Area forecast discussion
National Weather Service Spokane Washington
1045 PM PDT Wed may 22 2013
Synopsis...
a cool and wet period awaits the inland northwest care of a cold
upper level low. Occasional showers are expected each day through
the end of the week with cooler than normal temperatures. Snow
will also be possible over the mountains. Conditions could
moderate a bit by the weekend as the low moves out of the area
but it will be replaced by another cool low sometime early next week.
&&
Discussion...
second update for this evening: a band of nearly stationary light
to locally moderate precipitation remains in place across
boundary...northern Pend Oreille...and northern Stevens counties.
Following some calls to the counties...there is very little issues
regarding flooding from the 1-3 inches of rainfall over the last 2
days. Consequently, we have allowed the Flood Advisory to run its
course and allowed the product to expire as this band will finally
begin to drift north this evening as a dry slot now into
southeastern Washington punches northward.
There are still some nuisance showers that were tied to the
afternoon instability and some weak midlevel forcing that will be
around for the next few hours. The most organized activity is a
along a line extending from Omak to Coeur D Alene. A second
cluster near Walla Walla will drift north into southern Adams and
western Whitman counties within the hour. Lastly, isolated showers
continue to Blossom over the western Columbia Basin and drift west
into the east slopes. Each of these features will be capable of
brief heavy downpours and b-b size hail but should gradually
dissipate with the loss of daytime heating.
The key word is "should"...given the -30c cold pool aloft and
perhaps another midlevel circulation (vort max)...it is not a high
confidence forecast that the region will showers will
cease...especially over the east slopes and far western basin
within the proximity of the parent upper-low and we will maintain
a slight chance to chance wording.
As for temperatures...this is a tough forecast to say the least.
Most locations are carrying dewpoints that would keep temperatures
slightly above freezing tonight but given the clearing moving in
from the southeast under the dry slot...it will be a battle during
radiational cooling between going below freezing and formation of
fog. Several isolated locations like Winchester, Davenport,
Republic, Deer Park, and Priest Lake should reach freezing
overnight but there is low confidence that this will be widespread
enough throughout the zone to include in the freeze warning.
It still looks possible for the Idaho/Washington Palouse so will maintain the
warning and will include the valleys of idz004 (central Panhandle
mtns) and Camas Prairie which received much less precipitation
throughout the day and will experience a great deal of clearing
and light winds overnight and have the best shot for a hard freeze
(25-29f). Locations like Bonners Ferry which fell to 32f under
moderate snow today have rebounded back around 36f and should
quickly fog in tonight as the precipitation ends. /Sb
&&
Aviation...
06z tafs: an upper level low pressure area centered in the vicinity
of the aviation area will keep the threat for -shra vcnty keat and
kmwh through much of the night and thur morning. Aftn heating will
promote light but widely sct -shra across the region for just about
any location. Some showers may produce MVFR ceilings at times.
Additionally some late night and early morning fog could produce
brief IFR/LIFR visibilities with ksff/klws carrying the highest
threat for fog formation. Patchy frost will be possible near kpuw
and kdew. All terminals are expected to receive a break from pcpn
and VFR skies aft 02z. /Sb
&&
Preliminary point temps/pops...
Spokane 36 60 41 60 42 64 / 30 20 20 40 30 30
Coeur D'Alene 35 59 37 60 40 64 / 70 20 20 50 40 30
Pullman 32 59 37 57 40 64 / 20 20 20 50 20 30
Lewiston 36 66 44 64 45 71 / 20 20 10 50 20 30
Colville 35 63 37 68 41 69 / 70 30 30 50 50 40
Sandpoint 34 58 35 62 39 64 / 80 30 20 60 50 40
Kellogg 29 55 37 56 41 61 / 70 30 30 60 50 40
Moses Lake 39 66 41 69 45 72 / 20 20 20 30 20 10
Wenatchee 41 63 44 66 47 69 / 60 40 30 40 20 20
Omak 35 65 37 68 42 69 / 50 30 30 40 30 30
&&
Otx watches/warnings/advisories...
Idaho...freeze warning from 2 am to 7 am PDT Thursday for central
Panhandle mountains-Idaho Palouse-Lewis and southern Nez
Perce counties.
Washington...freeze warning from 2 am to 7 am PDT Thursday for Washington
Palouse.
&&
$$
