000 FXUS66 KOTX 100530 AFDOTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 1030 PM PDT SAT MAY 9 2009 .SYNOPSIS... HIGH PRESSURE WILL BRIEFLY BUILD OVER THE PACIFIC NORTHWEST ON SUNDAY BRINGING A DRY DAY TO THE REGION. THE FAIR WEATHER WILL BE SHORT LIVED. A COOL TROUGH OF LOW PRESSURE WILL RETURN SUNDAY NIGHT BRINGING SHOWERY...BREEZY...AND BELOW NORMAL TEMPERATURES BACK TO THE REGION. && .DISCUSSION... UPDATE FOR TONIGHT...INSTABILITY DRIVEN SHOWERS ARE QUICKLY WANING AS THE SUN SETS THIS EVENING. A WEAK VERTICAL SHEAR ENVIRONMENT COUPLED WITH ONLY MARGINAL SURFACE INSTABILITY AND WEAK BOUNDARY LAYER FLOW HAS ALLOWED ONLY UNIMPRESSIVE OROGRAPHICALLY ANCHORED DEVELOPMENT THIS AFTERNOON...AND WITH THE LOSS OF INSOLATION...THIS ACTIVITY WILL CONTINUE TO QUICKLY WANE. WHILE THE SHOWERS ACROSS THE NORTHERN ZONES HAVE INCREASED THE DEWPOINTS ACROSS THE NORTHERN VALLEYS INTO THE LOWER 40S IN SPOTS...THE BULK OF THE CWA HAS SEEN SLIGHTLY DRIER BOUNDARY LAYER AIR THAN LAST NIGHT INVADE. AS A RESULT OF THE DRIER BOUNDARY LAYER AIR AND LACK OF SIGNIFICANT SYNOPTIC CLOUD COVER...THE BULK OF THE CWA WILL SEE TEMPERATURES CRATER QUICKLY AFTER SUNSET. OVERNIGHT LOWS FOR MANY LOCATIONS HAVE BEEN CUT TO ACCOMMODATE THIS. IN THE NORTHERN VALLEYS...HIGHER DEWPOINTS AND QUICK RADIATION THIS EVENING WILL LIKELY AGAIN RESULT IN FOG FOR SOME LOCATIONS. HOWEVER...WITH THE STRONG SUN OF MAY...FOG WILL ONLY PERSIST A SHORT TIME AFTER SUNRISE WITH A NICE SUNDAY IN STORE. /FRIES && .AVIATION... SHOWERS FROM AFTERNOON INSTABILITY ARE ALL GONE SAVE FOR WEST OF KEAT IN THE CASCADES...AND THOSE SHOULD DISSIPATE IN THE NEXT COUPLE OF HOURS. ELSEWHERE...CLEAR SKIES WILL DOMINATE UNTIL SUNDAY AFTERNOON WHEN HIGH CLOUDS BEGIN TO INVADE IN ADVANCE OF THE NEXT SYSTEM. SOME FOG/STRATUS IS POSSIBLE NORTH OF KSFF AND KCOE TONIGHT AS THE NORTHERN VALLEYS SHOULD RADIATE TO THEIR DEWPOINTS IN THE NEXT COUPLE OF HOURS. OUTSIDE OF THE FOG...VFR CONDITIONS ARE EXPECTED AT ALL SITES THROUGH 06Z MONDAY. /FRIES && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 38 67 48 61 38 55 / 10 0 10 60 20 50 COEUR DALENE 36 66 45 60 38 53 / 10 0 20 60 20 60 PULLMAN 37 66 49 60 38 52 / 10 0 10 50 10 50 LEWISTON 42 73 52 66 42 57 / 0 0 0 40 10 50 COLVILLE 36 70 46 62 37 59 / 20 0 30 70 30 60 SANDPOINT 33 64 41 56 38 52 / 10 10 10 70 30 60 KELLOGG 37 65 45 56 36 47 / 10 0 10 70 20 70 MOSES LAKE 37 74 51 67 40 62 / 0 0 20 20 10 20 WENATCHEE 43 73 51 64 41 58 / 0 0 30 20 10 20 OMAK 41 73 45 66 36 61 / 10 0 40 40 10 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$