Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 290944
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
244 AM PDT TUE JUL 29 2014

.SHORT TERM...TODAY THROUGH THURSDAY. SOUTHERLY FLOW ALOFT WILL
CONTINUE FOR THE NEXT SEVERAL DAYS. MID AND HIGH LEVEL MOISTURE
WILL BE TRANSPORTED NORTHWARD ACROSS THE FORECAST AREA. INSTABILITY
WILL ALSO BE PRESENT EACH DAY AS SURFACE TEMPS ARE IN THE 90S TO
LOWER 100S AND MODEL CROSS SECTIONS CONTINUE TO SHOW MID LEVEL
INSTABILITY. WAITING ON STRONGER SHORT WAVES TO PROVIDE LIFT TO GET
MORE WIDESPREAD THUNDERSTORMS COVERAGE. NO SIGNIFICANT IMPULSES SEEN
ON SATELLITE FOR THE SHORT TERM...A COUPLE WEAK ONES VICINITY OF
NORTHERN CALIFORNIA. MODELS ARE SHOWING THESE WEAK SHORT WAVES
MOVING THROUGH AT TIMES OVER THE NEXT 3 DAYS WITH CONVECTION
CONCENTRATED MOSTLY OVER CENTRAL AND NORTHEAST OREGON. AS FOR
TEMPERATURES...THEY WILL REMAIN HOT. HIGHS TODAY WILL BE SIMILAR TO
YESTERDAY. HAVE ISSUED A HEAT ADVISORY FOR A PORTION OF THE
WASHINGTON COLUMBIA BASIN WHERE HIGHS WILL BE 100-105. SOME MID AND
HIGH LEVEL CLOUD COVER WILL KEEP OVERNIGHT LOWS FAIRLY WARM AS
WELL.  94

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY...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. THUNDERSTORMS ACTIVITY WILL BE ENHANCED BY HEATING DURING THE
AFTERNOON AND EVENING...BUT WEAK WAVES MAY TRIGGER NIGHTTIME
CONVECTION AS WELL. HOWEVER, MODELS DIVERGE ON DETAILS OF THE DAY TO
DAY SITUATION SO CONFIDENCE ON ANY PARTICULAR DAY IS LOW.

SOUTHWEST FLOW WILL BE OVER THE AREA THURSDAY NIGHT AND EARLY
FRIDAY. THE GFS BRINGS A WAVE INTO THE AREA FRIDAY AFTERNOON WHILE
THE ECMWF DEVELOPS A CLOSED LOW NEAR THE EASTERN WASHINGTON/OREGON
BORDER. HAVE KEPT A CHANCE OF THUNDERSTORMS OVER THE ENTIRE AREA ON
FRIDAY SINCE EITHER SCENARIO HAS MOIST UNSTABLE AIR WITH A TRIGGER
FOR CONVECTION. THE WAVE/UPPER LOW MOVES INTO MONTANA (GFS) OR NORTH
INTO CANADA (ECMWF) ON SATURDAY. BOTH MODELS INDICATE A WEAK WAVE
FORMING OFFSHORE AND MOVING INTO OREGON SATURDAY NIGHT AND SUNDAY.
THIS WILL REINFORCE THE SOUTHERLY FLOW AND KEEP A CHANCE OF
THUNDERSTORMS OVER EASTERN OREGON. MONDAY THE GFS KEEPS A SOUTHERLY
FLOW AND BRINGS ANOTHER WEAK WAVE TO ENHANCE THUNDERSTORM ACTIVITY.
THE ECMWF DEVELOPS A WESTERLY FLOW WITH THE BEST CONVECTIVE
POTENTIAL IN IDAHO AND MONTANA. THE GFS ENSEMBLES SHOW BOTH
SCENARIOS. KEPT A PERSISTENCE FORECAST WITH LOW CONFIDENCE IN
DETAILS. COONFIELD

&&

.12Z TAFS...VFR CONDITIONS ARE EXPECTED FOR THE NEXT 24 HOURS WITH
SCT MID-HIGH CLOUDS DEVELOPING THIS AFTERNOON. WILL ALSO SEE THE
DEVELOPMENT OF HIGH BASED CUMULUS CLOUDS AT KBDN AND KRDM IN THE
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. SURFACE WINDS WILL GENERALLY REMAIN BELOW 15 KTS FOR
THE NEXT 24 HOURS THOUGH KDLS MAY HAVE SOME GUSTS TO 20 KTS THIS
AFTERNOON AND EARLY EVENING.  76

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT 100  69  99  67 /  10  10  10  10
ALW 101  72 100  69 /   0   0  10  10
PSC 103  69 103  68 /   0   0   0   0
YKM 101  67  99  65 /   0   0   0   0
HRI 103  68 101  67 /   0   0  10  10
ELN 100  64  98  60 /   0   0   0   0
RDM  97  62  95  58 /  10  20  20  20
LGD  99  65  97  61 /  10  20  20  20
GCD  97  65  94  61 /  20  20  20  20
DLS  99  67  97  66 /   0   0  10  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM PDT WEDNESDAY
     WAZ028.

&&

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

$$

94/76/76





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