444
FXUS66 KOTX 210807
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
107 AM PDT MON JUL 21 2025
KEY MESSAGES
- SHOWER AND THUNDERSTORMS WITH HEAVY RAINFALL OVER THE
NORTHERN MOUNTAINS AND CASCADES MONDAY.
- ELEVATED FLASH FLOODING POTENTIAL FOR BURN SCARS AND AREAS OF
STEEP TERRAIN MONDAY, ESPECIALLY IN THE CASCADES. .
- SHOWERS AND ISOLATED THUNDERSTORMS IDAHO PANHANDLE AND EASTERN
WA MONDAY.
- ISOLATED TO SCATTERED THUNDERSTORMS TUESDAY REGION-WIDE.
- WARMER WITH BREEZY WINDS THURSDAY AND FRIDAY.
SYNOPSIS
SLOW MOVING SHOWERS AND THUNDERSTORMS WILL IMPACT THE NORTHERN
MOUNTAINS THIS AFTERNOON AND EVENING. HEAVY RAINFALL WILL BE
THE MAIN CONCERN WITH THESE STORMS. SHOWERS AND THUNDERSTORMS
WILL DEVELOP AGAIN TUESDAY ACROSS THE INLAND NORTHWEST. A
WARMING AND DRYING TREND WILL PREVAIL WEDNESDAY INTO FRIDAY WITH
BREEZY CONDITIONS RETURNING LATE IN THE WEEK.
DISCUSSION
MONDAY AND TUESDAY: COOL AND UNSETTLED WEATHER PATTERN IS IN
STORE FOR THE INLAND NW AS A MIDLEVEL LOW SWINGS THROUGH THE
REGION. ALTHOUGH THIS WILL BRING WELCOME RAINS TO A DROUGHT
STRICKEN AREA, LOCALIZED RAIN RATES MAY BECOME PROBLEMATIC AT
TIMES, ESPECIALLY IN STEEP TERRAIN AND BURN SCARS RESULTING IN
DEBRIS FLOWS OR LOCALIZED FLOODING. A FLOOD WATCH IS IN EFFECT
FOR MONDAY FOR CHELAN AND OKANOGAN COUNTIES TO ADDRESS THIS
POTENTIAL WITH EMPHASIS ON THE SENSITIVE BURN SCARS FROM THE
LAST 1-3 YEARS.
MONDAY WILL FEATURE TWO DIFFERENT WEATHER REGIMES THROUGH THE
EARLY AFTERNOON AS THE MIDLEVEL LOW TRACKS TOWARD RITZVILLE,
WA. SOUTH AND EAST OF THE LOW, THE ATMOSPHERE WILL FEATURE
OVERCAST SKIES AND STABLE WEATHER CONDITIONS WITH PERIODS OF
STEADY LIGHT RAINS AND/OR LIGHT SHOWERS. THIS INCLUDES LOCATIONS
LIKE LEWISTON, PULLMAN, AND KELLOGG. NORTH AND WEST OF THE LOW
CENTER, THE ATMOSPHERE WILL BE UNSTABLE WITH CONVECTION
DEVELOPING BY AS EARLY AS 10AM TO NOON AND CONTINUING THROUGH
THE EARLY EVENING. THIS INCLUDES COLVILLE TO OMAK AND ALL OF THE
CASCADES. SURFACE DEWPOINTS HAVE COME UP QUITE A BIT OVER THE
LAST 24 HOURS COURTESY OF SHOWERS EACH OF THE LAST TWO
AFTERNOONS AND MANY READINGS AT THE TIME OF THIS AFD ARE IN THE
UPPER 40S TO MID 50S. THIS FACTORS INTO THE EARLIER TIMING WHICH
HAS LOWERED CONVECTIVE TEMPS OR TEMPS FOR CELLS TO BEGIN
FORMING, PURELY FROM DAYTIME HEATING, INTO THE 60-65F. IT MAY BE
CLOSER TO NOON WHEN CELLS CAN GROW DEEP ENOUGH TO BEGIN PUTTING
OUT LIGHTNING STRIKES AND HEAVIER RAIN CORES. ON SUNDAY,
HEAVIER CELLS THAT DEVELOPED OVER THE NORTHERN MOUNTAINS AND
CASCADES WERE PRODUCING RAINFALL RATES OF 0.60/30 MIN. THINKING
THIS WILL BE CASE FOR MONDAY YET COVERAGE BECOMING WIDELY
SCATTERED VS ISOLATED. ANOTHER CONTRIBUTING FACTOR IS THE
LOCATION OF THE CAPE IN THE ATMOSPHERE WHICH REMAIN CENTERED IN
THE LOWER, WARMER PORTION AND LARGELY BELOW -10C WHICH FAVORS
COLLISION AND COALESCENCE OR ESSENTIALLY A WARM RAIN PROCESS
PRODUCING LARGER DROPS AS DROPS COLLIDE AND STICK TOGETHER.
THERE IS HIGH CONFIDENCE THAT HAIL OR WINDS WILL REMAIN ABSENT
IN THIS ACTIVITY AS UPDRAFTS WILL STRUGGLE TO SUSTAIN THEMSELVES
GIVEN 6-12KTS OF 0-6KM SHEAR. SO THESE WILL MAINLY BE QUICK
HEAVY RAINFALL MAKERS AND AS ONE DIES, THE NEXT ONE FORMS IN
CLOSE PROXIMITY. ALL THINGS CONSIDERED, COMMUNITIES ACROSS
NORTHERN AND CENTRAL WA SHOULD BE PREPARED FOR PERIODS OF
MODERATE TO HEAVY RAINFALL AND POTENTIAL FOR DEBRIS FLOWS IF
THESE CELLS WERE TO MOVE OVER A SENSITIVE AREA SUCH AS A BURN
SCAR. CELLS WILL EITHER BE STATIONARY OR DRIFT TO THE WEST AND
SOUTHWEST THROUGHOUT THE DAY.
BETWEEN THESE TWO WEATHER REGIMES, EXACT FORECAST DETAILS ARE BIT
MORE UNCERTAIN AS THE AIR MASS REMAINS DRY IN THE LOWER LEVELS
AND WILL LIKELY LACK ENOUGH CAPE DUE TO CLOUD COVER. THINKING
LIGHT SHOWERS WILL BE POSSIBLE AT SOME TIMES THROUGH THE DAY BUT
IMPACTS WILL BE MINIMAL. THIS INCLUDES MOSES LAKE TO SPOKANE
AND INTO CD'A-SANDPOINT.
MONDAY EVENING, THE STABLE WEATHER CONDITIONS OVER FAR SE WA
AND NC IDAHO WILL TRANSITION TOWARD MORE OF A CONVECTIVE REGIME
AS LATE JULY SUN BREAKS THROUGH AND A DRY SLOT WORKS INLAND
SOUTH OF THE LOW. THIS AREA CONTAINING 25-35 KTS OF SHEAR HAS
THE POTENTIAL FOR A FEW STRONGER CELLS MONDAY EVENING BUT CAM
MODELS CONTINUE TO INDICATE THIS THREAT WILL MAINLY MATERIALIZE
IN NE OREGON AND SKIRT THE CAMAS PRAIRIE. SOMETHING TO WATCH
CLOSELY AS THESE STORMS COULD PROVIDE A BIT MORE BITE WITH HAIL
AND GUSTY WINDS.
MONDAY NIGHT INTO TUESDAY: THE THREAT FOR HEAVY RAIN CORES WILL
WANE MONDAY NIGHT WITH THE LOSS OF HEATING. SHOWERS WILL LIKELY
CONTINUE ACROSS THE NORTHERN MOUNTAINS BUT THERE WILL BE
NOTICEABLE SHIFT IN THE TRACK OF SHOWERS BACK TO THE EAST AS THE
UPPER-LOW LIFTS INTO NW MONTANA AND WEST TO NORTHWEST WINDS
START TO INCREASE ON ITS BACKSIDE.
BY TUESDAY, ANOTHER DAY OF WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS LOOKS TO PLAGUE THE INLAND NW. SHOWERS WRAPPING
AROUND THE BACKSIDE OF THE LOW WILL PASS THROUGH E WA AND N ID
IN THE MORNING THEN AFTERNOON HEATING WILL PROMOTE AFTERNOON
INSTABILITY WITH SURFACE BASED CAPES SURGING BETWEEN 500-1000
J/KG, SEVERAL HUNDRED JOULES HIGHER THAN MONDAY. CAPE WILL ALSO
BE EXTENDING HIGHER INTO THE ATMOSPHERE TOWARD -25C. THIS WILL
BRING THE POTENTIAL FOR A FEW STRONGER CELLS CONTAINING A
COMBINATION OF HEAVY RAIN AND HAIL. SHEAR INCREASES SOME BUT
STILL NOTHING TO WRITE HOME ABOUT REMAINING NEAR 20KTS AT ITS
PEAK. SOMETIMES THE INCREASED CAPE CAN COMPENSATE FOR THE WEAKER
SHEAR FOR A FEW ORGANIZED UPDRAFTS. WIND GUSTS UP TO 30 MPH
CANNOT BE RULED OUT AS WELL. STORMS MOTION WILL BE TO THE EAST
AND SOUTHEAST. THE PRESENCE OF ICE IN THE STORMS WILL ALSO
INCREASE THE AMOUNT OF LIGHTNING STRIKES THAT STORMS WILL BE
CAPABLE OF PRODUCING AND WOULD EXPECT MORE STRIKES FROM
INDIVIDUAL CELLS ON TUESDAY VS MONDAY.
WEDNESDAY THROUGH THE WEEKEND: THERE REMAINS GOOD AGREEMENT
IN THE ENSEMBLE CLUSTERS FOR WEAK RIDGING TO EXPAND INLAND
ENDING THE RAIN THREAT FOR THE INLAND NW AND BRINGING WARMER
TEMPERATURES FOR WEDNESDAY AND THURSDAY. THE RIDGE IS FLATTENED
LATER THURSDAY INTO FRIDAY AS THE NEXT TROUGH APPROACHES. THIS
WILL BRING A RETURN OF BREEZY CONDITIONS AND ELEVATED FIRE
WEATHER CONDITIONS THROUGH THE CASCADE GAPS AND ACROSS THE
BASIN, PALOUSE, WEST PLAINS, AND FOOTHILLS OF THE BLUE
MOUNTAINS. THE INCOMING TROUGH LACKS APPRECIABLE MOISTURE AND IS
LARGELY DRY OUTSIDE 20% OF THE ENSEMBLES SHOWING SHOWERS AND
STORMS ALONG A RIBBON OF INSTABILITY INTERSECTING EXTREME SE WA
AND NC ID. LOOKS TO BE A GREAT WEEKEND TO ENJOY OUTSIDE
RECREATION WITH MINIMAL WEATHER IMPACTS. /SB
AVIATION
06Z TAFS: A TROUGH IS CARVING INTO THE INLAND NW. ON THE SOUTH
SIDE OF THE TROUGH, THERE IS TOP-DOWN MOISTENING FROM THE TRI-
CITIES TO PULLMAN/LEWISTON AND INTO THE IDAHO PANHANDLE. WEAK
ECHOES ARE BLOSSOMING WITH 40% CHANCE FOR SPRINKLES BUT STEADIER
RAINS WILL DEVELOP CLOSER TO SUNRISE. THE BAND WILL WAVER AT
TIMES WITH PERIODS OF RAIN OR SHOWERS POSSIBLE (40% CHANCE) AT
MOSES LAKE AND SPOKANE BUT TIMING COMES WITH SOME UNCERTAINTY.
OVER NORTHERN WA AND N ID, THE ATMOSPHERE IS MORE UNSTABLE.
REMNANTS OF SUNDAY'S CONVECTION WILL CONTINUE TO SLOWLY TAPER
OFF 06-09Z THEN FOCUS WILL SHIFT TOWARD WIDELY SCATTERED SHOWERS
AND THUNDERSTORMS BETWEEN 19-04Z. HEAVY DOWNPOURS AND ISOLATED
LIGHTNING STRIKES WILL BE THE MAIN CONCERNS WITH LOCAL MVFR
CONDITIONS LIKELY UNDER RAIN CORES. NORTHERN TERMINALS
INCLUDING BONNERS FERRY, COLVILLE, REPUBLIC, OMAK, PLAIN,
AND WINTHROP ARE LOOKING AT A 30-40% CHANCE FOR T-STORMS.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: FORECAST COMES
WITH MODERATE UNCERTAINTY REGARDING THE NORTHWARD EXTENT OF
STEADY RAIN INTO SPOKANE-CD'A MONDAY MORNING WITH 50/50 CHANCE
TO JUST HAVE BRIEF LIGHT SHOWERS OR PERIODS OF STEADY RAIN. CIGS
ACROSS THE NORTHERN MOUNTAINS AND AROUND THE CASCADES COULD BE
AS LOW AS 3000 FEET UNDER HEAVY SHOWERS OR STORMS MONDAY
AFTERNOON WITH PERIODS OF VIS AS LOW AS 3SM. LASTLY, THERE IS A
CHANCE FOR SWIFT MOVING T-STORMS, POTENTIALLY STRONGER TO TRACK
FROM NE OR INTO CENTRAL ID AND W MT BTWN 22-03Z. THESE STORMS
WILL BE MORE ORGANIZED WITH HAIL, HEAVY DOWNPOURS, FREQUENT
LIGHTNING, AND GUSTY WINDS. THERE IS A 60% CHANCE THESE REMAIN
SOUTH OF LEWISTON BUT WILL POSE A THREAT TO AVIATION AS THESE
PASS THROUGH. /SB
PRELIMINARY POINT TEMPS/POPS
SPOKANE 72 55 76 55 86 58 / 50 50 60 20 0 0
COEUR D'ALENE 71 55 73 54 83 57 / 60 70 70 30 10 0
PULLMAN 69 49 76 49 83 52 / 80 50 40 20 0 0
LEWISTON 77 61 83 62 91 64 / 80 50 30 10 0 0
COLVILLE 74 47 73 44 83 47 / 70 70 90 30 10 0
SANDPOINT 68 51 68 50 79 53 / 70 80 90 50 10 0
KELLOGG 67 55 71 56 80 59 / 80 60 70 30 10 0
MOSES LAKE 77 58 84 57 91 59 / 40 30 20 10 0 0
WENATCHEE 77 61 83 63 91 64 / 70 50 50 10 0 0
OMAK 79 58 83 57 91 60 / 80 70 70 10 0 0
OTX WATCHES/WARNINGS/ADVISORIES
WA...FLOOD WATCH FROM NOON PDT TODAY THROUGH THIS EVENING FOR
CENTRAL CHELAN COUNTY-OKANOGAN HIGHLANDS-OKANOGAN VALLEY-
WENATCHEE AREA-WESTERN CHELAN COUNTY-WESTERN OKANOGAN
COUNTY.
ID...NONE.
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