468
FXUS66 KPDT 042101
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
201 PM PDT FRI JUL 4 2025
SHORT TERM...THIS AFTERNOON THROUGH SUNDAY
AN UPPER-LEVEL LOW-
PRESSURE SYSTEM IS MOVING ONSHORE INTO WESTERN OREGON THIS
AFTERNOON, INDUCING WIDESPREAD CLOUDINESS AND PRECIPITATION OVER
THE FORECAST AREA.
THE FIRST OF TWO SHORTWAVES EMBEDDED WITHIN THE BROADER LOW IS
CONTINUING TO MOVE INLAND ACROSS EASTERN OREGON, WESTERN IDAHO,
AND SOUTHEAST WASHINGTON. ACTIVITY WITH THIS WAVE HAS DEVELOPED
INTO A WEAK DEFORMATION BAND AND IS SUPPRESSING AFTERNOON
TEMPERATURES.
MEANWHILE, CLEARING ACROSS CENTRAL OREGON AND THE OCHOCO-JOHN DAY
HIGHLANDS EARLY AFTERNOON HAS FACILITATED MODEST (250-500 J/KG)
SURFACE-BASED CAPE. THE SECOND SHORTWAVE IS MOVING INTO SOUTHWEST
OREGON AND IS PROGGED TO PROPAGATE IN INLAND OVER SOUTH-CENTRAL
AND EASTERN OREGON THROUGH THE REMAINDER OF THE AFTERNOON AND
EVENING. COUPLED WITH FALLING HEIGHTS ALOFT AS THE MAIN UPPER LOW
MOVES OVERHEAD, THIS SHOULD AID ADDITIONAL THUNDERSTORM
DEVELOPMENT PRIMARILY FOR DESCHUTES, CROOK, WHEELER, AND GRANT
COUNTIES.
OF NOTE, 12Z HREF NEIGHBORHOOD PROBABILITIES ARE HIGHLIGHTING UP
TO A 70% CHANCE OF 3-HR PRECIPITATION EXCEEDING 1 INCH OVER LAST
YEAR'S BURN SCARS IN THE OCHOCO-JOHN DAY HIGHLANDS. THE MAIN BURN
SCARS OF CONCERN INCLUDE THOSE ASSOCIATED WITH THE WILEY FLAT,
RAIL RIDGE, CRAZY CREEK, AND FALLS FIRES. AFTER COLLABORATION
WITH BOI, HAVE ISSUED A FLASH FLOOD WATCH FOR THE AFOREMENTIONED
BURN SCARS, VALID THROUGH 8PM PDT.
QUIETER WEATHER WILL RETURN SATURDAY AND SUNDAY AS THE LOW EXITS
TO THE EAST AND DRIER ZONAL FLOW ALOFT MOVES OVERHEAD.
PLUNKETT/86
LONG TERM...MONDAY THROUGH THURSDAY
CONFIDENCE IS INCREASING
IN WARM TO HOT WEATHER MONDAY THROUGH THURSDAY AS AN UPPER-LEVEL
RIDGE OF HIGH PRESSURE BUILDS OVER THE PACIFIC NORTHWEST. THAT
SAID, ENSEMBLE CLUSTERS DO DEPICT SOME DIFFERENCES IN THE 500-HPA
HEIGHT FIELD OVER THE REGION, MOST NOTABLY THE EVOLUTION OF A
CLOSED LOW THAT ALL CLUSTERS SHOW OFF THE NW CALIFORNIA COAST
MONDAY. ENSEMBLE MEAN 500-HPA HEIGHTS AND VORTICITY SHOW THE
AFOREMENTIONED LOW TRACKING INLAND ACROSS SOUTHERN OREGON AND THE
NORTHERN GREAT BASIN LATE TUESDAY THROUGH WEDNESDAY. FARTHER NORTH
ACROSS SOUTHERN BC, ROUGHLY HALF OF ENSEMBLE MEMBERS SHOW A
SHORTWAVE TROUGH PROPAGATING INLAND, SIGNIFICANTLY REDUCING THE
AMPLITUDE OF THE RIDGE OVER THE PACIFIC NORTHWEST. THE TRACK AND
TIMING OF THE CLOSED LOW AND SHORTWAVE WILL MODULATE TEMPERATURES
AS WELL AS SHOWER AND THUNDERSTORMS CHANCES. PROBABILITIES OF
SHOWERS AND THUNDERSTORMS ARE CURRENTLY TOO LOW (<10%) TO HAVE IN
THE FORECAST.
FORECAST HEATRISK RANGES FROM MODERATE (LEVEL 2 OF 4) ON MONDAY
AND WEDNESDAY TO MAJOR (LEVEL 3 OF 4) ON TUESDAY. THIS LEVEL OF
HEAT WOULD SUPPORT HEAT ADVISORIES FOR THE YAKIMA/KITTITAS
VALLEYS, LOWER COLUMBIA BASIN, AND FOOTHILLS OF THE NORTHERN BLUE
MOUNTAINS ON TUESDAY. PLUNKETT/86
AVIATION...18Z TAFS
VFR CONDITIONS ARE FORECAST THROUGH THE
VALID PERIOD FOR ALL SITES, THOUGH BDN/RDM HAVE A 20-30% CHANCE
OF TEMPORARY SUB-VFR CIGS AND/OR VSBYS IN SHOWERS OR THUNDERSTORMS
THIS AFTERNOON AND EARLY EVENING. CONFIDENCE IN PRECISE
TIMING/LOCATION WAS TOO LOW TO MENTION BEYOND VCSH AT ISSUANCE
TIME.
WINDS WILL BE PREDOMINANTLY 5-15 KTS FOR ALL SITES, WITH
GUSTS OF 15-25 KTS IN THE AFTERNOON AND EVENING HOURS, STRONGEST
AT DLS. PLUNKETT/86
FIRE WEATHER
THROUGH THIS EVENING, A LOW-PRESSURE SYSTEM
MOVING OVER THE PACIFIC NORTHWEST WILL FACILITATE WIDESPREAD
PRECIPITATION CHANCES, HIGHEST FOR OREGON. ADDITIONALLY, A CHANCE
OF THUNDERSTORMS IS FORECAST FOR CENTRAL OREGON AND THE BLUE
MOUNTAINS. CHANCES OF WETTING RAIN THROUGH THE EVENING ARE MEDIUM-
HIGH (50-80 PERCENT FOR THE BLUE MOUNTAINS) WITH LOW-MEDIUM
CHANCES (30-60 PERCENT) FOR THE REST OF CENTRAL AND EASTERN
OREGON. NO RED FLAG WARNINGS HAVE BEEN ISSUED DUE TO THE
ANTICIPATED WETTING RAIN, BUT FREQUENT CLOUD-TO-GROUND LIGHTNING
IS EXPECTED. THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LOCALLY
HEAVY RAINFALL, SMALL HAIL, AND STRONG, GUSTY OUTFLOW WINDS IN
EXCESS OF 60 MPH ACROSS SOUTHEAST DESCHUTES, CROOK, AND GRANT
COUNTIES THIS AFTERNOON AND EVENING. PLUNKETT/86
PRELIMINARY POINT TEMPS/POPS
PDT 57 86 56 91 / 20 0 0 0
ALW 61 86 60 90 / 10 0 0 0
PSC 59 89 56 92 / 10 0 0 0
YKM 59 88 57 91 / 10 0 0 0
HRI 59 89 57 93 / 10 0 0 0
ELN 58 85 57 88 / 10 0 0 0
RDM 43 82 45 89 / 20 0 0 0
LGD 52 81 53 87 / 30 0 0 0
GCD 47 82 51 89 / 60 0 0 0
DLS 56 84 57 90 / 10 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...FLASH FLOOD WATCH UNTIL 8 PM PDT THIS EVENING FOR ORZ506.
WA...NONE.
SHORT TERM...86
LONG TERM....86
AVIATION...86
FIRE WEATHER...86
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