Debris Flow in Washington, May 19, 2020

Area Forecast Discussion
National Weather Service Spokane WA
1229 PM PDT Tue May 19 2020

.SYNOPSIS...
The wet weather pattern continues with a chance of thunderstorms
possible each afternoon. Thunderstorms will be slow moving
especially over northeast Washington into north Idaho today and
Wednesday. Moderate to heavy rains are anticipated late tonight
into Wednesday evening across southeast Washington into north
Idaho. Rises on areas rivers are expected. Showers continue
Thursday into Friday with a drier and warmer period finally by the
weekend.

&&

.DISCUSSION...

...HEAVY RAIN TONIGHT INTO WEDNESDAY OVER SOUTHEAST WASHINGTON AND
THE SOUTHERN AND CENTRAL IDAHO Panhandle...

The morning model runs are in. Confidence in a prolonged heavy
rain event across southeast Washington and the central/southern
Idaho Panhandle continues to grow. Rainfall guidances from the
Weather Prediction Center hits the Pullman, Moscow, St Maries,
Pomeroy, and Winchester areas with a 36 hr rain total between 1.5
and 2.0 inches. Values from the High Resolution Ensemble Forecast
(HREF) forecast similar amounts. Basin wide rain amounts of this
magnitude are rare, and we expect abrupt and significant rises on
small streams and creeks by Wednesday morning, and rain will
likely persist well into early Thursday. Rapid rises are also
expected on several of our larger rivers in the Idaho Panhandle
and southeast Washington including the Coeur d'Alene, St Joe,
Clearwater, and the Palouse. Paradise Creek in Moscow is a
notoriously flood prone creek, and rain will likely cause this
creek to flood. A Flood Watch has been issued by regional NWS
offices for a significant chunk of the central and southern Idaho
Panhandle, southeast Washington, and parts of northeast Oregon.
/GKoch

&&

.AVIATION...
18Z TAFS: Our air mass is unusually cool and moist leading to an
abundance of low cloud. Look for stratocumulus to lift into a
bubbly cumulus deck between 18-20z. Rain showers are expected to
be the most concentrated over the mountainous terrain of northeast
Washington and the Idaho Panhandle this afternoon, but scattered
showers will be possible at our TAF sites as well with the best
chance between 21-01z. The organization of low pressure this
evening and through the night will produce a band of prolonged
moderate to heavy rain over the Idaho Panhandle and southeast
Washington. Look for lowering ceilings through the night and into
the early morning hours for KGEG, KSFF, KCOE, KPUW, and KLWS.
/GKoch

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        63  49  60  43  59  39 /  30  60 100  50  30  20
Coeur d'Alene  63  49  58  44  56  39 /  40  70 100  70  40  20
Pullman        59  45  54  43  55  37 /  40 100 100  60  40  20
Lewiston       63  52  60  48  62  44 /  50 100 100  50  40  30
Colville       69  48  69  43  64  40 /  50  30 100  40  50  40
Sandpoint      63  50  59  45  56  41 /  50  90 100  90  70  30
Kellogg        61  49  56  45  52  41 /  80 100 100  90  80  40
Moses Lake     71  50  76  46  67  41 /  40  20  30   0  10   0
Wenatchee      71  51  71  47  63  43 /  30  10   0  10  20  20
Omak           74  49  77  45  65  43 /  30  10  10  10  30  30

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Flood Watch from 11 PM PDT this evening through late Wednesday
     night for Central Panhandle Mountains-Coeur d'Alene Area-
     Idaho Palouse-Lewis and Southern Nez Perce Counties-
     Lewiston Area.

WA...Flood Watch from 11 PM PDT this evening through late Wednesday
     night for Lower Garfield and Asotin Counties-Northeast Blue
     Mountains-Washington Palouse.

&&

Hazardous Weather Outlook
National Weather Service Spokane WA
209 PM PDT Tue May 19 2020

IDZ001-WAZ034>037-041-042-044-201400-
Northern Panhandle-Moses Lake Area-Upper Columbia Basin-
Spokane Area-Northeast Mountains-Wenatchee Area-
East Slopes Northern Cascades-Waterville Plateau-
209 PM PDT Tue May 19 2020

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

No hazardous weather is expected at this time.

IDZ002>004-026-027-WAZ031>033-038-043-201400-
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-Okanogan Highlands-Okanogan Valley-
209 PM PDT Tue May 19 2020

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

Snowmelt across north central Washington; and moderate to heavy
rain for southeast Washington, the central and southern Idaho
Panhandle will occur. Various flood products have been issued for
these areas.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

Rivers will remain near or above bankfull through the week.