Flash Flood in Idaho, May 6, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
245 PM FRI MAY 6 2005

.SHORT TERM...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH MUCH OF
THE EVENING AS SHOWERS/STORMS CONVERGE OVER SOUTHWEST IDAHO.
GREATEST INSTABILITY AND LIFT REMAINS TO OUR EAST AND SOUTHEAST BUT
ATMOSPHERE ALSO DESTABILIZING OVER SOUTHWEST IDAHO AS WELL.
CONVECTIVE TEMP HAS BEEN REALIZED IN SOUTHWEST IDAHO AND
SHOWERS/THUNDERSTORMS RESPONDING. HARD TO NAIL DOWN ANY ONE AREA
RIPE FOR FLASH FLOODING POTENTIAL BUT STILL FEEL BAKER COUNTY OREGON
COULD BE A THREAT IF CONVECTION COULD ADVECT INTO THE AREA OF
PERSISTENT STRATIFORM RAIN WHICH HAS BEEN PARKED OVER THIS AREA FOR
MANY HOURS.  OTHERWISE...SOUTHWEST HIGHLANDS OR BOISE MOUNTAINS MAY
BE AREAS TO WATCH WITH SOIL CONDITIONS NOW RIPENED UP FROM
YESTERDAYS EVENT.  COULD EVEN SEE MORE URBAN FLOODING IN THE
TREASURE VALLEY IF STORMS ROLL IN THIS EVENING. VERY WEAK FLOW ALOFT
UNDER THE UPPER LOW WILL ONLY ACT TO ENHANCE HEAVY RAIN POTENTIAL
WITH SLOW MOVING EXCELLENT RAIN EFFICIENT STORMS. MODELS INDICATE
MAIN COMMA HEAD OF MOISTURE STAYS OVER THE AREA FOR MUCH OF THE
NIGHT THEN EVENTUALLY MOVES OFF TO THE EAST AND WEAKENS SATURDAY.  DO
NOT FEEL SEVERE STORMS ARE MUCH OF A THREAT THIS EVENING WITH LOW
SHEAR MOIST ENVIRONMENT...SO WILL HIGHLIGHT HEAVY RAIN POTENTIAL
AGAIN IN EVENING FORECASTS. BRIEF CLEARING MOVING ACROSS THE REGION
FROM WEST TO EAST SATURDAY AFTERNOON AND LASTING FOR THE FIRST HALF
OF MOTHERS DAY.  SUNDAY FOR THE MOST PART LOOKS LIKE A GOOD DAY
WITH RAIN HOLDING OFF AHEAD OF NEXT SYSTEM UNTIL EARLY MONDAY
MORNING.  THIS NEW WAVE MOVES INTO THE AREA DURING MONDAY WITH
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS AHEAD OF YET ANOTHER
CLOSED LOW SYSTEM.  TEMPERATURES TO REMAIN FAIRLY COOL FOR MAY UNDER
MOIST ACTIVE SHOWERY REGIME.

LONG TERM...FOR SOUTHWEST IDAHO AND SOUTHEAST OREGON MONDAY NIGHT
THROUGH FRIDAY. MODEL CONSISTENCY CONTINUES TO BE GOOD ALTHOUGH
THERE IS A TREND TOWARD SLIGHTLY SLOWER DEPARTURE OF THE UPPER LEVEL
TROUGH WEDNESDAY AND WEDNESDAY NIGHT. THIS COULD MEAN SLIGHTLY
COOLER MAX TEMPERATURES THURSDAY THAN THE CURRENT FORECAST. HOWEVER
FOR NOW THERE ARE NO UPDATES IN TEMPERATURES OR POPS. THE BEST
CHANCES OF PRECIPITATION WILL BE TUESDAY WITH THE UPPER LEVEL LOW
JUST MOVING IN OVER THE INTERMOUNTAIN REGION. PROBABILITIES
DECREASE WEDNESDAY AND DROP QUITE LOW FOR THURSDAY AND FRIDAY UNDER
A BUILDING UPPER LEVEL RIDGE. TEMPERATURES WILL BE A FEW DEGREES
BELOW NORMAL TUESDAY AND WEDNESDAY AND RETURN TO NEAR NORMAL FOR
THURSDAY AND FRIDAY.

&&

.AVIATION...WITH MOIST UNSTABLE AIR AND SURFACE LOW PRESSURE NEARLY
STATIONARY OVER THE CWFA AREAS OF SHOWERS WILL CONTINUE THROUGH
SATURDAY MORNING WITH SCATTERED MVFR AND LOCAL IFR CEILINGS AND
MOUNTAIN OBSCURATION. WIDELY SCATTERED THUNDERSTORMS WILL CONTINUE
THROUGH THE EVENING UNTIL ABOUT 05Z. THESE HAVE THE POTENTIAL FOR
LOCAL HEAVY RAINS BRIEFLY RESTRICTING VISIBILITIES. LOCAL VALLEY FOG
IS POSSIBLE AFTER 06Z.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
.ID...FLASH FLOOD WATCH 3PM MDT UNTIL 10PM MDT FOR ZONES 11 12 13 14
       15 AND 29.
.OR...FLASH FLOOD WATCH 3PM MDT (2PM PDT) UNTIL 10 PM MDT (9PM PDT)
       FOR ZNS 62 63 AND 64.

WEATHER.GOV/BOISE

DISCUSSION...GS
AVIATION.....JT
LONG TERM....JT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BOISE ID
531 AM MDT FRI MAY 6 2005

IDZ011>016-028>030-ORZ061>064-071145-
WEST CENTRAL MOUNTAINS-LOWER TREASURE VALLEY ID-BOISE MOUNTAINS-
UPPER TREASURE VALLEY-SOUTHWEST HIGHLANDS-WESTERN MAGIC VALLEY-
CAMAS PRAIRIE-OWYHEE MOUNTAINS-SOUTHERN TWIN FALLS COUNTY-
HARNEY COUNTY-BAKER COUNTY-MALHEUR COUNTY-
LOWER TREASURE VALLEY OR-
431 AM PDT FRI MAY 6 2005 /531 AM MDT FRI MAY 6 2005/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
IDAHO...SOUTHWEST IDAHO...WEST CENTRAL IDAHO...SOUTHEAST OREGON
AND NORTHEAST OREGON.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.