should keep White Pass
mainly snow.
Thursday: A small break in the precipitation as the current system
exits into Canada and the next system moves in from the south. A
weakening area of low pressure will head north out of the N
Pacific and move up the outer coast, opening up into a wave as it
does so. With southerly flow remaining in place aloft, expect rain
to be the predominant P-type for most areas with the higher
elevations on the Klondike Highway being the exception. Rain will
move in from south to north during the day Thursday. IVT values of
300 kg/m/s are associated with the plume of moisture out ahead of
this weak system. Currently expecting around an inch of rain in
the south with lesser amounts further north. Much of the southern
Panhandle was spared from the heavy rain today as the axis of
heaviest precipitation was aimed at the northern central
Panhandle; therefore flooding is not expected due to the
additional rainfall tomorrow across the south.
.LONG TERM.../Friday through Wednesday night/ The remains of the
atmospheric river will be moving east into British Columbia early
Friday. During the day Friday a wave from the south spread some
more light light to moderate rains there.
Models are struggling to handle the system that should be moving
in from the eastern pacific with placement, strength, and timing.
Could see another strong Fall/Winter storm for the panhandle that
continues into Saturday. Another strong front should spread in
across the gulf for sunday attached to a deep low 950 mb headed to
the western gulf. The model agreement is better for the Sunday
and continuing into the start of the week with the strong low
moving to PWS as it weakens.
Not sure if I want to jinx the idea by commenting on it, but if
it occurs, it would impact the weather and residents of SE AK.
Various long range solutions and ensembles from Wednesday onward
are beginning to hint of a ridge developing over the Gulf and
into the mainland part of the state. This could lead to break that
We will wait and see.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Strong Wind until 6 PM AKST this evening for AKZ022-023-026-027.
Strong Wind until 9 PM AKST this evening for AKZ025.
Areal Flood Advisory until midnight AKST tonight for AKZ020.
Flash Flood Watch through Thursday morning for AKZ018-019.
Strong Wind from 6 PM AKST this evening through late tonight for
AKZ018.
Winter Storm Warning until 6 AM AKST Thursday for AKZ018.
High Wind Warning until midnight AKST tonight for AKZ017.
MARINE...Gale Warning for PKZ022-041>043-051-053.
Small Craft Advisory for PKZ011>013-021-031>036-052.
&&
CM/Bezenek
Visit us at http://www.weather.gov/JuneauIn the hours before
Local storm report, Dec 2, 10:41 AM AKST, 5 hours 23 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1041 AM AKST WED DEC 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0400 PM HEAVY SNOW SKAGWAY 59.46N 135.31W
12/01/2020 E12.0 INCH SKAGWAY AK DEPT OF HIGHWAYS
12 INCHES OF SLUSH REPORTED IN TOWN.
&&
JSLocal storm report, Dec 2, 10:44 AM AKST, 5 hours 20 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1044 AM AKST WED DEC 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0400 PM HEAVY SNOW WHITE PASS 59.63N 135.16W
12/01/2020 E36.0 INCH SKAGWAY AK DEPT OF HIGHWAYS
36 INCHES OF NEW SNOW ESTIMATED BY ALASKA
DOT.
&&
JSLocal storm report, Dec 2, 10:45 AM AKST, 5 hours 19 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1045 AM AKST WED DEC 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0400 PM HEAVY SNOW 3 SSW WHITE PASS 59.59N 135.19W
12/01/2020 E28.0 INCH SKAGWAY AK DEPT OF HIGHWAYS
28 INCHES OF HEAVY SNOW ESTIMATED BY ALASKA
DOT.
&&
JSLocal storm report, Dec 2, 2:13 PM AKST, 1 hour 51 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
213 PM AKST WED DEC 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0624 PM FLOOD 4 NW JUNEAU 58.34N 134.49W
12/01/2020 JUNEAU AK PUBLIC
ADDITION TO EARLIER REPORT MENTIONING
HEATING OIL TANK BEING OVERTURNED BY A SMALL
MUDSLIDE. MULTIPLE RESIDENTIAL STRUCTURES
DAMAGED BY DEBRIS FLOW.
&&
JSLocal storm report, Dec 2, 2:57 PM AKST, 1 hour 7 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
257 PM AKST WED DEC 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0221 PM FLOOD 9 S PETERSBURG 56.68N 132.92W
12/01/2020 PETERSBURG CENSUS AAK MESONET
FALLS CREEK NEAR PETERSBURG FLSA2 REPORTED A
CREST OF 24.28 FEET.
&&
JSLocal storm report, Dec 2, 3:26 PM AKST, 38 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
326 PM AKST WED DEC 2 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0300 PM FLOOD 1 SE HAINES 59.22N 135.42W
12/02/2020 HAINES AK EMERGENCY MNGR
LARGE LANDSLIDE IMPACTING BEACH ROAD NEAR
HAINES. TIME AND LOCATION ARE APPROXIMATE.
&&
JSThe office that day
Everything else NWS Juneau, AK issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 2, 3:18 PM AKST | Gale Warning | AJK | 13 hr | |
| Dec 2, 3:38 PM AKST | Small Craft Advisory | AJK | 7 days | |
| Dec 3, 4:03 AM AKST | Small Craft Advisory | AJK | 24 hr | |
| Dec 3, 4:03 AM AKST | Small Craft Advisory | AJK | 60 hr | |
| Dec 3, 4:16 AM AKST | Small Craft Advisory | AJK | 11 hr |
Nearby
Flash Flood Warnings in Alaska, 2020Every flash flood warning in 2020
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.