FXUS66 KOTX 131217
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
449 AM PDT TUE MAY 13 2008
.SYNOPSIS...
A WARM FRONT WILL PUSH OVER THE INLAND NORTHWEST TODAY BRINGING
PLENTY OF CLOUDS AND A CHANCE OF PRECIPITATION THROUGH EARLY
WEDNESDAY. THEREAFTER...STRONG UPPER LEVEL HIGH PRESSURE WILL
BUILD RAPIDLY OVER THE REGION RESULTING IN DRY AND WARM CONDITIONS
FOR THE LATTER HALF OF THE WEEK.
&&
.DISCUSSION...
UPDATED AVIATION
TODAY AND TONIGHT... FOCUS THIS PERIOD WILL BE ON
THE INCOMING WARM FRONT AND WHAT LOOKS TO BE A RELATIVELY HIGH
POP/MODERATE QPF EVENT FOR THE EAST SLOPES OF THE CASCADES AND
EASTERN THIRD OF THE CWA THIS AFTERNOON INTO EARLY TONIGHT. WHILE
WE ARE NOT EXPECTING EXCESSIVE QPF BY ANY STRETCH AND THE BULK OF
THE LIFT WILL BE THE RESULT OF LOW LEVEL ISENTROPIC ASCENT ...THE
POTENTIAL FOR 0.30+ INCHES FOR AREAS NEAR THE CREST AND HIGHER
TERRAIN ACROSS THE CENTRAL ID PANHANDLE LOOKS PRETTY GOOD NEXT
24-30 HOURS GIVEN THE MOISTURE- LADEN FLOW REGIME.
SHORT-WAVE RIDGING THAT DOMINATED THIS PAST EVENING HAS SINCE FLATTENED
AND THE STRENGTHENING WESTERLY FLOW WAS BRINGING CONSIDERABLE MID AND
HIGH LEVEL CLOUDINESS OVER THE AREA EARLY THIS MORNING. REGIONAL RADAR
MOSAIC NOT SHOWING MUCH IN THE WAY OF ECHOES AS OF THIS WRITING. THE
ONE EXCEPTION WAS NEAR THE B.C. BORDER WHERE THE TAIL-END OF A SHORT-
WAVE CROSSING THE CENTRAL BC/ALBERTA BORDER HAD TOUCHED OFF A FEW
SHOWERS SHORTLY AFTER MIDNIGHT. THIS ACTIVITY SHOULD BE WELL NORTHEAST
OF OUR AREA BY DAYBREAK.
OTHERWISE...CEILINGS THUS FAR HAVE GENERALLY BEEN AOA 10-12 KFT
BUT THAT WILL BE CHANGING IN SHORT ORDER. A LOOK UPSTREAM SHOWS AN
IMPRESSIVE FETCH OF SUB- TROPICAL MOISTURE EXTENDING WELL TO THE
SOUTHWEST TO NEAR 30N. WITHIN THIS PLUME...AMSU-DERIVED PRECIPITABLE
WATER VALUES OF 1.5+ INCHES ARE COMMON. ALSO OF NOTE... THE REMNANTS
OF A FORMER TYPHOON HAVE BEGUN TO GET ABSORBED INTO THIS LARGE SCALE
PLUME. SO THE UPSHOT IS THAT PLENTY OF MOISTURE WILL BE DIRECTED INTO
THE PACNW THE NEXT 24-30 HOURS.
AS FAR AS LIFT GOES...BOTH THE GFS AND NAM ARE SIMILAR SHOWING
BROAD...MOIST ISENTROPIC ASCENT DEVELOPING IN EARNEST BY MID/LATE
MORNING. A COUPLE OF RELATIVELY MINOR WAVES WILL RIPPLE THROUGH...BUT
THE BULK OF THE LARGE-SCALE LIFT WILL BE ISENTROPICALLY DRIVEN.
HAVE NUDGED POPS UPWARD ACROSS EASTERN ZONES FOR THE AFTERNOON...WITH
LIKELY OR BETTER POPS FOR THE 00-06Z TIME FRAME. LIFT INITIALLY WILL
GO TOWARD TOP DOWN MOISTENING... BUT BUFKIT SOUNDINGS SHOW NEARLY
FULL COLUMN SATURATION BY EARLY/MID AFTERNOON. THE FACT THE LOWER
TROP HAS BEEN RELATIVELY COOL/MOIST OF LATE SHOULD ASSIST IN THIS
PROCESS. THE WESTERLY FLOW SHOULD STILL PRODUCE A DECENT SHADOW IN THE
LEE OF THE CASCADES...BUT SUSPECT WE MAY SEE A BIT MORE TRACE-TYPE
AMOUNTS HERE GIVEN THE MOISTURE. RAISED POPS A LITTLE...BUT STILL
TRENDING WELL BELOW GUIDANCE.
BEST PRECIP CHANCES WILL SHIFT INTO THE CENTRAL ID PANHANDLE...CAMAS
PRAIRIE AND EASTERN SECTIONS OF THE PALOUSE TONIGHT AS MID-LEVEL
FLOW BECOMES MORE NWLY IN RESPONSE TO THE AMPLIFYING RIDGE OFF THE
COAST.
AS FOR TEMPS...HAVE TRENDED MAXES DOWN A FEW DEGREES TODAY GIVEN
WHAT SHOULD BE A SOLID OVERCAST BY MID/LATE MORNING AND THEN
AREAS OF PRECIP FOR THE MID/LATE AFTERNOON. HIGHS GENERALLY IN THE
LOWER TO MID 50S WITH LOWER TO MID 60S FOR THE UPPER BASIN. LOWS
TONIGHT UP A FEW DEGREES. /KJONES
WEDNESDAY THROUGH MONDAY...A RIDGE AMPLIFIES OVER THE WESTERN
STATES AT THE START OF THIS PERIOD AND BECOMES THE DOMINATE
FEATURE THROUGH AT LEAST SATURDAY...BEFORE SOME SHORT-WAVES MAKE
A GO AT THE REGION. WEDNESDAY...A WARM FRONT WILL CONTINUE TO LIFT
NORTHEAST THROUGH THE AREA AS THE RIDGE STARTS TO BUILD. A
WESTERLY FLOW BECOMES NWLY AND MOISTURE REMAINS POISED AT THE
CASCADES AND EASTERN THIRD OF THE CWA...WITH AT LEAST SOME MODEST
ISENTROPIC LIFT IN THE 290-300K LAYER ACROSS THE EASTERN AND
SOUTHEAST CWA. THE AREAS OUTLINED ABOVE WILL HAVE THE BEST CHANCE
FOR CONTINUING PRECIP ON WEDNESDAY. THE LIFT DOES WEAKEN...HOWEVER
...AND THE MOISTURE ERODES WEDNESDAY AFTERNOON INTO WEDNESDAY
NIGHT...LEADING TO AN OVERALL REDUCTION OF THE PRECIP RISK
THROUGH THE DAY. THE LEE SIDE AND DEEPER BASIN ZONES WILL REMAIN
DRY IN THE WESTERLY FLOW. THURSDAY TO SATURDAY...THE RIDGE RAMPS
UP ITS DOMINANCE AND DRIER AND CLEARER WEATHER IS FORECAST.
SATURDAY NIGHT THROUGH MONDAY...GUIDANCE BEGINS TO EJECT SOME
SHORT-WAVE DISTURBANCES FROM THE BROADER CENTRAL PACIFIC TROUGH.
WHILE THERE REMAINS QUESTIONS ABOUT TIMING AND HOW EFFECTIVE THESE
FEATURES WILL BE IN INFILTRATING THE RIDGE...THE NEXT CHANCE FOR
PRECIP WILL COME SUNDAY AND MONDAY. THE BEST CHANCES WILL BE IN
THE MTN ZONES.
CONDITIONS CONTINUE TO LOOK FAVORABLE FOR TEMPERATURES SURGING
WELL ABOVE NORMAL THIS PERIOD...WITH 850 TEMPS RISING TO THE UPPER
TEENS AND LOW 20S FRIDAY AND SATURDAY. 1000-500 MB THICKNESSES
ALSO SURGE ABOVE 570 DM. MODELS ARE IN GOOD AGREEMENT AND HAVE
BEEN PERSISTENT IN SHOWING THESE VALUES FOR SEVERAL RUNS NOW.
HIGHS AROUND 10 TO 20 DEGS ABOVE NORMAL ARE FORECAST BY FRIDAY AND
SATURDAY. (FORECAST VALUES ARE STILL ABOUT 5 DEGREES BELOW THE
RECORD HIGHS.) IF THE RIDGE IS SLOWER IN BREAKING DOWN...SUNDAY'S
TEMPERATURES COULD BE SIMILARLY WARM AS SATURDAY'S. THE FORECAST
DOES HOLD ONTO A COOLING TREND INTO MONDAY...BUT TEMPERATURES ARE
STILL FORECAST TO BE ABOVE AVERAGE.
A HYDROLOGIC OUTLOOK (SEAESFOTX) IS STILL IN PLACE FOR RIVERS AND
STREAMS IN THE REGION. WITH THE HIGH SNOW PACK AND MILDER
TEMPERATURES FORECAST THIS WEEK...SEVERAL RIVERS ACROSS EASTERN
WASHINGTON AND NORTHERN IDAHO WILL BE AT A HEIGHTENED RISK FOR
FLOODING. THESE INCLUDE RIVERS SUCH AS THE SPOKANE...COEUR
D'ALENE...ST. JOE...AND MOYIE. RIVERS NEAR THE CASCADES AND
OKANOGAN REGION (SUCH AS THE STEHEKIN...ENTIAT AND OKANOGAN) ARE
ALSO AT SOME RISK...THOUGH ATTM ARE NOT EXPECTED TO MOVE ABOVE
FLOOD STAGE. SMALLER STREAMS AND CREEKS WILL ALSO BE AT A RISK FOR
FLOODING. /JCOTE
&&
.AVIATION...
A VERY MOIST AIRMASS IS STREAMING INTO EASTERN WA AND NORTHERN ID
CURRENTLY. EXPECT CIGS TO LOWER FROM 9-10K FT THIS MORNING DOWN TO
5-6K FT ACROSS ALL TAF SITES AS VIRGA SATURATES THE LAYERS. LIGHT
RAIN WILL BEGIN TO REACH THE SURFACE ACROSS ALL TAF SITES 19-01Z.
THE WINDOW FOR PRECIP IS SMALL IN KEAT...ONLY 23-01Z AS THE RAIN
SHADOW DEVELOPS. THERE WILL BE A PERIOD OF ENHANCED PRECIP ACROSS
THE KGEG-KSFF-KCOE-KPUW DURING THE 00-04Z PERIOD WITH CONDITIONS FALLING
TO MVFR AT TIMES. AFT 04-06Z THERE IS A LACK OF CONFIDENCE IN THE
FORECAST WHETHER STRATUS WILL FORM OR WHETHER PRECIP CONTINUES TO
DOMINATE ACROSS KGEG-KSFF-KCOE-KPUW THROUGH 12Z. /BODNAR
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 52 43 67 44 77 49 / 30 60 20 0 0 0
COEUR D'ALENE 52 42 66 43 78 47 / 30 60 30 0 0 0
PULLMAN 56 45 67 46 74 48 / 20 60 40 0 0 0
LEWISTON 61 51 72 51 81 54 / 20 50 20 0 0 0
COLVILLE 55 42 72 43 84 46 / 40 60 20 0 0 0
SANDPOINT 53 41 64 41 80 44 / 30 60 30 10 0 0
KELLOGG 50 41 60 41 76 42 / 30 90 60 10 0 0
MOSES LAKE 64 45 76 48 85 53 / 20 20 10 0 0 0
WENATCHEE 60 51 74 53 87 57 / 20 20 10 0 0 0
OMAK 59 44 76 46 88 50 / 40 20 10 10 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
