122
FXUS66 KPDT 151046
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
246 AM PST FRI NOV 15 2024
SHORT TERM...TODAY THROUGH SUNDAY
AN UPPER LEVEL TROUGH CONTINUES
TO SLOWLY PASS OVER THE FORECAST AREA THIS MORNING AND WILL MOVE OFF
TO THE EAST OVERNIGHT. MEANWHILE, THE COOL UNSETTLE CONDITIONS WILL
CONTINUE TO PRODUCE SOME SHOWERS MAINLY OVER THE EASTERN MOUNTAINS
THROUGH THE DAY THAT COME TO AN END OVERNIGHT AS A BRIEF RIDGE OF
HIGH PRESSURE TRIES TO BUILD INTO THE REGION. THE SNOW SHOWERS
COULD PRODUCE SOME LOCAL ACCUMULATIONS OF 1 TO 3 INCHES THROUGH THIS
EVENING. THE INCOMING UPPER LEVEL RIDGE WILL PROVIDE A BRIEF DRY
SPELL THROUGH SATURDAY MORNING BEFORE THE NEXT SYSTEM BEGINS TO PUSH
OVER THE CASCADES IN THE AFTERNOON. THIS WILL BE A WARM FRONT THAT
WILL CONTINUE TO PUSH EAST ACROSS THE FORECAST SATURDAY NIGHT.
INITIAL SNOW LEVELS WILL START OUT AROUND 2000 TO 3000 FEET IN THE
AFTERNOON AND THEN CLIMB OVERNIGHT THROUGH MIDDAY SUNDAY TO 4000 TO
6000 FEET. THIS WILL LEAD TO SOME INITIAL LIGHT SNOW ACCUMULATIONS
AT ELEVATIONS BETWEEN 2000 TO 4000 FEET BEFORE CHANGING OVER TO RAIN
OVERNIGHT INTO EARLY SUNDAY MORNING. THE WARM FRONT WILL ALSO BE
ACCOMPANIED BY INCREASING SOUTHERLY WINDS OVERNIGHT INTO SUNDAY
WHICH WILL AID IN BOOSTING TEMPERATURES.
A COLD FRONT WILL FOLLOW LATE SUNDAY AND PUSH ACROSS THE FORECAST
AREA OVERNIGHT. SNOW LEVELS WILL BEGIN TO LOWER OVER THE CASCADES
IN THE LATE AFTERNOON AND EVENING PERIOD AND THEN CONTINUE PUSHING
EASTWARD OVERNIGHT LOWERING TO AROUND 2000 FEET OVER THE ENTIRE
FORECAST AREA BY MONDAY MORNING. THE CASCADE CREST IS LIKELY
TO SEE THE BRUNT OF SNOWFALL WITH A 50-70% POSSIBILITY OF 4 TO 8
INCHES AT PASS LEVELS. HIGHER ACCUMULATIONS WILL BE LIKELY IN
THE HIGHER ELEVATIONS. EASTERN MOUNTAINS WILL ALSO SEE SOME
ACCUMULATIONS IN THE RANGE OF 2 TO 5 INCHES. A WIND SHIFT TO
WESTERLY WINDS WILL ALSO OCCUR WITH THE FRONTAL PASSAGE.
LONG TERM...MONDAY THROUGH FRIDAY
MODELS ARE IN AGREEMENT WITH
WET CONDITIONS OCCURRING THROUGH THE LONG TERM PERIOD FROM THESE
PROGRESSIVE SYSTEMS. BASED ON THE NBM, THE FIRST SYSTEM MONDAY WILL
BRING QPF AMOUNTS UP TO 1" WITH A 50-80% PROBABILITY OVER THE WA/OR
CASCADES, LEAVING THE LOW ELEVATIONS AT 0.25-0.50". AS THE UPPER
RIDGE BUILDS OVER TUESDAY, MOUNTAIN SHOWERS MAY LINGER OVER THE
CASCADES UP TO 0.50" FROM THE INITIAL UPPER TROUGH (40-60% PROB).
THE REMAINING FORECAST AREA WILL BE DRY UNTIL STRONGER FRONTAL
SYSTEMS RETURN STARTING TUESDAY NIGHT ONWARDS. THE NBM SUGGESTED A
30-50% PROB OF QPF AMOUNTS EXCEEDING TO 1" AT THE CASCADES THROUGH
FRIDAY. THE LOW ELEVATIONS WILL BE AROUND 0.25" OR HIGHER BUT
CHANCES ARE LOW (<20%), GIVEN THE RIDGING PATTERN.
WEST TO SOUTHWESTERLY WIND ALOFT WILL INDUCE SOME BREEZY WINDS (15-
25 MPH) INTO THE FORECAST AREA WITH GUSTS AT 25-35 MPH OVER THE
MOUNTAINS MONDAY BEFORE RETURNING TUESDAY NIGHT INTO WEDNESDAY
MORNING. THERE IS A 50-60% PROB OF WIND GUSTS UP TO 35 MPH OCCURRING
AT THE SIMCOE HIGHLANDS, HIGH TERRAINS OF CENTRAL OR, AND SANTIAM
PASS FOR MONDAY. THE NBM PROB WILL REMAIN AT 50-60% FOR THE OCHOCO-
JOHN DAY HIGHLANDS, HIGH TERRAINS OF CENTRAL OR, AND PORTIONS OF THE
NORTHERN BLUES TUESDAY NIGHT BEFORE STEADILY DECREASING WEDNESDAY
LATE MORNING.
MONDAY'S TROUGH WILL ALSO BRING SNOW LEVELS DOWN TO 2-2.5KFT AND
THEN FURTHER TO 1-1.5KFT TUESDAY (>70% CONFIDENCE). WITH THE RIDGE
OVER THE PACNW THROUGH THE REST OF WORK WEEK, SNOW LEVELS INCREASE
FROM 2-3 KFT ON WEDNESDAY TO 5KFT OR ABOVE THURSDAY ONWARDS. CHANCES
OF SNOW ACCUMULATION AT 4-6" ARE MODERATE TO HIGH (50-90%) FOR THE
CASCADES AND NORTHERN BLUES FOR MONDAY. HOWEVER, THE CASCADES MIGHT
HAVE SNOW ACCUMULATING UP TO 8" MONDAY INTO TUESDAY (30-60% PROB).
TEMPERATURES WILL BE BELOW NORMAL IN THE BEGINNING OF THE LONG TERM
BEFORE RETURNING SEASONABLE WEDNESDAY THROUGH THE REST OF WORK WEEK.
FEASTER/97
AVIATION...06Z TAFS
VFR CONDITIONS CURRENTLY AT ALL SITES, WHICH
WILL STAY THE COURSE THROUGH THE PERIOD. THE ONLY EXCEPTIONS WILL BE
OVER CENTRAL OREGON (KRDM/KBDN) AND ALONG THE BLUE MOUNTAIN
FOOTHILLS (KALW/KPDT) AS CEILINGS ARE EXPECTED TO DROP TO OVC030 AND
OVC015 RESPECTIVELY THROUGH THE OVERNIGHT PERIOD. BREEZY AFTERNOON
CONDITIONS ARE ANTICIPATED AT KDLS WITH GUSTS OF UP TO 23 KTS
POSSIBLE. ALL OTHER SITES WILL EXPERIENCE WINDS OF 10 KTS OR LESS
THROUGH THE PERIOD. CEILINGS LOOK TO LIFT TOWARD THE END OF THE
PERIOD ACROSS ALL SITES. 75
PRELIMINARY POINT TEMPS/POPS
PDT 45 27 46 41 / 30 10 0 90
ALW 46 31 49 40 / 40 20 0 90
PSC 51 30 49 42 / 10 0 10 60
YKM 51 25 44 36 / 0 0 20 80
HRI 51 30 50 40 / 10 0 0 70
ELN 47 24 42 35 / 0 0 20 90
RDM 42 22 44 39 / 10 0 20 60
LGD 41 25 41 36 / 70 40 0 90
GCD 40 22 41 34 / 50 20 0 90
DLS 52 30 49 39 / 10 0 40 90
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...91
LONG TERM....97
AVIATION...97
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