Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 280840
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
140 AM PDT MON JUL 28 2014

.SHORT TERM...TODAY THROUGH WEDNESDAY...AN UPPER RIDGE OVER THE
INLAND WEST AND A TROUGH IN THE GULF OF AK WILL CONTINUE TO KEEP A
SOUTHWEST FLOW OVER THE REGION AND CWA. THIS PATTERN WILL CAUSE HOT
AND DRY CONDITIONS TO PERSIST THROUGH THE SHORT TERM PERIOD GOING
INTO THE LONG TERM. SOME LIMITED MID LEVEL MONSOONAL MOISTURE WILL
CONTINUE TO BE PULLED NORTHWARD INTO THE CWA...ESPECIALLY SOUTHERN
AREAS. THE ATMOSPHERE WILL BECOME UNSTABLE DUE TO HEATING EACH
AFTERNOON. THIS COMBINED WITH THE MID LEVEL MOISTURE AND CAPE WILL
RESULT IN ISOLATED AFTERNOON AND EVENING THUNDERSTORMS EACH DAY OVER
PORTIONS OF CENTRAL AND NORTHEAST OREGON. TODAY ANY THUNDERSTORMS
THAT FORM WILL BE CONFINED TO CENTRAL OREGON AND THE JOHN DAY
HIGHLANDS. ELSEWHERE THE ATMOSPHERE WILL BE TOO DRY. THUNDERSTORM
POTENTIAL COVERAGE WILL INCREASE EACH DAY SPREADING SLOWLY NORTHWARD
AND EASTWARD AS THE AREA OF INSTABILITY INCREASES. THE BEST CHANCES
FOR ANY THUNDERSTORMS WILL BE OVER CENTRAL OREGON AND THE OREGON
CASCADE EAST SLOPES. THE LOWER LEVELS WILL BE QUITE DRY SO ANY
THUNDERSTORMS WILL BE HIGH BASED WITH LITTLE RAINFALL REACHING THE
GROUND. THUS THERE COULD BE A FIRE WEATHER CONCERN DUE TO LIGHTNING
IGNITING NEW WILDFIRES. TEMPERATURES WILL BE HOT...BUT NOT QUITE AS
HOT AS PREVIOUSLY EXPECTED. MAXIMUM TEMPERATURES WILL WARM TO AROUND
100-103 IN THE LOWER ELEVATIONS WITH 80S AND 90S ELSEWHERE. TUESDAY
WILL BE THE HOTTEST DAY AND THEN THERE WILL BE SLIGHT COOLING AS MID
AND HIGH CLOUDS INCREASE DUE TO CONVECTION. NIGHT TIME TEMPERATURES
WILL REMAIN WARM DUE TO THE MID AND HIGH CLOUDS PREVENTING STRONG
RADIATIONAL COOLING. HOWEVER...TEMPERATURES ARE NO LONGER EXPECTED
TO REACH HEAT ADVISORY CRITERIA ANYMORE. THIS WEATHER PATTERN WILL
PERSIST INTO THE EXTENDED FORECAST PERIOD. 88

.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...EASTERN OREGON AND
WASHINGTON WILL BE ON THE WESTERN SIDE OF AN UPPER LEVEL RIDGE
THROUGH THE LONG TERM PERIOD. SUBSIDENCE FROM THE RIDGE WILL BRING
SOUTH TO SOUTHWEST FLOW AND HOT TEMPERATURES TO THE REGION. THIS
SOUTHERLY FLOW WILL ALSO BRING MONSOON MOISTURE INTO THE AREA AT
TIMES. THERE WILL BE A THREAT FOR THUNDERSTORMS EACH DAY AS UNSTABLE
SOUTHERLY FLOW COMBINES WITH DAYTIME HEATING. THIS THREAT WILL
INCREASE LATER IN THE WEEK AS MONSOON MOISTURE INCREASES. CLOUD
DEBRIS FROM THUNDERSTORMS KEEP WILL KEEP OVERNIGHT LOWS ELEVATED
WITH 60S TO LOWER 70S EXPECTED AT LOWER ELEVATIONS.

MODELS HAVE BEEN CONSISTENT WITH THE OVERALL PATTERN AND INCREASING
INSTABILITY WITH TIME...BUT INDIVIDUAL WEAK WAVES THAT WOULD ENHANCE
INSTABILITY...CONVECTIVE ACTIVITY...AND MONSOONAL MOISTURE ADVECTION
VARY WITH EACH MODEL RUN. THUNDERSTORMS ACTIVITY WILL BE ENHANCED BY
HEATING DURING THE AFTERNOON AND EVENING...BUT WEAK WAVES MAY
TRIGGER NIGHTTIME CONVECTION AS WELL.   COONFIELD

&&

.AVIATION...12Z TAFS...VFR CONDITIONS ARE EXPECTED FOR THE NEXT 24
HOURS WITH SCT MID AND SCT-BKN HIGH CLOUDS. WILL ALSO SEE THE
DEVELOPMENT OF HIGH BASED CUMULUS CLOUDS AT KBDN AND KRDM LATE
MONDAY AFTERNOON. THESE CLOUDS WILL SPREAD NORTH AND NORTHEAST INTO
THE EVENING. STRAY THUNDERSTORMS MAY DEVELOP OVER CENTRAL OREGON
AFTER 21Z AND COULD IMPACT KBDN AND KRDM UNTIL 05Z. AT THIS TIME
CONFIDENCE OF OCCURRENCE OF A STORM AT THESE TWO SITES IS TOO LOW TO
INCLUDE IN TAF. LIGHT TERRAIN DRIVEN WINDS WILL BECOME NORTHERLY AT
10 KT OR LESS DURING THE AFTERNOON.  76

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  98  67  99  68 /   0   0  10  10
ALW 100  71 101  74 /   0   0   0   0
PSC 102  68 103  70 /   0   0   0   0
YKM  98  68 100  68 /   0   0   0   0
HRI 101  66 102  68 /   0   0   0   0
ELN  96  65  97  65 /   0   0   0   0
RDM  94  57  93  58 /  20  20  20  20
LGD  93  61  93  61 /  10  10  20  20
GCD  94  66  93  66 /  20  20  20  20
DLS  97  68  96  68 /   0   0   0   0

&&

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

&&

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

$$

88/76/76








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