Area Forecast Discussion
Issued by NWS Pendleton, OR

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901
FXUS66 KPDT 040946
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
246 AM PDT WED MAY 4 2016

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT...LOW PRESSURE SYSTEM
WILL CONTINUE TO MOVE CLOSER TO THE CALIFORNIA COAST. THIS WILL
CONTINUE TO SPIN UP WARM MOIST AIR FROM THE SOUTH TODAY.  AS A
RESULT SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ACROSS THE AREA.
THE BETTER CHANCE OF THUNDER WILL BE ACROSS CENTRAL AND NORTHEAST
OREGON. GUSTY WINDS AND HAIL WILL BE POSSIBLE OUT OF THESE STORMS.
GFS/NAM AVERAGE CAPE VALUES ACROSS THE CENTRAL AND NORTHEAST
MOUNTAINS THIS AFTERNOON RANGE FROM 1000-2000 J/KG...WITH ALL OTHER
AREAS RANGING FROM 500-1000 J/KG. 0-6KM SHEAR VALUES ARE AROUND 30-
40 KTS...WITH 0-3KM SRH VALUES 100-350 M2/S2 COULD SUGGEST SOME
ORGANIZED CONVECTION.  RIGHT NOW SPC ONLY HAS A GENERAL THUNDER
THREAT FOR OUR AREA TODAY...BUT HAVE PUT GUSTY WIND AND SMALL HAIL
IN THE FORECAST FOR ALL AREAS. PWAT VALUES WILL BE AROUND AN INCH
ACROSS THE AREA...SUGGESTING POSSIBLE HEAVY RAIN AT TIMES WITH THESE
SHOWERS/STORMS.

AS THE UPPER LEVEL LOW TRACKS INLAND OVERNIGHT SOME FORCING ALONG
WITH ELEVATED INSTABILITY WILL STILL BE OVER THE NORTHEAST PORTIONS
OF THE FORECAST AREAS. SO WILL CONTINUE SLIGHT CHANCE THUNDER
THROUGH  THE OVERNIGHT PERIOD.

THURSDAY COULD BE AN INTERESTING DAY FOR THE NORTHEAST MOUNTAINS.
SPC CURRENTLY HAS A MARGINAL RISK FOR SEVERE WEATHER OVER
WALLOWA...UNION...COLUMBIA...AND EASTERN UMATILLA COUNTY.  CAPE
VALUES RANGE FROM 1000-2500 J/KG WITH 45-50 KTS OF SHEAR AND SRH
VALUES >200 M2/S2.  IN ADDITION THE POSITION OF THE LOW DURING THE
AFTERNOON WOULD FAVOR A SOUTHEAST UPSLOPE FLOW...AS WELL AS 500 MB
DIFFLUENCE OVER THE AREA...AIDING IN RAPID AIR ASCENT.  HAVE ADDED
SPECIAL WORDING TO THE MARGINAL THREAT AREA FOR
WIND/HAIL/RAIN/LIGHTNING.  AS WE HEAD INTO THE EVENING THE
THUNDERSTORM THREAT SHOULD JUST BE LIMITED TO THE NORTHEAST OREGON
MOUNTAINS...THEN TAPERING OFF TO SHOWERS OVERNIGHT.  CONTINUE TO
MONITOR THE FORECAST FOR UPDATES ON THURSDAYS THUNDERSTORM
POTENTIAL.  WEBER

.LONG TERM...FRIDAY THROUGH WEDNESDAY...A LARGE UPPER LEVEL LOW WILL
MOVE FROM CALIFORNIA THROUGH THE FOUR CORNERS AREA INTO THE PLAINS
STATES DURING THE PERIOD WHICH WILL LEAD TO A GRADUAL DRYING TREND
FOR THE PACIFIC NW BY LATER IN THE WEEKEND AND EARLY NEXT WEEK. FOR
FRIDAY MOISTURE CIRCULATING ON THE N SIDE OF THE LOW WILL KEEP AT
LEAST SOME CHANCE FOR SHOWERS AND THUNDERSTORMS OVER THE SOUTHERN
AND EASTERN PORTION OF THE FORECAST AREA ESPECIALLY DURING THE
AFTERNOON AND EVENING. IT WILL ALSO BE BREEZY TO WINDY WITH GUSTY
NELY WINDS. ON SATURDAY AND SUNDAY RAIN CHANCES WILL DIMINISH AND BE
CONFINED TO JUST THE EXTREME EASTERN PORTION OF THE FORECAST AREA.
IT WILL BE WINDY SUNDAY EVENING WITH SOME POTENTIAL FOR WIND
ADVISORIES IN GORGE AND KITTITAS VALLEY. FOR MONDAY THROUGH
WEDNESDAY A DRY NWLY FLOW WILL BECOME ESTABLISHED. TEMPERATURES WILL
BE MOSTLY IN THE 80S FOR HIGHS LOWER ELEVATIONS THROUGH SUNDAY THEN
70S MONDAY THROUGH WEDNESDAY. 78

&&

.AVIATION...12Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE
FORECAST PERIOD. SCATTERED SHOWERS WILL AFFECT THE TAF SITES MOSTLY
AFTER 21Z. THERE WILL BE THE POTENTIAL FOR TSRA BUT WILL HOLD OFF ON
INCLUDING IN THE TAFS FOR NOW. BEST POTENTIAL FOR TSRA WILL BE FROM
21Z-03Z. CIGS WILL GENERALLY BE FROM 7-12K FEET AGL. WINDS WILL BE
MOSTLY 5-15 KT THIS AFTERNOON BUT A LITTLE STRONGER AND GUSTY AT
KDLS. 78

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  79  50  73  50 /  30  60  50  30
ALW  81  54  74  52 /  30  50  50  40
PSC  83  54  78  54 /  20  60  40  30
YKM  82  51  78  50 /  30  60  30  20
HRI  80  51  76  51 /  30  50  40  30
ELN  79  48  74  47 /  40  60  30  20
RDM  73  42  67  40 /  60  70  60  30
LGD  80  45  71  45 /  30  50  60  60
GCD  78  47  71  46 /  40  50  70  70
DLS  79  51  76  50 /  40  60  40  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON

$$

89/78/78



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