000 FXUS66 KOTX 152325 AAA AFDOTX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SPOKANE WA 325 PM PST THU JAN 15 2009 .SYNOPSIS... A STRONG RIDGE OF HIGH PRESSURE WILL PERSIST OVER THE PACIFIC NORTHWEST THROUGH EARLY NEXT WEEK. THE MOUNTAINS WILL LIKELY EXPERIENCE PERIODS OF CLEAR SKIES...WHILE THE LOW ELEVATIONS WILL BE TRAPPED IN LOW CLOUDS AND FOG. AIR STAGNATION WILL BE A PROBLEM FOR VALLEY LOCATIONS WITH THE PRESENCE OF LIGHT WINDS AND A PROLONGED STRONG LOW LEVEL INVERSION. && .DISCUSSION... UPDATED AVIATION DISCUSSION. TONIGHT THROUGH SUNDAY...FOG AND STRATUS STILL DOMINATE THE BULK OF THE LOWER ELEVATIONS OF THE FORECAST AREA THIS AFTERNOON. OUTSIDE OF A LITTLE DOWNSLOPE FROM EASTERLY FLOW OFF THE CENTRAL PANHANDLE MOUNTAINS INTO THE PULLMAN AREA AND EASTERN PALOUSE...LARGELY CLOUDY CONDITIONS PREVAIL OVER MOST LOCATIONS BELOW 3500 FEET OR SO...WHICH LINES UP NICELY WITH THE 12Z KOTX SOUNDING. NEARLY THIS EXACT SAME PATTERN LOOKS PERSIST FOR SEVERAL DAYS. THE GFS AND NAM BOTH GRADUALLY MOVE SURFACE HIGH PRESSURE UNDER THE LARGE SCALE RIDGE TOWARD THE IDAHO PANHANDLE...WHICH SHOULD WORK TO CONTINUE AND STRENGTHEN THE EAST TO WEST GRADIENT THAT HAS BEEN DEVELOPING ACROSS THE AREA. EASTERLY FLOW SHOULD KEEP THE PALOUSE RELATIVELY CLEAR...WHILE LOWER BOUNDARY LAYER RH VALUES LOOK TO GRADUALLY ADVECT INTO THE CWA FROM THE NORTHEAST BY THE SECOND HALF OF THE WEEKEND. EXAMINING BUFKIT SOUNDINGS FROM BOTH THE NAM AND GFS IN CONJUNCTION WITH THE BOUNDARY LAYER RH LOWERING...IT SEEMS THE BASIN WILL BE THE LIKELY CANDIDATE TO STAY TOTALLY CLOUDY THROUGHOUT THE SHORT TERM OF THE FORECAST...WITH THE WEST PLAINS OF SPOKANE LIKELY ALSO STAYING LARGELY CLOUDY. ELSEWHERE...LOWER BOUNDARY LAYER RH SHOULD ALLOW AT LEAST SOME REDUCTION IN CLOUD COVER. WHILE CLOUDS WILL BE REDUCING SOME THROUGH THE WEEKEND...INVERSION STRENGTH DOES NOT EVEN LOOK TO WAVER. SURFACE TO 850 MB TEMPERATURE DIFFERENTIALS STILL RUNNING ON THE ORDER OF 10C WITH NO DISCERNIBLE VERTICAL MIXING WOULD STILL RESULT IN A DECENT AMOUNT OF STRATUS...EVEN WITH LOWER BOUNDARY LAYER RH VALUES BECOMING LESS AND LESS SUPPORTIVE OF FOG. BECAUSE OF THIS...THE AIR STAGNATION ADVISORY WILL CONTINUE THROUGH EARLY NEXT WEEK. UNDER THE STRATUS AND IN THE FOG...DIURNAL TEMPERATURE CHANGES WILL BE VERY SMALL...PROBABLY ONLY A DEGREE OR TWO PER DAY. HOWEVER...IN THE MOUNTAINS...WITH 850 MB TEMPERATURES SURPASSING +10C...TEMPERATURES WILL COMMONLY BE IN THE 50S IN THE CASCADES AND OKANOGAN HIGHLANDS BEFORE WARMER AIR ADVECTS EASTWARD TOWARD THE IDAHO PANHANDLE WITH THE RIDGE AXIS BY THE END OF THE WEEKEND. /FRIES SUNDAY NIGHT THROUGH THURSDAY...THE UPPER LEVEL RIDGE AXIS WILL BE NUDGED EAST TO EASTERN IDAHO AND WESTERN MONTANA BY AN APPROACHING PACIFIC TROUGH AT THE START OF THE WORK WEEK. AS THE TROUGH NEARS THE NORTHWEST COAST THE UPPER FLOW SPLITS...WITH A SHORTWAVE SLIDING ACROSS CENTRAL BC AND THE REMAINDER OF THE ENERGY DROPPING INTO A CLOSED LOW OFF THE CALIFORNIA COAST. THE INLAND NORTHWEST WILL BE LEFT BETWEEN THE TWO SYSTEMS. MODELS ARE IN MUCH BETTER AGREEMENT WITH THE SPLIT FLOW AS THE 12Z GFS HAS MOVED TOWARD THE ECMWF SOLUTION. POPS HAVE BEEN REMOVED FROM THE TUESDAY/TUESDAY NIGHT PERIOD AND REDUCED TO A SLIGHT CHANCE IN THE MOUNTAINS FOR THE END OF THE FORECAST PERIOD. THE CLOSED LOW WILL MOVE ASHORE TO OUR SOUTH ON WEDNESDAY BUT MAY TRACK CLOSE ENOUGH TO ALLOW SOME WRAP AROUND MOISTURE TO AFFECT THE FORECAST AREA. PERSISTENT LOW LEVEL INVERSIONS WILL KEEP FOG AND LOW STRATUS TRAPPED OVER MOST OF THE VALLEYS THROUGH MIDWEEK. DIURNAL TEMPERATURE SWINGS WILL CONTINUE TO BE QUITE SMALL FOR MOST VALLEYS. ANY AREAS THAT SEE SUNSHINE WILL WARM UP SIGNIFICANTLY COMPARED TO THOSE STUCK IN THE GLOOM. /KELCH && .AVIATION... A STRENGTHENING RIDGE ALOFT WITH A WEAK HIGH PRESSURE AT THE SURFACE WILL ALLOW THE PERSISTENCE OF A STRONG INVERSION OVER THE VALLEYS AND COLUMBIA BASIN. NORTH OF INTERSTATE 90 INCLUDING THE KGEG VCNTY TAF SITES...KEAT...AND KMWH...LIFR AND VLIFR VISIBILITIES AND CEILINGS WILL PERSIST WITH LITTLE OR NO IMPROVEMENT THROUGH 00Z SATURDAY. FOG AND LOW STRATUS IS SPREADING EAST TO THE PULLMAN AREA THIS AFTERNOON AND MAY AFFECT THE KPUW TAF SITE AFTER 03Z FRIDAY. VFR CONDITIONS AT KLWS ARE EXPECTED TO DETERIORATE TONIGHT AS LOW STRATUS DEVELOPS AGAIN. /EK && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 26 31 27 31 25 31 / 0 0 0 0 0 0 COEUR D`ALENE 29 32 29 32 27 32 / 0 0 0 0 0 0 PULLMAN 31 43 31 40 30 39 / 0 0 0 0 0 0 LEWISTON 33 38 33 38 30 39 / 0 0 0 0 0 0 COLVILLE 26 34 27 33 23 33 / 0 0 0 0 0 0 SANDPOINT 28 32 29 32 23 32 / 0 0 0 0 0 0 KELLOGG 30 39 30 35 29 31 / 0 0 0 0 0 0 MOSES LAKE 23 33 24 35 26 31 / 0 0 0 0 0 0 WENATCHEE 25 33 26 33 27 32 / 0 0 0 0 0 0 OMAK 25 30 26 30 25 30 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...AIR STAGNATION ADVISORY UNTIL 4 PM PST TUESDAY FOR CENTRAL PANHANDLE MOUNTAINS...COEUR D`ALENE AREA...IDAHO PALOUSE... LEWIS AND SOUTHERN NEZ PERCE COUNTIES...LEWISTON AREA... NORTHERN PANHANDLE. WA...AIR STAGNATION ADVISORY UNTIL 4 PM PST TUESDAY FOR EAST SLOPES NORTHERN CASCADES...LOWER GARFIELD AND ASOTIN COUNTIES... MOSES LAKE AREA...NORTHEAST BLUE MOUNTAINS...NORTHEAST MOUNTAINS...OKANOGAN HIGHLANDS...OKANOGAN VALLEY...SPOKANE AREA...UPPER COLUMBIA BASIN...WASHINGTON PALOUSE... WATERVILLE PLATEAU...WENATCHEE AREA. DENSE FOG ADVISORY UNTIL 12 PM PST FRIDAY FOR SPOKANE AREA... UPPER COLUMBIA BASIN. && $$