Flash Flood and Hail in Washington, May 4, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
204 PM PDT WED MAY 4 2005

.SYNOPSIS...A PACIFIC STORM SYSTEM WILL MOVE INTO OREGON ON
THURSDAY BRINGING A THREAT OF RAIN THROUGH FRIDAY...MAINLY TO
SOUTHEAST WASHINGTON AND THE SOUTHERN IDAHO PANHANDLE. SATURDAY
SHOULD BE DRY BEFORE ANOTHER STORM SYSTEM MOVES INTO THE AREA ON
SUNDAY.

&&

.DISCUSSION...
TONIGHT...SHALLOW CONVECTION FIRING OVER MUCH OF THE HIGHER
TERRAIN WITH JUST A FEW LIGHTNING STRIKES. THIS CONVECTION IS
LARGELY DIURNALLY BASED EXCEPT FOR THE NORTHERN/EASTERN MOUNTAINS
WHERE THIS MORNINGS SHORT WAVE IS STILL PROVIDING SOME LIFT.
EXPECT ALL OF THIS ACTIVITY TO DIE OFF THIS EVENING. DESPITE
CLEARING SKIES...HIGH DEWPOINTS WILL KEEP MIN TEMPERATURES MILD.

THURSDAY...NEXT PACIFIC SYSTEM PROGGED BY ALL MODELS TO DIG WELL
TO OUR SOUTH...INTO OREGON AND NORTHERN CALIFORNIA. WE TYPICALLY
SEE GOOD WRAP-AROUND PRECIP BANDS AT THIS TIME OF YEAR FROM THESE
SYSTEMS. UNFORTUNATELY THIS SYSTEM WILL BE A BIT TOO FAR SOUTH TO
AFFECT MUCH OF MY AREA...WITH THE BEST CHANCES OF PRECIPITATION
OVER MY SOUTHEASTERN ZONES. MIGHT ALSO SEE SOME SHOWERS ALONG THE
SOUTHERN CASCADES IN THE EASTERLY UPSLOPE. THE MODELS HAVE BEEN
FAIRLY CONSISTENT IN FORECASTING THE TRACK OF THIS LOW. BUT I HAVE
SPREAD MY POPS A BIT FARTER NORTH ON THE OUTSIDE CHANCE THAT THE
LOW DOESNT DIG AS FAR SOUTH AS PROGGED.

FRIDAY AND SATURDAY...SLOW BUT PROGRESSIVE PATTERN CONTINUES.
OREGON LOW SLOWLY EJECTS TO THE NORTHEAST...KEEPING BEST THREAT
OF PRECIP SOUTH AND EAST OF SPOKANE. A SHORT WAVE COMING DOWN FROM
BC WILL HELP INITIATE SOME WESTERLY FLOW WHICH WILL CLEAR AND DRY
US OUT FOR SATURDAY...DROPPING TEMPS A FEW DEGREES AS WELL. RJ

SATURDAY NIGHT THROUGH WEDNESDAY...MODELS HAVE BEEN FAIRLY
CONSISTENT IN MAKING THE UPPER LEVEL LOW CURRENTLY SOUTH OF THE
ALEUTIAN ISLANDS THE PRIMARY INFLUENCE ON AREA WEATHER THROUGH THE
PERIOD. WATER VAPOR IMAGERY ALREADY SHOWS FLOW UPSTREAM OF THE LOW
STRENGTHENING AND ENERGY FROM THE NORTHERN LATITUDES BEGINNING TO
PROPAGATE SOUTHWARD INTO THE PARENT TROUGH. MODELS DIG THE LOW
SOUTHEASTWARD TOWARD THE COAST WITH THE MINOR SHORT WAVE RIDGE
AXIS OVER THE AREA SHIFTING EASTWARD OVER WESTERN MONTANA
SATURDAY. THE RIDGE AXIS SHIFTING EASTWARD OPENS THE DOOR FOR
MINOR PERTURBATIONS RIPPLING ALONG THE SOUTHWESTLY FLOW ALOFT TO
TAP INTO THE SOME OF THE POTENTIAL INSTABILITY OVERLYING THE
REGION...TRIGGERING SHOWER ACTIVITY... PRIMARILY OVER THE
MOUNTAINS. A NEGATIVE TILT SHORT WAVE IS PROJECTED TO EJECT FROM
THE LOW SUNDAY GENERATING SHOWERS AND ISOLATED THUNDERSTORMS
ACROSS THE REGION INTO SUNDAY NIGHT. MAIN LOW IS FORECASTED ALONG
THE OREGON COAST BY MONDAY MORNING WITH MOST THE UPPER FORCING
FOCUSED SOUTHWARD OVER CA AND NV BUT MINOR WAVES ROTATING AROUND
THE LOW LIKELY TO MOVE THROUGH OUR REGION...CONTINUING THE THREAT
OF SHOWER ACTIVITY THROUGH MONDAY NIGHT. GENERAL TROUGHINESS LIES
OVER THE REGION THROUGH WEDNESDAY AS THE LOW MEANDERS OVER THE
CENTRAL ROCKY MOUNTAIN STATES BEFORE GETTING CAUGHT UP IN THE
SOUTHERN STREAM AND SLOWLY EJECTING NORTHEASTWARD TOWARD THE
DAKOTAS. THE THREAT OF SPORADIC SHOWER ACTIVITY WILL GRADUALLY
DIMINISH FROM WEST TO EAST TUESDAY THROUGH WEDNESDAY. TEMPERATURES
WILL CONTINUE TO TREND SLIGHTLY ABOVE TO NEAR NORMAL THROUGH
WEDNESDAY. /JVW

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        49  67  49  69  44  67 /  30  10  20  20  10  10
COEUR DALENE  47  68  47  66  44  64 /  40  10  20  20  10  10
PULLMAN        46  65  45  62  42  63 /  20  20  40  50  10  10
LEWISTON       49  71  52  67  47  69 /  10  30  40  60  20  10
COLVILLE       44  72  43  75  42  69 /  40  20   0  10  10  10
SANDPOINT      44  68  45  68  44  63 /  40  20  20  20  10  20
WALLACE        46  67  43  62  41  60 /  40  30  40  30  20  20
MOSES LAKE     51  73  48  77  47  73 /  20   0   0   0  10  10
WENATCHEE      50  74  53  76  50  71 /  20   0   0   0  10   0
OMAK           47  74  47  80  46  71 /  20  10   0   0  10   0

&&

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