000 FXUS66 KOTX 250958 AFDOTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 243 AM PDT MON JUN 25 2007 .SYNOPSIS... AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE ACROSS WASHINGTON TODAY BRINGING THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS TO THE INLAND NORTHWEST. COOL AND UNSETTLED WEATHER WILL LINGER INTO MONDAY NIGHT NORTH IDAHO. WARMER TEMPERATURES ARE IN THE FORECAST FOR TUESDAY AS HIGH PRESSURE RETURNS TO THE REGION. && .DISCUSSION... TODAY AND TONIGHT...FCST FOCUS WILL BE ON SNOW LEVELS AND THUNDER POTENTIAL TODAY. UPPER TROF AND VORT COMPLEX IS NOW CROSSING THE CASCADES...AND WILL MOVE RAPIDLY E THRU ERN WA AND N ID...REACHING NW MT LATER TODAY. TEMPS ALOFT IN THE TROF AXIS WILL CONTRIBUTE TO VERY STEEP MID-LEVEL LAPSE RATES. THIS INSTABILITY WILL TAG TEAM WITH RESPECTABLE LG-SCALE FORCING FOR ASCENT AND LEAD TO A RE-LAUNCHING OF SHOWERS BY LATE MORNING OR MIDDAY FOR THE NE THIRD OF MY CWA. ISOLATED THUNDER ALREADY THIS MORNING OVER N ID...AND WILL REMAIN IN THE FCST FOR MUCH OF NERN WA AND N ID AS MODIFIED SOUNDINGS REMAIN FAVORABLE FOR THUNDER MUCH OF TODAY. HOWEVER...GIVEN THE QUICK-MOVING NATURE OF THE WAVE...RISING HTS AND WARMING TEMPS ALOFT WILL MEAN THE DEEPEST INSTABILITY WILL OCCUR CLOSER TO 18Z RATHER THAN THE USUAL LATE AFTERNOON PEAK HEATING. WHATS LEFT OF THE UPPER TROF COMPLEX WILL EXIT E INTO THE NRN ROCKIES TONIGHT...LEADING TO A TREND TWD RAPID STABILIZATION IN THE MID-LEVELS AND DECREASING LG- SCALE FORCING FOR ASCENT. THIS WILL HELP TO STEADILY LESSEN THE SHOWER INTENSITY AND AREAL COVERAGE FOR THE N ID ZONES...WITH SHOWERS ENDING COMPLETELY VERY EARLY IN THE EVENING OR LATE AFTERNOON. SNOW LEVELS BASED ON WET BULB ZERO HTS AND 850-700MB MEAN TEMPS WILL BE LOW ENOUGH TO MENTION SNOW SHOWERS DOWN TO 6000 FT MSL THIS MORNING. KMLP NOW 32F AND SNOWING AT 6100 FT. ACCUMULATING SNOWS WILL GENERALLY BE LIMITED TO ELEVATIONS ABOVE 6500 FEET...LEAVING THE PASSES CLEAR. PATCHY RIVER VALLEY FOG WILL BE HAVE TO CONSIDERED FOR THE DEEPER VALLEYS OF NE WA TONIGHT. BZ TUESDAY THROUGH SUNDAY...OVERALL ONLY MINOR TWEAKS MADE TO THIS PART OF THE FORECAST. UPPER LOW NOW IN THE GULF OF ALASKA NEAR 50N/15OW WILL SLOWLY DROP SOUTH AND SLIGHTLY EAST THROUGH THE WEEK. A STRONG UPPER RIDGE OVER THE MIDWEST...AND THE CLOSED LOW OFF THE COAST WILL RESULT IN A SOUTH TO SOUTHWEST FLOW OVER THE INLAND NORTHWEST. EMBEDDED SHORT WAVES SWINGING AROUND THE OFFSHORE LOW WILL KEEP THE THREAT FOR MAINLY MOUNTAIN SHOWERS...BUT WITH A HINT OF ELEVATED INSTABILITY THROUGH THE WEEK NO AREAS CAN BE FREE OF SHOWER THREAT. WEDNESDAY LIKELY WILL BE THE WARMEST DAY OVER THE AREA AS A THERMALLY INDUCED SURFACE LOW IS OVER EASTERN WA/IDAHO. THIS DAY ALSO HAS THE BEST CHANCE FOR THUNDERSTORMS OVER THE IDAHO PANHANDLE WITH A THETA-E RIDGE OVER THE AREA...850-500MB LAPSE RATES OF 8-9C/KM...STRONG SFC HEATING UNDER THE THERMAL TROUGH...AND LIFTED INDEX VALUES BTWN -2 TO -4C. THERE IS ALSO A DECENT AMOUNT OF SHEAR TO SUPPORT STRONG STORMS WITH 0-6KM AGL SHEAR VALUES OF 50 KTS. HOWEVER...THERE IS A HIGH DEGREE OF CONVECTIVE INHIBITION OF 100-200 J/KG. AND WITH THE LACK OF ANY STRONG SHORT WAVES TO OVERCOME THE CONVECTIVE INHIBITION...WILL KEEP POPS AT SLIGHT CHANCE. A GRADUAL COOLING TREND INTO FRIDAY IS EXPECTED AS THE THERMAL TROUGH MOVES EAST INTO MONTANA IN RESPONSE TO THE SLOWLY APPROACHING UPPER LOW. THE BEST SFC BASED INSTABILITY FOR THUNDERSTORMS WILL ALSO BE FOCUSED FURTHER EAST AS WELL...BUT WILL HAVE TO MONITOR THREAT FOR ELEVATED INSTABILITY WITH 700-500MB THETA-E LAPSE RATES NEAR 0C/KM AT TIMES. JW && .AVIATION... VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES THROUGH 06Z TUE. THE MAIN AVIATION THREAT WILL REVOLVE AROUND THUNDER CHANCES. SUSPECT MOST OF THE LIGHTNING WILL EVADE THE TAF LOCATIONS...HOWEVER BEST CHANCES IF ANY WERE TO FORM SHOULD BE NORTH OF KGEG-KCOE WITH THE THREAT LINGERING THROUGH 16-18Z. && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 67 45 81 54 85 56 / 40 0 0 0 0 20 COEUR DALENE 66 41 81 52 85 54 / 40 0 0 0 10 20 PULLMAN 64 41 81 48 84 53 / 20 0 0 0 0 10 LEWISTON 73 48 87 58 90 60 / 20 0 0 0 0 10 COLVILLE 69 42 84 50 90 50 / 50 0 0 0 10 20 SANDPOINT 60 40 77 49 85 50 / 70 0 0 0 10 20 KELLOGG 62 40 81 51 88 57 / 70 0 0 0 20 20 MOSES LAKE 76 45 86 56 89 60 / 10 0 0 0 0 10 WENATCHEE 75 50 84 60 85 62 / 10 0 0 0 0 10 OMAK 74 43 85 53 88 57 / 30 0 0 0 0 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$