Area forecast discussion
National Weather Service Spokane Washington
518 PM PDT Sat may 18 2013
Synopsis...
scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low Parks itself over the inland
northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
Discussion...
late afternoon update to the forecast for this evening. Added some
isolated thunderstorms across mainly Okanogan County to Ferry
County. Laps data shows cape values up to around 400 j/kg and we
have already seen a handful of lightning strikes this afternoon
across this area. The thunderstorm threat will mainly only go
through until sunset. Once we lose our surface heating across
these areas, we shouldn't retain enough instability for
thunderstorms to continue. Also added some isolated showers across the
basin as the next wave crosses the Cascades. Radar imagery does show
some weak echoes developing across the Moses Lake area into the
upper Columbia Basin. These showers are not expected to produce
much in the way of rainfall, but we could see around a hundredth
or so through this evening underneath these showers. The hrrr
model has the possibility for these showers reaching the Spokane
area around 8:00 pm; however, the best forcing with this wave across
the basin will remain more over our southern zones, so not
expecting much from these showers once they get this far east into
the Spokane area. /Svh
&&
Aviation...
00z tafs: an upper level trough and weak disturbances embedded
within will aid in generating showers especially over the
mountains. Isolated thunderstorms will also be possible mainly
over the mountains north of the Columbia Basin though 03z this
evening. Westerly flow in the mid levels will lead to downslope
flow off the Cascades with dry conditions persisting at keat/kmwh.
Taf sites that receive showers could see low stratus forming after
15z but confidence is low that conditions will fall below VFR for
any taf site. /Ek
&&
Preliminary point temps/pops...
Spokane 45 66 46 72 52 75 / 10 20 10 0 0 20
Coeur D'Alene 45 65 44 71 47 75 / 10 30 20 0 0 30
Pullman 43 63 42 71 47 76 / 10 20 10 0 0 20
Lewiston 49 68 49 77 53 83 / 10 20 10 0 0 20
Colville 45 72 43 78 45 79 / 30 20 20 10 10 40
Sandpoint 43 65 42 71 44 75 / 10 50 30 10 10 30
Kellogg 44 60 46 69 50 74 / 10 40 30 10 10 20
Moses Lake 47 76 46 80 50 79 / 10 10 0 0 0 20
Wenatchee 49 73 49 78 53 74 / 10 0 0 0 0 20
Omak 45 74 43 77 46 76 / 50 10 10 0 0 30
&&
Otx watches/warnings/advisories...
Idaho...none.
Washington...none.
&&
$$
