Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 240221
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
720 PM PDT WED APR 23 2014

.UPDATE...SHOWERS CONTINUE TO INCREASE OVER THE CWA FROM WEST TO
EAST AS THE NEXT WEATHER SYSTEM MOVES INTO THE REGION. A WARM FRONT
WILL MOVE UP ACROSS THE CWA THIS EVENING AND OVERNIGHT BRINGING RAIN
TO THE FORECAST AREA. SNOW LEVELS WILL BE HIGH...ABOVE 5000 FEET SO
SNOW WILL ONLY BE EXPECTED ON THE HIGHEST PEAKS. THE COLD FRONT WITH
THIS SYSTEM WILL MOVE ACROSS THE CWA ON THURSDAY. THE COLD FRONT
SHOULD BE EAST OF THE CASCADES BY 18Z AND TO THE IDAHO BORDER BY
00Z. THE ATMOSPHERE WILL BECOME MORE UNSTABLE ON THURSDAY WITH THE
COLDER MOVING IN ALOFT. AS SUCH THERE WILL ALSO BE A SLIGHT CHANCE
OF THUNDERSTORMS OVER THE EASTERN AND NORTHEAST MOUNTAINS IN THE
AFTERNOON. THESE THUNDERSTORMS ARE NOT EXPECTED TO BECOME SEVERE
THOUGH SOME COULD PRODUCE SMALL HAIL AND GUSTY WINDS. THE ACTIVE
WEATHER PATTERN WILL PERSIST WITH ANOTHER SYSTEM MOVING INTO THE CWA
ON FRIDAY AND AGAIN SATURDAY NIGHT INTO SUNDAY WITH MORE RAIN OR
RAIN SHOWERS. CURRENT FORECAST LOOKS TO BE ON TRACK. 88

&&

.AVIATION...THERE MAY BE BRIEF PERIODS OF MVFR AND POSSIBLY EVEN IFR
CONDITIONS TONIGHT DUE TO LOWERED CIGS AND SHOWERS REDUCING
VISIBILITY. HOWEVER MOST OF THE TIME VFR CONDITIONS WILL PREVAIL.
WINDS WILL RANGE FROM 5 TO 15 KTS OVERNIGHT AND THEN WILL INCREASE
TO 10 TO 20 KTS WITH LOCALLY 15 TO 25 KTS ON THURSDAY AS A COLD
FRONT MOVES ACROSS THE CWA AND MIXES DOWN STRONGER WINDS FROM ALOFT
WITH CONVECTIVE RAIN SHOWERS AND POSSIBLY EVEN THUNDERSTORMS. THE
THUNDERSTORM THREAT WILL PRIMARILY BE AT KPDT AND KALW. 88

&&

.PREV DISC... /ISSUED 225 PM PDT WED APR 23 2014/

SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT. THE CHALLENGE WITH THIS
PACKAGE IS THE RAIN CHANCES ACROSS THE AREA. A STORM SYSTEM WILL
SPREAD ADDITIONAL CLOUDS AND SHOWERS TO THE REGION TONIGHT AND
THURSDAY AS A LOW PRESSURE SYSTEM APPROACHES THE PACNW COAST TOWARD
THE END OF THE WORK WEEK. THE ATMOSPHERE ALSO BECOMES INCREASINGLY
UNSTABLE THURSDAY AFTERNOON AND AN ISOLD TSRA IS POSSIBLE OVER THE
EASTERN ZONES. THE SYSTEM MOVES INTO WA/OR FRIDAY AND THE UNSETTLED
WEATHER WILL PERSIST INTO FRIDAY NIGHT. THE BEST CHANCES FOR PCPN
SHOULD OCCUR LATER TONIGHT AND THURSDAY BEFORE LESSENING INTO
THURSDAY NIGHT. HOWEVER THE CHANCES FOR SHOWERS WILL PERSIST
ESPECIALLY IN THE AREA MOUNTAINS. SNOW LEVELS SHOULD REMAIN ABOVE 4K
FEET DESPITE COOLER TEMPERATURES EXPECTED BY FRIDAY.

LONG TERM...SATURDAY THROUGH WEDNESDAY NIGHT...UPPER LEVEL TROUGH
OVER THE AREA WILL PUSH OFF TO THE EAST SATURDAY...WITH PROGRESSIVE
WESTERLY FLOW TO FOLLOW.  A BREAK IN THE MOISTURE SATURDAY INTO
SUNDAY...BUT STILL A CHANCE FOR SHOWERS OVER THE MOUNTAINS AND A
SLIGHT CHANCE ACROSS THE VALLEYS.  OVERALL...SNOW LEVELS WILL BE
3500-4500 FEET SATURDAY INTO SUNDAY...WITH SNOW LEVELS RISING MONDAY
ONWARD.  BY MONDAY NIGHT...A DRIER SOUTHWEST FLOW WILL SET IN AND
SNOW LEVELS ARE EXPECTED TO RISE BETWEEN 6500-7500 FEET.  AN UPPER
LEVEL RIDGE WILL BUILD OVER THE AREA FOR THE EXTENDED.  TEMPERATURES
WILL START OFF IN THE MID 60S ACROSS THE LOWER ELEVATIONS OVER THE
WEEKEND...AND SHOULD BE IN THE MID 70S BY TUESDAY AND WEDNESDAY.
THERE IS SOME DISCREPANCIES WITH MODEL CONSISTENCY AND CONTINUITY
AFTER TUESDAY.  GFS MODEL HAS A STRONG COLD FRONT TO PUSH THROUGH
THE AREA...WITH INCREASED CHANCES OF PRECIPITATION.  THUNDERSTORMS
CAN`T BE RULED OUT WITH THIS SCENARIO AS WELL.  HOWEVER...ECMWF
CONTINUES TO HOLD ONTO THE UPPER LEVEL RIDGE WITH CONTINUED WARM AND
DRY TEMPERATURES.  LEANING TOWARD THE ECMWF FOR THE
EXTENDED...THEREFORE THE CURRENT FORECAST REFLECTS DRIER AND
SLIGHTLY WARMER WEDNESDAY AFTERNOON AND EVENING.  NO THUNDER HAS
BEEN ADDED TO THE EXTENDED...AS CONFIDENCE IS NOT HIGH ENOUGH TO
MENTION.  WEBER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  44  58  39  57 /  60  70  60  50
ALW  47  58  42  58 /  60  80  60  50
PSC  48  64  43  63 /  60  60  20  20
YKM  41  59  35  60 /  50  50  20  10
HRI  46  62  42  61 /  60  60  40  30
ELN  40  57  36  59 /  50  60  20  10
RDM  39  55  30  49 /  60  50  60  60
LGD  43  53  36  52 /  70  80  70  70
GCD  38  54  34  46 /  60  80  70  80
DLS  46  60  40  60 /  70  60  40  40

&&

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

THREAT INDEX
THURSDAY : GREEN
FRIDAY : GREEN
SATURDAY : GREEN

GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.

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

$$

88/89/88







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