Flash Flood in Idaho, May 8, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
238 PM PDT SUN MAY 8 2005

.SYNOPSIS...A SERIES OF PACIFIC WEATHER DISTURBANCES WILL BRING
A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TO EASTERN WASHINGTON
AND NORTHERN IDAHO THROUGH MID-WEEK. AN UPPER LEVEL RIDGE IS
EXPECTED TO BEGIN BUILDING OVER THE REGION INITIATING DRY
CONDITIONS AND A WARMING TREND.

&&

.DISCUSSION...
TONIGHT...TWO NEGATIVELY TILED SHORTWAVES EJECTING NORTHEASTWARD
FROM THE STILL DEEPENING OFFSHORE TROUGH WILL KEEP OUR WEATHER
UNSETTLED THROUGH THE NIGHT. THE FIRST SHORTWAVE IS ALREADY MOVING
INTO SOUTHERN WA AND THE ID PANHANDLE. SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ARE ALREADY DEVELOPING OUT AHEAD OF THIS
FEATURE...SHOWER ACTIVITY WILL INCREASE AS THIS WAVE PROPAGATES
NORTHEASTWARD. THE SECOND...STRONGER WAVE IS APPARENT ON SATELLITE
IMAGERY OVER SOUTHERN OREGON AND WILL MOVE ACROSS THE REGION THIS
EVENING WITH THUNDERSTORM ACTIVITY BECOMING INHIBITED DUE TO THE
LOSS OF SURFACE HEATING. ADDED SMALL HAIL WITH THUNDERSTORMS THIS
EVENING DUE TO FAVORABLE WBZ HEIGHTS NEAR 7000 AGL AND MARGINAL
CAPES 200 TO 400 J/KG..HOWEVER CAPES JUST SOUTH OF OUR REGION ARE
PROJECTED TO 1000+ J/KG EARLY THIS EVENING. /JVW

MONDAY THROUGH TUESDAY NIGHT.
MONDAY LOOKS LIKE A WET AND STORMY DAY ACROSS MOST OF THE INLAND
NORTHWEST AS REGION FEELS EFFECT OF STRONG UPPER LEVEL TROUGH AND
PLENTY OF MOISTURE AND DYNAMICS. HOW MONDAY PLAYS OUT HAS SOME
DIFFERENCE DEPENDING ON THE MODEL...BUT ALMOST ANY SOLUTION SHOWS A
WET DAY DAY. ETA MODEL SHOWS VERY STRONG DYNAMICS WITH APPROACHING
SHORTWAVE MONDAY AFTERNOON WITH HIGH CAPES AND A STRONG SHEER WHICH
COULD SUPPORT THE POTENTIAL FOR SEVERE THUNDERSTORMS ACROSS EASTERN
WA AND NORTH IDAHO. GFS NOT A STRONG WITH DYNAMICS BUT STILL PLENTY
WET. FOR NOW WILL MENTION CATEGORICAL POPS FOR SHOWERS AND
SCATTERED THUNDERSTORMS...BUT WILL HAVE TO SEE IF NEXT MODEL RUNS
STILL SUPPORT THE POSSIBILITY OF SEVERE THUNDERSTORMS. MONDAY NIGHT
THE CWA IS STILL UNDER THE EFFECT OF THE MOIST TROUGH AND WILL GO
WITH HIGH POPS AGAIN. A LITTLE DRIER ON TUESDAY...BUT STILL ENOUGH
MOISTURE AND INSTABILITY TO KEEP POPS IN THE FORECAST.

WEDNESDAY THROUGH SUNDAY...MODELS IN SURPRISINGLY GOOD
AGREEMENT WEDNESDAY THROUGH FRIDAY. UPPER LEVEL LOW WILL
MOVE EAST-NORTHEAST THROUGH IDAHO AND INTO MONTANA. THE
THREAT OF WRAPAROUND MOISTURE INTO THE SOUTHEAST ZONES WILL KEEP
CHANCE POPS IN THE FORECAST FOR WEDNESDAY AND WEDNESDAY NIGHT. HIGH
PRESSURE BEGINS BUILDING INTO THE REGION FROM THE WEST THURSDAY.
THIS WILL BRING A DRYING AND WARMING TREND THURSDAY AND FRIDAY. BY
SATURDAY THE MODELS BEGIN TO DIVERGE ON SOLUTIONS. THE ECMWF KEEPS AN
UPPER LEVEL DISTURBANCE TOGETHER AND SLOWLY MOVES IT INLAND LATE IN
THE WEEKEND...MEANWHILE THE GFS IS INDICATING SPLIT FLOW OVER THE
WEST. WILL LEAN TOWARDS THE ECMWF SOLUTION AND BEGIN TO INCREASE POPS
ACROSS MAINLY THE MOUNTAIN ZONES BEGINNING SATURDAY NIGHT LINGERING
THROUGH THE EXTENDED PERIOD. WILL ALSO SHOW AN INCREASE IN
TEMPERATURES THROUGH THE REMINDER OF THE PERIOD. TEMPS SHOULD
INCREASE TO ABOVE SEASONAL NORMALS FRIDAY THROUGH SUNDAY. /TOBIN

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        48  60  43  58  40  63 /  50  90  60  40  20   0
COEUR DALENE  48  61  43  56  40  63 /  50  90  70  60  20  10
PULLMAN        48  57  43  57  40  62 /  50  80  50  50  30  10
LEWISTON       48  64  46  60  43  67 /  50  70  50  50  40  30
COLVILLE       44  63  44  62  38  67 /  50  90  60  50  20   0
SANDPOINT      46  64  45  58  39  63 /  60 100  80  60  20   0
WALLACE        41  59  40  54  37  58 /  60 100  80  70  50  20
MOSES LAKE     49  68  46  65  42  72 /  60  60  40  20  20  10
WENATCHEE      51  66  48  64  46  71 /  60  60  40  20  10  10
OMAK           46  66  46  63  41  72 /  50  70  40  30  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&