Tornado Warning 1, NWS Pocatello, ID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
1052 AM MDT THU AUG 6 2009

.UPDATE...RESENT TO INCLUDE FLASH FLOOD WATCH FOR REMAINDER OF
TODAY. DMH

&&

.PREV DISCUSSION... /ISSUED 1015 AM MDT THU AUG 6 2009/

UPDATE...COMPLICATED SCENARIO SHAPING UP FOR TODAY INTO FRIDAY.
PER SAT IMAGERY EASTERN IDAHO UNDER DRY SLOT WITH CLEA SKIES OVER
MOST OF THE FCST AREA. THIS COULD POSE A SIGNIFICANT PROBLEM DUE
TO SHORTWAVE AND MOISTURE SPINNING INTO REGION TODAY AHEAD OF
OPENING UPPER LOW. VARIOUS INGREDIENTS COMING TOGETHER FOR
POTENTIAL FOR SEVERE WEATHER...TRANSITIONING TO HEAVY RAIN EVENT
INTO FRIDAY UNDER UPPER TROUGH FOR CENTRAL MOUNTAINS. HAVE MADE A
FEW MINOR ADJUSTMENTS TO GRIDS FOR TODAY MAINLY TO ADD STRONGER
WORDING FOR THUNDERSTORMS. WILL TRY TO COMPLETE FORECAST GRIDS AS
QUICKLY AS POSSIBLE FOR PENDING RADAR WATCH THIS AFTERNOON. DMH

PREV DISCUSSION... /ISSUED 305 AM MDT WED AUG 5 2009/

DISCUSSION...DEEP UPPER LOW OVER NRN CA THIS MORNING IS EXPECTED TO
DRIFT NE INTO ID BY FRI MORNING. THIS WILL RESULT IN A SIGNIFICANT
CHANGE TO THE WEATHER PATTERN. FOR TODAY...SW UPPER WINDS WILL
INTENSIFY WITH THE APPROACH OF THE UPPER LOW. COOLING UPPER TEMPS
WILL FURTHER DESTABILIZE THE AIRMASS THIS AFTN. AS A RESULT...SOME
OF THE TSTMS THIS AFTN AND EVE MAY GET A LITTLE STRONG WITH GUSTY
WINDS AND HAIL.

AS THE UPPER LOW MOVES CLOSER...PRECIP WILL REMAIN FAIRLY WIDESPREAD
THRU FRI NIGHT. MOST LOOKS TO BE IN THE CEN MTNS. NAM MODEL IS
RUNNING HIGH QPF NUMBERS OVER THE CEN MTNS TODAY THRU FRIDAY NIGHT
.BUT HAVE TEMPERED THOSE NUMBERS SOMEWHAT. JUST SEEMED TOO HIGH.
WITH STRONG SOUTHERLY FLOW...THE HIGHEST PRECIP AMOUNTS SHOULD BE IN
THE CEN MTNS AND UPPER SNAKE HIGHLANDS...WITH THE LOWEST AMOUNTS
OVER THE SOUTHERN HIGHLANDS AND THE ADJACENT SNAKE RIVER PLAIN.
PRECIP WILL TAPER OFF BY SATURDAY AS THE UPPER LOW MOVES OUT OF THE
AREA. WEAK ZONAL FLOW BECOMES DOMINANT ON SUNDAY...WITH THE FLOW
TURNING TO THE SW ON MONDAY. THIS PATTERN REMAINS THRU THE REST OF
THE FCST PERIOD...WITH ONLY LOW CHC POPS IN THE NRN MTNS.

TEMPS WILL BE SIGNIFICANTLY COOLER ON FRI...WITH THE HIGHEST TEMPS
ONLY TOPPING OUT IN THE UPPER 60S. COOL TEMPS WILL REMAIN THRU THE
WEEKEND...WITH SOME MODERATION ON SUNDAY. HEDGES

AVIATION...SHOWERS AND THUNDERSTORMS BECOME SCATTERED TO NUMEROUS
TODAY AFTER 20Z WITH PACIFIC LOW MOVING INLAND. SURFACE LOW PRESSURE
CENTER MOVES FROM NEAR KENV TO NEAR KRXE BY 06Z WITH ADDITIONAL
WAVES ON THAT FRONTAL BOUNDARY POSSIBLE. THUNDERSTORM WIND GUSTS TO
55 MPH WITH SMALL HAIL POSSIBLE. SPC HIGHLIGHTS SLIGHT RISK OF
SEVERE THUNDERSTORMS THIS AFTERNOON. CONDITIONS WILL GENERALLY BE
VFR EXCEPT VICINITY OF MOUNTAINS AFTER 21Z. MVFR CEILINGS BECOME
SCATTERED WITH SHOWERS OVERNIGHT AS THE UPPER LOW TRACKS THROUGH THE
CENTRAL IDAHO MOUNTAINS. BREEZY SOUTH TO WEST WINDS IN THE SOUTH
CENTRAL HIGHLANDS...EASTERN HIGHLANDS AND SNAKE PLAIN 21Z TO 12Z. RS

FIRE WEATHER...A STRONG PACIFIC LOW PRESSURE SYSTEM MOVES INLAND
TODAY AND TRACKS THROUGH CENTRAL IDAHO TONIGHT AND FRIDAY WITH A
VARIETY OF CHANGING WEATHER. THE ASSOCIATED SURFACE LOW WILL TRACK
FROM NEAR WENDOVER AT NOON TIME TO NEAR REXBURG AROUND MIDNIGHT
TONIGHT. SOUTHERLY WINDS BECOME BREEZY BY 2100 HOURS THIS AFTERNOON
FROM THE SOUTHERN SAWTOOTH TO THE TARGHEE FOREST. WINDS SHIFT TO
WESTERLY IN THE MIDDLE SNAKE RIVER VALLEY ABOUT 2300 HOURS AND
REMAIN BREEZY THROUGH EARLY FRIDAY MORNING.  SCATTERED THUNDERSTORMS
ARE EXPECTED THIS AFTERNOON WITH ISOLATED SEVERE THUNDERSTORMS
POSSIBLE. WETTING RAINS BECOME LIKELY IN THE CENTRAL MOUNTAINS THIS
AFTERNOON WITH MOST ALL MOUNTAINS HAVING A CHANCE OF HEAVY
PRECIPITATION AS THE LOW TRACKS NORTHEAST. A SHARP COOL DOWN TO THE
60S IS EXPECTED FRIDAY. RS

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 10 PM MDT THIS EVENING FOR IDZ018-031-
032.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE POCATELLO ID
410 AM MDT THU AUG 6 2009

IDZ017>025-031-032-071015-
EASTERN MAGIC VALLEY-SAWTOOTH MOUNTAINS-UPPER SNAKE HIGHLANDS-
UPPER SNAKE RIVER PLAIN-LOWER SNAKE RIVER PLAIN-
SOUTH CENTRAL HIGHLANDS-CARIBOU HIGHLANDS-
CACHE VALLEY/IDAHO PORTION-WASATCH MOUNTAINS/IDAHO PORTION-
BIG AND LITTLE WOOD RIVER REGION-LOST RIVER/PAHSIMEROI-
410 AM MDT WED AUG 5 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN IDAHO.

.DAY ONE...TODAY AND TONIGHT

NUMEROUS THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING OVER
THE CENTRAL MOUNTAINS AND THE UPPER SNAKE HIGHLANDS. ELSWHERE...
SCATTERED THUNDERSTORMS ARE EXPECTED. THERE IS THE POSSIBILITY FOR
AN ISOLATED SEVERE THUNDERSTORM WITH LARGE HAIL AND DAMAGING WIND
THIS AFTERNOON AND EVENING IN CENTRAL AND EASTERN IDAHO.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED ON
FRIDAY. ISOLATED THUNDERSTORMS ARE EXPECTED IN THE CENTRAL MOUNTAINS
SATURDAY THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

WE ASK TRAINED SPOTTERS AND CITIZENS TO REPORT SIGNIFICANT
WEATHER CONDITIONS WHEN IT IS SAFE TO DO SO. THESE CONDITIONS MAY
INCLUDE HAIL...TORNADOES...STRONG WIND...DUST STORMS...SNOWFALL...
EXTREME COLD TEMPERATURES...FREEZING RAIN OR HEAVY RAIN...DENSE
FOG...AND FLOODING OR ICE JAMS. INFORMATION ABOUT THESE HAZARDOUS
CONDITIONS SHOULD BE CALLED INTO YOUR NATIONAL WEATHER SERVICE
OFFICE IN POCATELLO USING THE 1-800 SEVERE WEATHER HOTLINE...OR
208-233-0834.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE POCATELLO
1150 AM MDT THU AUG 6 2009

IDZ018-061830-
CUSTER ID-
1150 AM MDT THU AUG 6 2009

THE NATIONAL WEATHER SERVICE IN POCATELLO HAS ISSUED A

SIGNIFICANT WEATHER ADVISORY FOR...
  WEST CENTRAL CUSTER COUNTY IN CENTRAL IDAHO

UNTIL 1230 PM MDT

AT 1145 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 10 MILES WEST OF ATLANTA..MOVING NORTHEAST AT 35
MPH. THIS STORM IS MOVING TOWARD STANLEY AND THE SAWTOOTH MOUNTAINS
INCLUDING ALTURAS...PETTITT...REDFISH AND STANLEY LAKES.

IF YOU ARE IN THE AREA FROM SAWTOOTH CITY TO LOWER STANLEY OR WEST
OF THAT LINE...YOU ARE IN AN AREA WHERE WEATHER WARNINGS MAY BE
ISSUED WITHIN THE NEXT HALF HOUR OR SO.

HAIL UP TO THE SIZE OF NICKELS HAS OCCURRED WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
  RURAL WESTERN CUSTER COUNTY...

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

LAT...LON 4441 11522 4444 11523 4459 11517 4431 11467
      4394 11495 4394 11497 4399 11498 4401 11503
      4403 11505 4408 11500 4411 11505 4413 11502
      4420 11516 4427 11517 4432 11527
TIME...MOT...LOC 1745Z 223DEG 31KT 4382 11532