Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 012341
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
441 PM PDT SUN MAY 1 2016

.SYNOPSIS...
High pressure will be over the region through Monday resulting in
above normal temperatures through. The warm temperatures will melt
mountain snow and cause rivers to rise. The high pressure weather
pattern shifts east on Tuesday. This will result in a cooler,
unsettled pattern. There will be a good chance for showers and
thunderstorms with locally heavy rain by Wednesday, lasting into
Thursday. Improving conditions will begin again on Friday lasting
into the weekend.


&&

.DISCUSSION...
Tonight through Monday Night... The warming trend started in
earnest today as high pressure began to build over the region.
With the surface based high to the north some north and northeast
breezes gusting to 20 mph kicked in this afternoon over the entire
Inland Northwest. Overnight winds will settle down but an lighter
east component to the wind can be expected tomorrow as well.
Overnight fog will be much less extensive than this morning
especially in the northern valleys where the air mass has dried a
bit. It`s still not quite warm enough to rule out isolated patches
of frost overnight tonight in sheltered northern valleys so still
keep a watch out for frost sensitive plants if you are in a frost
prone area this time of year. The Republic and Okanogan Highlands
areas between Colville and Deer Park may have isolated pockets of
short term frost Early Monday.  Monday looks to be 3-5 degrees
warmer and continued dry and clear. Monday night high clouds will
start filtering in from the south as a weather system approaches
this will bring a mild night overnight into early Tuesday with
freezing valley temperatures not expected.

It`s the end of another month and last April ranked number one
all time in average temperature for April for several cities.

...VERY WARM MONTHLY AVERAGE TEMPERATURES ACROSS THE INLAND NORTHWEST...

LOCATION            APRIL 2016      RANK    PREVIOUS    YEAR    RECORD
                    AVERAGE TEMP            RECORD              BEGAN

WENATCHEE WWTP      59.1            1       58.5        1934    1931
SPOKANE             54.7            2       56.5        1934    1881
LEWISTON            57.5            3       59.0        1934    1881

Check out other city`s rankings at:
http://www.wrh.noaa.gov/total_forecast/getprod.php?wfo=otx&pil=PNS&sid=OTX

Tuesday...High pressure will get pushed to the east of the Continental
Divide allowing a deep low pressure system to move towards the
region on Tuesday. Southerly flow will result in the warmest
temperatures of the week with highs in the 70s and 80s. Southerly
flow will also increase mid and upper level moisture advecting
into the region for increasing sky cover. Model guidance has been
consistent and similar showing enough moisture moving to the
Cascades for a chance of showers and embedded thunderstorms,
mainly west of a line along highway 97 and highway 202. Warm
temperatures with increasing dew points will keep run off into
area rivers and streams on the high side, and we are expecting
rises on area rivers through the week.

...Locally heavy rain is expected Wednesday and Thursday...

Wednesday through Friday...We are expecting an increase in the
active weather through this period. The upper level low will
slowly, ever so slowly, move into the region with several weak
waves moving through the western portion of the forecast area
Wednesday and early Thursday, before shifting to the eastern zones
Thursday and Friday. Moisture will steadily increase to 250-300
percent of normal Wednesday and Thursday. The aforementioned waves
will tap into surface and mid level instability for widespread
showers and thunderstorms.

For Tuesday night and Wednesday the focus of the heaviest precipitation
and the best chance for thunderstorms will be along the Cascades.
0-6km shear is strong enough to support some isolated stronger
storms at times. Because of the slow movement of the low the
biggest impact will be localized heavy precipitation. While
showers will be widespread the focus of the heaviest precipitation
will be on the 2014 and 2015 burn scars along the east slopes of
the Cascades and possibly the Okanogan Highlands. Debris flows and
localized flash flooding near the burn scars will be possible and
we will have to monitor this closely. Very warm temperatures on
Tuesday will drop 5-10 degrees on Wednesday but remain on the warm
side of normal.

Showers will remain widespread Wednesday night and Thursday.
The best instability will shift east along the Idaho Panhandle by
Thursday afternoon. Some localized lightning may be possible for
the Cascades but the best chance will be across the eastern third
of the forecast area. Again the biggest concern and impacts will
be the localized heavy precipitation for all of the mountain
zones. Already soggy soils will not be able to handle additional
rain fall, increasing the run off into area rivers and streams.
This raises the concern for debris flows and localized flooding.

Friday through Sunday the upper level low will drop southeast and
away for the region. This will allow a flop over ridge to build
into the region Saturday and Sunday. Before then wraparound
moisture will keep the chance of showers in the forecast for the
Panhandle, the Blue mountains and the Camas Prairie, but with much
less accumulations. By Saturday and Sunday warmer and drier
conditions will return to the region. Temperatures will likely
warm to 5-10 degrees above normal. Tobin

&&

.AVIATION...
00Z TAFS: VFR conditions will prevail at all TAF sites under
building high pressure and clear sky. /Pelatti


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        48  78  52  81  54  76 /   0   0  10   0  10  30
Coeur d`Alene  44  78  47  81  50  78 /   0   0   0   0  10  20
Pullman        44  77  46  80  48  73 /   0   0   0   0  10  20
Lewiston       47  81  50  85  52  79 /   0   0   0  10  10  30
Colville       41  81  43  84  47  79 /   0   0  10   0  10  40
Sandpoint      39  77  41  79  44  77 /   0   0   0  10  10  20
Kellogg        40  78  42  80  45  77 /   0   0   0  10  10  20
Moses Lake     43  83  46  85  51  77 /   0   0   0   0  10  40
Wenatchee      50  82  53  82  56  75 /   0   0  10  10  40  50
Omak           46  81  48  83  52  76 /   0   0  10  10  20  60

&&

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

$$



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