FXUS65 KPIH 222052
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
200 PM MST TUE DEC 22 2009

.SHORT TERM...TONIGHT THROUGH FRIDAY. THE LATEST SATELLITE IMAGERY 
WAS SHOWING A BROAD LOW CIRCULATION ACCELERATING SSE THROUGH ERN 
OREGON THIS AFTERNOON WITH SEVERAL WELL DEFINED CIRCULATIONS 
ROTATING ABOUT THE LOW. ONE SUCH CIRCULATION WAS LIFTING NNE ALONG 
THE NEVADA/UTAH BORDER AND IS EXPECTED TO LIFT INTO SRN IDAHO LATE 
THIS AFTERNOON/EARLY THIS EVENING HELPING TO SUSTAIN CONTINUED 
SNOWFALL ACROSS THE REGION THROUGH THE EVENING. HENCE...THE WARNINGS 
AND ADVISORIES CURRENTLY POSTED ACROSS THE SRN HIGHLANDS/SNAKE PLAIN 
WILL CONTINUE INTO THE EVENING HOURS BEFORE ENDING AROUND MIDNIGHT. 
AFTER MIDNIGHT...THE LOW WILL HAVE SHIFTED INTO WRN ARIZONA WITH 
RAPIDLY DECREASING CLOUD COVER AND PRECIPITATION POTENTIAL. 
TEMPERATURES SHOULD COOL SHARPLY ACROSS THE CNTRL MOUNTAINS TONIGHT 
WHERE THE BEST CLEARING IS EXPECTED TO OCCUR WHILE THE SNAKE PLAIN 
AND SE HIGHLANDS REMAIN UNDER A PARTIALLY PROTECTIVE LOW CLOUD 
COVER. A SECONDARY LOW...CURRENTLY LOCATED OVER THE CANADIAN 
ROCKIES...WILL DIG SSE INTO/THROUGH MONTANA WEDNESDAY/WEDNESDAY 
NIGHT WHICH SHOULD PROVIDE A WEAK NW UPSLOPE FLOW FOR THE ERN 
HIGHLANDS DURING THE DAY WEDNESDAY. MUCH DRIER AND COLDER CONDITIONS 
WILL FOLLOW WEDNESDAY NIGHT THROUGH FRIDAY AS A SHARP RIDGE OF HIGH 
PRESSURE BUILDS ALONG THE PAC COAST. HUSTON

.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. COLD BUT DRY RIDGING 
PATTERN REMAINS IN PLACE ACROSS THE GREAT BASIN THROUGH THE WEEKEND. 
MODELS STILL HAVING PROBLEMS WITH CONSISTENCY BEGINNING SUNDAY NIGHT 
AS THE NEXT SYSTEM APPROACHES THE WEST COAST.  THE GFS COMPLETELY 
SPLITS THE SYSTEM...LEAVING A BUBBLE HIGH OVER IDAHO AND STEERING 
SYSTEMS NORTH AND SOUTH OF THE AREA.  THE ECMWF MEANWHILE DOES A 
BETTER JOB BREAKING DOWN THE RIDGE AND MOVING THE SYSTEM...ALBEIT 
WITH A SPLIT...OVER EASTERN IDAHO.  THE MOST RECENT MODEL RUNS ARE 
AT ODDS WITH RUNS FROM 24 HOURS AGO...SO THEREFORE CONFIDENCE IS LOW 
AT THIS TIME.  HAVE LEFT BULK OF FORECAST INTACT...WITH ISOLATED 
POPS IN THE HIGHER ELEVATIONS SUNDAY AND BEYOND.  OTHERWISE... 
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE PERIOD. 
&&

.AVIATION...A SLOW MOVING BAND OF LIGHT TO MODERATE SNOW CONTINUES 
TO DRIFT EASTWARD ACROSS EASTERN IDAHO THIS AFTERNOON. THIS BAND 
WILL GRADUALLY FALL APART THROUGH THE EVENING HOURS AS DRIER AIR 
WORKS ITS WAY INTO THE REGION.  EXPECT ALL TAF LOCATIONS TO CONTINUE 
SEEING IFR CONDITIONS THROUGH 00Z. VISIBILITY WILL IMPROVE THIS 
EVENING AS THE SNOW COMES TO AN END FROM WEST TO EAST...HOWEVER 
MOISTURE AND CLOUDS WILL KEEP LOW CEILINGS AND POSSIBLY SOME 
FLURRIES IN PLAY TONIGHT.  CEILINGS IMPROVE WEDNESDAY MORNING. 
&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY CONTINUES UNTIL MIDNIGHT FOR 
IDZ017-021-023>025.

WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR IDZ032.

WINTER STORM WARNING UNTIL MIDNIGHT FOR IDZ022.

WINTER STORM WARNING UNTIL 5 PM MST THIS AFTERNOON FOR IDZ018-031.
&&

$$