Flooding and Heavy Rain in Idaho, May 20 to 22, 2020

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

.SYNOPSIS...
North Idaho and the eastern third of Washington will experience a
prolonged period of moderate to locally heavy rain tonight,
Wednesday, and Wednesday night. Many areas will receive more than
an inch of rain with a few spots over the Palouse and southern
Idaho Panhandle getting up to 2 inches. Creeks and streams are
expected to rise sharply Wednesday and Thursday. The threat of
heavy rain will move out of the Inland Northwest Thursday. The
weather over the weekend will improve with temperatures warming
closer to average.

&&

.DISCUSSION...
Rest of tonight...Scattered shower and isolated thunderstorm
activity over the Cascades and the deep basin has tapered off and
things will probably remain generally quiet over these western
zones for the rest of the night. Meanwhile over the eastern half
of the forecast area front of showers has enveloped the area from
the northeast and represents the vanguard of the sloppy return
flow around the Great Basin/Central Idaho upper level low which
will cause a general increase in showers and eventually stratiform
rain across all of the Idaho Panhandle zones and much of far
eastern Washington for the next 24 to 36 hours...with the
consequent areal flooding threat especially across the
southeastern zones. Expect a general deterioration into a wet
Wednesday for the rest of the night over the east. /Fugazzi

&&

.AVIATION...
06Z TAFS: A moist air mass will prevail over the region for the
next 24 hours. 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 with MVFR/IFR
ceilings and possible IFR vis in RA and BR through 00Z especially
at the KPUW and KLWS TAF sites. Some marginal improvement is
possible after 00Z at the KGEG/KSFF and KCOE TAF sites as the
deformation rain band shifts to the east. The KMWH and KEAT TAF
sites will be under the far western fringe of this system...and
benefit from westerly downslope flow off the Cascades for mainly
VFR conditions but with gusty west winds through tonight and
Wednesday. /MJF

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        49  58  43  57  38  55 /  60 100  50  30  20  50
Coeur d'Alene  50  56  44  53  39  53 /  70 100  70  40  20  60
Pullman        47  54  44  54  37  53 /  90 100  60  40  20  50
Lewiston       52  58  48  60  43  60 / 100 100  50  40  30  40
Colville       51  64  46  58  40  57 /  30 100  40  50  40  70
Sandpoint      50  57  46  53  41  51 /  90 100  90  70  30  80
Kellogg        49  56  43  52  39  50 / 100 100  90  80  40  80
Moses Lake     53  74  48  65  41  66 /  20  30   0  10   0  10
Wenatchee      53  74  49  64  43  63 /  10   0  10  20  20  10
Omak           50  77  46  64  43  63 /  10  10  10  30  30  40

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Flood Watch 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 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.