614
FXUS66 KPDT 150247
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
747 PM PDT SUN AUG 14 2022
EVENING UPDATE
THE PREVIOUS FORECAST REMAINS ON TRACK WITH
LITTLE TO NO CHANGES NEEDED THIS EVENING. BROAD WEST-SOUTHWEST
FLOW ALOFT REMAINS IN PLACE ACROSS THE PACIFIC NORTHWEST WHILE AN
AREA OF HIGH PRESSURE SLOWLY RETROGRADES WESTWARD AND AMPLIFIES
OVER UTAH/NEVADA MONDAY AND TUESDAY, RESULTING IN INCREASING
HEIGHTS LOCALLY. EXPECT DRY CONDITIONS TO PERSIST HOWEVER
TEMPERATURES WILL RISE INTO THE MIDWEEK, PEAKING IN THE TRIPLE
DIGITS FOR MUCH OF THE COLUMBIA BASIN BY WEDNESDAY. BEYOND THE HOT
WEATHER WE’LL HAVE TO KEEP AN EYE ON SOME MID-LEVEL MONSOONAL
MOISTURE AND INSTABILITY MOVING IN FROM THE SOUTH WEDNESDAY
AFTERNOON THROUGH THE END OF THE WEEK. WHILE MODEL AGREEMENT AND
CONFIDENCE IN CONVECTIVE ACTIVITY IS FAIRLY LOW AT THIS POINT, IT
COULD RESULT IN THE RETURN OF THUNDERSTORMS TO SPOTS LIKE CENTRAL
OREGON AND THE CENTRAL/SOUTHERN BLUE MTNS, THUS ELEVATING FIRE
WEATHER CONCERNS. 99
PREV DISCUSSION
/ISSUED 440 PM PDT SUN AUG 14 2022/
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...BENIGN WEATHER,
EXCEPT FOR INCREASING TEMPERATURES THROUGH MID WEEK, WILL
PERSIST. BY WEDNESDAY, HIGH TEMPERATURES WILL BE IN THE UPPER 90S
OVER THE RIDGES IN THE LOWER COLUMBIA BASIN TO NEAR 105 IN THE
HANFORD AREA. ELSEWHERE, CONDITIONS WILL ALSO BE GRADUALLY HEATING
UP AGAIN. THE FORECAST AREA IS UNDER A MORE ZONAL TO SOUTHWEST
FLOW ALOFT TODAY. THE ATMOSPHERE IS DRY AND STABLE. IT IS SO
STABLE THAT EVEN THE MOUNTAINS ARE FREE FROM ANY CUMULUS CLOUDS SO
FAR THIS AFTERNOON. WILL LIKELY NEED AN EXCESSIVE HEAT WATCH OR A
HEAT ADVISORY ISSUED BY MONDAY.
ANOTHER CONCERN WILL BE THE POTENTIAL FOR CRITICAL FIRE WEATHER
CONDITIONS, ESPECIALLY IN CENTRAL OR AND THE EASTERN/NORTHEAST
MOUNTAINS, INCLUDING THE WA BLUE MOUNTAINS BY MIDWEEK. THIS IS DUE
TO THE INCREASING CHANCES OF THUNDERSTORMS WITH ABUNDANT
LIGHTNING DUE TO SOME MONSOONAL MOISTURE AND INSTABILITY WORKING
ITS WAY NORTHWARD INTO THE FORECAST AREA BY WEDNESDAY. THIS
COMBINED WITH THE HOT TEMPERATURES, STEEP LAPSE RATES AND
INCREASING INSTABILITY WILL RESULT IN INCREASING CHANCES OF
THUNDERSTORMS. MAY NEED FIRE WEATHER HIGHLIGHTS ISSUED BY MONDAY
OR TUESDAY FOR THURSDAY AND FRIDAY. FOR NOW WILL HEADLINE THE FIRE
WEATHER PLANNING FORECAST FOR THESE EXPECTED CHANGES COMING.
THE DETERMINISTIC MODELS ARE IN GOOD AGREEMENT WITH EACH OTHER
AND WITH THE SREF THROUGH THE SHORT TERM PERIOD. CLUSTER ANALYSIS
FOR DAY 3 SHOWS LITTLE VARIANCE IN THE EOF1 AND EOF2 FIELDS ON DAY
3. THE PHASE SPACE CLUSTER PLOTS SHOW THAT THE ECMWF HAS THE
LEAST AMOUNT OF VARIANCE WITH THE DETERMINISTIC VS THE ENSEMBLE.
THE GEFS AND CMCE HAVE GREATER VARIANCE ON THE PHASE SPACE CLUSTER
PLOTS. REGARDLESS OF THIS, ALL MODELS ARE SHOWING AN UPPER RIDGE
BUILDING INTO THE PACNW THROUGH MID WEEK WITH TRIPLE DIGIT
HEAT RETURNING IN THE LOWER ELEVATIONS RETURNING BY MIDWEEK.
WINDS WILL BE LIGHT FOR THE NEXT FEW DAYS AND GENERALLY TERRAIN
DRIVEN DURING THE NIGHT AND EARLY MORNING HOURS. THEY WILL BE
MORE DOMINATED BY THE GENERAL WINDS IN THE AFTERNOONS AND
EVENINGS. HOWEVER, WIND SPEEDS WILL BE LIGHT DURING THE SHORT TERM
PERIOD, EXCEPT POSSIBLY FOR LOCALLY AFTERNOON BREEZY WINDS IN THE
EASTERN COLUMBIA GORGE AND THE KITTITAS VALLEY AS IS TYPICAL. 88
LONG TERM...WEDNESDAY THROUGH SUNDAY...FOCUS IN THE LONG TERM
CONTINUES TO BE THE HEAT POTENTIAL STARTING IN THE MIDDLE OF THE
WORK WEEK AND POTENTIALLY LASTING THROUGH THE WEEKEND, HOWEVER
ENSEMBLES AND GUIDANCE REMAIN OUT OF SYNC, HINDERING
FORECAST CONFIDENCE. OVERALL MODELS ARE IN CONSENSUS ON BUILDING A
RIDGE OF SOME KIND OVER THE PACNW DURING THE MIDDLE OF THE WORK
WEEK, BUT DISCREPANCIES ARISE WHEN DEPICTING THE MAGNITUDE OF THE
RIDGE, AS WELL AS POTENTIAL SURGES OF SW MOISTURE THAT WOULD NOT
ONLY INJECT POSSIBLE CLOUD COVER OVER OUR AREA, BUT ALSO PROVIDE FOR
SOME STORM CHANCES IN AND AROUND CENTRAL OR.
LOOKING AT ENSEMBLE GUIDANCE, OVERALL VALUES ON TEMPERATURES HAVEN'T
CHANGED MUCH FROM RUN TO RUN, WITH HIGHS AROUND 105 SUGGESTED FOR
THE PEAK OF THE HEAT WEDNESDAY AND THURSDAY FOR THE LOWER BASIN,
WITH AROUND 100 FOR THE FOOTHILLS OF THE BLUES, GORGE, ADJACENT
LOWLANDS AND DOWN INTO CENTRAL OR AND 90S ELSEWHERE. BIGGEST SHIFT
IN THE HEAT FORECAST IS TOWARD THAT OF A LONGER-DURATION EVENT, AS
BOTH NBM AND ENSEMBLES SUGGEST TRIPLE DIGIT TEMPS COULD LAST AS LONG
AS SUNDAY. LOOKING AT HEATRISK, SUGGESTION IS TOWARD THAT OF AN
ADVISORY, AS THE MAGNITUDE OF THE HEAT DOESN'T STAND TO BE
PARTICULARLY SEVERE AT THIS TIME, BUT THE DURATION OF THE HEAT WILL
HAVE TO BE TAKEN INTO CONSIDERATION WHEN ISSUING ANY HEADLINES THIS
WEEK.
AS FAR AS MODEL DISCREPANCIES ARE CONCERNED, ENSEMBLE CLUSTERING IS
SMOOTHING OUT A POTENTIAL CUT-OFF LOW TO OUR SOUTH DEPICTED BY
DETERMINISTIC GUIDANCE THAT MAY PROVIDE A SURGE OF MOISTURE INTO THE
SOUTHERN CWA. GIVEN THE LIGHT PRECIP SIGNAL ACROSS THE GFS AND
ECMWF, AS WELL AS THE TAIL END OF THE 12Z NAM, HAVE OPTED TO LEAVE
IN A SLIGHT CHANCE OF STORMS FOR CENTRAL OR WEDNESDAY AND THURSDAY
EVENING, HOWEVER CONFIDENCE IS LOW AS MID-LEVEL MOISTURE LOOKS TO BE
LACKING AND ELEVATED INSTABILITY IS NOT PARTICULARLY STRONG. REST OF
THE FORECAST AREA LOOKS TO BE DRY THROUGH MOST OF THE PERIOD, UNTIL
DETERMINISTIC GUIDANCE AND A FEW ENSEMBLE MEMBERS INTRODUCE AN OFF-
SHORE LOW BY THE END OF THE WEEKEND. WILL LEAVE OUT ANY MENTION OF
PRECIP OR STORMS THIS FAR OUT, BUT WILL KEEP AN EYE ON THIS FEATURE
GIVEN THE CURRENT CONSENSUS ACROSS BOTH THE GFS AND ECMWF. EVANS/74
AVIATION
VFR CONDITIONS WILL PERSIST AT ALL TAF SITES FOR THE
NEXT 24 HOURS. SKIES ARE EXPECTED TO REMAIN MOSTLY CLEAR WITH
WINDS GENERALLY FROM 10 TO 20 MPH DURING THE DAY. 97
PRELIMINARY POINT TEMPS/POPS
PDT 56 93 58 94 / 0 0 0 0
ALW 60 95 61 97 / 0 0 0 0
PSC 62 96 62 98 / 0 0 0 0
YKM 58 94 58 96 / 0 0 0 0
HRI 59 97 61 99 / 0 0 0 0
ELN 58 93 60 95 / 0 0 0 0
RDM 49 92 53 94 / 0 0 0 0
LGD 53 92 57 95 / 0 0 0 0
GCD 54 95 56 99 / 0 0 0 0
DLS 61 94 63 98 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
UPDATE...99
SHORT TERM...89
LONG TERM....74
AVIATION...97
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