000 FXUS66 KPDT 131745 AAA AFDPDT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PENDLETON OR 945 AM PST MON FEB 13 2012 .UPDATE...AN UPPER TROUGH CONTINUES TO CROSS THE AREA. THE MAIN ENERGY IS DIVING INTO CENTRAL CALIFORNIA AND ONLY SOME VERY LIGHT SHOWERS REMAIN THIS MORNING. HEAVIEST PRECIPITATION IS IN CENTRAL OREGON AND ON THE ORDER OF A COUPLE OF HUNDREDTHS OF AN INCH OF RAIN OR PERHAPS A HALF INCH OF SNOW. AM ONLY SEEING WEAK RETURNS ON THE RADAR AND THEY ARE DIMINISHING RAPIDLY. HAVE CUT BACK ON POPS THIS MORNING AND DRIED OUT MOST OF THE COLUMBIA BASIN. THIS AFTERNOON ANOTHER WAVE CURRENTLY MOVING THROUGH BRITISH COLUMBIA AND NORTHWESTERN WASHINGTON WILL MOVE INTO THE AREA. RADAR SHOWS A LITTLE MORE ACTIVITY WITH THIS BAND SO HAVE KEPT A SLIGHT CHANCE OF SHOWERS IN THE LOWER ELEVATIONS AND A CHANCE IN THE MOUNTAINS. DO NOT EXPECT MUCH PRECIPITATION WITH THIS WAVE, PERHAPS A FEW HUNDREDTHS OF AN INCH OF RAIN OR ANOTHER HALF INCH OR SO OF SNOW ABOVE 3000 FEET. OTHERWISE FORECAST IS IN GOOD SHAPE. MADE A FEW MINOR TEMPERATURE ADJUSTMENTS IN A COUPLE OF PLACES. UPDATE ALREADY OUT. PERRY && .AVIATION...18Z TAFS...WEAK UPPER TROUGH MOVING ACROSS THE REGION TODAY. EXPECT CEILINGS 060-080 FOR REMAINDER OF THIS MORNING, THEN CLOUDS BASES THINNING THIS AFTERNOON WITH VFR CONDITIONS. SNOW HAS ENDED AT KRDM KBDN THIS MORNING. SURFACE WINDS 5-10KT. SOME RAIN SHOWERS ARE POSSIBLE AT KALW BEGINNING AROUND 14/07Z LATE THIS EVENING FOR 3-4 HOURS. OTHERWISE, PRECIPITATION IS EXPECTED MAINLY IN THE BLUE MOUNTAINS TONIGHT ASSOCIATED WITH A WEAK SYSTEM CLIPPING SE WASHINGTON AND NE OREGON. CEILINGS AT KRDM, KBDN, KALW, AND KPDT WILL LOWER AROUND 020 FT AGL FOR MVFR CONDITIONS. ELSEWHERE CLOUD BASES WILL BE 040-100 FT AGL TONIGHT. POLAN .PREVIOUS DISCUSSION... /ISSUED 350 AM PST MON FEB 13 2012/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT...AN ELONGATED UPPER TROUGH REMAINS OVER THE WESTERN U.S. EARLY THIS MORNING. THE BULK OF THE ENERGY WITHIN THIS TROUGH IS DROPPING SOUTH-SOUTHEAST INTO NORTHERN CALIFORNIA. A FAIR AMOUNT OF CLOUD COVER EXTENDS NORTH TO SOUTH FROM CENTRAL WASHINGTON TO SOUTH-CENTRAL OREGON. VERY LIGHT PRECIP RETURNS ARE SHOWING UP ON RADAR OVER NORTH-CENTRAL AND CENTRAL OREGON, BUT SO FAR VERY LITTLE PRECIP HAS ACTUALLY REACHED THE GROUND AS THE AIR MASS IS STILL VERY DRY. THE AREA OF HEAVIEST PRECIP HAS MOVED SOUTH OUT OF SOUTHWEST OREGON, THUS EXPECT ONLY LIGHT PRECIP TODAY. ANY PRECIP THAT WE GET TODAY WILL BE ASSOCIATED WITH THE REMNANTS OF THE ELONGATED UPPER TROUGH AS IT MOVES EAST ACROSS THE REGION. HAVE LOWERED POPS SOME FOR TODAY MOST AREAS WITH THE ONLY AREAS STILL IN THE LIKELY RANGE ARE THE CASCADE EAST SLOPES THIS MORNING. BUILDING SURFACE HIGH PRESSURE MAY KEEP SOME SHOWERS GOING OVER THE MOUNTAINS AND ADJACENT FOOTHILLS TONIGHT DUE TO UPSLOPE AFFECTS. THESE SHOWERS SHOULD GRADUALLY DECREASE OVERNIGHT. THE REGION WILL BE UNDER A TRANSITORY UPPER RIDGE TUESDAY MORNING FOR MOSTLY DRY CONDITIONS. THE NEXT PACIFIC SYSTEM WILL MOVE INTO THE PACIFIC NORTHWEST TUESDAY AFTERNOON AND MOVE THROUGH THE AREA TUESDAY NIGHT. THERE REMAINS CONSIDERABLE UNCERTAINTY AS TO THE STRENGTH AND TRACK OF THIS SYSTEM. AS SUCH WILL KEEP A GENERALLY BROAD BRUSH FORECAST GOING TUESDAY AFTERNOON THROUGH TUESDAY NIGHT. 90 LONG TERM...WEDNESDAY THROUGH SUNDAY. A PROGRESSIVE PATTERN WILL CONTINUE FOR THE REGION THIS WEEK AS UPPER LEVEL LOWS/TROUGHS MOVE ACROSS THE PACIFIC NORTHWEST EVERY FEW DAYS. MODELS STILL HAVING SOME DIFFICULTY COMING INTO AGREEMENT ON THE TRACK AND TIMING OF THESE FEATURES. AS THE TUESDAY SYSTEM DEPARTS THE AREA AN UPPER LEVEL RIDGE WILL BUILD IN ON WEDNESDAY WITH FAIR WEATHER. THE NEXT SYSTEM WILL MOVE THROUGH ON THURSDAY ALTHOUGH THIS ONE LOOKS PRETTY WEAK. SOME LIGHT RAIN AND MOUNTAIN SNOW LATER IN THE DAY AT BEST. UPPER RIDGE BUILDS BACK ON FRIDAY. A STRONGER UPPER LOW MOVES THROUGH OVER THE WEEKEND HOWEVER THE TRACK ON THIS ONE IS STILL VARIABLE IN THE MODEL DATA. WILL KEEP FORECAST AS IS WITH A CHANCE OF RAIN AND SNOW. WITH THIS TYPE OF PATTERN DO NOT EXPECT SIGNIFICANT CHANGES IN TEMPERATURES DAY TO DAY. HIGHS MOSTLY IN THE 40S WITH LOWS IN THE 20S AND 30S. WIDESPREAD FOG NOT LIKELY TO BE AN ISSUE EITHER. 94 && .PRELIMINARY POINT TEMPS/POPS... PDT 45 33 44 29 / 20 30 20 30 ALW 46 35 45 33 / 20 30 20 30 PSC 48 29 47 29 / 20 10 20 20 YKM 45 26 44 24 / 20 10 20 30 HRI 47 28 46 28 / 20 20 20 30 ELN 43 27 42 25 / 30 10 20 30 RDM 43 23 44 19 / 50 20 20 30 LGD 44 28 43 27 / 20 40 30 30 GCD 44 27 41 24 / 30 30 20 30 DLS 47 34 46 32 / 40 10 20 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. && THREAT INDEX TODAY : GREEN TUESDAY : GREEN WEDNESDAY : 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 $$ 83/94/94