757
FXUS66 KPDT 060440
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
940 PM PDT SUN JUL 5 2026
KEY MESSAGES
- WARMING TREND CONTINUES, PEAKING TUESDAY.
- ISOLATED THUNDERSTORMS POSSIBLE THROUGH TUESDAY.
- DRY AND WINDY CONDITIONS TUESDAY.
*FIRE WEATHER WATCH ISSUED*
DISCUSSION
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS DRY CONDITIONS
UNDER MOSTLY CLEAR SKIES. THIS IS A RESULT OF A WEAK AND DRY
COLD FRONT THAT HAS STALLED OVER SOUTHEAST OREGON, BRINGING
SLIGHTLY COOLER HIGH TEMPERATURES ACROSS THE REGION. THE UPPER
LEVEL RIDGE WILL REBUILD MONDAY AND TUESDAY, ENHANCING SOUTHWEST
FLOW ALOFT AND INCREASING HIGH TEMPERATURES BACK INTO THE
MID-90S MONDAY AND NEARING THE TRIPLE DIGITS FOR AREAS ACROSS
THE LOWER COLUMBIA BASIN ON TUESDAY. THE NBM SUGGESTS A 30-40%
CHANCE OF REACHING 100 DEGREES ACROSS TRI-CITIES AND WALLA
WALLA. THESE HIGH TEMPERATURES, COUPLED WITH MINOR OVERNIGHT
RELIEF DUE TO MORNING LOWS STILL AROUND 60 DEGREES, WILL LEAD TO
AREAS OF MODERATE (2 OUT OF 4) HEATRISK MONDAY AND TUESDAY.
THESE AREAS WILL BE MORE CONFINED TO THE EASTERN GORGE, HANFORD
AREA, AND THE YAKIMA/KITTITAS VALLEYS ON MONDAY, BEING MORE
WIDESPREAD ACROSS THE LOWER COLUMBIA BASIN AND BLUE MOUNTAIN
FOOTHILLS ON TUESDAY.
AN UPPER LEVEL SHORTWAVE WILL APPROACH FROM THE SOUTH THIS
EVENING INTO MONDAY, ALLOWING FOR A SLIGHT CHANCE (10%) OF
DEVELOPING THUNDERSTORMS ACROSS CENTRAL OREGON THIS EVENING.
CHANCES WILL MATERIALIZE AROUND 1600 AND PEAK AFTER 2000 FOR
SOUTHERN DESCHUTES, CROOK, AND GRANT COUNTIES. BETTER
THUNDERSTORM CHANCES (20-30%) ARE EXPECTED ON MONDAY AS TWO
WEAK SHORTWAVES CONVERGE AND A SURFACE LOW DEVELOPS OVER THE
COLUMBIA BASIN. CAPE VALUES OF 400-500 J/KG AND LOW LEVEL LAPSE
RATES OF 7-7.4/KM WOULD PROVIDE ENOUGH INSTABILITY FOR STORMS TO
INITIATE, WHICH ALIGNS WITH THE STORM PREDICTION CENTER
INCLUDING OUR SOUTHERN AND EASTERN ZONES IN THEIR GENERAL
THUNDERSTORMS (0 OUT OF 5) CATEGORY. THESE AREAS WOULD PRIMARILY
INCLUDE DESCHUTES, GRANT, CROOK, UNION, AND WALLOWA COUNTIES.
THE SURFACE LOW AGAIN DEVELOPS OVER THE COLUMBIA BASIN TUESDAY
AS AN INCOMING UPPER LEVEL TROUGH MOVES INLAND ALONG THE BRITISH
COLUMBIA COAST. THIS WILL BRING A MORE WIDESPREAD THREAT OF
ISOLATED THUNDERSTORMS ACROSS THE BLUE MOUNTAINS AND EXTENDING
THROUGH CENTRAL AND EASTERN OREGON, ALBEIT LOW (10-20%) CHANCES
AT THIS TIME. WIND SHEAR IS BETWEEN 15-25 KTS EACH DAY, WHICH
RELATES TO SLOW MOVING STORM CELLS THAT SHOULD NOT DEVELOP
ENOUGH FOR SEVERE THUNDERSTORM CONDITIONS. THUS, GUSTY WINDS,
LIGHTNING, AND SMALL HAIL ARE THE MAIN CONCERNS.
THE INCOMING UPPER LEVEL TROUGH ON TUESDAY WILL NOT ONLY
PROMOTE THUNDERSTORM POTENTIAL ACROSS OUR EASTERN MOUNTAIN AND
CENTRAL OREGON ZONES, BUT WILL ALSO INCREASE WINDS ACROSS THE
COLUMBIA BASIN AND KITTITAS VALLEY. THIS IS DUE TO THE PRESSURE
GRADIENT BETWEEN THE INCOMING TROUGH AND DEPARTING UPPER LEVEL
RIDGE, WHICH ENHANCES INTO MONTANA AND SOUTHERN SASKATCHEWAN.
WEST WINDS OF 10-20 WITH GUSTS UP TO 30 MPH COUPLED WITH
AFTERNOON HUMIDITIES IN THE LOW TO MID-TEENS WILL LEAD TO
ELEVATED FIRE WEATHER CONCERNS. THIS HAS WARRANTED THE ISSUANCE
OF A FIRE WEATHER WATCH ACROSS THESE AREAS THROUGH THE
AFTERNOON AND EVENING ON TUESDAY.
NEAR NORMAL TEMPERATURES ARE EXPECTED WEDNESDAY ONWARD AS FLOW
ALOFT BECOMES MORE ZONAL. BREEZY DIURNAL WINDS WILL STILL OCCUR
ACROSS THE EASTERN GORGE THROUGH THE WEEK, EXTENDING ACROSS THE
LOWER COLUMBIA BASIN FRIDAY INTO SATURDAY AS ANOTHER UPPER LEVEL
TROUGH APPROACHES THE AREA. 75
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
SHOWERS OVER CENTRAL OREGON MAY LEAD TO A BRIEF VISIBILITY DROP
TO MVFR AT BDN OR RDM MONDAY AFTERNOON (ABOUT A 10% CHANCE).
OTHER THAN THAT THERE ARE NO IMPACTS TO TERMINALS AS WINDS
REMAIN BELOW 12 KNOTS AND CEILINGS ARE BETWEEN 10 TO 24KFT OVER
THE TAF PERIOD.
FIRE WEATHER
THE PRESENT UPPER LEVEL RIDGE TO OUR SOUTHEAST AND THE INCOMING
SHORTWAVES THIS EVENING AND AGAIN ON MONDAY WILL KEEP THE
ISOLATED THUNDERSTORM THREAT ACROSS CENTRAL AND EASTERN OREGON,
WITH THE BEST CHANCES EXPECTED ON MONDAY. PRECIPITABLE WATER OF
AROUND 0.70" WILL LEAD TO THE POTENTIAL FOR A BRIEF DOWNPOUR,
BUT IT IS MORE LIKELY THAT THE MAJORITY OF DEVELOPED
THUNDERSTORMS MAY SAY DRY. ANY CELLS DEVELOPING TODAY SHOULD
STAY TO OUR SOUTH, BUT MONDAY'S EXTENT MOVES FURTHER NORTH INTO
ZONES: OR696, OR700, AND OR705. THUNDERSTORMS WILL ALSO BE
POSSIBLE FOR ZONES: OR693, OR694, OR695, OR697. OR698, AND
OR699, BUT THESE ZONES HAVE YET TO BE DEEMED RED FLAG READY
RELATED TO CURRENT FUEL STATUS. THUNDERSTORMS AGAIN DEVELOP ON
TUESDAY ASSOCIATED WITH A LARGER TROUGH PASSAGE ACROSS CENTRAL
CANADA, BUT INCREASED PRECIPITABLE WATER OF AROUND 0.90" SHOULD
INHIBIT THE OCCURRENCE OF DRY LIGHTNING.
TUESDAY'S INCOMING TROUGH WILL ALSO LEAD TO CRITICAL FIRE
WEATHER CONCERNS ACROSS THE LOWER COLUMBIA BASIN AND THE
KITTITAS VALLEY ASSOCIATED WITH BREEZY WINDS AND LOW HUMIDITIES.
THUS, A FIRE WEATHER WATCH HAS BEEN ISSUED FOR OR/WA691 AND WA
690 BETWEEN 11 AM AND 10 PM TUESDAY. SUSTAINED WEST WINDS OF
10-20 MPH WITH GUSTS UP TO 30 MPH AND HUMIDITIES AS LOW AS 13%
WILL BE POSSIBLE. THE NBM ADVERTISES A 50-80% CHANCE OF RED FLAG
CONDITIONS BEING MET FOR ALL AREAS INCLUDED IN THE CURRENT WATCH.
75
PRELIMINARY POINT TEMPS/POPS
PDT 55 89 58 95 / 0 0 0 0
ALW 58 91 62 97 / 0 0 0 0
PSC 56 93 59 99 / 0 0 0 0
YKM 58 95 61 98 / 0 0 0 0
HRI 56 92 60 97 / 0 0 0 0
ELN 54 92 59 92 / 0 0 0 0
RDM 53 89 54 91 / 0 20 10 10
LGD 54 87 56 93 / 0 10 0 10
GCD 55 87 54 94 / 0 50 10 10
DLS 60 96 64 92 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY
EVENING FOR WAZ690-691.
OR...FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY
EVENING FOR ORZ691-703.
DISCUSSION...75
AVIATION...71
FIRE WEATHER...75
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