Flash Flood and Hail in Washington, June 25, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WASHINGTON
230 PM PDT FRI JUN 25 2004

.SYNOPSIS...
THE NARROW UPPER LEVEL RIDGE WHICH HAS PROVIDED THE REGION WITH ABOVE
NORMAL TEMPERATURES...WILL BREAK DOWN ON SATURDAY WITH THE ARRIVAL
OF A WEAK UPPER TROUGH. THUNDERSTORM ACTIVITY WILL INCREASE ACROSS
THE INLAND NORTHWEST ESPECIALLY DURING THE AFTERNOON AND EVENING
HOURS. A BRIEF COOL DOWN IS EXPECTED FOR SUNDAY. WEAK WESTERLY FLOW
WILL PREVAIL INTO NEXT WEEK WITH MORE WARM AND UNSTABLE WEATHER
CONDITIONS.

&&

.DISCUSSION...
TONIGHT THROUGH MONDAY...UPPER RIDGE AXIS...STILL POISED OVER ERN
WA...WILL GRADUALLY WEAKEN OVERNIGHT INTO SATURDAY. DEFORMATION
BANDS ACROSS SRN BC IN ADDITION TO THE ELEVATED HEAT SOURCE HAS
PROMPTED ANOTHER ROUND OF THUNDERSTORM ACTIVITY CONFINED MAINLY TO
THE MOUNTAINS. EXPECT THIS ACTIVITY TO DIMINISH OVERNIGHT WITH LACK
OF ANY LINGERING DYNAMICS. THE BIG WEATHER CHANGE WILL ARRIVE ON
SATURDAY AS THE RIDGE AXIS BREAKS DOWN AS A NEGATIVELY TILTED
PACIFIC TROUGH BRUSHES ACROSS THE AREA. THE TREND WITH THIS TROUGH
HAS BEEN SLOWER AND FARTHER OFFSHORE. THIS WILL PRODUCE LESS WIND
ACROSS THE REGION...WITH THE EXCEPTION OF THE LEE OF THE CASCADES
WHERE DOWN-SLOPING CONDITIONS WILL PEAK BY SAT EVENING. A
COMBINATION OF STRONG DYNAMICS AND IMPRESSIVE INSTABILITY WILL LEAD
TO A CHANCE OF THUNDERSTORMS STARTING IN THE CASCADES BY 18Z...AND
SPREADING EASTWARD ACROSS NE WA AND THE PANHANDLE IN THE EVENING
HOURS. CONVECTIVE ACTIVITY WILL DECREASE SATURDAY NIGHT...WHILE THE
UPPER LEVEL LOW LIFTS NORTHWARD AND WEAKENS OVER BC. THIS WILL
PLACE THE INLAND NW UNDER WEAK WESTERLY FLOW FOR SUNDAY INTO MONDAY.
THE 850 MB THERMAL THROUGH SHIFTS INTO MT BY SUNDAY FOR A BRIEF DAY
OF COOLING OF ABOUT 5 DEGREES...BUT BEGINS TO NUDGE BACK TO THE
WEST FOR MORE WARM CONDITIONS. WILL EXPECT MORE DIURNALLY DRIVEN
THUNDERSTORM ACTIVITY IN THE NRN MOUNTAINS. /RFOX.

MONDAY NIGHT THROUGH FRIDAY...THE REGION REMAINS UNDER A GENTLE WEST
TO SOUTHWEST FLOW WITH WEAK IMPULSES RIPPLING THROUGH THE FLOW.
THE LINGERING UPPER LOW LIFTS INTO NRN BC...WHILE A BROAD TROUGH
DEVELOPS OVER CA.  THE 850 MB THERMAL RIDGE NUDGES BACK TO THE WA/ID
BORDER BY MID WEEK FOR A RETURN OF MORE UNSEASONABLY WARM CONDITIONS.
THE ATMOSPHERE WILL REMAIN UNSTABLE WITH MORE ROUNDS OF AFTERNOON AND
EVENING THUNDERSTORM ACTIVITY...ESPECIALLY IN THE ERN ZONES. THE GFS
SHOWS A KICKER TO PUSH AN UPPER LEVEL TROUGH AXIS INTO THE REGION
BY FRIDAY WITH SLIGHTLY COOLER CONDITIONS. /RFOX.

&&

.PRELIMINARY POINT TEMPS/POPS...

SPOKANE        064 089 057 083 054 084/ 10 30 30 20 20 10
COEUR DALENE  062 085 056 080 050 081/ 20 40 30 20 20 10
PULLMAN        058 086 054 079 049 080/ 10 30 30 20 20 10
LEWISTON       065 092 062 086 058 087/ 10 30 20 20 20 05
COLVILLE       060 089 057 083 050 084/ 20 40 30 40 20 20
SANDPOINT      055 082 055 083 047 084/ 20 40 30 40 20 20
WALLACE        057 075 050 074 047 075/ 20 40 40 30 20 20
MOSES LAKE     062 088 061 085 055 086/ 10 20 10 05 10 05
WENATCHEE      069 089 064 085 060 086/ 10 30 20 05 10 05
OMAK           064 089 064 088 053 089/ 10 20 20 05 10 10
&&

.OTX...
ID...NONE.
WA...NONE.