Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 232055
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
155 PM MST MON FEB 23 2015

.SHORT TERM...TONIGHT THROUGH THURSDAY. EARLY AFTERNOON SATELLITE
IMAGERY WAS SHOWING AN AMPLIFIED UPPER RIDGE ALONG THE PAC COAST
EXTENDING INTO CNTRL BRITISH COLUMBIA WITH A DRY NE FLOW ACROSS SRN
IDAHO. THE GFS/NAM REMAIN CONSISTENT WITH THE IDEA THAT THE RIDGE
WILL WEAKEN AND FOLD OVER INTO THE NW STATES TUESDAY AS A PAC
DISTURBANCE TOPS THE RIDGE AND DIGS INTO VANCOUVER ISLAND. AN
INCREASING CHANCE OF SNOW IS EXPECTED LATE TUESDAY AFTERNOON THROUGH
TUESDAY NIGHT ACROSS THE NE AND ERN HIGHLANDS AS THE DISTURBANCE
DIGS SE ALONG THE CONTINENTAL DIVIDE. SECONDARY ENERGY ROTATING
THROUGH MONTANA WILL HELP TO SUSTAIN ONGOING SHOWERS ACROSS THE NE
MOUNTAINS THROUGH THE DAY WEDNESDAY WHILE FURTHER UPSTREAM...THE
NEXT PAC DISTURBANCE TOPS THE RETROGRADING UPPER RIDGE. THE GFS AND
NAM DIFFER IN THE EVOLUTION OF THE RETROGRADING RIDGE RESULTING IN
DISPARATE STORM TRACKS WITH THE NAM FAVORING A MORE NORTHERLY
APPROACH ALONG THE CONTINENTAL DIVIDE WHILE THE GFS IS FURTHER
SOUTHWEST ACROSS OREGON...SW IDAHO AND INTO NE NEVADA. DUE  THE
DIFFERING SOLUTIONS...WE WILL USE A BLENDED APPROACH UNTIL WE CAN
WORK OUT THE DETAILS OVER THE NEXT COUPLE OF DAYS. THE BIG NEWS HERE
IS WHAT LOOKS TO BE A PATTERN CHANGE/ADJUSTMENT WHICH WILL OPEN THE
DOOR FOR A SERIES OF INCOMING DISTURBANCES IN THE LONG TERM. HUSTON

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY NIGHT. A SERIES OF UPPER
DISTURBANCES WILL RIDE DOWN THE BACK SIDE OF A PERSISTENT
HIGH-AMPLITUDE RIDGE EXTENDING INTO THE GULF OF ALASKA. THE FIRST
DISTURBANCE WILL DROP INTO WA/OR. THE GFS SOLUTION DEPICTS A CLOSED
LOW JUST OFF THE WA/OR COAST WHILE THE 12Z ECMWF IS TRENDING IN THAT
DIRECTION AS WELL. MOST OF THE ENERGY LOOKS TO DRIVE INTO
CALIFORNIA...BUT SHOULD LEAVE WEAKER DYNAMICS WITH SOME LESS
ORGANIZED SHOWER ACTIVITY OVER SE IDAHO. SPLIT-FLOW PATTERN MUCH
MORE PRONOUNCED AS UPPER LOW DROPS INTO THE GREAT BASIN WITH THE
NORTHERN BRANCH COMING INTO PLAY THROUGH SUNDAY. BY SUNDAY
NIGHT...DRIER CONDITIONS EXPECTED AS A TRANSIENT UPPER RIDGE MOVE
INTO THE PAC NW. THIS WILL BE FOLLOWED UP BY ANOTHER DISTURBANCE
THAT WILL ENTER THE REGION MONDAY NIGHT AND TUESDAY. HINSBERGER
&&

.AVIATION...DRY NORTH/NORTHEASTERLY FLOW SHOULD KEEP WIDESPREAD VFR
CONDITIONS THROUGH THE PERIOD WITH LIGHT WINDS. HINSBERGER
&&

.PIH WATCHES/WARNINGS/ADVISORIES...NONE.
&&

$$






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