Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Spokane Washington
640 am PDT sun may 3 2015

Synopsis...

Today will be mild and sunny with light winds. Monday will be
quite warm with widespread 70s returning to the region. A strong
cold front is expected Monday night and will likely return our
temperatures into the 60s Tuesday. Cooler and breezy weather is
in the forecast for Tuesday. Spotty showers will be possible
Tuesday and Wednesday followed by the potential for gusty
northeast winds Thursday and Friday.

&&

Discussion...
today through Monday night...a closed low clearly seen on infrared
satellie imagery out in the eastern Pacific Ocean near 50n/145w
will move east...reaching Vancouver Island Monday night. Until
then...clear skies will be the rule except for a few high clouds
passing through at times. Temperatures will warm today under
abundant sunshine...with 850mb temps near 11c supporting valley
highs mostly in the upper 60s to mid 70s. On Monday as the flow
becomes southwest ahead of the approaching low and abundant sun
persists...850mb temps warm further to near 14c with widespread
70s expected. A few low 80s will also occur in the warmest spots
such as Moses Lake and Lewiston.

For Monday night...weather changes begin as a strong cold front
tracks across the region. Models continue to show a band of
elevated convection ahead of the cold front from the Blue
Mountains extending north-northeast into the Idaho Panhandle. Models are
showing the Lewiston area, Palouse, and central Panhandle
mountains most likely to be impacted...with the Spokane area and
NE Washington mountains possibly on the western fringes of this
activity. Instability parameters are marginal for thunderstorms
although a few strikes are not out of the question. After a mild
Monday...850mb temps by Tuesday morning drop to 0 to -2c along
the Cascade crest and 0 to 3c over the Idaho Panhandle. This will
result in rapidly falling snow levels...although moisture looks
limited with only the Cascade passes having a threat for light
snow showers by Tuesday morning. This type of air mass change will
also result in breezy winds...with the potential for local gusts
of 25-35 mph for a brief period with the front passage. Jw

Tuesday and wednesday: there is better agreement between the
medium range models Tuesday and Wednesday than there has been in
recent days. The NAM, GFS, and European model (ecmwf) bring an upper low inland on
Tuesday and stretch it apart on Wednesday. The Heart of the cold
pool instability on the 00z runs doesn't even make it into eastern
Washington or north Idaho before the 500mb low shears southward
Wednesday night into Thursday. The evolution of the 00z runs is
not a favorable scenario for meaningful precipitation for much of
the inland northwest. Tuesday's precipitation chances were lowered
over the Idaho Panhandle and the eastern third of Washington. The
00z models have a dry slot over these areas and if they are
correct, it may be tough to get any showers Tuesday afternoon and
evening east of the Cascades. Wednesday could be our best shot
for showers under the decaying cold pool. Models a day ago
suggested a band of wrap around precipitation Wednesday or
Thursday. That scenario does not show up for our area any longer
with the precipitation shield much further south into southern
Idaho.

Thursday through saturday: Thursday and Friday look to be mainly
dry. The most significant weather could be the development of
gusty northeast winds. The 00z European model (ecmwf) and GFS depict a day or two
with a tight northeast surface pressure gradient between a deep
low in the Great Basin and high pressure over Alberta and central
Montana. The pressure pattern resembles a winter time Arctic
outbreak, but 850mb temperatures actually suggest that our
temperatures will actually be warming up Thursday into Friday.
Weird to see prolonged northeast winds with warming temperatures.
If the winds materialize (sustained 15 to 20 mph with gusts up to
30 mph), blowing dust could become a concern in the Columbia Basin.
April was much drier than normal, and portions of the open wheat
country have been "worked" in recent weeks. /Gkoch

&&

Aviation...
12z tafs: dry westerly flow aloft will keep the region mainly
cloud-free through 06z Monday except some Flat Mountain cumulus
during the aftn hours. A slight increase in NE winds expected
14-18z at kcoe...otherwise winds will primarily be light and
terrain driven. Jw

&&

Preliminary point temps/pops...
Spokane 70 42 76 43 60 37 / 0 0 0 20 10 10
Coeur D'Alene 69 38 75 42 59 36 / 0 0 0 30 20 20
Pullman 70 37 75 42 59 35 / 0 0 0 30 20 10
Lewiston 76 45 81 49 65 41 / 0 0 10 30 20 20
Colville 73 38 78 47 63 35 / 0 0 0 10 20 30
Sandpoint 68 33 73 44 59 33 / 0 0 0 30 30 20
Kellogg 69 38 75 40 57 34 / 0 0 0 50 30 20
Moses Lake 75 42 80 46 66 40 / 0 0 0 0 10 20
Wenatchee 75 49 79 46 64 43 / 0 0 0 10 20 20
Omak 73 40 78 39 65 37 / 0 0 0 10 20 20

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...none.
&&

$$

National Weather Service Glossary of Abbreviations