Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 102336
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
436 PM PDT THU JUL 10 2014

.SYNOPSIS...

A prolonged heat wave will continue across the Inland Northwest
through this weekend and may linger well into next week. Mid to
upper 90s will be common, with triple digit heat in the Lewiston
area and portions of the Columbia Basin. There will be potential
for monsoonal moisture to invade the region early next week, with
some threat of thunder, but otherwise the forecast is dry.

&&

.DISCUSSION...
Tonight through Saturday...A building upper level ridge will bring
another warming trend with most valleys on Saturday reaching
between 95 to 100 degrees. The ridge will result in dry conditions
although there will be one wave to monitor coming up the back
side of the ridge out of Oregon on Saturday. This will weaken
significantly as it heads north into Washington and is not
expected to be much of a player. Although models do show
increasing instability over the Cascades in the afternoon where
isolated thunderstorms could develop by evening. There is quite a
bit of model disagreement on the amount of instability with the
NAM the most aggressive with this idea. Often the NAM is overdone
in the Washington Cascades with CAPE values so have sided towards
the more subdued GFS solution. JW

Saturday night through Tuesday...An interregnum in the
repetitiously banal "hot and dry...hot and dry" stretch of
weather looks increasingly possible during this period. It will
still be hot...but the latest ECMWF and GFS are honing in on a
solution that features an upper level short wave or even a weak
closed low aloft transiting the forecast area especially during
the Monday-Tuesday time frame. Both models keep a strong surface
thermal trough anchored over the Columbia Basin during this
transit...but the wave will bring some cooling aloft and
significantly higher moisture...leading to the increased
instability and thunderstorm potential starting over the Cascades
Sunday night and spreading out over the basin on Monday and into
the Idaho Panhandle Monday afternoon through Tuesday. Details are
uncertain at this time and forecast will need further refinement
in the coming days...but there is growing confidence that Monday
especially will feature a chance of thunderstorms...probably
initially dry but increasingly wet given the near 1 inch of
precipitable water available for convective fuel.

Temperatures are a major point of uncertainty during this
evolution. The strong surface thermal trough which will not move
or be disturbed by any identifiable cold fronts will promote
continued anomalously warm temperatures. Daytime cloud cover (too
far out to pin down at this time) may inhibit daytime insolation
in areas...and higher moisture content will make available
insolation less efficient in heating the air mass...adding to
this rat`s nest of variables is the potential for actual rain and
thunderstorm gust fronts...but any cloud cover at night will
inhibit nocturnal radiational cooling and allow higher sultry
morning starting points for further daytime heating...especially
if daytime cloud cover is minimal outside of convective cells. The
safe bet is continued well above normal readings but those keeping
track of "days above 90" or "days above 100" at any particular
location may see an interruption during this period. /Fugazzi

Tuesday Night through Thursday: The upper level ridge pumps right
back up Tuesday night after the wave exits the area. Models have
been flip flopping on the idea of a potential wave/tough moving
into British Columbia on Thursday and flattening the ridge some.
Temperatures will still remain well above average for this time of
the year. GFS is hinting at some monsoonal moisture moving up the
west coast and into the flattened ridge on Thursday. The best
moisture currently looks to stretch across northern WA and ID.
Models showing some very weak energy moving across the area as
well. Main threat looks to be a high cirrus shield. But cannot
rule out the possibility of some thunderstorms. GFS does show some
decent instability. Have added a slight chance of thunder for
northern WA and ID Thursday afternoon and evening. But confidence
is low this far out, am confident models will continue to be
inconsistent and therefore the forecast will continue to change as
well. /Nisbet

&&

.AVIATION...
00Z TAFS: High pressure over the region with a very dry air mass
will keep clouds to a minimum through Friday with VFR conditions
expected at all TAF sites. Area wildfires will produce haze from
time to time during the day and smoke layers aloft, especially
at EAT and perhaps MWH. /J. Cote`

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        61  93  64  95  66  97 /   0   0   0   0   0  10
Coeur d`Alene  56  91  58  94  61  96 /   0   0   0   0   0  10
Pullman        49  91  53  94  55  96 /   0   0   0   0   0  10
Lewiston       61  98  65 101  67 104 /   0   0   0  10  10  10
Colville       55  96  54  98  58 100 /   0   0   0   0   0  10
Sandpoint      52  89  53  92  55  96 /   0   0   0   0   0  10
Kellogg        55  91  56  93  60  94 /   0   0   0   0  10  10
Moses Lake     60  98  63 101  67 102 /   0   0   0   0   0  10
Wenatchee      65  96  67 100  72 102 /   0   0   0   0   0  10
Omak           62  95  61 100  66 103 /   0   0   0   0   0  10

&&

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

$$



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