057
FXUS66 KOTX 291213
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
513 AM PDT Wed May 29 2024

.SYNOPSIS...
A cool and showery day with afternoon thunderstorms will occur
today, followed by areas of frost overnight into Thursday morning
and again for Friday morning. Drier weather is expected Thursday
and Friday. A chance of mountain showers returns on Saturday
followed by the potential for more widespread rain early next
week. There is increasing confidence for above normal temperatures
for the latter half of next week.

&&

.DISCUSSION...

Today through Thursday night: Cold front swung through yesterday
making way for the cold upper level trough to make its entrance
today. A -28 Celsius cold pool at 500 mbs will move in right over
the eastern Washington by this afternoon. This will result in
steepening mid level lapse rates with a conditionally unstable
atmosphere. All we need is the sun, and there will be plenty of
that early in the day to erode the inversion and destabilize the
lower levels of the atmosphere. Skinny CAPE in the neighborhood of
200-400 J/kg is expected by peak heating this afternoon. The
northern mountains of eastern Washington will destabilize first by
11AM this morning, followed by the higher terrain in the
Panhandle by noon, and then the Columbia Basin between 1-2PM. By
2-5PM, widely scattered showers can be expected regionwide.
Chances will be less (10-20%) in the lee of the Cascades, to
around 40-60% in the Spokane/Cd`A areas and Palouse, to 60-80%
across the higher terrain of northeast Washington and the Idaho
Panhandle.

Thunderstorms will be more likely today compared to yesterday:
the Columbia Basin will see a 15% chance for thunderstorms up to
around 30% chances over the Northeast Mountains into the Idaho
Panhandle. Thunderstorms will develop in a weak shear environment
meaning that storms will collapse fairly quickly and spit out up
to a handful of lightning strikes before decaying. Other hazards
that can be expected are gusty outflow winds of up to 40 mph, pea
sized hail, and brief heavy downpours. Have a plan to seek shelter
if deciding to enjoy outdoor activities this afternoon or
evening. Winds will continue to be breezy through this afternoon
and evening with gusts of up to 30-35 mph with the synoptically
forced winds. As previously mentioned, these winds may be enhanced
with convection today.

Showers and cloud cover will dissipate quickly with the loss of
daytime heating this evening. The focus for tonight will turn to
widespread frost development. Drier air will continue to funnel in
with yesterday`s frontal passage. Dew points are expected to dip
down into the upper 20s. Winds will weaken overnight, but won`t
completely die off across the exposed areas of the Columbia Basin.
Air flow across these areas from Wenatchee to Moses Lake, Ritzville,
Davenport, Spokane, and the Palouse region will keep temperatures
from bottoming out near freezing. Winds will die off however in
the northern mountain valleys overnight and low temperatures have
been lowered to between 30-34 degrees across much of the lower
elevations there. This include Republic, Colville, Chewelah, Deer
Park, Newport, Ione, and Metaline Falls to name a handful of
communities. These areas are under a freeze watch that includes
tonight and Thursday night. Winds will be even weaker Thursday
night without much increase in temperatures aloft, which should
result in a second night of strong radiational cooling and the
potential for freezing temperatures again. There will be pockets
in the Cascades and the Idaho Panhandle that may reach freezing,
but not widespread enough to warrant a freeze watch. More areas
may require a frost advisory tonight, and possibly for Thursday
night as well. Take action now to protect crops or sensitive
vegetation from frost or freeze damage.

Ridging of higher pressure will be nosing in on Thursday resulting
in a mush drier day. We are hanging on to isolated showers across
the far northeast portion of the region, which mainly just includes
the Northern Panhandle. Equilibrium levels don`t look to be high
enough to achieve the charge separation needed for thunderstorm
development Thursday afternoon. /SVH

Friday through Tuesday: Dry conditions and seasonably warm
conditions are forecast for Friday under a brief period of ridging.
And while some uncertainty does remain for the weekend into early
next week, we are anticipating increasing chances for showers,
especially by Sunday night and Monday. Occasionally breezy winds are
also expected each day, though any gusts are currently looking to
remain below 30 mph. Beyond the 7-day forecast, building high
pressure is looking more likely for late next week with much warmer
temperatures favored. /KD

&&

.AVIATION...
12Z TAFS: Drier air behind a cold front will promote VFR
conditions into Wednesday. Winds will also be breezy due to cold
air advection behind the cold front with west winds gusting to
20-25 kts with locally stronger gusts. Some of these enhanced
gusts will occur Wednesday afternoon as showers increase across
the region. Convective allowing models (CAMs) are in good
agreement of locally enhanced gusts as high as 35-40 kts, but
location and timing carry low confidence. Isolated thunderstorms
are expected as well, with the best chances over Northeast
Washington into the Idaho Panhandle. There will be enough
instability for thunderstorm chances down into the Spokane/Coeur
d`Alene area and the Palouse after 21Z. Hazards with
thunderstorms may include gusty outflow winds, pea sized hail, and
brief heavy downpours with visibility down to around 4SM. /SVH

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Convection is expand across much of the Inland Northwest after 18Z
today. However, there is low confidence for thunderstorms to
impact airport terminals: less than 10% chance for KEAT-KEPH-KMHW,
a 15-25% chance for KLWS-KPUW-KGEG-KSFF, and a 30% chance at KCOE.
/SVH

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

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        60  37  65  35  71  48 /  60  50   0   0   0   0
Coeur d`Alene  58  36  62  37  69  46 /  70  70   0   0   0   0
Pullman        57  35  60  37  68  47 /  40  60   0   0   0   0
Lewiston       67  42  70  44  77  53 /  40  50   0   0   0   0
Colville       59  32  65  34  71  43 /  80  60   0   0   0   0
Sandpoint      58  36  61  37  67  45 /  90  80  20   0   0   0
Kellogg        55  38  59  39  67  48 /  60  80  10   0   0   0
Moses Lake     66  36  72  38  76  53 /  30  10   0   0   0   0
Wenatchee      64  41  69  44  75  56 /  20  10   0   0   0   0
Omak           65  36  70  39  75  50 /  40  10   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Freeze Watch from late tonight through Friday morning for
     Northeast Mountains-Okanogan Highlands.

&&

$$