425
FXUS66 KOTX 201729
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1029 AM PDT SUN JUL 20 2025
KEY MESSAGES
- TEMPERATURES COOL INTO THE 70S AND 80S THROUGH TUESDAY.
- SHOWER AND THUNDERSTORM CHANCES OVER THE NORTHERN MOUNTAINS
SUNDAY AND EXPAND REGIONWIDE MONDAY AND TUESDAY.
- ELEVATED FLASH FLOODING POTENTIAL FOR BURN SCARS AND AREAS OF
STEEP TERRAIN MONDAY AND TUESDAY DUE TO THE SLOW-MOVING
NATURE OF STORMS.
SYNOPSIS
TEMPERATURES WILL BE COOLING NEAR TO BELOW NORMAL THROUGH
TUESDAY. SLOW MOVING SHOWERS AND THUNDERSTORMS WILL IMPACT THE
NORTHERN MOUNTAINS TODAY THEN BECOME MORE WIDESPREAD ON MONDAY
AND TUESDAY. HEAVY RAINFALL WILL BE THE MAIN CONCERN WITH THESE
STORMS. A WARMING AND DRYING TREND WILL PREVAIL WEDNESDAY
ONWARD AS LOW PRESSURE MOVES OUT OF THE AREA.
DISCUSSION
SUNDAY: BROAD UPPER-LEVEL TROUGH CONTINUES TO CARVE INTO THE PACNW
DELIVERING QUITE THE CHANGE IN WEATHER CONDITIONS RELATIVE TO
THE LAST TWO MONTHS. ON SATURDAY, ISOLATED TO SCATTERED SHOWERS
AND WET THUNDERSTORMS TRACKED ACROSS THE NORTHERN MOUNTAINS
DELIVERING ANYWHERE FROM 0.05 TO 0.25" OF SPOTTY RAINFALL. AS WE
MOVE INTO SUNDAY, TEMPERATURES AT THE SURFACE WILL COOL ANOTHER
1 TO 3 DEGREES FAHRENHEIT BUT A REINFORCING SHORTWAVE DROPPING
INTO THE TROUGH WILL LOWER 500H TEMPERATURES ANOTHER 1-2C. THIS
WILL EQUATE TO AN UPWARD TREND IN AFTERNOON INSTABILITY OVER THE
NORTHERN MOUNTAINS OF IDAHO AND WASHINGTON ONCE AGAIN AND A BIT
MORE COVERAGE OF SHOWERS AND THUNDERSTORMS STARTING AROUND 1PM
AND CONTINUING INTO THE EVENING HOURS. SEVERAL CAMS INCLUDING
THE HRRR INDICATE MORE CONVECTION OVER THE NORTHERN CASCADES
COMPARED TO SATURDAY AS FAR SOUTH AS LAKE CHELAN. CELLS THAT
DEVELOP SUNDAY AFTERNOON OVER NE WA AND N ID WILL DRIFT TO
NORTHEAST AS THEY DID ON SATURDAY. CELLS OVER THE NORTH CASCADES
WILL BE INFLUENCED BY LITTLE TO NO STEERING FLOW WITH NEAR
STATIONARY MOVEMENT BEFORE DRIFTING WEST BY THE EVENING AS THE
REINFORCING SHORTWAVE DROPS DOWN THE COAST OF WESTERN WA AND
BEGINS TO EVOLVE INTO A CLOSED LOW. PWATS WILL NOT BE TERRIBLY
HIGH AND ON THE ORDER OF 0.60 TO 0.75" WITH SBCAPE RUNNING
BETWEEN 150-300 J/KG ON AVERAGE AND AS HIGH AS 600-700 J/KG
WHERE THERE IS AMPLE SUNSHINE THROUGH LATE AFTERNOON. 0-6KM
SHEAR STARTS OFF BETWEEN 15-20KTS IN THE EARLY AFTERNOON THEN
DECREASES TOWARD 10KTS AS THE DAY WEARS ON AND INTO THE EVENING.
AS SUCH, THUNDERSTORMS SHOULD BE OF THE PULSE NATURE WITH SHORT
LIFE SPANS BUT AS ONE UPDRAFT COLLAPSES, ANOTHER WILL FORM
NEARBY. HEAVIER DOWNPOURS WILL BECOME MORE COMMON ON SUNDAY WITH
HEAVIER CORES PRODUCING 0.10-0.25". A FEW CAMS SUGGEST LOCALLY
HIGHER AMOUNTS IN THE NORTH CASCADES SO THIS IS SOMETHING THAT
WILL NEED TO BE MONITORED CLOSELY NEAR BURN SCARS. OUTSIDE THE
NORTHERN MOUNTAINS, CONDITIONS WILL BE DRY WITH INCREASING MID
AND HIGH CLOUDS STREAMING IN FROM THE WEST. WINDS WILL NOT BE AS
STRONG AS SATURDAY BUT STILL BREEZY ACROSS THE COLUMBIA BASIN,
WEST PLAINS, PALOUSE, AND INTO THE CENTRAL IDAHO PANHANDLE WITH
SPEEDS OF 10-15 MPH AND GUSTS UP TO 20 MPH.
MONDAY: A CLOSED UPPER-LOW WILL SLOWLY DRIFT WEST TO EAST THROUGH
THE REGION DELIVERING COOL TEMPERATURES AND WIDELY SCATTERED
SHOWERS AND THUNDERSTORMS. THERE WILL BE A GOOD AMOUNT OF CLOUD
COVER OVER THE EASTERN THIRD OF WA AND IDAHO PANHANDLE TO LIMIT
AFTERNOON INSTABILITY UNTIL VERY LATE IN THE DAY THUS LIGHTNING
CHANCES WILL BE LOWEST (10-15%). RAINFALL AMOUNTS FOR LOCATIONS
LIKE RITZVILLE, PULLMAN, SPOKANE, SANDPOINT, AND SAINT MARIES
WILL MOST LIKELY RANGE FROM A FEW HUNDRETHS TO 0.15" COMING WITH
A 10-20% CHANCE FOR 0.10" OR MORE. THE FOCUS MORE ACTIVE
WEATHER WILL BE ACROSS THE NORTHERN MOUNTAINS WRAPPING BACK INTO
CENTRAL WA INCLUDING COLVILLE, REPUBLIC, OMAK, WINTHROP,
CHELAN, WENATCHEE, AND PLAIN. THESE AREAS SHOULD BE ON THE
NORTHERN PERIPHERY OF THE MAIN CLOUD SHIELD WITH A 40-60% CHANCE
FOR AMPLE SURFACE HEATING AND SB CAPE IN EXCESS OF 400 J/KG.
CAM MODELS ARE SHOWING WIDELY SCATTERED CELLS WITH POCKETS OF
MODERATE TO HEAVY RAIN. WIND SHEAR OF 10-20KTS IS NOT FAVORABLE
FOR ORGANIZED OR LONG-LIVED UPDRAFTS BUT CELL MOVEMENT WILL BE
FROM EAST TO WEST/SOUTHWEST AT 10-15 MPH WHICH IS A FAVORABLE
STORM MOTION FOR HEAVY RAIN PRODUCERS IN THE CASCADES. GIVEN
MARGINAL PWATS AND CAPE, FLOODING ISSUES WILL COME FROM A
COMBINATION OF TRAINING CELLS (SEVERAL CELLS MOVING OVER THE
SAME AREA) AND WARM RAIN PROCESSES AS FORECAST SOUNDINGS
INDICATE THE GREATEST CONCENTRATION OF CAPE IN THE LOWER
ATMOSPHERE OR GENERALLY WARMER THAN -10C. ALL THINGS CONSIDERED,
MONDAY AFTERNOON WILL BE A DAY TO KEEP AN EYE TO THE SKY IF YOU
HAVE OUTDOOR PLANS, ESPECIALLY IN CENTRAL AND NORTHERN
WASHINGTON. THERE WILL NOT BE MUCH IN THE WAY OF WIND WITH THESE
CELLS. ONE THING I NOTICED WITH SOME OF THE HI-RES MODELS THAT
ARE STARTING TO TRICKLE IN WOULD BE FOR THE CLOUD SHIELD AND
MORE WIDESPREAD SHOWERS TO SET UP FURTHER NORTH. THIS COULD
LIMIT INSTABILITY PARAMETERS FOR CENTRAL AND NORTHERN WA AND
LOWER THE THREAT FOR THE HEAVIER PRECIP CORES.
THE OTHER AREA OF ELEVATED INSTABILITY WILL BE ACROSS EXTREME
SOUTHEASTERN WA AND THE LOWER IDAHO PANHANDLE STRETCHING FROM
THE BLUE MOUNTAINS TO CENTRAL PANHANDLE MOUNTAINS. BREAKS IN THE
CLOUDS IN THE AFTERNOON LEADS TO A SECONDARY AREA WHERE CAPE
PROBABILITIES FOR 400 J/KG RANGE BETWEEN 20-40%. THIS AREA WILL
ALSO BE LOCATED SOUTH OF THE MIDLEVEL LOW AND IN AN AREA OF
ENHANCED 500MB WINDS WITH HREF 0-6KM SHEAR ON THE ORDER OF
30-40KTS. IF CLOUDS BREAKS ARE SUFFICIENT AND CAPES REACH 500
J/KG OR GREATER, WOULD NOT RULE OUT A FEW ORGANIZED CELLS WITH
HAIL AND GUSTY WINDS. ASOTIN, LEWISTON, WINCHESTER, AND LENORE
ARE THE AREAS THAT WOULD BE WITHIN THIS SECONDARY AREA.
TUESDAY: THE UPPER-LOW WILL CONTINUE TO SPIN OVER THE REGION
WITH A SLIGHT DRIFT TO THE EAST YET ANOTHER SHORTWAVE IS
PROGGED TO DROP INTO ITS BACKSIDE WITH A REINFORCING SHOT OF
COOLER AIR ALOFT. AS SUCH, WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR MUCH OF THE INLAND
NW. NBM SHIFTS THE HIGHEST CAPES INTO THE IDAHO PANHANDLE AND
NORTHEASTERN WA BUT WOULD NOT RULE OUT CONVECTION IN SOME FORM
JUST ABOUT ANYWHERE. NE WA AND N ID CARRY THE HIGHEST
PROBABILITIES FOR POCKETS OF WETTING RAINS AND LOCALIZED AMOUNTS
IN EXCESS OF 0.25".
WEDNESDAY - SUNDAY: THERE IS GOOD AGREEMENT IN THE ENSEMBLE CLUSTERS
FOR AN EXTENSION OF THE OFFSHORE RIDGE TO EXPAND INLAND ENDING
THE RAIN THREAT FOR THE INLAND NW AND BRINGING WARMER
TEMPERATURES. THE RIDGE IS FLATTENED BY THURSDAY WITH NEARLY
100% OF THE ENSEMBLES SHOWING ANOTHER TROUGH ARRIVING ON FRIDAY.
THIS SYSTEM LOOKS TO LACK APPRECIABLE MOISTURE IS REFLECTED IN
THE NBM POPS WHICH ARE BELOW 15% AT THIS TIME. THE SYSTEM WILL
BRING AN UPTICK IN WINDS, ESPECIALLY IN THE OPEN WHEAT COUNTRY
AND CASCADE GAPS. NOT SEEING ANY OF THE ANOMALY CHARTS LIGHT UP
BUT WOULD BE PREPARED FOR INCREASED BREEZINESS AND AT LEAST A
RETURN TO ELEVATED FIRE WEATHER CONDITIONS. /SB
AVIATION
18Z TAFS: VFR CONDITIONS THROUGH THE 24 HOUR PERIOD. CONVECTION
WILL DEVELOP OVER THE NORTHERN MOUNTAINS SUNDAY BETWEEN
1300-0400. HEAVY DOWNPOURS AND ISOLATED LIGHTNING STRIKES WILL
BE THE MAIN CONCERNS WITH LOCAL MVFR CONDITIONS UNDER RAIN
CORES. NORTHERN TERMINALS INCLUDING BONNERS FERRY, COLVILLE,
REPUBLIC, OMAK, AND WINTHROP ARE LOOKING AT A 20-30% CHANCE FOR
T-STORMS. MAINLY THICKENING MID AND HIGH LEVEL CLOUDS FOR THE
COLUMBIA BASIN, PALOUSE, AND SPOKANE-CD'A AREA.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HIGH CONFIDENCE
THAT VFR CONDITIONS WILL CONTINUE AT ALL TAF SITES. LOW
CONFIDENCE FOR T-STORMS TO IMPACT OMAK, REPUBLIC, COLVILLE, AND
BONNERS FERRY DIRECTLY.
PRELIMINARY POINT TEMPS/POPS
SPOKANE 81 61 72 56 77 54 / 0 10 40 30 50 20
COEUR D'ALENE 81 59 72 55 76 54 / 0 10 40 50 60 30
PULLMAN 78 54 70 49 77 50 / 0 20 50 30 30 10
LEWISTON 88 65 80 62 86 62 / 10 30 50 20 20 10
COLVILLE 81 49 71 47 72 44 / 30 30 60 60 70 20
SANDPOINT 78 54 69 52 69 49 / 10 20 60 70 80 40
KELLOGG 77 59 67 57 72 56 / 10 20 60 50 60 30
MOSES LAKE 84 61 77 57 84 57 / 0 10 30 20 20 10
WENATCHEE 85 64 78 63 83 62 / 10 20 50 20 40 10
OMAK 86 60 78 58 84 57 / 30 40 70 50 50 10
OTX WATCHES/WARNINGS/ADVISORIES
WA...NONE.
ID...NONE.
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