Flooding in Washington, May 5 to 7, 2017

Area Forecast Discussion
National Weather Service Spokane WA
517 PM PDT Fri May 5 2017

.SYNOPSIS...
A slow moving frontal system will be the focus for showers and
isolated thunderstorms through this evening. Saturday will be
cooler with showers lingering over the Idaho Panhandle and far
eastern Washington. Monday and Tuesday will have the best chance
of being dry next week. Unsettled weather will likely return by
Wednesday night or Thursday.

&&

.DISCUSSION...
Tonight...An upper level trough off the coast will continue to
result in south-southwest flow aloft over the region tonight with
a slow moving cold front over NE Washington that will edge into
the Idaho Panhandle tonight. Plenty of instability remains with
LAPS analysis as of 1 pm indicating surface based CAPE of
500-1000 J/KG over the Upper Columbia Basin, Okanogan Valley,
northeast Mountains, Idaho Panhandle, as well as the Blue
Mountains/Lewiston/Camas Prairie areas. Even higher CAPE of 1500
J/KG was evident over the Baker City, OR area with stronger storms
developing over the Oregon Blue Mountains that will likely track
into far SE Washington, the Lewiston area, and possibly the
Central Panhandle Mountains late this afternoon into the evening
hours. Storms will continue to initiate through early this evening
over NE Washington into the north Idaho Panhandle as well. With
0-6km shear values of 45-60 kts some storms are expected to be
long lived and capable of producing isolated large hail. Also the
very moisture rich atmosphere could producing isolated flash
flooding mainly near burn scars over the northern mountains. The
current flash flood watches run through 5 pm but these may need to
be extended a few hours.  The Cascades, Moses Lake area, and the
lower portions of the palouse should stay free of thunderstorms as
cooler more stable marine air continues to poor in behind the
cold front. Thunderstorm activity is expected to die down after
sunset although enough instability is present that a few may
linger into the late evening especially closer to the
Idaho/Montana border. Overnight the mid level front stalls over
far Eastern Washington and north Idaho with a band of rain showers
expected to linger over these areas. JW

Saturday through Monday: The upper level trough axis will push
onto the coast Saturday. Light rain will continue across extreme
eastern WA and north ID during the morning and by the afternoon
most of the showers should reside in north ID. Temperatures will
continue their downward trend with 7 to 10 degrees below average
for this time of the year. Boy wasn't our warm up brief?? Temps
Sat will be in the mid 50s to mid 60s. We will see a few degrees
of warming Sunday and then again on Monday, so we will be back up
to average readings Monday of mid 60s to lower 70s in the valleys
around the region. The trough axis crosses the Cascades early
Sunday. Our moist southerly flow will transition to a drier
northwesterly flow through the day. The best chance of showers
will once again reside in the north ID Panhandle, which will
decrease by evening, with a dry forecast for Monday. Monday the
models are showing a weather disturbance moving through southern
BC. The strongest energy looks to remain north of the boarder and
with the drier air across our region, think we will just see some
flat cumulus across northern WA and ID. /Nisbet

Monday night through Wednesday...Through this period the forecast
should be mainly dry as high pressure builds into the region from
the east. But the the reason for the ridge to build is because of
another robust weather system expected to set up off the coast
late in the day Wednesday. The upper level flow will change form
westerly to southerly through the period. This will do 2 things
allow temperatures to increase and allow deeper moisture to slowly
advect into the region. Temperatures will increase to the upper
60s to mod 70s on Tuesday and in the 70s on Wednesday. With
increased moisture we expect clouds to be on the increase through
the day Wednesday. And there will be a low end chance for a few
mountain showers late in the day, but confidence in showers are
pretty low right now.

Wednesday night through Friday...The aforementioned upper level
low is expected to close off and then slowly move inland Friday
and Saturday. This is where confidence in the models begins to
fall apart. While they all show the region getting showers and
possibly thunderstorms, the timing and intensity are different.
There will be time to dial in the forecast over the next few days,
but for now the chance for showers were bumped up both Thursday
night and Friday. With increased unsettled weather temperatures
will go down and it will be possible for highs to drop down to or
below seasonal averages by Friday and into the weekend. We can
also expected gusty southwest winds with any of these storms.
Tobin

&&

.AVIATION...
00Z TAFS: A cold front is moving through the eastern portion of
the forecast area as of 500 PM this afternoon. Numerous showers
and scattered thunderstorms were forming along the front and
pushing eastward. This will affect the KGEG/KSFF/KCOE/KPUW/KLWS
TAF sites through 02z. The showers and thunderstorms will push
into the Panhandle mountains through the evening resulting in
mountain obscurations. In addition southwest winds are increasing
across the lower east slopes and the basin with localized gust
25-30kts. After a brief lull early this evening isolated to
scattered showers will again increase across the eastern zones
between 08-18z as the trough moves through the region. Cigs will
fluctuate between VFR/MVFR with the showers. Partial clearing is
expected after 18z. Tobin

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        43  56  42  61  43  65 /  70  60  10  10   0   0
Coeur d'Alene  43  56  41  60  41  65 /  80  60  20  10   0   0
Pullman        41  53  41  58  41  64 /  80  50  20  10   0   0
Lewiston       46  57  46  63  45  69 /  70  50  30  10   0   0
Colville       48  61  42  64  42  68 /  50  30  10  10   0   0
Sandpoint      47  56  40  59  38  63 /  70  50  20  20  10   0
Kellogg        43  51  40  56  39  63 /  80  60  60  20  10  10
Moses Lake     45  64  41  68  43  72 /  10  10   0   0   0   0
Wenatchee      43  61  41  65  44  69 /  10   0   0   0   0   0
Omak           45  65  41  67  43  71 /  20  10   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

Hazardous Weather Outlook
National Weather Service Spokane WA
509 AM PDT Fri May 5 2017

WAZ034-041>044-061215-
MOSES LAKE AREA-WENATCHEE AREA-EAST SLOPES NORTHERN CASCADES-
OKANOGAN VALLEY-WATERVILLE PLATEAU-
509 AM PDT Fri May 5 2017

This Hazardous Weather Outlook is for portions of Central
Washington...East Central Washington and North Central
Washington.

.DAY ONE...TODAY AND TONIGHT

Thunderstorms will be possible today, mainly earlier in the day.
Storms may produce brief gusty winds, small hail and locally heavy
downpours. The threat of Flash Flooding will decrease during the
afternoon as the main thunderstorm threat moves off to the east.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

No hazardous weather expected at this time.

IDZ002>004-026-027-WAZ031>033-035-036-061215-
COEUR D'ALENE AREA-IDAHO PALOUSE-CENTRAL PANHANDLE MOUNTAINS-
LEWISTON AREA-LEWIS AND SOUTHERN NEZ PERCE COUNTIES-
NORTHEAST BLUE MOUNTAINS-LOWER GARFIELD AND ASOTIN COUNTIES-
WASHINGTON PALOUSE-UPPER COLUMBIA BASIN-SPOKANE AREA-
509 AM PDT Fri May 5 2017

This Hazardous Weather Outlook is for portions of North Idaho...
North Central Idaho...East Central Washington...Northeast
Washington and Southeast Washington.

.DAY ONE...TODAY AND TONIGHT

Thunderstorms will be possible Friday. Some may be strong with
brief gusty and potentially damaging winds, hail and locally
heavy rain. The locally heavy rain will also bring a threat of
localized debris flows or landslides, largely in the steeper
terrain or near recent burn scars.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

No hazardous weather expected at this time.

IDZ001-WAZ037-038-061215-
NORTHERN PANHANDLE-NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS-
509 AM PDT Fri May 5 2017

This Hazardous Weather Outlook is for portions of North Idaho...
North Central Washington and Northeast Washington.

.DAY ONE...TODAY AND TONIGHT

Thunderstorms will be possible Friday. Some may be strong with
brief gusty and potentially damaging winds, hail and locally
heavy rain. The locally heavy rain will also bring a threat of
flash flooding and debris flows or landslides, largely in the
steeper terrain and near recent burn scars.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

No hazardous weather expected at this time.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SPOKANE WA
506 PM PDT FRI MAY 5 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0504 PM     HAIL             LAPWAI                  46.40N 116.80W
05/05/2017  M0.75 INCH       NEZ PERCE          ID   PUBLIC

&&

BW

Special Weather Statement
National Weather Service Spokane WA
622 PM PDT FRI MAY 5 2017

IDZ001-004-060200-
Central Panhandle Mountains ID-Northern Panhandle ID-
622 PM PDT FRI MAY 5 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN BONNER AND
NORTHWESTERN SHOSHONE COUNTIES UNTIL 700 PM PDT...

At 621 PM PDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles northwest of Ponderay to 10 miles south
of Clark Fork. Movement was northeast at 35 mph.

Winds in excess of 40 mph will be possible with these storms.

Locations impacted include...
Sandpoint, Ponderay, Kootenai, Clark Fork, East Hope, Hope, Elmira,
Colburn, Cabinet and Schweitzer Mountain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If on or near the north end of Lake Pend Oreille, get out of the
water and move indoors or inside a vehicle. Remember, lightning can
strike out to 10 miles from the parent thunderstorm. If you can hear
thunder, you are close enough to be struck by lightning. Move to
safe shelter now! Do not be caught on the water in a thunderstorm.

&&

LAT...LON 4801 11605 4794 11621 4850 11681 4850 11605
TIME...MOT...LOC 0121Z 232DEG 30KT 4836 11667 4800 11623

SVH