684
FXUS66 KOTX 011106
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
406 AM PDT Wed May 1 2024

.SYNOPSIS...
The weather will stay unsettled and chilly until the week`s end,
with a slight increase in temperatures from Thursday into Friday.
The weekend forecast is looking more certain and its hedging
toward another bout of cool and wet weather, particularly on
Sunday. Expect cool temperatures and sporadic showers to persist
into early next week.

&&

.DISCUSSION...

Today through Thursday Night...Today, the weather will get a bit
warmer but remain cooler than normal by about 5 degrees with high
temperatures in the mid 50s to low 60s. Shower will make a come
back, mostly affecting the Idaho Panhandle and far northeast WA.
With the temperatures rise, the precipitation will likely fall as
just rain, not a mix of rain and graupel. Tonight`s temperatures will
be slightly warmer but there is still a threat of frost with
temperatures in the 30s.

Tomorrow, the low will shift into eastern Montana, while another
forms off the coast. Between the two lows, a weak ridge will build,
with warmer temperatures reaching into the 60s. Shower coverage will
be less again, with them mainly contained over the higher terrain in
the ID Panhandle. The rest of the CWA will remain dry with clear to
party clear skies. /KM

Friday...The cool and unstable upper level low that region has
been subject to the last couple of days will likely move east of
the area on Friday as a shortwave ridge moves over the Inland NW.
This should result in a relatively mild day compared to the last
several days with 850 mb temperatures climbing into the 7-9C. This
translates to high temperatures generally in the 60s with a few
lower 70s over the LC Valley and lower Columbia Basin. Most
locations will be dry as there is limited moisture and even less
synoptic lifting. However they may be just enough orographic
ascent and residual instability to trigger some light showers over
the ID Panhandle mountains.

Saturday...Another deep upper level low and associated occluded
front is forecast to move onto the WA/OR coast which pushes the
shortwave ridge into western MT by afternoon. This transition will
also lead to a significant increase in atmospheric moisture with
the precipitable water values rising from below normal on Friday
to nearly 150% of normal by afternoon. Temperatures could prove
tricky depending on the speed of the front. It now looks like the
eastern third of WA and north ID could be as warm if not a little
warmer than Fridays readings, however there is a lot of model
spread with high temperatures ranging from the lower 60s to lower
70s in the Spokane area. Over central WA there is still a lot of
model spread but good confidence that it will be cooler than
Friday. Meanwhile precipitation amounts will generally range from
0.05-0.15 over central WA and generally less than 0.05
elsewhere.

Saturday night into Sunday...Model confidence is growing about
the track of the aforementioned upper level low. Yesterdays runs
showed large deviations with most of the GEFS runs taking the
upper low well south into NV, whereas the other model suites kept
it over the northern half of Oregon. Now it seems the farther
north solution is favored. This would result in a rather wet and
cool forecast. Precipitation amounts will depend on where a
deformation band, north of the upper low, is expected to set up.
There is a wide variation in where that is expected to occur but
it is likely to be somewhere over the Inland NW. There is a 40-50%
of seeing precipitation amounts above a half inch during this
period across SE WA into the central ID Panhandle with the
Spokane/CdA seeing a 15-20% of seeing similar amounts. While the
exact precipitation forecast will be difficult, suffice it to say
most of the region will be wet. Whats more certain is the
temperatures will plummet significantly due to the cloud cover and
rain. It still seems the NBM is playing catch up with this
cooling trend as it is on the warmer end of the model suites and
is significantly warmer than most of the deterministic models. We
could very well see highs remaining in the 40s. The chances of
that are around 55% for Pullman, 45% for CdA, and 30-35% for the
Spokane area. Needless to say those with outdoor plans on Sunday
need to plan accordingly.

Monday and Tuesday...Model consensus still looks much better than
what we expect over the weekend. Although the deep trough is
expected to drift east of the region, we will remain under the
influence of a broad upper level trough focused over much of the
PacNW. This will result in continued cooler than normal weather
with occasional showers. fx

&&

.AVIATION...
12Z TAFS: IFR stratus will form between KGEG and KPUW through
17Z. Otherwise, VFR conditions will prevail through the
forecast. Showers today will remain contained to the ID Panhandle
with Central and Eastern Washington remaining dry.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Low confidence in MVFR stratus forming at TAF sites between KGEG
and KPUW.

-----------------------

Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https://www.weather.gov/otx/avndashboard

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        59  34  62  36  66  46 /  20  10  10   0   0  10
Coeur d`Alene  55  33  60  37  63  43 /  30  20  20  10   0  10
Pullman        53  31  58  35  63  46 /  20   0  10   0   0  10
Lewiston       60  36  65  41  71  48 /  20   0  10   0   0  10
Colville       61  31  64  33  66  41 /  20  10  20  10  10  10
Sandpoint      53  36  59  36  61  42 /  50  30  40  20  20  10
Kellogg        48  36  55  36  61  43 /  60  30  40  20  20  10
Moses Lake     66  32  68  36  71  50 /   0   0   0   0   0  30
Wenatchee      63  39  66  42  67  51 /   0   0   0   0  10  30
Omak           65  37  69  40  68  49 /  10  10   0   0  10  20

&&

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

$$