Flash Flood Warning 4, NWS Pocatello, ID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO IDAHO
920 AM MDT WED SEP 21 2005

.DISCUSSION...
CURRENT RADAR SHOWING EXTENSIVE AREA OF RAIN EXTENDING FROM
RICHFIELD NORTHEAST THROUGH IDAHO FALLS GENERALLY NORTH OF
INTERSTATE 86.  HEAVIEST RAIN HAS SET UP A BIT NORTHWEST OF WHERE
EXPECTED AS H5 LOW IS NOW OPENED AND TRACKING EAST.  GOOD
CIRCULATION STILL PRESENT IN NORTHERN NEVADA WITH OLD LOW AND THIS
MOVES TO SOUTHERN IDAHO BY 21Z.  THINK THREAT FOR RAIN WILL CONTINUE
UNTIL THIS TROF PASSES TO EAST OF REGION BY 03Z.  THINK PRECIP WILL
SPREAD BACK INTO FAR SE AND STARTING TO SEE AN INDICATION OF THIS
WITH SHOWERS STARTING TO DEVELOP OVER CASSIA COUNTY AGAIN THIS
MORNING.  LATEST NAM 12Z RUN DID HAVE HEAVY BAND CURRENTLY PLACED
WELL FROM NORTH OF BURLEY TO IDAHO FALLS AND ENHANCES PRECIP THIS
AFTERNOON OVER SOUTHERN SNAKE PLAIN AND SOUTHEAST HIGHLANDS WHERE
CURRENT HIGH POPS ARE.  DONT THINK WILL MAKE TOO MANY CHANGES TO
CURRENT GRIDS AS THEY STAND.  CONVECTION STILL NOT PRESENT...BUT
THINK MAY STILL SEE SOME TSTMS AS REMNANTS OF LOW/TROF SLIDE
NORTHEAST THROUGH REGION.
GK

.PREV DISCUSSION...MOISTURE CONTINUES TO STREAM NORTHWARD THIS AM
INTO EASTERN ID AHEAD OF GREAT BASIN UPPER LOW. RADAR TRENDS ARE
SHOWING SHOWERS BECOMING MORE NUMEROUS OVER THE SNAKE PLAIN AND
HIGHLANDS...WITH VERY WEAK RETURNS FURTHER WEST AND NORTH. SFC
DEWPOINTS ARE WELL INTO THE 40S AND LOWER 50S IN THE SHOWER REGIME
WHILE DEWPOINTS WERE STILL ONLY IN THE 20S AND 30S IN THE CENTRAL
MTNS. IT APPEARS THAT THE GFS IS DOING PRETTY WELL WITH REGARD TO
PRECIP COVERAGE AND IS STILL THE MODEL OF CHOICE. MODELS HAVE BACKED
OFF SOME ON THE STRENGTH OF THE SYSTEM...AND ALSO PW/S ARE NOT AS
HIGH COMPARED WITH PRIOR SOLUTIONS. THIS MEANS THAT QPF AMOUNTS WONT
BE AS HIGH AS PREVIOUSLY THOUGHT...BUT POPS FOR TODAY STILL LOOK
GOOD WITH LIKELY OR BETTER POPS FOR THE SNAKE PLAIN AND POINTS EAST
AND SOUTH...WITH SCATTERED POPS AT BEST FOR THE CENTRAL MTNS.
CONTINUED WITH THE DRYING TREND OVERNIGHT WITH POPS LIMITED TO
MAINLY THE EASTERN HIGHLANDS UNTIL AROUND MIDNIGHT AS SYSTEM WEAKENS
AND RAPIDLY MOVES EAST.

KEPT FORECAST DRY ON THURSDAY BEFORE NEXT SYSTEM MOVES IN ON FRIDAY.
SFC LOW TRACKS ALONG THE ID/UT BORDER PER GFS WITH COLDER AIR MOVING
INTO THE CENTRAL MTNS BY AFT WITH SNOW LEVELS LOWERING TO AROUND
8000 FEET. TROF LIFTS NORTHEAST OF THE AREA ON SATURDAY. MODELS ARE
NOW DEVELOPING THE NEXT LOW PRESSURE SYSTEM FURTHER WEST THAN
EARLIER RUNS...PLACING THE LOW CENTER NEAR SAN FRANCISCO. THIS WOULD
MEAN THAT MOST OF THE WEEKEND WILL BE DRY BEFORE THE LOW MAKES THE
MOVE NORTHEAST EARLY NEXT WEEK AS IT TRACKS THROUGH THE REGION. FOR
THE TIME BEING...WOULD LIKE TO LEAVE IN A LEAST SOME LOW POPS SINCE
THIS IS A NEW MODEL TREND. THE LOW WILL EJECT NORTHEAST MON-TUE
LEAVING THE FORECAST UNSETTLED. A BROAD-BRUSHED FORECAST SEEMS TO BE
THE BEST APPROACH AT THIS TIME WITH A SLIGHT CHANCE OF SHOWERS
SAT-TUE AND TEMPS CLOSE TO SEASONAL NORMS.  WAW
&&

.AVIATION...SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED ACROSS ALL
OF SE ID TODAY. CONDITIONS SHOULD REMAIN VFR...WITH BRIEF PERIODS OF
MVFR CONDITIONS IN TSTMS. PRECIPITATION WILL DIMINISH OVERNIGHT.
HEDGES
&&

.PIH WATCHES/WARNING/ADVISORIES...NONE.
&&

WEATHER INFORMATION ON-LINE 24-HOURS A DAY
(ALL LOWER-CASE LETTERS)

WWW.WEATHER.GOV/POCATELLO

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE POCATELLO ID
600 AM MDT WED SEP 21 2005

IDZ017>025-031-032-221200-
LOST RIVER/PASHIMEROI-CACHE VALLEY/IDAHO PORTION-
SOUTH CENTRAL HIGHLANDS-WASATCH MOUNTAINS/IDAHO PORTION-
LOWER SNAKE RIVER PLAIN-SAWTOOTH MOUNTAINS-EASTERN MAGIC VALLEY-
BIG AND LITTLE WOOD RIVER REGION-UPPER SNAKE RIVER PLAIN-
CARIBOU HIGHLANDS-UPPER SNAKE HIGHLANDS-
600 AM MDT WED SEP 21 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN IDAHO

.DAY ONE...
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

SPOTTER INFORMATION STATEMENT...
WE ASK ALL TRAINED SPOTTERS TO REPORT SIGNIFICANT WEATHER CONDITIONS.
THIS WOULD INCLUDE ALL HAIL...WIND...HEAVY RAIN AND FLOODING REPORTS.
THIS INFORMATION SHOULD BE CALLED INTO THE LOCAL NATIONAL WEATHER
SERVICE OFFICE IN POCATELLO USING THE 1-800 SEVERE WEATHER HOTLINE...
OR OTHER STANDARD OPERATING PROCEDURES.

WEATHER INFORMATION ON-LINE 24-HOURS A DAY
(ALL LOWER-CASE LETTERS)

WWW.WEATHER.GOV/POCATELLO