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Area forecast discussion 
National Weather Service Spokane Washington
1115 am PDT Friday may 29 2015

Synopsis...
scattered showers and thunderstorms will continue today. A few
storms in the Cascades and northern mountains could become strong
with heavy rain and hail. Expect a warming trend into the
weekend, with highs in the 80s, with a lingering threat of mainly
mountain showers and thunderstorms. The next best chance of
showers and thunderstorms arrives by next Monday and Tuesday with
the potential for some stronger storms and the return of cooler
temperatures.

&&

Discussion...
morning update: we have issued a Flash Flood Watch for the east
slopes of the Cascades. We anticipate similar afternoon
instability to setup across the region today...but with subtle
differences. One will be a slightly stronger corridor of winds
coming across the Cascades. This will increase 0-6km shear from
10kts observed on thur to 20-25kts this afternoon. In addition,
there will be a "kicker" or shortwave currently present on
satellite over northwest Washington. So confidence is increasing for
thunderstorms; especially north of Hwy 2. So the potential is
there for deep convection producing heavy rain and hail...with
most uncertainty related to storm motion. It is likely that storms
will be moving more than yesterday given the mean wind in the
layer but the intensity may be stronger. Additionally, the air
mass remains quite moist with precipitable waters near 0.75" over the Cascades and
0.80" over NE Washington and nrn Idaho which is roughly 120-170% of normal.

My other concern for this afternoon will be the potential for
strong storms over the northern mtns zones of WA/ID. Given above
reasoning and potential for the shortwave passage during peak
heating, I imagine storms will be a bit more organized or deeper
than what we saw yesterday. This will increase the risk for
hail...with sizes generally ranging from dime to nickels but a few
stronger storms may approach hail to the size of quarters. These
storms will also bring heavy rainfall but should be moving a bit
quicker today. Outflow winds toward 40 mph will be possible and
could complicate the thunder forecast, especially in the upper
reaches of the Columbia Basin. /Sb

&&

Aviation...18z tafs: we anticipate an active thunderstorm day
across the northern mountains...with emphasis north of Hwy 2. There
is a small chance that outflow from these storms initiate storms
vcnty of the terminals from Wenatchee to Coeur D Alene but confidence
is low. As these storms depart/dissipate around sunset...focus will
turn toward a secondary weak disturbance traversing the region btwn
6-15z. There is some uncertainty on coverage but model trends is to
develop widely scattered elevated showers and thunderstorms east of a
line from Moses Lake to Republic. /Sb




&&

Preliminary point temps/pops...
Spokane 82 60 83 59 80 58 / 10 30 30 10 10 20
Coeur D'Alene 82 58 82 56 80 56 / 10 30 30 10 10 20
Pullman 81 58 79 57 79 55 / 10 30 30 10 20 40
Lewiston 88 63 86 62 87 61 / 10 40 30 20 30 30
Colville 83 55 84 54 83 55 / 50 40 30 20 10 10
Sandpoint 81 53 81 53 78 53 / 30 30 30 20 10 20
Kellogg 81 55 80 54 81 53 / 20 30 40 20 20 30
Moses Lake 89 59 89 58 86 61 / 10 20 10 0 10 20
Wenatchee 89 62 89 60 84 62 / 20 10 10 0 10 20
Omak 87 57 89 53 85 56 / 40 20 20 10 10 10

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...Flash Flood Watch from 1 PM this afternoon to 8 PM PDT this
evening for east slopes northern Cascades.

&&

$$

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